1: \input texinfo
2: @paragraphindent 0
3: @setfilename freem.info
4: @settitle The FreeM Manual
5:
6: @copying
7: This manual is for FreeM, (version 0.64.0-rc1), which is a free software implementation of the M programming language.
8:
9: Print-optimized versions of this book are typeset in @emph{Computer Modern} by the author using the @emph{GNU Texinfo} tools.
10:
11: Copyright @copyright{} 2014-2025 Coherent Logic Development LLC
12:
13: @quotation
14: Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover texts, and with no Back-Cover Texts.
15: @end quotation
16: @end copying
17:
18: @titlepage
19:
20: @title The FreeM Manual
21: @subtitle @sc{The Official Manual of FreeM}
22: @subtitle Version 0.64.0-rc1
23: @c@vskip 10pt
24: @c@center @image{freem-logo-sm,,,,.png}
25: @author Serena Willis
26: @page
27: @vskip 0pt plus 1filll
28: @insertcopying
29: @end titlepage
30: @contents
31:
32: @ifnottex
33: @node Top
34: @top The FreeM Manual
35:
36: This is the official manual for the FreeM programming language.
37: @end ifnottex
38:
39: @dircategory The FreeM Manual
40: @direntry
41: * FreeM: (freem). The FreeM M programming language.
42: @end direntry
43:
44: @menu
45: * Introduction:: About the FreeM Project, its history, and its goals.
46: * Document Conventions:: Conventions used in this manual.
47: * A Note on Standards:: FreeM positioning regarding the M Development Committee.
48: * FreeM Invocation:: How to invoke FreeM from the command line.
49: * The FreeM Environment Daemon:: Managing shared resources in the FreeM environment.
50: * The FreeM Direct-Mode Environment:: Executing M programs interactively.
51: * Debugging:: The program development cycle of FreeM.
52:
53: * Directives:: Per-Routine Language Directives.
54: * Intrinsic Special Variables:: Intrinsic Special Variables.
55: * Intrinsic Functions:: Intrinsic Functions.
56: * OBJECT Methods:: Methods for OBJECT variables.
57: * STRING Methods:: Methods for STRING variables.
58: * Commands:: Commands.
59: * Structured System Variables:: Structured System Variables.
60: * Operators:: FreeM Operators.
61:
62: * Routines:: The units of M code in FreeM.
63: * Types:: FreeM data types.
64: * Globals:: FreeM persistent sparse arrays.
65: * Concurrency Control:: @code{LOCK}ing and transaction processing.
66: * Local Variables:: In-memory variables.
67: * Scoping:: Scoping in FreeM.
68: * Decision Constructs:: @code{IF}, @code{THEN}, @code{ELSE}, @code{$SELECT}, and postconditionals.
69: * Branch Constructs:: Labels, @code{GOTO}, @code{DO}, and @code{JOB}.
70: * Loop Constructs:: The @code{FOR} loop.
71: * Modular Programming:: Extrinsic functions and subroutines.
72: * Object-Oriented Programming:: Classes and objects in FreeM.
73: * Libraries:: System and user libraries.
74: * Sequential I/O:: Processing sequential files in FreeM.
75: * Network I/O:: Handling network sockets in FreeM.
76: * Extended Global References:: Accessing globals in non-default namespaces.
77: * Global Aliasing:: Defining alternate names for globals.
78: * Global Mappings:: Mapping global names to non-default namespaces.
79:
80: * Asynchronous Event Handling:: Handling asynchronous events in FreeM.
81: * Global Triggers:: Responding to global accesses in M code.
82: * Synchronous Event Handling:: Synchronous events in FreeM.
83:
84:
85: * GUI Programming with MWAPI:: Creating graphical interfaces in FreeM.
86:
87: * User-Defined Z Commands:: Adding your own Z commands to FreeM.
88: * User-Defined Z Functions:: Adding your own Z functions to FreeM.
89: * User-Defined SSVNs:: Adding your own SSVNs to FreeM.
90:
91: * Language Dialects:: Controlling FreeM standards compliance.
92:
93: * System Library Routines:: FreeM built-in library of M routines.
94:
95: * Interrupt Handling:: How FreeM handles interrupts.
96: * Error Processing:: How to handle errors in M program code.
97: * FreeM Error Codes:: Explanations of each FreeM error code.
98:
99: * System Configuration:: Configuring your FreeM installation.
100: * Accessing FreeM from C Programs:: How to use the mlib interface.
101:
102: * FreeM Administrator:: The fmadm system manager tool.
103: * FreeM Legacy Utilities:: FreeM legacy system manager utilities.
104: * FreeM VIEW Commands and Functions:: Getting and setting info about FreeM internals.
105: * Implementation Limits:: FreeM limitations.
106: * US-ASCII Character Set:: The US-ASCII character set.
107: * FreeM Project Coding Standards:: How to write code for submission to the FreeM project.
108:
109: * Index:: Complete index.
110: @end menu
111:
112: @node Introduction
113: @unnumbered Introduction
114:
115: FreeM started its life as @emph{FreeMUMPS}, written for MS-DOS and ported to SCO UNIX by a mysterious individual going by the name of "Shalom ha-Ashkenaz". It was released to MUG Deutschland in 1998. In 1999, Ronald L. Fox ported FreeM to the Red Hat Linux 5 distribution of the GNU/Linux operating system. Thereafter, maintenance was taken over by the Generic Universal M Project, which changed its name first to Public Standard MUMPS and then by popular request to FreeM.
116:
117: When GT.M was open-sourced in late 1999, FreeM and GUMP were essentially abandoned. L.D. Landis, the owner of the original GUMP SourceForge project, and one of FreeM's significant contributors, passed maintenance of FreeM and ownership of its SourceForge project to Serena Willis in 2014. At this point, FreeM would not compile or run on modern Linux systems, so steps were taken to remedy the most pressing issues in the codebase. Limitations on the terminal size (previously hard-coded to 80x25) were lifted, and new @code{$VIEW} functions were added to retrieve the terminal size information. @code{$X} and @code{$Y} intrinsic special variables were updated to support arbitrary terminal sizes, and FreeM was once again able to build and run.
118:
119: In February of 2020, work began in earnest to build a development and support infrastructure for FreeM and begin the careful process of refining it into a more stable and robust application.
120:
121: For more information on FreeM history, see @code{@emph{$PREFIX}/share/freem/doc/freem_history.*} (distributed in PostScript, PDF, and plain text formats).
122:
123: @section Production Readiness
124:
125: FreeM is not yet production-ready. There are several show-stopping bugs that preclude a general release for public use:
126:
127: @itemize @bullet
128:
129: @item
130: @code{@ref{VIEW}} commands and @code{@ref{$VIEW()}} functions are used extensively to configure and inspect the run-time behavior of FreeM, rather than the "canonical" SSVN-based approach.
131:
132: @item
133: Server sockets are not yet implemented.
134:
135: @item
136: There are some situations that can result in segmentation faults and/or lock-ups.
137:
138: @item
139: In spite of our best efforts, this manual is not yet complete.
140:
141: @end itemize
142:
143: @section Contributors
144: Current contributors denoted with a @emph{+} following their name and role.
145: @cindex contributors, ha-Ashkenaz, Shalom
146: @cindex contributors, Best, John
147: @cindex contributors, Diamond, Jon
148: @cindex contributors, Fox, Ronald L.
149: @cindex contributors, Gerum, Winfried
150: @cindex contributors, Kreis, Greg
151: @cindex contributors, Landis, Larry
152: @cindex contributors, Milligan, Lloyd
153: @cindex contributors, Morris, Steve
154: @cindex contributors, Murray, John
155: @cindex contributors, Pastoors, Wilhelm
156: @cindex contributors, Schell, Kate
157: @cindex contributors, Schofield, Lyle
158: @cindex contributors, Stefanik, Jim
159: @cindex contributors, Trocha, Axel
160: @cindex contributors, Walters, Dick
161: @cindex contributors, Whitten, David
162: @cindex contributors, Wicksell, David
163: @cindex contributors, Willis, Serena
164: @cindex contributors, Zeck, Steve
165:
166: @itemize @bullet
167:
168: @item
169: Shalom ha-Ashkenaz (Original Implementer)
170:
171: @item
172: John Best (IBM i and OS/400)
173:
174: @item
175: Jon Diamond (Library, Utilities, Conformance)
176:
177: @item
178: Ronald L. Fox (Initial port to Red Hat 5/libc-6)
179:
180: @item
181: Winfried Gerum (Code, Advice, MTA coordination)
182:
183: @item
184: Greg Kreis (Hardhats coordination, Dependencies)
185:
186: @item
187: Larry Landis (Coordination, Code, Documentation)
188:
189: @item
190: Rick Marshall (Testing, MDC Conformance) @emph{+}
191:
192: @item
193: Lloyd Milligan (Code, Testing, Documentation)
194:
195: @item
196: Steve Morris (Code, Microsoft)
197:
198: @item
199: John Murray (Code, Conformance)
200:
201: @item
202: Wilhelm Pastoors (Testing, Documentation)
203:
204: @item
205: Kate Schell (Coordination, Conformance, MTA, MDC, Advice)
206:
207: @item
208: Lyle Schofield (Advice, Prioritization, Tracking, Project Management)
209:
210: @item
211: Jim Stefanik (GNU/Linux on s390x, IBM AIX, IBM z/OS)
212:
213: @item
214: Axel Trocha (Code, Utilities)
215:
216: @item
217: Dick Walters (Project Lead, Chief Coordinator, MTA)
218:
219: @item
220: David Whitten (QA Test Suite, MDC, Advice) @emph{+}
221:
222: @item
223: David Wicksell (Debugging, Code, Testing) @emph{+}
224:
225: @item
226: Serena Willis (Current Maintainer and Project Lead) @emph{+}
227:
228: @item
229: Steve Zeck (Code)
230:
231: @end itemize
232:
233: @node Document Conventions
234: @chapter Document Conventions
235: @cindex document conventions
236: @cindex conventions
237:
238: @section Formatting Conventions
239:
240: This manual uses the following formatting conventions:
241: @itemize
242: @item Code examples, filesystem paths, and commands are presented in @code{monospace}
243: @item Placeholders where the reader is expected to supply a replacement value are presented in @code{@emph{monospace italics}}, and depending on context, may be surrounded by angle brackets
244: @item New terminology is introduced in @emph{proportional italics}
245: @end itemize
246:
247: @section Definitions
248:
249: FreeM uses abbreviations for common language elements:
250:
251: @table @asis
252: @item @emph{$PREFIX}
253: Refers to the base filesystem location within which FreeM is installed. For most distribution methods of FreeM, @emph{$PREFIX} represents either @code{/} or @code{/usr/local}.
254: @item @emph{dlabel}
255: Refers to a label in an M routine, beginning in the first column of the line. Can be a @emph{name} or an @emph{intlit}.
256: @item @emph{entryref}
257: Refers to an M routine entry point, denoted in the format @code{@emph{dlabel} [+@emph{intexpr}][^@emph{routine}]}.
258: @item @emph{expr}
259: Refers to any expression. Often presented in the format @emph{expr V <type>}, where @emph{V} means @emph{giving}; e.g., @emph{expr V lvn} means @emph{expression giving local variable name}.
260: @item @emph{glvn}
261: Refers to the name of an M global, local, or structured system variable.
262: @item @emph{gvn}
263: Refers to the name of an M global variable.
264: @item @emph{intexpr}
265: Refers to an integer expression.
266: @item @emph{intlit}
267: Refers to an integer literal.
268: @item @emph{ISV}, @emph{isv}
269: Refers to an M intrinsic special variable; @code{$JOB} and @code{$IO} are examples of ISVs.
270: @item @emph{L}
271: Indicates a @emph{list} of the following item, e.g., @emph{L gvn} means @emph{list of global variable names}.
272: @item @emph{lvn}
273: Refers to the name of an M local variable.
274: @item @emph{postcondition}
275: A @emph{tvexpr} immediately following a command verb affecting that command's execution.
276: @item @emph{strlit}
277: Refers to an M string literal.
278: @item @emph{ssvn}
279: Refers to the name of an M structured system variable.
280: @item @emph{tvexpr}
281: Refers to a truth-valued expression, i.e., an expression interpreted as a truth value.
282: @end table
283:
284: @node A Note on Standards
285: @chapter A Note on Standards
286: @cindex MDC
287: @cindex M Development Committee
288: @cindex ANSI X11.1
289: @cindex standards, ANSI
290: @cindex standards, MDC
291:
292: FreeM attempts to implement as many features as possible from the M Development Committee's unpublished @emph{Millennium Draft Standard}, as well as its predecessors.
293:
294: The maintainer of FreeM (who is also the author of this book) is largely in favor of standardization efforts, and hopes that the MDC will resume activities, and will happily participate if it does so in an open, public, transparent, and democratic manner. Until then, however, FreeM will attempt to improve the M language, in cooperation with other free software M implementers where possible. Any breaking changes introduced in future MDC releases of the @emph{Standard} (such as the rumored @emph{M5}) which prove incompatible with FreeM will be handled via the @code{$DIALECT} special variable (to be changed to @code{$ZDIALECT} in a coming release).
295:
296: The conformance document required per the @emph{Standard} should be installed as a @code{man} page on any computer system where FreeM is made available. Simply type @code{man freem_conformance} to access.
297:
298: @node FreeM Invocation
299: @chapter FreeM Invocation
300: @cindex invocation, command-line
301: @cindex options, command-line
302:
303: @section Synopsis
304: @example
305: $ @command{./freem} [@emph{OPTIONS}...] [[-r <entryref>] | [--routine=<entryref>]]
306: @end example
307:
308: When FreeM loads, it searches the @code{SYSTEM} namespace for the @code{%SYSINIT} routine, and begins executing it.
309:
310: When @code{-r} or @code{--routine} are passed on the command line, FreeM will load and run the specified routine after running @code{%SYSINIT}. Beginning with FreeM 0.1.7, routines invoked in this manner are no longer required to perform their own namespace setup with @code{VIEW} commands.
311:
312: @section %SYSINIT Routine
313:
314: The @code{%SYSINIT} routine runs every time a FreeM interpreter process starts. This routine defines some useful constants, enables handling of @code{TRIGGER} events, and handles the execution of code passed via the @code{-x|--execute} or routines passed via @code{-r|--routine}.
315:
316: Do not modify the supplied @code{%SYSINIT} routine to add site-specific startup items. Instead, create a @code{LCLINIT} routine in the @code{USER} namespace of one or more environments. @code{%SYSINIT} will automatically run @code{LCLINIT} each time it starts.
317:
318: @section Command-Line Options
319: @cindex options, command-line
320:
321: @table @asis
322:
323: @item @option{-d}, @option{--daemon}
324: Starts the FreeM environment daemon, exactly one of which must be running at all times in order for FreeM interpreter and fmadm processes to function.
325:
326: @item @option{-e}, @option{--environment}
327: Selects the environment to be used. If no environment is specified, @code{DEFAULT} is used.
328:
329: @item @option{-k}, @option{--nofork}
330: When used with @option{-d} or @option{--daemon}, causes the FreeM environment daemon to run instead in the foreground. Useful for debugging.
331:
332: @item @option{-S}, @option{--shmsize}
333: When used with @option{-d} or @option{--daemon}, specifies the number of bytes of shared memory FreeM will allocate for the @code{LOCK} table, job table, and IPC table. This will determine the maximum number of concurrent FreeM processes and @code{LOCK}s available in this environment.
334:
335: @item @option{-c}, @option{--config}
336: Specify a configuration file other than @code{$PREFIX/etc/freem.conf}.
337:
338: @item @option{-h}, @option{--help}
339: Display a help message showing valid FreeM options.
340:
341: @item @option{-i}, @option{--import}
342: Causes your UNIX environment variables to be imported into FreeM's local symbol table.
343:
344: @item @option{-f}, @option{--filter}
345: Allows your M routines to be used as UNIX filters.
346:
347: @item @option{-n @emph{<namespace-name>}}, @option{--namespace=@emph{<namespace-name>}}
348: Selects the FreeM namespace to be entered on startup. Must be defined in @file{/etc/<environment>/freem.conf}.
349:
350: @item @option{-r @emph{<entryref>}}, @option{--routine=@emph{<entryref>}}
351: Causes @code{<entryref>} to be executed at load, instead of @code{%SYSINIT}.
352:
353: @item @option{--standard=@emph{<standard>}}
354: Sets the default FreeM dialect to use for new routine buffers.
355:
356: Valid values for @code{@emph{<standard>}} are as follows:
357:
358: @table @code
359: @item @code{M77}
360: Restricts FreeM to use only features specified by the 1977 M standard.
361: @item @code{M84}
362: Restricts FreeM to use only features specified by the 1984 M standard.
363: @item @code{M90}
364: Restricts FreeM to use only features specified by the 1990 M standard.
365: @item @code{M95}
366: Restricts FreeM to use only features specified by the 1995 M standard.
367: @item @code{MDS}
368: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
369: @item @code{M5}
370: Restricts FreeM to use only features proposed by the upcoming M5 standard.
371: @item @code{FREEM}, @code{EXTENDED}
372: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{$DIALECT}.
373: @end table
374:
375: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{@emph{<standard>}}.
376:
377: @item @option{-v}, @option{--version}
378: Displays FreeM version information.
379:
380: @item @option{-x @emph{<mcode>}}, @option{--execute=@emph{<mcode>}}
381: Executes M code @code{<mcode>} at startup.
382:
383: @end table
384:
385: @section Using FreeM for Shell Scripting
386: @cindex routines, as shell scripts
387: @cindex shebang line
388: @cindex shell scripting
389:
390: FreeM M routines can be used as shell scripts by providing a @emph{shebang} line beginning with @code{#!/path/to/freem} as the first line of the routine.
391: The following example presumes that FreeM is installed at @file{/usr/local/bin/freem} and uses the @code{USER} namespace:
392:
393: @example
394: #!/usr/local/bin/freem
395: MYSCRIPT ;
396: SET ^$JOB($JOB,"NAMESPACE")="USER"
397: WRITE "This is output from an M routine used as a shell script.",!
398: Q
399: @end example
400:
401: Currently, the script needs to have a @file{.m} file extension. You will also need to select an appropriate namespace in your script using the @code{SET ^$JOB($JOB,"NAMESPACE")="@emph{<namespace>}"} command before attempting to call other routines or access globals.
402:
403: You will also need to set the script's permissions to @emph{executable} in order for this to work:
404:
405: @example
406: $ chmod +x @emph{myscript.m}
407: @end example
408:
409: @node The FreeM Environment Daemon
410: @chapter The FreeM Environment Daemon
411: @cindex daemon, freem
412:
413: The FreeM environment daemon manages shared resources for a given FreeM environment. These include the lock table, job table, inter-process communication, and concurrency control for transaction processing. Unlike some M implementations, the FreeM environment daemon does @emph{not} function as a write daemon for global storage.
414:
415: One daemon process is required per FreeM environment, and can be started in the following ways, in order of preference:
416:
417: @example
418: $ sudo fmadm start environment [-e=<environment-name>]
419: @end example
420:
421: @example
422: $ freem --daemon [--nofork] [--environment=<environment-name>] [--shmsize=<bytes>]
423: @end example
424:
425: If the daemon is started with @option{--nofork}, it will run in the foreground and its output will be reflected on the terminal. Otherwise, the daemon will run as a child process in the background and immediately return terminal control to the shell. The latter option is recommended in most cases.
426:
427: The @option{--environment} option will start the daemon for the specified @emph{environment-name}. The default environment, if unspecified, is called @code{DEFAULT}. If using an environment other than @code{DEFAULT}, interpreter processes that wish to also connect to the same environment must also use the @option{--environment} option when starting, and @code{libfreem} clients must also pass the environment name as the first argument to the @code{freem_init()} function. Environments allow you to run multiple, isolated instances of FreeM on the same machine, whose globals and routines are distinct and unique.
428:
429: The @option{--shmsize} option specifies the size in bytes of the FreeM shared memory segment. The default is 4194304 bytes. Increasing the size of the FreeM shared memory segment will, at the cost of increased memory usage, increase the number of concurrent jobs and lock table entries available to the environment; decreasing the size of the segment will have the expected opposite effect. Note that you must also pass @option{--shmsize} with the same number of bytes to any interpreter process to be used with an environment whose daemon uses a non-default shared memory segment size.
430:
431: Attempting to start a FreeM interpreter process without a daemon running with the same environment name will result in an error.
432:
433: @node The FreeM Direct-Mode Environment
434: @chapter The FreeM Direct-Mode Environment
435: @cindex command line interface
436: @cindex direct mode
437: @cindex execution, interactive
438: @cindex modes, programmer
439:
440:
441: The FreeM direct-mode environment is the mode entered when FreeM is invoked without the use of @option{-r @emph{<entryref>}} or @option{--routine=@emph{<entryref>}}:
442:
443: @example
444: Coherent Logic Development FreeM version 0.64.0-rc1 (x86_64-pc-linux-gnu)
445: Copyright (C) 2014, 2020, 2021 Coherent Logic Development LLC
446:
447:
448: USER>
449: @end example
450:
451: The prompt (@code{DEFAULT.USER>}) displays the current environment and namespace, @code{DEFAULT} and @code{USER}, respsectively. If any uncommitted direct-mode transactions have been started, the prompt will change to reflect the current value of @code{@ref{$TLEVEL}}:
452:
453: @example
454: TL1:DEFAULT.USER>
455: @end example
456:
457: In the above example, @code{TL1} indicates that @code{@ref{$TLEVEL}} is currently @emph{1}.
458:
459: @section Direct-Mode Commands
460:
461: When you are in direct mode, in addition to M commands, a number of internal commands are available to help developers be more productive:
462:
463: @table @asis
464:
465: @item @command{?}
466: Accesses FreeM online help. Requires GNU @command{info(1)} to be installed on your local system.
467:
468: @item @command{events}
469: Writes a list of @emph{event classes} and their @code{ABLOCK} counts:
470:
471: @example
472: DEFAULT.USER> events
473:
474: Event Class Processing Mode ABLOCK Count
475: ----------- --------------- ------------
476: COMM Disabled 0
477: HALT Disabled 0
478: IPC Disabled 0
479: INTERRUPT Disabled 0
480: POWER Disabled 0
481: TIMER Disabled 0
482: USER Disabled 0
483: WAPI Disabled 0
484: TRIGGER Disabled 0
485: @end example
486:
487:
488: @anchor{trantab}
489: @item @command{trantab}
490: Displays information about any uncommitted transactions currently in-flight for this process.
491:
492: @anchor{glstat}
493: @item @command{trantab}
494: Displays statistics about globals that have been opened in the current FreeM process.
495:
496: @anchor{jobtab}
497: @item @command{jobtab}
498: Displays a summary of the FreeM job table.
499:
500: @anchor{locktab}
501: @item @command{locktab}
502: Displays a list of @code{LOCK}s held in the current environment.
503:
504: @anchor{rbuf}
505: @item @command{rbuf}
506: Lists the status of all FreeM routine buffers.
507:
508: @anchor{wh}
509: @item @command{wh}
510: Forces an immediate flush of this process's @code{readline} history buffer to disk.
511:
512: @anchor{shmstat}
513: @item @command{shmstat}
514: Displays the configuration of FreeM shared memory. Intended only for advanced debugging of the FreeM environment.
515:
516: @anchor{shmpages}
517: @item @command{shmpages}
518: Lists the status of each FreeM shared memory page. Intended only for advanced debugging of the FreeM environment.
519:
520: @anchor{history}
521: @item @command{history}
522: Prints a list of all the direct-mode commands you have entered across all sessions.
523:
524: @anchor{rcl}
525: @item @command{rcl @emph{<history-index>}}
526: Allows you to recall command number @emph{<history-index>} and run it again. Obtain the value for @emph{<history-index>} from the output of the @command{history} command.
527:
528: @item @command{!!}
529: Launches a subshell within the FreeM direct mode, allowing the user to run operating system commands.
530:
531: @example
532: DEFAULT.USER> !!
533:
534: Type Ctrl-D to exit from the shell
535: $ uname -a
536: Linux hesperos 4.19.0-17-amd64 #1 SMP Debian 4.19.194-3 (2021-07-18) x86_64 GNU/Linux
537: $ exit
538:
539: DEFAULT.USER>
540: @end example
541:
542: @item @command{!@emph{<external-command>}}
543: Invokes a shell to run @emph{<external-command>} from within FreeM. This temporarily disables @command{SIGALRM} handling in FreeM, which may interrupt the use of event-driven M programming commands including @command{ASTART} and @command{ASTOP}.
544:
545: If the @command{>} character is supplied immediately preceding @emph{<external-command>}, FreeM will append the contents of an M local or global variable referenced in @code{^$JOB($JOB,"PIPE_GLVN")} to the standard input stream of @emph{<external-command>}.
546:
547: If the @command{<} character is supplied immediately preceding @emph{<external-command>}, FreeM will take the standard output stream of @emph{<external-command>} and store it in M local or global variable referenced by @code{^$JOB($JOB,"PIPE_GLVN")}.
548:
549: The data value in the unsubscripted M local or global contains the number of lines in the input or output. Subscripts @code{(1)..(@emph{n})} contain the data for lines 1-@emph{n}.
550:
551: @end table
552:
553: @cindex HALT, in direct-mode
554: If you issue a @code{@ref{HALT}} command at the direct-mode prompt, you will exit out of FreeM. However, if you issue a @code{@ref{HALT}} command when @code{@ref{$TLEVEL}} is greater than zero, you will be given the opportunity to commit or rollback any pending transactions:
555:
556: @example
557: DEFAULT.USER> TSTART
558:
559:
560: TL1:DEFAULT.USER> SET ^MYGLOBAL=1
561:
562:
563: TL1:DEFAULT.USER> HALT
564:
565: UNCOMMITTED TRANSACTIONS EXIST:
566:
567: $TLEVEL 1*
568: Operations for Transaction ID: k8xj1de
569: 1: action = 0 key = ^MYGLOBAL data = 1
570:
571: Would you like to c)ommit or r)ollback the above transactions and their operations? ($TLEVEL = 1) r
572:
573:
574: Transactions have been rolled back.
575: @end example
576:
577: In the above example, the user selected @code{r} to rollback the single pending transaction.
578:
579: @section REPL Functionality
580: @cindex REPL, direct-mode
581:
582: FreeM direct mode allows you to enter M expressions directly from the direct-mode prompt, as long as they begin with a number:
583:
584: @example
585: DEFAULT.USER> S DENOM=10
586:
587:
588: DEFAULT.USER> 100/DENOM
589:
590: 10
591: DEFAULT.USER>
592: @end example
593:
594: Such expressions will be immediately evaluated, and the result printed on @code{@ref{$IO}}.
595:
596: @node Debugging
597: @chapter Debugging
598: @cindex debugging
599:
600: @section Debugging Synopsis
601: FreeM includes an interactive debugger, entered using the @code{BREAK "DEBUG"} command. The debugger is also entered if @code{Ctrl-C} is pressed, @code{Ctrl-C} handling is enabled, and you are in direct mode.
602:
603: If you would like to enter the debugger automatically each time an error is encountered, add the following to your @code{LCLINIT} routine:
604:
605: @example
606: S $ETR="B ""DEBUG"""
607: @end example
608:
609: @section Debugging Commands
610: The debugger uses its own unique command language, where M commands are unavailable. Commands are as follows:
611:
612: @table @asis
613: @item @code{exit}, @code{quit}
614: Exits the debugger and returns to direct mode or normal program execution.
615: @item @code{e} @emph{glvn}, @code{examine} @emph{glvn}
616: Prints the value of @emph{glvn} to the terminal.
617: @item @code{t}, @code{trace}
618: Toggles @emph{trace mode} on and off. When trace mode is on, FreeM will display information about each @code{DO} or @code{GOTO} command encountered, including the routine which invoked the branch, which type of branch was invoked, and the target of the branch.
619: @item @code{s}, @code{step}
620: Single-steps through FreeM code command-by-command.
621: @item @code{n}, @code{next}
622: Single-steps through FreeM code line-by-line.
623: @item @code{c}, @code{cont}, @code{continue}
624: Resumes normal program execution, disabling single-step mode.
625: @item @code{bt}, @code{backtrace}
626: Produces a stack trace.
627: @item @code{h}, @code{halt}
628: Halts the process being debugged and returns control to the operating system.
629: @item @code{w [[+|-|?]@emph{<glvn>}]}, @code{watch [[+|-|?]@emph{<glvn>}]}
630: With no arguments, toggles watchpoints on and off. With @code{+}, adds @emph{<glvn>} to the watchlist. With @code{-}, removes @emph{<glvn>} from the watchlist. With @code{?}, queries the watch status of @emph{<glvn>}.
631: @end table
632:
633: @node Directives
634: @chapter Directives
635: @cindex directives
636:
637: In FreeM, a directive is an instruction embedded in an M comment, and passed to the interpreter to affect a change that is specific to the current routine only.
638:
639: The format of a directive is @code{;%@emph{<directive-name>}}, where @code{@emph{<directive-name>}} is one of the directives listed below.
640:
641: @menu
642: * %DIALECT:: Sets the M dialect in effect.
643: @end menu
644:
645: @anchor{%DIALECT}
646: @section %DIALECT
647: @cindex %DIALECT
648: @cindex directives, %DIALECT
649:
650: Sets the M dialect in effect for the current routine buffer; also sets the @code{$DIALECT} special variable to match. See also @ref{$DIALECT}.
651:
652: @emph{Syntax}
653:
654: @example
655: ;%DIALECT @emph{<dialect>}
656: @end example
657:
658: Valid values for @code{@emph{<dialect>}} are as follows:
659:
660: @table @code
661: @item @code{M77}
662: Restricts FreeM to use only features specified by the 1977 M standard.
663: @item @code{M84}
664: Restricts FreeM to use only features specified by the 1984 M standard.
665: @item @code{M90}
666: Restricts FreeM to use only features specified by the 1990 M standard.
667: @item @code{M95}
668: Restricts FreeM to use only features specified by the 1995 M standard.
669: @item @code{MDS}
670: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
671: @item @code{M5}
672: Restricts FreeM to use only features proposed by the upcoming M5 standard.
673: @item @code{FREEM}, @code{EXTENDED}
674: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{%DIALECT}.
675: @end table
676:
677: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{%DIALECT}.
678:
679:
680: @node Intrinsic Special Variables
681: @chapter Intrinsic Special Variables
682: @cindex variables, intrinsic special
683:
684: @menu
685: * $DEVICE:: $IO device status.
686: * $DIALECT:: Current M dialect.
687: * $ECODE:: Latest M error code.
688: * $ESTACK:: Error stack info.
689: * $ETRAP:: Standard error handler code.
690: * $HOROLOG:: Current date and time.
691: * $IO:: Current I/O device.
692: * $JOB:: PID of current process.
693: * $KEY:: Characters terminating last @code{READ} command.
694: * $PDISPLAY:: Current primary MWAPI display.
695: * $PRINCIPAL:: I/O channel of terminal.
696: * $REFERENCE:: Most recent global reference.
697: * $QUIT:: Whether a @code{QUIT} command requires an argument in the current execution context.
698: * $STACK:: Current program execution stack level.
699: * $STORAGE:: Number of bytes available in the heap.
700: * $SYSTEM:: MDC system ID of FreeM.
701: * $TEST:: Truth value of last conditional expression or result of certain @code{LOCK} operations.
702: * $TLEVEL:: Current level of transaction nesting.
703: * $WITH:: Current variable prefix set by @code{ZWITH} command.
704: * $X:: Current horizontal screen position.
705: * $Y:: Current vertical screen position.
706: * $ZA:: Current position of file on @code{$IO}.
707: * $ZB:: Most recent keystroke.
708: * $ZCONTROLC:: Control-C handling flag.
709: * $ZDATE:: Current date in locale-specific representation.
710: * $ZERROR:: Last error message.
711: * $ZHOROLOG:: Date and time, including milliseconds.
712: * $ZINRPT:: State of the interrupt enable/disable flag.
713: * $ZJOB:: PID of parent process, if applicable.
714: * $ZLOCAL:: Last local variable reference.
715: * $ZNAME:: Name of current M routine.
716: * $ZPRECISION:: Digits of arithmetical precision.
717: * $ZREFERENCE:: Last gvn referenced.
718: * $ZSYSTEM:: Return value of last external command.
719: * $ZTIME:: Current time in locale-specific representation.
720: * $ZTRAP:: Entryref to be executed on error condition.
721: * $ZUT:: Microseconds since the UNIX epoch.
722: * $ZVERSION:: Version of FreeM and GNU host triplet.
723: @end menu
724:
725: @node $DEVICE
726: @section $DEVICE
727: @cindex $DEVICE
728: @cindex intrinsic special variables, $DEVICE
729:
730: Returns the status of the device currently in use.
731:
732: If @code{$DEVICE} returns @emph{1}, an error condition exists on the current device. In this case, there will be two additional fields separated by commas, indicating the internal FreeM error code representing the error present on the device and a text explanation of the error.
733:
734: @node $DIALECT
735: @section $DIALECT
736: @cindex $DIALECT
737: @cindex intrinsic special variables, $DIALECT
738:
739: Returns or sets the language dialect of the current routine.
740:
741: Valid values for @code{$DIALECT} are as follows:
742:
743: @table @code
744: @item @code{M77}
745: Restricts FreeM to use only features specified by the 1977 M standard.
746: @item @code{M84}
747: Restricts FreeM to use only features specified by the 1984 M standard.
748: @item @code{M90}
749: Restricts FreeM to use only features specified by the 1990 M standard.
750: @item @code{M95}
751: Restricts FreeM to use only features specified by the 1995 M standard.
752: @item @code{MDS}
753: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
754: @item @code{M5}
755: Restricts FreeM to use only features proposed by the upcoming M5 standard.
756: @item @code{FREEM}, @code{EXTENDED}
757: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{$DIALECT}.
758: @end table
759:
760: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{$DIALECT}.
761:
762: @node $ECODE
763: @section $ECODE
764: @cindex $ECODE
765: @cindex intrinsic special variables, $ECODE
766:
767: Returns a comma-delimited list of error conditions currently present, and is writable. An empty @code{$ECODE} indicates no errors.
768:
769: Writing a value in the format @code{,<error-code>,} into @code{$ECODE} will raise that error condition.
770:
771: @node $ESTACK
772: @section $ESTACK
773: @cindex $ESTACK
774: @cindex intrinsic special variables, $ESTACK
775:
776: Returns the depth of the program execution stack since the last time @code{$ESTACK} was @code{NEW}ed. @code{NEW}-able, but not @code{SET}-able. Differs from the @code{@ref{$STACK}} ISV in that it is @code{@ref{NEW}}-able, and resets to a value of 0 when @code{@ref{NEW}}ed.
777:
778: @node $ETRAP
779: @section $ETRAP
780: @cindex $ETRAP
781: @cindex intrinsic special variables, $ETRAP
782:
783: Sets or retrieves the M code that is run when an error is encountered or @code{@ref{$ECODE}} is set to a non-blank value. @code{$ETRAP} code executes when @code{$ECODE} becomes non-blank.
784:
785:
786: @node $HOROLOG
787: @section $HOROLOG
788: @cindex $HOROLOG
789: @cindex intrinsic special variables, $HOROLOG
790:
791: Returns a string containing the current date and time as @code{<days>,<seconds>}, where @code{<days>} represents the number of days since the M epoch (midnight on 31 December 1840),
792: and @code{<seconds>} represents the number of seconds since the most recent midnight.
793:
794: @cartouche
795: @quotation
796: @emph{FreeM Extension}
797:
798: In FreeM, @code{$HOROLOG} is @code{@ref{SET}}table. Setting @code{$HOROLOG} will set the system clock if your user account has the appropriate permissions. If your user account does not have permissions to modify the system clock, FreeM will raise a @code{ZPROTECT} error.
799: @end quotation
800: @end cartouche
801:
802: @node $IO
803: @section $IO
804: @cindex $IO
805: @cindex intrinsic special variables, $IO
806:
807: Represents the current input/output device. Read-only.
808:
809: @node $JOB
810: @section $JOB
811: @cindex $JOB
812: @cindex intrinsic special variables, $JOB
813:
814: Represents the process ID of the FreeM instance currently in use.
815:
816: @node $KEY
817: @section $KEY
818: @cindex $KEY
819: @cindex intrinsic special variables, $KEY
820:
821: Represents the sequence of control characters that terminated the last @code{@ref{READ}} command on @code{@ref{$IO}}.
822:
823: @node $PDISPLAY
824: @section $PDISPLAY
825: @cindex $PDISPLAY
826: @cindex intrinsic special variables, $PDISPLAY
827:
828: Represents the current principal display for M Windowing API operations. Commonly used as an index into the @code{@ref{^$DISPLAY}} structured system variable.
829:
830: @node $PRINCIPAL
831: @section $PRINCIPAL
832: @cindex $PRINCIPAL
833: @cindex intrinsic special variables, $PRINCIPAL
834:
835: Represents the primary input/output device. Usually a terminal or virtual terminal.
836:
837: @node $REFERENCE
838: @section $REFERENCE
839: @cindex $REFERENCE
840: @cindex intrinsic special variables, $REFERENCE
841:
842: Returns the last @emph{glvn} referenced. Can be @code{@ref{SET}}, and also stacked with @code{@ref{NEW}}.
843:
844: @node $QUIT
845: @section $QUIT
846: @cindex $QUIT
847: @cindex intrinsic special variables, $QUIT
848:
849: If the current execution context was invoked as an extrinsic function, @code{$QUIT} returns @emph{1}. Otherwise, returns @emph{0}.
850:
851: When @code{$QUIT} returns @emph{1}, a subsequent @code{@ref{QUIT}} command must have an argument.
852:
853: @node $STACK
854: @section $STACK
855: @cindex $STACK
856: @cindex intrinsic special variables, $STACK
857:
858: Represents the current stack level.
859:
860: @node $STORAGE
861: @section $STORAGE
862: @cindex $STORAGE
863: @cindex intrinsic special variables, $STORAGE
864:
865: Represents the number of bytes of free space available in FreeM's heap.
866:
867: @node $SYSTEM
868: @section $SYSTEM
869: @cindex $SYSTEM
870: @cindex intrinsic special variables, $SYSTEM
871:
872: Returns the MDC system ID of FreeM, as well as the environment ID of the current environment.
873:
874: @node $TEST
875: @section $TEST
876: @cindex $TEST
877: @cindex intrinsic special variables, $TEST
878:
879: @code{$TEST} is a writable, @code{@ref{NEW}}-able ISV that is @emph{1} if the most recently evaluated expression was @emph{true}. Otherwise, returns @emph{0}.
880:
881: @code{$TEST} is implicitly @code{NEW}ed when entering a new stack frame for extrinsic functions and argumentless @code{@ref{DO}}. @code{$TEST}
882: is @emph{not} implicitly @code{NEW}ed when a new stack frame is entered with an argumented @code{DO}.
883:
884: For single-line @code{@ref{IF}} or @code{@ref{ELSE}} expressions, you may use @code{@ref{THEN}} to stack @code{$TEST} until the end of the line. All new code should employ @code{THEN} in this manner, as stacking @code{$TEST} prevents a wide range of coding errors that can be very challenging to detect and eliminate.
885:
886: @node $TLEVEL
887: @section $TLEVEL
888: @cindex $TLEVEL
889: @cindex intrinsic special variables, $TLEVEL
890:
891: Returns a numeric value indicating the current level of transaction nesting in the process. When @code{$TLEVEL} is greater than @emph{0},
892: uncommitted transactions exist.
893:
894: @node $WITH
895: @section $WITH
896: @cindex $WITH
897: @cindex intrinsic special variables, $WITH
898:
899: Returns the variable prefix set by the @code{@ref{ZWITH}} command.
900:
901: @node $X
902: @section $X
903: @cindex $X
904: @cindex intrinsic special variables, $X
905:
906: Represents the current column position of the FreeM cursor.
907:
908: @cartouche
909: @quotation
910: In FreeM, setting @code{$X} will move the FreeM cursor.
911: @end quotation
912: @end cartouche
913:
914:
915: @node $Y
916: @section $Y
917: @cindex $Y
918: @cindex intrinsic special variables, $Y
919:
920: Represents the current row position of the FreeM cursor.
921:
922: @cartouche
923: @quotation
924: In FreeM, setting @code{$Y} will move the FreeM cursor.
925: @end quotation
926: @end cartouche
927:
928:
929: @node $ZA
930: @section $ZA
931: @cindex $ZA
932: @cindex intrinsic special variables, $ZA
933: @cindex intrinsic special variables, implementation-specific
934:
935: On the @code{HOME} device, always @code{0}. On other devices, returns the current position of the file opened on I/O channel @code{@ref{$IO}}.
936:
937: @node $ZB
938: @section $ZB
939: @cindex $ZB
940: @cindex intrinsic special variables, $ZB
941: @cindex intrinsic special variables, implementation-specific
942:
943: Represents the last keystroke.
944:
945: @node $ZCONTROLC
946: @section $ZCONTROLC
947: @cindex $ZCONTROLC
948: @cindex intrinsic special variables, $ZCONTROLC
949: @cindex intrinsic special variables, implementation-specific
950:
951: Returns the status of the Ctrl-C flag and resets it to @emph{false}.
952:
953: @node $ZDATE
954: @section $ZDATE
955: @cindex $ZDATE
956: @cindex intrinsic special variables, $ZDATE
957: @cindex intrinsic special variables, implementation-specific
958:
959: Returns the current date, in the preferred representation for the current system locale.
960:
961: @node $ZERROR
962: @section $ZERROR
963: @cindex $ZERROR
964: @cindex intrinsic special variables, $ZERROR
965: @cindex intrinsic special variables, implementation-specific
966:
967: Returns the last error message.
968:
969: @node $ZHOROLOG
970: @section $ZHOROLOG
971: @cindex $ZHOROLOG
972: @cindex intrinsic special variables, $ZHOROLOG
973: @cindex intrinsic special variables, implementation-specific
974:
975: Output @code{@ref{$HOROLOG}}-style time, with the addition of milliseconds.
976:
977: @node $ZINRPT
978: @section $ZINRPT
979: @cindex $ZINRPT
980: @cindex intrinsic special variables, $ZINRPT
981: @cindex intrinsic special variables, implementation-specific
982:
983: Gets or sets the interrupt enable/disable flag.
984:
985: @node $ZJOB
986: @section $ZJOB
987: @cindex $ZJOB
988: @cindex intrinsic special variables, $ZJOB
989: @cindex intrinsic special variables, implementation-specific
990:
991: Returns the @code{@ref{$JOB}} value of the parent process if the current process was started by a @code{@ref{JOB}} command. Otherwise, returns an empty string.
992:
993: @node $ZLOCAL
994: @section $ZLOCAL
995: @cindex $ZLOCAL
996: @cindex intrinsic special variables, $ZLOCAL
997: @cindex intrinsic special variables, implementation-specific
998:
999: Returns the last local variable referenced.
1000:
1001: @node $ZNAME
1002: @section $ZNAME
1003: @cindex $ZNAME
1004: @cindex intrinsic special variables, $ZNAME
1005: @cindex intrinsic special variables, implementation-specific
1006:
1007: Returns the name of the current routine.
1008:
1009: @node $ZPRECISION
1010: @section $ZPRECISION
1011: @cindex $ZPRECISION
1012: @cindex intrinsic special variables, $ZPRECISION
1013: @cindex intrinsic special variables, implementation-specific
1014:
1015: Gets or sets the number of digits of numeric precision used for fixed-point decimal arithmetic. If @code{^$JOB($JOB,"MATH")} is @code{IEEE754}, @code{$ZPRECISION} defaults to 16 digits, with a maximum of 16 digits. If @code{^$JOB($JOB,"MATH")} is @code{FIXED}, @code{$ZPRECISION} defaults to 100 digits, with a maximum of 20,000 digits.
1016:
1017: @xref{^$JOB}.
1018:
1019: @node $ZREFERENCE
1020: @section $ZREFERENCE
1021: @cindex $ZREFERENCE
1022: @cindex intrinsic special variables, $ZREFERENCE
1023: @cindex intrinsic special variables, implementation-specific
1024:
1025: Returns the last @emph{gvn} referenced.
1026:
1027: @node $ZSYSTEM
1028: @section $ZSYSTEM
1029: @cindex $ZSYSTEM
1030: @cindex intrinsic special variables, $ZSYSTEM
1031: @cindex intrinsic special variables, implementation-specific
1032:
1033: Represents the return value of the last external command run with @code{!}.
1034:
1035: @node $ZTIME
1036: @section $ZTIME
1037: @cindex $ZTIME
1038: @cindex intrinsic special variables, $ZTIME
1039: @cindex intrinsic special variables, implementation-specific
1040:
1041: Returns the system time in the preferred representation for the current system locale.
1042:
1043: @node $ZTRAP
1044: @section $ZTRAP
1045: @cindex $ZTRAP
1046: @cindex intrinsic special variables, $ZTRAP
1047: @cindex intrinsic special variables, implementation-specific
1048:
1049: Sets or retrieves the entryref to be executed when an M program execution error occurs under FreeM-style or DSM 2.0-style error processing.
1050:
1051: In FreeM-style error processing, @code{$ZTRAP} is specific to each program execution stack level.
1052:
1053: In DSM 2.0-style error processing, @code{$ZTRAP} is the same for all program execution stack levels.
1054:
1055: When FreeM encounters an error, if @code{$ZTRAP} is nonempty and @code{$ETRAP} is empty, FreeM will perform an implicit @code{@ref{GOTO}} to the entryref indicated in @code{$ZTRAP}.
1056:
1057: If @code{$ETRAP} is nonempty when FreeM encounters an error, the value of @code{$ZTRAP} is ignored, whether FreeM-style or DSM 2.0-style error processing is enabled.
1058:
1059: @node $ZUT
1060: @section $ZUT
1061: @cindex $ZUT
1062: @cindex intrinsic special variables, $ZUT
1063: @cindex intrinsic special variables, implementation-specific
1064:
1065: Returns the number of microseconds elapsed since the UNIX epoch (Jan 1, 1970 0:00:00).
1066:
1067: @node $ZVERSION
1068: @section $ZVERSION
1069: @cindex $ZVERSION
1070: @cindex intrinsic special variables, $ZVERSION
1071: @cindex intrinsic special variables, implementation-specific
1072:
1073: Returns the version of FreeM in use, as well as the GNU host triplet for the current FreeM build.
1074:
1075: See @emph{https://wiki.osdev.org/Target_Triplet}.
1076:
1077: @node Intrinsic Functions
1078: @chapter Intrinsic Functions
1079:
1080: @menu
1081: * $ASCII():: Return ASCII code for character in string.
1082: * $CHAR():: Return character for one or more ASCII codes.
1083: * $DATA():: Retrieve definition and characteristics of array node.
1084: * $EXTRACT():: Return a substring of a string.
1085: * $FIND():: Find position of substring within string.
1086: * $FNUMBER():: Format a number according to formatting codes.
1087: * $GET():: Return value of glvn or a default if undefined.
1088: * $INSTANCEOF():: Determine if lvn is an instance of a class.
1089: * $JUSTIFY():: Right-justify a string based on specified length.
1090: * $LENGTH():: Return length or delimiter-based piece count of string.
1091: * $NAME():: Return canonical name from string representation of glvn.
1092: * $NEXT():: Return next numeric subscript following given glvn.
1093: * $ORDER():: Return next subscript at same level of specified glvn.
1094: * $PIECE():: Return one or more delimited pieces of a string.
1095: * $QLENGTH():: Return subscript count of glvn.
1096: * $QSUBSCRIPT():: Return a specified subscript from glvn.
1097: * $QUERY():: Return next subscript of specified glvn.
1098: * $RANDOM():: Return pseudorandom integer up to a maximum value.
1099: * $REVERSE():: Reverse a string.
1100: * $SELECT():: Return value from first true condition in list of expressions.
1101: * $STACK():: Return information about the program stack.
1102: * $TEXT():: Return line of code from a routine.
1103: * $TRANSLATE():: Substitute specified characters in a string.
1104: * $TYPE():: Return class of the specified lvn.
1105: * $VIEW():: Retrieve implementation-specific information.
1106: * $ZBOOLEAN():: Perform boolean operations on numeric arguments.
1107: * $ZCALL():: Unknown.
1108: * $ZCRC():: Generate checksum of a string argument.
1109: * $ZDATA():: Unknown.
1110: * $ZDATE():: Convert @code{@ref{$HOROLOG}} string into human-readable date.
1111: * $ZEDIT():: Unknown.
1112: * $ZHOROLOG():: Convert date/time values to @code{@ref{$HOROLOG}} format.
1113: * $ZKEY():: Unknown.
1114: * $ZLENGTH():: Unknown.
1115: * $ZLSD():: Compute Levenshtein distance between two arguments.
1116: * $ZM():: Unknown.
1117: * $ZNAME():: Unknown.
1118: * $ZNEXT():: Unknown.
1119: * $ZORDER():: Unknown.
1120: * $ZPIECE():: Unknown.
1121: * $ZPREVIOUS():: Unknown.
1122: * $ZREPLACE():: Replace all instances of a substring within a string.
1123: * $ZSYNTAX():: Perform syntax check on string argument.
1124: * $ZTIME():: Convert a @code{@ref{$HOROLOG}} string into human-readable time.
1125: @end menu
1126:
1127: @node $ASCII()
1128: @section $ASCII
1129: @cindex $ASCII
1130: @cindex intrinsic functions, $ASCII
1131:
1132: Returns the ASCII code (in decimal) for one character in a string.
1133:
1134: @example
1135: SET RESULT=$ASCII(@emph{<string>}[,@emph{<index>}])
1136: @end example
1137:
1138:
1139: If @emph{<index>} is not supplied, @code{$ASCII} will return the ASCII code of the first character. Otherwise, returns the ASCII code of the character at position @emph{<index>}.
1140:
1141: @node $CHAR()
1142: @section $CHAR
1143: @cindex $CHAR
1144: @cindex intrinsic functions, $CHAR
1145:
1146: Returns a string of characters corresponding to a list of ASCII codes.
1147:
1148: @example
1149: SET RESULT=$CHAR(@emph{<ascii-code>}[,@emph{<ascii-code>},...])
1150: @end example
1151:
1152: @node $DATA()
1153: @section $DATA
1154: @cindex $DATA
1155: @cindex intrinsic functions, $DATA
1156:
1157: Returns a numeric value 0, 1, 10, or 11, depending on whether a referenced node is defined, has data, or has children:
1158:
1159: @example
1160: SET RESULT=$DATA(@emph{<node>})
1161: @end example
1162:
1163: The return values are as follows:
1164:
1165: @example
1166: 0: @emph{<node>} is undefined
1167: 1: @emph{<node>} has data but no children
1168: 10: @emph{<node>} has children but no data
1169: 11: @emph{<node>} has children and data
1170: @end example
1171:
1172: @node $EXTRACT()
1173: @section $EXTRACT
1174: @cindex $EXTRACT
1175: @cindex intrinsic functions, $EXTRACT
1176:
1177: Extracts a substring of a string.
1178:
1179: The first argument is the source string.
1180:
1181: The optional second argument specifies the starting position of the substring to extract, and defaults to @code{1}.
1182:
1183: The optional third argument specifies the ending position of the substring to extract, and defaults to the value of the second argument, or @code{1}.
1184:
1185: This example will extract the string @emph{FreeM} into the local variable @code{M}.
1186:
1187: @example
1188: SET NAME="FreeM is the best!"
1189: SET M=$EXTRACT(NAME,1,5)
1190: @end example
1191:
1192: It is also possible to use @code{$EXTRACT} on the left-hand side of a @code{SET} assignment in order to modify a substring:
1193:
1194: @example
1195: DEFAULT.USER> SET FOO="ABCDEFG"
1196:
1197:
1198: DEFAULT.USER> SET $EXTRACT(FOO,1,3)="XYZ"
1199:
1200:
1201: DEFAULT.USER> WRITE FOO
1202:
1203: XYZDEFG
1204: @end example
1205:
1206: @node $FIND()
1207: @section $FIND
1208: @cindex $FIND
1209: @cindex intrinsic functions, $FIND
1210:
1211: Finds the character immediately following the first occurence of a substring within a string.
1212:
1213: The first argument is the source string.
1214:
1215: The second argument is the substring to be located.
1216:
1217: The optional third argument indicates the position within the source string at which to begin searching.
1218:
1219: @node $FNUMBER()
1220: @section $FNUMBER
1221: @cindex $FNUMBER
1222: @cindex intrinsic functions, $FNUMBER
1223:
1224: Formats a number according to a particular set of formatting codes.
1225:
1226: The first argument is the number to format.
1227:
1228: The second argument is the series of formatting codes:
1229:
1230: @table @asis
1231: @item 'P' or 'p'
1232: Will display negative numbers within parentheses instead of showing a minus sign.
1233: @item , (comma)
1234: Will add commas as thousands separators.
1235: @item +
1236: Will include a plus sign for positive numbers. Not compatible with 'P' or 'p'.
1237: @item -
1238: Will remove the minus sign from negative numbers. Not compatible with 'p' or 'P'.
1239: @item 't' or 'T'
1240: Will place the sign after the number instead of before the number.
1241: @end table
1242:
1243: The optional third argument is a number indicating how many digits to which the fractional part of the number will be zero-padded.
1244:
1245: @node $GET()
1246: @section $GET
1247: @cindex $GET
1248: @cindex intrinsic functions, $GET
1249:
1250: Returns the value of a local, global, or SSVN if the specified item is defined, or a default value otherwise.
1251:
1252: The first argument is the local, global, or SSVN to be examined.
1253:
1254: The optional second argument is the default value to be returned if the referenced item is undefined, and defaults to the empty string.
1255:
1256: @node $INSTANCEOF()
1257: @section $INSTANCEOF
1258: @cindex $INSTANCEOF
1259: @cindex intrinsic functions, $INSTANCEOF
1260: @cindex object functions, $INSTANCEOF
1261:
1262: Returns @code{1} if the specified @emph{lvn} is an instance of class @emph{class}, or @code{0} otherwise.
1263:
1264: The first argument is a string representing a valid FreeM local variable.
1265:
1266: The second argument is a string representing a valid FreeM class.
1267:
1268: @example
1269: DEFAULT.USER> N STR=$$^%STRING
1270:
1271: DEFAULT.USER> W $INSTANCEOF("STR","^%STRING")
1272: 1
1273: @end example
1274:
1275: @node $JUSTIFY()
1276: @section $JUSTIFY
1277: @cindex $JUSTIFY
1278: @cindex intrinsic functions, $JUSTIFY
1279:
1280: Right-justifies a string based on a specified fixed length.
1281:
1282: The first argument is the source string.
1283:
1284: The second argument is the character length of the output.
1285:
1286: The optional third argument controls the number of fractional digits to be included in the output, and defaults to the number of digits specified in the first argument.
1287:
1288: @node $LENGTH()
1289: @section $LENGTH
1290: @cindex $LENGTH
1291: @cindex intrinsic functions, $LENGTH
1292:
1293: Returns the length of a string, or the number of items in a list delimited by a specified character (as used by @code{@ref{$PIECE()}}).
1294:
1295: The first argument is the source string.
1296:
1297: The optional second argument is the list delimiter to be used. When this argument is omitted, the length of the string in characters is returned.
1298:
1299: @node $NAME()
1300: @section $NAME
1301: @cindex $NAME
1302: @cindex intrinsic functions, $NAME
1303:
1304: Returns the canonical name reference along with some or all of its subscripts.
1305:
1306: The first argument is the source name.
1307:
1308: The optional second argument indicates the maximum subscript count to be returned, and defaults to the subscript count of the source name.
1309:
1310: @node $NEXT()
1311: @section $NEXT
1312: @cindex $NEXT
1313: @cindex intrinsic functions, $NEXT
1314:
1315: Deprecated. Use @code{$ORDER} instead.
1316:
1317: @node $ORDER()
1318: @section $ORDER
1319: @cindex $ORDER
1320: @cindex intrinsic functions, $ORDER
1321:
1322: Returns the previous subscript or next subscript in a local, global, or a subset of structured system variables.
1323:
1324: The first argument is the subscripted local, global, or SSVN.
1325:
1326: The optional second argument can be @code{1} to retrieve the next subscript, or @code{-1} to return the previous.
1327:
1328: @node $PIECE()
1329: @section $PIECE
1330: @cindex $PIECE
1331: @cindex intrinsic functions, $PIECE
1332:
1333: @emph{Syntax}
1334:
1335: @code{$PIECE(@emph{s},@emph{d}[,@emph{n}[,@emph{end}]])}
1336:
1337: Accesses the @code{n}th through @code{end} @code{d}-delimited pieces of string @code{s}.
1338:
1339: The first argument is the string to be evaluated.
1340:
1341: The second argument is the delimiter to be used.
1342:
1343: The optional third argument is the first @code{d}-delimited piece to access, and defaults to @code{1}.
1344:
1345: The optional fourth argument is the final @code{d}-delimited piece to access, and defaults to the value of the third argument (@code{n}).
1346:
1347: Can be used on the left-hand side of an expression in order to @code{@ref{SET}} a value into a @code{d}-delimited piece of @code{s}, as in:
1348:
1349: @example
1350: ; ^snw="this^is^a^piece"
1351: SET $PIECE(^snw,"^",2)="isn't" ; => "this^isn't^a^piece"
1352: @end example
1353:
1354: @node $QLENGTH()
1355: @section $QLENGTH
1356: @cindex $QLENGTH
1357: @cindex intrinsic functions, $QLENGTH
1358:
1359: @emph{Syntax}
1360:
1361: @example
1362: @code{$QLENGTH(@emph{expr V glvn})}
1363: @end example
1364:
1365: Returns the number of subscripts in @emph{glvn}.
1366:
1367: @emph{Example}
1368: @example
1369: @code{SET SUBCT=$QLENGTH("^GBL(1,2,3)") ; => 3}
1370: @end example
1371:
1372: @node $QSUBSCRIPT()
1373: @section $QSUBSCRIPT
1374: @cindex $QSUBSCRIPT
1375: @cindex intrinsic functions, $QSUBSCRIPT
1376:
1377: @emph{Syntax}
1378:
1379: @example
1380: @code{$QSUBSCRIPT(@emph{expr V glvn},@emph{expr V n})}
1381: @end example
1382:
1383: In the RHS form, returns the @emph{n}th subscript of @emph{glvn}.
1384:
1385: @emph{Example}
1386:
1387: @example
1388: @code{SET SUB=$QSUBSCRIPT("^GBL(1,2,3)",2) ; => 2}
1389: @end example
1390:
1391: @emph{Syntax}
1392:
1393: @example
1394: @code{SET $QSUBSCRIPT(@emph{expr V glvn},@emph{expr V n})=@emph{expr} ; => ^GBL(1,4,3)}
1395: @end example
1396:
1397: In the LHS form, sets the @emph{n}th subscript of @emph{glvn} to @emph{expr}.
1398:
1399: @node $QUERY()
1400: @section $QUERY
1401: @cindex $QUERY
1402: @cindex intrinsic functions, $QUERY
1403:
1404: Returns the next subscripted reference in a global.
1405:
1406: @emph{Syntax}
1407:
1408: @example
1409: @code{$QUERY(@emph{glvn})}
1410: @end example
1411:
1412: @emph{Example}
1413:
1414: We will assume the following data structure exists:
1415: @example
1416: ^snw(1)=1
1417: ^snw(1,2)="foo"
1418: ^snw(2)=3
1419: ^snw(3)=""
1420: @end example
1421:
1422: The following code will retrieve the next subscripted name after @code{^snw(1)}:
1423:
1424: @example
1425: @code{SET NEXTNAM=$QUERY(^snw(1)) ; => ^snw(1,2)}
1426: @end example
1427:
1428: @node $RANDOM()
1429: @section $RANDOM
1430: @cindex $RANDOM
1431: @cindex intrinsic functions, $RANDOM
1432:
1433: @emph{Syntax}
1434:
1435: @example
1436: $RANDOM(@emph{max})
1437: @end example
1438:
1439: Returns a pseudo-random integer in the range of @code{0..@emph{max} - 1}
1440:
1441: @node $REVERSE()
1442: @section $REVERSE
1443: @cindex $REVERSE
1444: @cindex intrinsic functions, $REVERSE
1445:
1446: @emph{Syntax}
1447:
1448: @example
1449: $REVERSE(@emph{s})
1450: @end example
1451:
1452: Returns the reverse of string @emph{s}.
1453:
1454: @emph{Example}
1455:
1456: @example
1457: SET FOO=$REVERSE("ABC") ; => CBA
1458: @end example
1459:
1460: @node $SELECT()
1461: @section $SELECT
1462: @cindex $SELECT
1463: @cindex intrinsic functions, $SELECT
1464:
1465: Returns a value corresponding to the first true condition in a list of conditional expressions. Each argument is an expression, followed by a colon, followed by an expression whose value will be returned if the first expression is true. If no expressions are true, error condition @code{M4} is raised.
1466:
1467: @emph{Example}
1468:
1469: @example
1470: SET FOO=$SELECT(1=2:"math is broken",1=1:"the world makes sense") ; => "the world makes sense"
1471: @end example
1472:
1473: @node $STACK()
1474: @section $STACK
1475: @cindex $STACK
1476: @cindex intrinsic functions, $STACK
1477:
1478: Returns information about the program execution stack. The @code{$STACK} intrinsic function has both a one-argument form and a two-argument form.
1479:
1480: @emph{Syntax (One-Argument)}
1481:
1482: @example
1483: $STACK(@emph{<num>})
1484: @end example
1485:
1486: If @emph{num} is @code{0}, returns the command with which this FreeM instance was invoked.
1487:
1488: If @emph{num} is @code{-1}, returns the current program execution stack level.
1489:
1490: If @emph{num} represents a valid program execution stack depth above @code{0}, returns one of the following values indicating the reason for which the referenced program execution stack level was created:
1491:
1492: @table @asis
1493:
1494: @item @code{$$}
1495: If @code{$STACK(@emph{<num>})="$$"}, program execution stack level @code{num} was created as the result of an extrinsic function call
1496:
1497: @item @emph{<m-command>}
1498: If @code{$STACK(@emph{<num>})} returns a valid M command, the referenced program execution stack level was created as a result of the @emph{m-command} command.
1499:
1500: @end table
1501:
1502: @emph{Syntax (Two-Argument})
1503:
1504: @example
1505: $STACK(@emph{<num>},"[ECODE|MCODE|PLACE]")
1506: @end example
1507:
1508: Returns the error codes, M program code, or entryref applicable to the action that created program execution stack level @emph{num}.
1509:
1510: @node $TEXT()
1511: @section $TEXT
1512: @cindex $TEXT
1513: @cindex intrinsic functions, $TEXT
1514:
1515: Returns a line of code from a routine.
1516:
1517: @node $TRANSLATE()
1518: @section $TRANSLATE
1519: @cindex $TRANSLATE
1520: @cindex intrinsic functions, $TRANSLATE
1521:
1522: Replaces characters in a string.
1523:
1524: The first argument is a string expression representing the text to be changed.
1525:
1526: The second argument is a list of characters to replace.
1527:
1528: The third argument is a list of characters to use as the replacements for the characters in the second argument.
1529:
1530: @emph{Example}
1531:
1532: @example
1533: DEFAULT.USER> W $TRANSLATE("twig","wt","rb")
1534: brig
1535: @end example
1536:
1537: @node $TYPE()
1538: @section $TYPE
1539: @cindex $TYPE
1540: @cindex intrinsic functions, $TYPE
1541: @cindex object functions, $TYPE
1542:
1543: Returns a string giving the class of the object specified in the parameter.
1544:
1545: @xref{Object-Oriented Programming}
1546:
1547: @node $VIEW()
1548: @section $VIEW
1549: @cindex $VIEW
1550: @cindex intrinsic functions, $VIEW
1551:
1552: @node $ZBOOLEAN()
1553: @section $ZBOOLEAN
1554: @cindex $ZBOOLEAN
1555: @cindex intrinsic functions, $ZBOOLEAN
1556: @cindex intrinsic functions, implementation-specific
1557:
1558:
1559: Performs @emph{boolean-operation} on numeric arguments @emph{A} and @emph{B}.
1560:
1561: @emph{Syntax}
1562:
1563: @example
1564: SET RESULT=$ZBOOLEAN(@emph{A},@emph{B},@emph{boolean-operation})
1565: @end example
1566:
1567: @code{$ZBOOLEAN} Operations (@emph{boolean-operation} values)
1568:
1569: @table @code
1570: @item 0
1571: Always @emph{false}
1572: @item 1
1573: @code{A AND B}
1574: @item 2
1575: @code{A AND NOT B}
1576: @item 3
1577: @code{A}
1578: @item 4
1579: @code{NOT A AND B}
1580: @item 5
1581: @code{B}
1582: @item 6
1583: @code{A XOR B}
1584: @item 7
1585: @code{A OR B}
1586: @item 8
1587: @code{A NOR B}
1588: @item 9
1589: @code{A EQUALS B}
1590: @item 10
1591: @code{NOT B}
1592: @item 11
1593: @code{A OR NOT B}
1594: @item 12
1595: @code{NOT A}
1596: @item 13
1597: @code{NOT A OR B}
1598: @item 14
1599: @code{A NAND B}
1600: @item 15
1601: Always @emph{true}
1602: @end table
1603:
1604: @node $ZCALL()
1605: @section $ZCALL
1606: @cindex $ZCALL
1607: @cindex intrinsic functions, $ZCALL
1608: @cindex intrinsic functions, implementation-specific
1609:
1610: Purpose unknown.
1611:
1612: @node $ZCRC()
1613: @section $ZCRC
1614: @cindex $ZCRC
1615: @cindex intrinsic functions, $ZCRC
1616: @cindex intrinsic functions, implementation-specific
1617:
1618: Returns a checksum of @code{arg1}.
1619:
1620: @emph{Syntax}
1621:
1622: @code{$ZCRC(@emph{arg1})}
1623:
1624: @code{SET VAR=$ZCRC("MUMPS") ; => 86}
1625:
1626: @node $ZDATA()
1627: @section $ZDATA
1628: @cindex $ZDATA
1629: @cindex intrinsic functions, $ZDATA
1630: @cindex intrinsic functions, implementation-specific
1631:
1632: Purpose unknown.
1633:
1634: @node $ZDATE()
1635: @section $ZDATE
1636: @cindex $ZDATE
1637: @cindex intrinsic functions, $ZDATE
1638: @cindex intrinsic functions, implementation-specific
1639:
1640: Converts a @code{@ref{$HOROLOG}} string into a human-readable date.
1641:
1642: @emph{Syntax}
1643:
1644: @example
1645: SET VAR=$ZDATE($H[,@emph{<format-string>}])
1646: @end example
1647:
1648: The optional @emph{<format-string>} follows the same rules as the UNIX @code{strftime} function. If @emph{<format-string>} is omitted, the value of @code{^$SYSTEM("ZDATE_FORMAT")} is used (typically @code{%x}).
1649:
1650: @xref{^$SYSTEM}
1651:
1652: @node $ZEDIT()
1653: @section $ZEDIT
1654: @cindex $ZEDIT
1655: @cindex intrinsic functions, $ZEDIT
1656: @cindex intrinsic functions, implementation-specific
1657:
1658: Purpose unknown.
1659:
1660: @node $ZHOROLOG()
1661: @section $ZHOROLOG
1662: @cindex $ZHOROLOG
1663: @cindex intrinsic functions, $ZHOROLOG
1664: @cindex intrinsic functions, implementation-specific
1665:
1666: Converts date and/or time values producible by @code{@ref{$ZDATE()}} or @code{@ref{$ZTIME()}} to @code{@ref{$HOROLOG}} format.
1667:
1668: @emph{Syntax}
1669:
1670: @example
1671: $ZHOROLOG(@emph{<date-value>},@emph{<format-string>})
1672: @end example
1673:
1674: @emph{<date-value>} is a date or time string compatible with the formats from @code{@ref{$ZDATE()}} or @code{@ref{$ZTIME}}.
1675:
1676: @emph{<format-string>} is a format string of the same format as used by the @code{strptime(3)} UNIX function.
1677:
1678: @node $ZKEY()
1679: @section $ZKEY
1680: @cindex $ZKEY
1681: @cindex intrinsic functions, $ZKEY
1682: @cindex intrinsic functions, implementation-specific
1683:
1684: Purpose unknown.
1685:
1686: @node $ZLENGTH()
1687: @section $ZLENGTH
1688: @cindex $ZLENGTH
1689: @cindex intrinsic functions, $ZLENGTH
1690: @cindex intrinsic functions, implementation-specific
1691:
1692: Purpose unknown.
1693:
1694: @node $ZLSD()
1695: @section $ZLSD
1696: @cindex $ZLSD
1697: @cindex intrinsic functions, $ZLSD
1698: @cindex intrinsic functions, implementation-specific
1699:
1700: Returns the Levenshtein distance between two arguments. The Levenshtein distance represents the minimum number of edits needed to change the first argument into the second argument.
1701:
1702: @emph{Syntax}
1703:
1704: @code{SET VAR=$ZLSD(@emph{arg1},@emph{arg2})}
1705:
1706: @emph{Example}
1707:
1708: @code{SET VAR=$ZLSD("KITTENS","MITTENS") ; => 1}
1709:
1710: @node $ZM()
1711: @section $ZM
1712: @cindex $ZM
1713: @cindex intrinsic functions, $ZM
1714: @cindex intrinsic functions, implementation-specific
1715:
1716: Purpose unknown.
1717:
1718: @node $ZNAME()
1719: @section $ZNAME
1720: @cindex $ZNAME
1721: @cindex intrinsic functions, $ZNAME
1722: @cindex intrinsic functions, implementation-specific
1723:
1724: Purpose unknown.
1725:
1726: @node $ZNEXT()
1727: @section $ZNEXT
1728: @cindex $ZNEXT
1729: @cindex intrinsic functions, $ZNEXT
1730: @cindex intrinsic functions, implementation-specific
1731:
1732: Purpose unknown.
1733:
1734: @node $ZORDER()
1735: @section $ZORDER
1736: @cindex $ZORDER
1737: @cindex intrinsic functions, $ZORDER
1738: @cindex intrinsic functions, implementation-specific
1739:
1740: Purpose unknown.
1741:
1742: @node $ZPIECE()
1743: @section $ZPIECE
1744: @cindex $ZPIECE
1745: @cindex intrinsic functions, $ZPIECE
1746: @cindex intrinsic functions, implementation-specific
1747:
1748: Purpose unknown.
1749:
1750: @node $ZPREVIOUS()
1751: @section $ZPREVIOUS
1752: @cindex $ZPREVIOUS
1753: @cindex intrinsic functions, $ZPREVIOUS
1754: @cindex intrinsic functions, implementation-specific
1755:
1756: Purpose unknown.
1757:
1758: @node $ZREPLACE()
1759: @section $ZREPLACE
1760: @cindex $ZREPLACE
1761: @cindex intrinsic functions, $ZREPLACE
1762: @cindex intrinsic functions, implementation-specific
1763:
1764: Replaces all instances of @code{arg2} with @code{arg3} in string @code{arg1}.
1765:
1766: @emph{Syntax}
1767: @code{$ZREPLACE(@emph{arg1},@emph{arg2},@emph{arg3})}
1768:
1769: @emph{Example}
1770:
1771: @code{SET VAR=$ZREPLACE("CAT","C","B") ; => BAT}
1772:
1773: @node $ZSYNTAX()
1774: @section $ZSYNTAX
1775: @cindex $ZSYNTAX
1776: @cindex intrinsic functions, $ZSYNTAX
1777: @cindex intrinsic functions, implementation-specific
1778:
1779: @code{$ZSYNTAX} performs a very basic syntax check on @emph{expr V mcode}. Checks only for illegal commands, mismatched brackets, mismatched quotes, missing or surplus arguments, or surplus commas.
1780:
1781: @emph{Syntax}
1782: @example
1783: $ZSYNTAX(@emph{expr V mcode})
1784: @end example
1785:
1786: If no syntax error is found, returns the empty string.
1787:
1788: If a syntax error is found, returns a number indicating the position in @emph{expr V mcode} at which the error was found, followed by a comma, and the FreeM error code that was found.
1789:
1790: @node $ZTIME()
1791: @section $ZTIME
1792: @cindex $ZTIME
1793: @cindex intrinsic functions, $ZTIME
1794: @cindex intrinsic functions, implementation-specific
1795:
1796: Converts a @code{@ref{$HOROLOG}} string into a human-readable time.
1797:
1798: @emph{Syntax}
1799:
1800: @example
1801: SET VAR=$ZTIME($H[,@emph{<format-string>}])
1802: @end example
1803:
1804: The optional @emph{<format-string>} follows the same rules as the UNIX @code{strftime(3)} function. If @emph{<format-string>} is omitted, the value of @code{^$SYSTEM("ZTIME_FORMAT")} is used (typically @code{%X}).
1805:
1806: @node OBJECT Methods
1807: @chapter OBJECT Methods
1808:
1809: These methods are part of the @code{^%OBJECT} class, from which all FreeM objects ultimately inherit.
1810:
1811: Please note that classes may override @code{^%OBJECT} methods (or methods of any class) in order to provide results more fitting to the class's abstraction goals.
1812:
1813: @menu
1814: * $$TONUMBER:: Returns the canonical numeric representation of the object.
1815: * $$TYPE:: Returns the fully-qualified class name of the object.
1816: * $$VALUE:: Returns the value of the object.
1817: @end menu
1818:
1819: @node $$TONUMBER
1820: @section $$TONUMBER
1821:
1822: Returns (when applicable) a canonical numeric representation of the referenced object.
1823:
1824: @emph{Syntax}
1825:
1826: @example
1827: W $$MYOBJECT.TONUMBER(),!
1828: @end example
1829:
1830: If no canonical numeric representation of the object is possible, will return the empty string.
1831:
1832: @node $$TYPE
1833: @section $$TYPE
1834:
1835: Returns the fully-qualified class of the referenced object.
1836:
1837: @emph{Syntax}
1838:
1839: @example
1840: W $$MYOBJECT.TYPE()
1841: @end example
1842:
1843: Note that M variables that are created by non-object-oriented means will be objects of the @code{^%STRING} class.
1844:
1845: @node $$VALUE
1846: @section $$VALUE
1847:
1848: Returns the value of the referenced object.
1849:
1850: @emph{Syntax}
1851:
1852: @example
1853: W $$MYOBJECT.VALUE()
1854: @end example
1855:
1856: @node STRING Methods
1857: @chapter STRING Methods
1858:
1859: These are methods inherent to the @code{^%STRING} class, which is the default class for M variables created without specifying a class.
1860:
1861: @menu
1862: * $$ASCII:: Return the ASCII code of a character within the string.
1863: * $$DATA:: Return tree characteristics of the string.
1864: * $$DISTANCE:: Determine Levenstein distance between this string and another.
1865: * $$EXTRACT:: Return a substring of the string.
1866: * $$FIND:: Find the position of a substring within the string.
1867: * $$FNUMBER:: Format numbers.
1868: * $$JUSTIFY:: Pad the string to specific positions.
1869: * $$LENGTH:: Return the length of the string.
1870: * $$PIECECOUNT:: Return the count of pieces existing between instances of a delimiter.
1871: * $$PIECE:: Return a delimited subset of the string.
1872: * $$REPLACE:: Replace instances of a substring within the string.
1873: * $$REVERSE:: Reverse the order of characters in the string.
1874: * $$TOLOWER:: Return a lowercase version of the string.
1875: * $$TOUPPER:: Return an uppercase version of the string.
1876: * $$TRANSLATE:: Replace individual characters within the string.
1877: @end menu
1878:
1879: @node $$ASCII
1880: @section $$ASCII
1881:
1882: Returns the ASCII code of a character within the string. See @ref{$ASCII()}.
1883:
1884: @emph{Syntax}
1885:
1886: @example
1887: W $$MYOBJECT.ASCII(3)
1888: @end example
1889:
1890: The above example returns the ASCII code in position 3 of string object @code{MYOBJECT}.
1891:
1892: @node $$DATA
1893: @section $$DATA
1894:
1895: Returns the value of the @code{$DATA} intrinsic function as performed on the value of the object. See @ref{$DATA()}.
1896:
1897: @emph{Syntax}
1898:
1899: @example
1900: W $$MYOBJECT.DATA()
1901: @end example
1902:
1903: @node $$DISTANCE
1904: @section $$DISTANCE
1905:
1906: Returns the Levenstein distance between the string and another string. See @ref{$ZLSD()}.
1907:
1908: @emph{Syntax}
1909:
1910: @example
1911: W $$MYOBJECT.DISTANCE("someString")
1912: @end example
1913:
1914: @node $$EXTRACT
1915: @section $$EXTRACT
1916:
1917: Returns a substring of the string. See @ref{$EXTRACT()}.
1918:
1919: @emph{Syntax}
1920:
1921: @example
1922: $$<objectName>.EXTRACT(<start>,<end>)
1923: @end example
1924:
1925:
1926: @node $$FIND
1927: @section $$FIND
1928:
1929: Finds the character immediately following the first occurence of a substring within a string.
1930:
1931: The first argument is the substring to be located.
1932:
1933: The second argument is the position within the string at which to begin searching.
1934:
1935: See @ref{$FIND()}.
1936:
1937: @node $$FNUMBER
1938: @section $$FNUMBER
1939:
1940: Formats a number according to a set of formatting codes.
1941:
1942: The argument is a series of formatting codes. See @ref{$FNUMBER()} for details.
1943:
1944: @node $$JUSTIFY
1945: @section $$JUSTIFY
1946:
1947: Right-justifies a string based on a specified fixed length.
1948:
1949: The first argument is the character length of the output.
1950:
1951: The second argument controls the number of fractional digits to be included in the output, and defaults to the number of digits specified in the first argument.
1952:
1953: See @ref{$JUSTIFY()} for details.
1954:
1955: @node $$LENGTH
1956: @section $$LENGTH
1957:
1958: Returns the length of the string.
1959:
1960: @node $$PIECECOUNT
1961: @section $$PIECECOUNT
1962:
1963: Returns the number of items in a list delimited by the character specified in the argument.
1964:
1965: @node $$PIECE
1966: @section $$PIECE
1967:
1968: @emph{Syntax}
1969:
1970: @code{$PIECE(@emph{d}[,@emph{n}[,@emph{end}]])}
1971:
1972: Accesses the @code{n}th through @code{end} @code{d}-delimited pieces of the string.
1973:
1974: The first argument is the delimiter to be used.
1975:
1976: The optional second argument is the first @code{d}-delimited piece to access, and defaults to @code{1}.
1977:
1978: The optional third argument is the final @code{d}-delimited piece to access, and defaults to the value of the third argument (@code{n}).
1979:
1980:
1981: @node $$REPLACE
1982: @section $$REPLACE
1983:
1984: @emph{Syntax}
1985: @code{myString.$$REPLACE(@emph{arg1},@emph{arg2})}
1986:
1987: Replaces all instances of @code{arg2} with @code{arg3} in @code{myString}.
1988:
1989: @node $$REVERSE
1990: @section $$REVERSE
1991:
1992: Returns the reverse of the string.
1993:
1994: @node $$TOLOWER
1995: @section $$TOLOWER
1996:
1997: Returns an all-lowercase version of the string.
1998:
1999: @node $$TOUPPER
2000: @section $$TOUPPER
2001:
2002: Returns an all-uppercase version of the string.
2003:
2004: @node $$TRANSLATE
2005: @section $$TRANSLATE
2006:
2007: Identical to @ref{$TRANSLATE()}, except that the arguments are shifted left by one, and the input string is implicit (the object).
2008:
2009: @node Commands
2010: @chapter Commands
2011: @cindex commands
2012:
2013: @menu
2014: * @@:: Execute the following expression as M code.
2015: * !:: Run an external program or command.
2016: * !!:: Launch a subshell from FreeM direct mode.
2017: * ABLOCK:: Increment the block counter for one or more event classes.
2018: * ASTART:: Enable asynchronous event handling for one or more event classes.
2019: * ASTOP:: Disable asynchronous event handling for one or more event classes.
2020: * AUNBLOCK:: Decrement the block counter for one or more event classes.
2021: * BREAK:: Interrupt a running routine to allow interactive debugging.
2022: * CLOSE:: Close an input/output device.
2023: * DO:: Transfer program control to one or more subroutines or introduces a new execution level.
2024: * ELSE:: Execute the remainder of a line if @code{@ref{$TEST}} evaluates @emph{false}.
2025: * FOR:: Repeat execution of a line or block of code.
2026: * GOTO:: Unconditionally transfer program execution to a supplied @emph{entryref}.
2027: * HALT:: Terminate the current FreeM interpreter instance.
2028: * HANG:: Temporarily suspend the running program.
2029: * IF:: Execute the remainder of a line if a conditional expression evaluates @emph{true}.
2030: * JOB:: Execute an @emph{entryref} in a child process.
2031: * KILL:: Remove data from a local, global, or structured system variable.
2032: * KSUBSCRIPTS:: Kill only the descendant subscripts of a local, global, global, or structured system variable.
2033: * KVALUE:: Kill only the value of a local, global, or structured system variable.
2034: * LOCK:: Control advisory locking for concurrency control.
2035: * MERGE:: Merge contents of one local, global, or structured system variable into another.
2036: * NEW:: Introduce a new scope for a specified local variable or intrinsic special variable or instantiate an object.
2037: * OPEN:: Open a sequential or socket input/output device.
2038: * QUIT:: End execution of the current process level, optionally with return value.
2039: * READ:: Read input from an input/output device.
2040: * SET:: Set the value of a local variable, global, intrinsic special variable, or structured system variable.
2041: * TCOMMIT:: Commit a transaction.
2042: * THEN:: Preserve @code{@ref{$TEST}} until the end of the current line.
2043: * TROLLBACK:: Roll back all pending transactions.
2044: * TSTART:: Introduce a new transaction processing level.
2045: * USE:: Set the currently-active input/output device.
2046: * VIEW:: Modify FreeM internal parameters.
2047: * WRITE:: Write output to current input/output device.
2048: * XECUTE:: Interpret string as M code.
2049: * ZASSERT:: Raise error when a conditional expression evaluates @emph{false}.
2050: * ZBREAK:: Enable/disable ZBREAK mode.
2051: * ZCONST:: Define a constant that cannot be altered after initial definition.
2052: * ZGOTO:: @code{GOTO} with @code{BREAK} control.
2053: * ZHALT:: Exit FreeM job with return value.
2054: * ZINSERT:: Insert code into routine buffer.
2055: * ZJOB:: Invoke job, ignoring any timeouts.
2056: * ZLOAD:: Load routine into routine buffer.
2057: * ZMAP:: Map a global name to a non-default namespace.
2058: * ZNEW:: Unknown.
2059: * ZPRINT:: Print contents of routine buffer.
2060: * ZQUIT:: Quit multiple stack levels at once.
2061: * ZREMOVE:: Remove code from routine buffer.
2062: * ZSAVE:: Save routine buffer to disk.
2063: * ZTHROW:: Programmatically raise an error condition.
2064: * ZTRAP:: Raise a FreeM error.
2065: * ZUNMAP:: Remove a mapping of a global to a non-default namespace.
2066: * ZWATCH:: Enable or disable watchpoints, or set or clear watchpoints on specified globals, locals, or structured system variables.
2067: * ZWITH:: Set prefix for future variable references.
2068: * ZWRITE:: Write local variable, global, or structured system variable to @code{@ref{$IO}}.
2069: @end menu
2070:
2071: @node @@
2072: @section @@
2073: @cindex @@
2074: @cindex commands, @@
2075: @cindex commands, implementation-specific
2076: @cindex commands, non-standard
2077:
2078: Executes FreeM code @emph{expr V mcode}.
2079:
2080: @emph{Syntax}
2081:
2082: @example
2083: @@@emph{expr V mcode}
2084: @end example
2085:
2086: @emph{Example (Using Variable)}
2087:
2088: @example
2089: DEFAULT.USER> SET FOO="WRITE ""HELLO WORLD"",!"
2090: DEFAULT.USER> @@FOO
2091:
2092: HELLO WORLD
2093:
2094: DEFAULT.USER>
2095: @end example
2096:
2097: @emph{Example (Using String Literal)}
2098:
2099: @example
2100: DEFAULT.USER> @@"WRITE ""HELLO WORLD"",!"
2101:
2102: HELLO WORLD
2103:
2104: DEFAULT.USER>
2105: @end example
2106:
2107: @emph{Example (Using Indirection)}
2108:
2109: @example
2110: DEFAULT.USER> SET FOO="BAR"
2111:
2112: DEFAULT.USER> SET BAR="WRITE ""HELLO WORLD"",!"
2113:
2114: DEFAULT.USER> @@@@FOO
2115:
2116: HELLO WORLD
2117:
2118: DEFAULT.USER>
2119: @end example
2120:
2121:
2122: @node !
2123: @section !
2124: @cindex !
2125: @cindex commands, !
2126: @cindex commands, external
2127: @cindex commands, non-standard
2128: @emph{FreeM Extension}
2129:
2130: Invokes a shell to run @emph{<external-command>} from within FreeM. This temporarily disables @command{SIGALRM} handling in FreeM, which may interrupt the use of event-driven M programming commands including @command{ESTART} and @command{ESTOP}.
2131:
2132: If the @command{<} character is supplied immediately preceding @emph{<external-command>}, FreeM will append the contents of M local variable @code{%} to @emph{<external-command>} as standard input.
2133:
2134: If the @command{>} character is supplied immediately preceding @emph{<external-command>}, FreeM will take the standard output stream of @emph{<external-command>} and store it in M local variable @code{%}.
2135:
2136: @code{%} contains the number of lines in the input or output. @code{%(1)..%(@emph{n})} contains the data for lines 1-@emph{n}.
2137:
2138: @node !!
2139: @section !!
2140: @cindex !!
2141: @cindex commands, !!
2142: @cindex commands, external
2143: @cindex commands, non-standard
2144: @emph{FreeM Extension}
2145:
2146: Launches a subshell within the FreeM direct mode, allowing the user to run operating system commands.
2147:
2148: @example
2149: DEFAULT.USER> !!
2150:
2151: Type Ctrl-D to exit from the shell
2152: $ uname -a
2153: Linux hesperos 4.19.0-17-amd64 #1 SMP Debian 4.19.194-3 (2021-07-18) x86_64 GNU/Linux
2154: $ exit
2155:
2156: DEFAULT.USER>
2157: @end example
2158:
2159:
2160: @node ABLOCK
2161: @section ABLOCK
2162: @cindex ABLOCK
2163: @cindex commands, ABLOCK
2164:
2165: Increments the event block counter for one or more event classes. While the block counter for an event class is greater than zero, registered event handlers for that event class will not execute, and will instead be queued for later execution once the block counter reaches zero (all blocks removed).
2166:
2167: An implicit @code{ABLOCK} on all event classes occurs when an event handler subroutine is executing. As soon as a @code{QUIT} is reached within an event handler, an implicit @code{ABLOCK} will occur.
2168:
2169: @emph{Syntax}
2170:
2171: @example
2172: ABLOCK@emph{:postcondition}
2173: @end example
2174:
2175: In its argumentless form, @code{ABLOCK} increments the block counter for @emph{all} event classes, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2176:
2177: @example
2178: ABLOCK@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2179: @end example
2180:
2181: In its inclusive form, @code{ABLOCK} increments the block counters for all event classes named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2182:
2183: @example
2184: ABLOCK@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN}
2185: @end example
2186:
2187: In its exclusive form, @code{ABLOCK} increments the block counters for all event classes @emph{except for} those named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2188:
2189:
2190: @node ASTART
2191: @section ASTART
2192: @cindex ASTART
2193: @cindex commands, ASTART
2194:
2195: Enables asynchronous event handling for one or more event classes.
2196:
2197: @emph{Syntax}
2198:
2199: @example
2200: ASTART@emph{:postcondition}
2201: @end example
2202:
2203: In its argumentless form, @code{ASTART} enables asynchronous event handling for all event classes, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2204:
2205: @example
2206: ASTART@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2207: @end example
2208:
2209: In its inclusive form, @code{ASTART} enables asynchronous event handling for all event classes named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2210:
2211: @example
2212: ASTART@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN})
2213: @end example
2214:
2215: In its exclusive form, @code{ASTART} enables asynchronous event handling for all event classes @emph{except for} those named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2216:
2217: @node ASTOP
2218: @section ASTOP
2219: @cindex ASTOP
2220: @cindex commands, ASTOP
2221:
2222: Disables asynchronous event handling for one or more event classes.
2223:
2224: @emph{Syntax}
2225:
2226: @example
2227: ASTOP@emph{:postcondition}
2228: @end example
2229:
2230: In its argumentless form, @code{ASTOP} disables asynchronous event handling for all event classes, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2231:
2232: @example
2233: ASTOP@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2234: @end example
2235:
2236: In its inclusive form, @code{ASTOP} disables asynchronous event handling for all event classes named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2237:
2238: @example
2239: ASTOP@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN})
2240: @end example
2241:
2242: In its exclusive form, @code{ASTOP} disables asynchronous event handling for all event classes @emph{except for} those named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2243:
2244: @node AUNBLOCK
2245: @section AUNBLOCK
2246: @cindex AUNBLOCK
2247: @cindex commands, AUNBLOCK
2248:
2249: Decrements the event block counter for one or more event classes.
2250:
2251: @emph{Syntax}
2252:
2253: @example
2254: AUNBLOCK@emph{:postcondition}
2255: @end example
2256:
2257: In its argumentless form, @code{AUNBLOCK} decrements the block counter for @emph{all} event classes, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2258:
2259: @example
2260: AUNBLOCK@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2261: @end example
2262:
2263: In its inclusive form, @code{AUNBLOCK} decrements the block counters for all event classes named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2264:
2265: @example
2266: AUNBLOCK@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN}
2267: @end example
2268:
2269: In its exclusive form, @code{AUNBLOCK} decrements the block counters for all event classes @emph{except for} those named in the list, provided the optional @emph{postcondition} is either @emph{true} or omitted.
2270:
2271:
2272: @node BREAK
2273: @section BREAK
2274: @cindex BREAK
2275: @cindex commands, BREAK
2276:
2277: Interrupts running routine to allow interactive debugging.
2278:
2279: @emph{Syntax}
2280:
2281: @example
2282: @code{BREAK@emph{:postcondition}}
2283: @end example
2284:
2285: In its argumentless form, @code{BREAK} suspends execution of running code, provided the optional @emph{postcondition} is @emph{true} or omitted.
2286:
2287: @example
2288: @code{BREAK@emph{:postcondition} @emph{breakflag}}
2289: @end example
2290:
2291: @emph{FreeM Extension}
2292:
2293: In its single-argument form, @code{BREAK} enters the interactive debugger or sets @emph{Ctrl-C} handling and error handling characteristics, provided the optional @emph{postcondition} is @emph{true} or omitted.
2294: The following table enumerates the possible values of @emph{breakflag}
2295:
2296: @table @code
2297: @item "DEBUG"
2298: Enters the interactive debugger
2299: @item 0
2300: Disables @emph{Ctrl-C} handling
2301: @item -2
2302: Enables normal FreeM error handling
2303: @item 2
2304: Enables @emph{Digital Standard MUMPS} v2 error handling
2305: @item @emph{any integer value other than 0, 2, or -2}
2306: Enables @emph{Ctrl-C} handling
2307: @end table
2308:
2309: @node CLOSE
2310: @section CLOSE
2311: @cindex CLOSE
2312: @cindex commands, CLOSE
2313:
2314: Closes an input/output device.
2315:
2316: @emph{Syntax}
2317:
2318: @example
2319: @code{CLOSE@emph{:postcondition}}
2320: @end example
2321:
2322: In its argumentless form, @code{CLOSE} closes all I/O devices except for device 0 (the @code{HOME} device), provided the optional @emph{postcondition} is @emph{true} or omitted.
2323:
2324: @example
2325: @code{CLOSE@emph{:postcondition} @emph{channel}}
2326: @end example
2327:
2328: In its single-argument form, @code{CLOSE} closes the I/O device associated with channel @emph{channel}, provided that @emph{channel} represents a currently-open device, and the optional @emph{postcondition} is @emph{true} or omitted.
2329:
2330: @node DO
2331: @section DO
2332: @cindex DO
2333: @cindex commands, DO
2334:
2335: In its inclusive form, transfers program control to one or more specified subroutines, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. Line levels of entryrefs specified in the argument list must be one, or error @code{M14} is raised.
2336:
2337: @emph{Syntax}
2338:
2339: @example
2340: DO[@emph{:postcondition}] @emph{entryref}[@emph{:postcondition}[,...]]
2341: @end example
2342:
2343: @cartouche
2344: @quotation
2345: @emph{Non-Standard Behavior}
2346:
2347: FreeM allows @code{DO} @emph{entryref}s to follow the format of @code{+@emph{intexpr}}. In this case, the value of @emph{intexpr} will be interpreted as an offset from the first line of the current routine.
2348: @end quotation
2349: @end cartouche
2350:
2351: In its argumentless form, transfers control to the following block of code where the line level is one greater than the level at which @code{DO} was encountered, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2352:
2353: @emph{Syntax}
2354:
2355: @example
2356: DO[@emph{:postcondition}]
2357: @end example
2358:
2359: @node ELSE
2360: @section ELSE
2361: @cindex ELSE
2362: @cindex commands, ELSE
2363:
2364: Executes the remainder of the line of code on which @code{ELSE} is encountered only if @code{$TEST} evaluates to @emph{false}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2365:
2366: @emph{Syntax}
2367:
2368: @example
2369: ELSE[@emph{:postcondition}]
2370: @end example
2371:
2372: @cartouche
2373: @quotation
2374: @emph{Non-Standard Behavior}
2375:
2376: FreeM allows a @emph{postcondition} on @code{ELSE}. While explicitly forbidden in the @emph{Standard}, it was decided that FreeM should allow postconditions everywhere, both for the sake of foolish consistency (the likes of which Emerson warned against), and for the benefit of entrants to a hypothetical future obfuscated M contest, and those with a Machiavellian predisposition to wicked perversions and undue cleverness.
2377:
2378: Using postconditions on @code{ELSE} should be strictly avoided in production code, as they have no practical use, and may contribute to technical debt, hardening of the arteries, hobgoblins, a small mind, a surfeit of logic, climate change, @emph{Daily WTF} rants, or the meltdown of global financial markets.
2379: @end quotation
2380: @end cartouche
2381:
2382: @node FOR
2383: @section FOR
2384: @cindex FOR
2385: @cindex commands, FOR
2386:
2387: In its argumentless form, repeatedly executes the remainder of the line on which @code{FOR} was encountered until a @code{QUIT}, @code{GOTO}, or end-of-line is encountered, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2388:
2389: @emph{Syntax}
2390:
2391: @example
2392: FOR[@emph{:postcondition}]
2393: @end example
2394:
2395: @cartouche
2396: @quotation
2397: @emph{Non-Standard Behavior}
2398:
2399: When @code{$DIALECT} is set to @code{FREEM}, FreeM allows a @emph{postcondition} on @code{FOR}. Much like postconditions on @code{ELSE} and @code{IF}, this is explicitly forbidden in the @emph{standard}. The expression contained in the @emph{postcondition} is evaluated on each iteration of the @code{FOR} loop, and if it does not evaluate @emph{true}, the loop will be immediately exited. The effect is roughly similar to @code{WHILE} constructs present in other languages, but absent from standard M.
2400:
2401: As with all non-standard features of FreeM, please exercise caution when using this feature, especially in code that is expected to run in other, less preternaturally-inclined M implementations.
2402: @end quotation
2403: @end cartouche
2404:
2405: In its sentinel form, repeatedly executes the remainder of the line and sets a sentinel variable on each iteration, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2406:
2407: On the first iteration of the loop, @emph{glvn} will be set to @emph{initalizer-expression}. On each subsequent iteration, @emph{glvn} will be incremented by @emph{increment-expression}, and the loop will terminate when @emph{glvn} meets or exceeds the value of @emph{max-expression}.
2408:
2409: @emph{Syntax}
2410:
2411: @example
2412: FOR[@emph{:postcondition}] @emph{glvn}=@emph{initializer-expression}:@emph{increment-expression}:@emph{max-expression}
2413: @end example
2414:
2415: @emph{Example}
2416:
2417: @example
2418: DEFAULT.USER> FOR I=1:1:10 WRITE I,!
2419:
2420: 1
2421: 2
2422: 3
2423: 4
2424: 5
2425: 6
2426: 7
2427: 8
2428: 9
2429: 10
2430:
2431: DEFAULT.USER> FOR I=2:2:10 WRITE I,!
2432:
2433: 2
2434: 4
2435: 6
2436: 8
2437: 10
2438: @end example
2439:
2440: In its explicit parameter form, a variable is set to each of a series of explicit values, once per iteration, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. The loop terminates when no more values are available.
2441:
2442: @emph{Syntax}
2443:
2444: @example
2445: FOR[@emph{:postcondition}] @emph{glvn}=@emph{expr1}[,..@emph{exprN}]
2446: @end example
2447:
2448: @emph{Example}
2449:
2450: @example
2451: DEFAULT.USER> FOR I=60,"FOO",-3,"George",1450,$HOROLOG WRITE I,!
2452:
2453: 60
2454: FOO
2455: -3
2456: George
2457: 1450
2458: 66106,52388
2459: @end example
2460:
2461: @node GOTO
2462: @section GOTO
2463: @cindex GOTO
2464: @cindex commands, GOTO
2465:
2466: Transfers program execution to another line of code, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. Attempting to @code{GOTO} a different line level or a different block when the line level of @code{GOTO} is greater than one will raise error @code{M45}.
2467:
2468: @emph{Syntax}
2469:
2470: @example
2471: GOTO[@emph{:postcondition}] @emph{entryref}
2472: @end example
2473:
2474: @cartouche
2475: @quotation
2476: @emph{Non-Standard Behavior}
2477:
2478: FreeM allows @code{GOTO} @emph{entryref}s to follow the format of @code{+@emph{intexpr}}. In this case, the value of @emph{intexpr} will be interpreted as an offset from the first line of the current routine.
2479: @end quotation
2480: @end cartouche
2481:
2482:
2483: @node HALT
2484: @section HALT
2485: @cindex HALT
2486: @cindex commands, HALT
2487:
2488: Halts program execution and frees resources allocated during execution, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2489:
2490: @emph{Syntax}
2491:
2492: @example
2493: HALT[@emph{:postcondition}]
2494: @end example
2495:
2496: @node HANG
2497: @section HANG
2498: @cindex HANG
2499: @cindex commands, HANG
2500:
2501: Temporarily suspends the program for @emph{expr} seconds, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. Values of @emph{expr} that are zero or less than zero are ignored.
2502:
2503: @emph{Syntax}
2504:
2505: @example
2506: HANG[@emph{:postcondition}] @emph{expr}
2507: @end example
2508:
2509: @cartouche
2510: @quotation
2511: @emph{Non-Standard Behavior}
2512:
2513: FreeM supports sub-second values for @emph{expr}.
2514: @end quotation
2515: @end cartouche
2516:
2517: @node IF
2518: @section IF
2519: @cindex IF
2520: @cindex commands, IF
2521:
2522: In its argumented form, allows the remainder of the line of code following @code{IF} to execute only if all @emph{tvexpr}s evaluate to @emph{true}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2523:
2524: @emph{Syntax}
2525: @example
2526: IF[@emph{:postcondition}] @emph{tvexpr}[,...@emph{tvexpr}]
2527: @end example
2528:
2529: In its argumentless form, allows the remainder of the line of code following @code{IF} to execute only if @code{$TEST} evaluates to @emph{1}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2530:
2531:
2532: @emph{Syntax}
2533: @example
2534: IF[@emph{:postcondition}] @emph{command...}
2535: @end example
2536:
2537: @cartouche
2538: @quotation
2539: @emph{Style Recommendation}
2540:
2541: In the interest of readability and maintainability, we recommend avoiding the argumentless form of @code{IF} in new code. It is an obsolete relic of an era when routine sizes were severely limited, and can be difficult to spot, as the use of whitespace (@code{IF @emph{command}}) makes the intent of its use non-obvious at a glance. It is also far too easy to inadvertently delete the extra space, leading to program errors easily avoided otherwise.
2542:
2543: We recommend explicitly checking the value of @code{$TEST} instead, as in @code{IF $TEST @emph{command}} or @code{@emph{command}:$TEST ...}, as this makes the intent immediately clear both to M newcomers and seasoned experts, and sacrifices nothing of value, even on the oldest computer systems where FreeM can be used today.
2544: @end quotation
2545: @end cartouche
2546:
2547: @node JOB
2548: @section JOB
2549: @cindex JOB
2550: @cindex commands, JOB
2551:
2552: Executes @emph{entryref} in a separate process, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2553:
2554: @emph{Syntax}
2555: @example
2556: JOB[@emph{:postcondition}] @emph{entryref}[:@emph{job-parameters}[:@emph{timeout}]]
2557: @end example
2558:
2559: If @emph{timeout} is supplied, FreeM will set @code{$TEST} to @emph{1} if the child process completes within @emph{timeout} seconds.
2560:
2561: @node KILL
2562: @section KILL
2563: @cindex KILL
2564: @cindex commands, KILL
2565:
2566: In its inclusive form, @code{KILL} deletes the specified @emph{glvn}s and their descendant subscripts, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2567:
2568: @emph{Syntax}
2569: @example
2570: KILL[@emph{:postcondition}] @emph{glvn}[,...@emph{glvn}]
2571: @end example
2572:
2573: In its exclusive form, @code{KILL} deletes all local variables @emph{except} for those specified by @emph{lvn}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2574:
2575: @emph{Syntax}
2576: @example
2577: KILL[@emph{:postcondition}] (@emph{lvn}[,...@emph{lvn}])
2578: @end example
2579:
2580: In its argumentless form, @code{KILL} deletes all local variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2581:
2582: @emph{Syntax}
2583: @example
2584: KILL[@emph{:postcondition}]
2585: @end example
2586:
2587: @node KSUBSCRIPTS
2588: @section KSUBSCRIPTS
2589: @cindex KSUBSCRIPTS
2590: @cindex commands, KSUBSCRIPTS
2591:
2592: Kills only the descendant subscripts (but not the data value) of a referenced global, local, or SSVN (where allowed).
2593:
2594: @emph{Syntax}
2595:
2596: @example
2597: KSUBSCRIPTS@emph{:postcondition} @emph{var1},...
2598: @end example
2599:
2600: In the above @emph{inclusive} form, @code{KVALUE} will kill the descendant subscripts at each local, global, or SSVN node specified in the list (provided that the optional @emph{postcondition} is @emph{true} or omitted), but will leave the data value intact.
2601:
2602: @cartouche
2603: @quotation
2604: @emph{Note}
2605: The below @emph{argumentless} and @emph{exclusive} forms of @code{KSUBSCRIPTS} are not implemented in FreeM, as of version 0.64.0-rc1, but are planned for a future release.
2606: @end quotation
2607: @end cartouche
2608:
2609: @example
2610: KSUBSCRIPTS@emph{:postcondition}
2611: @end example
2612:
2613: In the above @emph{argumentless} form, @code{KSUBSCRIPTS} will kill the descendant subscripts at the root of each local variable (provided that the optional @emph{postcondition} is @emph{true} or omitted), but will leave data values intact.
2614:
2615: @example
2616: KSUBSCRIPTS@emph{:postcondition} (@emph{var1},...)
2617: @end example
2618:
2619: In the above @emph{exclusive} form, @code{KSUBSCRIPTS} will kill the descendant subscripts of all local variables, @emph{with the exception of} those named in the list, provided that the optional @emph{postcondition} is @emph{true} or omitted, while leaving their data values intact.
2620:
2621:
2622: @node KVALUE
2623: @section KVALUE
2624: @cindex KVALUE
2625: @cindex commands, KVALUE
2626:
2627: Kills only the data value (but not descendant subscripts) of a referenced global, local, or SSVN (where allowed).
2628:
2629: @emph{Syntax}
2630:
2631: @example
2632: KVALUE@emph{:postcondition} @emph{var1},...
2633: @end example
2634:
2635: In the above @emph{inclusive} form, @code{KVALUE} will kill the data values at each local, global, or SSVN node specified in the list (provided that the optional @emph{postcondition} is @emph{true} or omitted), but will leave descendant subscripts intact.
2636:
2637: @cartouche
2638: @quotation
2639: @emph{Note}
2640: The below @emph{argumentless} and @emph{exclusive} forms of @code{KVALUE} are not implemented in FreeM, as of version 0.64.0-rc1, but are planned for a future release.
2641: @end quotation
2642: @end cartouche
2643:
2644: @example
2645: KVALUE@emph{:postcondition}
2646: @end example
2647:
2648: In the above @emph{argumentless} form, @code{KVALUE} will kill the data values at the root of each local variable (provided that the optional @emph{postcondition} is @emph{true} or omitted), but will leave descendant subscripts intact.
2649:
2650: @example
2651: KVALUE@emph{:postcondition} (@emph{var1},...)
2652: @end example
2653:
2654: In the above @emph{exclusive} form, @code{KVALUE} will kill the data values of all local variables, @emph{with the exception of} those named in the list, provided that the optional @emph{postcondition} is @emph{true} or omitted, while leaving their descendant subscripts intact.
2655:
2656: @node LOCK
2657: @section LOCK
2658: @cindex LOCK
2659: @cindex commands, LOCK
2660:
2661: Acquires or releases ownership of names.
2662:
2663: In its argumentless form, @code{LOCK} releases ownership of all names previously locked by the current process, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2664:
2665: @emph{Syntax}
2666: @example
2667: LOCK[@emph{:postcondition}]
2668: @end example
2669:
2670: In its incremental form, increments or decrements the lock counter for each specified @emph{name}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. Ownership of each @emph{name} is considered to be the current process as long as the lock counter for @emph{name} is greater than zero. If @emph{timeout} is specified, FreeM will wait no more than @emph{timeout} seconds in attempting to acquire ownership of @emph{name}.
2671:
2672: If @code{LOCK} succeeds within @emph{timeout}, @code{$TEST} is set to @emph{1}. Otherwise, @code{$TEST} is set to @emph{0}.
2673:
2674: @emph{Syntax}
2675: @example
2676: LOCK[@emph{:postcondition}] [+|-]@emph{name}[:@emph{timeout}][,...[+|-]@emph{name}[:@emph{timeout}]]
2677: @end example
2678:
2679: @emph{Example}
2680:
2681: This example will increment the lock counter for @code{^SNW} and decrement the lock counter for @code{^MJR}.
2682:
2683: @example
2684: LOCK +^SNW,-^MJR
2685: @end example
2686:
2687: In its non-incremental form, @code{LOCK} releases all @code{LOCK}s held by the current process, and then attempts to acquire a lock on each @emph{name}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. If @emph{timeout} is supplied, FreeM will attempt to lock @emph{name} for no more than @emph{timeout} seconds.
2688:
2689: If @code{LOCK} succeeds within @emph{timeout}, @code{$TEST} is set to @emph{1}. Otherwise, @code{$TEST} is set to @emph{0}.
2690:
2691: @emph{Syntax}
2692: @example
2693: LOCK[@emph{:postcondition}] @emph{name}[:@emph{timeout}][,...@emph{name}[:@emph{timeout}]]
2694: @end example
2695:
2696: @node MERGE
2697: @section MERGE
2698: @cindex MERGE
2699: @cindex commands, MERGE
2700:
2701: Merges the contents of one global, local, or SSVN subtree to another global, local, or SSVN.
2702:
2703: @emph{Syntax}
2704:
2705: @example
2706: @code{MERGE A=^$JOB}
2707: @end example
2708:
2709: The above example will merge the @code{^$JOB} SSVN into the @code{A} local. Note that the FreeM implementation of @code{MERGE} does not yet support multiple merge arguments. Returns error @code{M19} if either the source or the target variable are descendants of each other.
2710:
2711: @node NEW
2712: @section NEW
2713: @cindex NEW
2714: @cindex commands, NEW
2715:
2716: In all forms of @code{NEW}, @emph{name} must be a local variable name or @code{NEW}-able structured or intrinsic system variable.
2717:
2718: In its inclusive form, @code{NEW} saves each specified @emph{name} on the process stack and removes it, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. When the current stack frame is exited, the previous values are restored.
2719:
2720: @emph{Syntax}
2721:
2722: @example
2723: NEW[@emph{:postcondition}] @emph{name}[,...@emph{name}]
2724: @end example
2725:
2726: In its exclusive form, @code{NEW} saves all local variables @emph{except} those named (each @emph{name}) and removes them, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. When the current stack frame is exited, the previous values are restored.
2727:
2728: @emph{Syntax}
2729: @example
2730: NEW[@emph{:postcondition}] (@emph{name}[,...@emph{name}])
2731: @end example
2732:
2733: In its argumentless form, @code{NEW} saves all local variables and removes them, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. When the current stack frame is exited, the previous values are restored.
2734:
2735: @emph{Syntax}
2736: @example
2737: NEW@emph{:postcondition} @emph{name}=@emph{expr}
2738: @end example
2739:
2740: In its initializing form, @code{NEW} stacks variable @emph{name} and sets its value to @emph{expr}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. When the current stack frame is exited, the previous value is restored.
2741:
2742: @emph{Syntax}
2743: @example
2744: NEW@emph{:postcondition} @emph{name}=$%@emph{^CLASS}(@emph{initializer-list})
2745: @end example
2746:
2747: In its object-oriented form, @code{NEW} creates an instance of class @emph{^CLASS} in local variable @emph{name} and calls the constructor of @emph{^CLASS}, passing @emph{initializer-list} as its argument(s).
2748:
2749: @node OPEN
2750: @section OPEN
2751: @cindex OPEN
2752: @cindex commands, OPEN
2753:
2754: Opens sequential or socket I/O devices and files and associates them with a numeric FreeM input/output channel.
2755:
2756: @emph{Syntax (Sequential Files)}
2757:
2758: @example
2759: @code{OPEN@emph{:postcondition} @emph{channel}:"@emph{filename}/@emph{access-mode}"}
2760: @end example
2761:
2762: Opens @emph{filename} for reading and/or writing, and associates the file with FreeM I/O channel @emph{channel}, provided that the optional @emph{postcondition} is @emph{true} or omitted.
2763: The below table lists the valid options for @emph{access-mode}:
2764:
2765: @table @code
2766: @item r
2767: Read-only access
2768: @item w
2769: Create a new file for write access
2770: @item a
2771: Write access; append to existing file
2772: @item r+
2773: Read/write access
2774: @end table
2775:
2776: @cartouche
2777: @quotation
2778: @emph{I/O Path}
2779:
2780: You cannot specify a fully-qualified filesystem path in the FreeM @code{OPEN} command. By default, FreeM will assume that @emph{filename} exists in the directory indicated in @code{^$JOB($JOB,"CWD")}. If you wish to
2781: access files in other directories, you must first set the @emph{I/O Path} in @code{^$JOB($JOB,"IOPATH")}.
2782:
2783: The following example will set the I/O path to @code{/etc}:
2784:
2785: @example
2786: @code{SET ^$JOB($JOB,"IOPATH")="/etc"}
2787: @end example
2788:
2789: @end quotation
2790: @end cartouche
2791:
2792: If @emph{channel} was already @code{OPEN}ed in the current process, calling @code{OPEN} on the same channel again implicitly closes the file or device currently associated with @emph{channel}.
2793:
2794: @emph{Syntax (Network Sockets)}
2795:
2796: Network sockets use a dedicated range of FreeM I/O channels ranging from 100-255. @code{OPEN}ing a socket I/O channel does @emph{not} implicitly connect the socket. Connecting the socket to the specified remote host is accomplished by the @code{/CONNECT} control mnemonic supplied to the @code{USE} command.
2797:
2798: @example
2799: OPEN@emph{:postcondition} @emph{socket-channel}:"@emph{hostname-or-address}:@emph{port}:@emph{address-family}:@emph{connection-type}"
2800: @end example
2801:
2802: @emph{Socket Parameters}
2803:
2804: @table @emph
2805:
2806: @item socket-channel
2807: The socket I/O channel to use. This must be in the range of 100-255.
2808:
2809: @item hostname-or-address
2810: The hostname or IP address to connect to. If a hostname is supplied, @code{OPEN} will implictly do a name lookup, the mechanism of which is typically determined by the configuration of @code{/etc/nsswitch.conf} on most UNIX and UNIX-like platforms.
2811:
2812: @item port
2813: The TCP or UDP port to which the socket will connect on the remote host.
2814:
2815: @item address-family
2816: The address family to use. Either @emph{IPV4} or @emph{IPV6}.
2817:
2818: @item connection-type
2819: Which connection type to use. Either @emph{TCP} or @emph{UDP}.
2820:
2821: @end table
2822:
2823: If you do not specify the address family and connection type, they will default to @emph{IPV4} and @emph{TCP}, respectively.
2824:
2825: @node QUIT
2826: @section QUIT
2827: @cindex QUIT
2828: @cindex commands, QUIT
2829:
2830: @code{QUIT} will end execution of the current process level, optionally returning @emph{expr}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2831:
2832: @code{QUIT} with @emph{expr} when an argument is not expected will raise error @code{M16}; @code{QUIT} without @emph{expr} when an argument is expected will raise error @code{M17}.
2833:
2834: Argumentless @code{QUIT} may also be used to exit a @code{FOR} loop occurring on the same line.
2835:
2836: @emph{Syntax}
2837: @example
2838: QUIT[@emph{:postcondition}] [@emph{expr}]
2839: @end example
2840:
2841: @node READ
2842: @section READ
2843: @cindex READ
2844: @cindex commands, READ
2845:
2846: The @code{READ} command takes input from I/O channel @code{$IO} and stores it into specified variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2847:
2848: @emph{Syntax}
2849: @example
2850: READ[@emph{:postcondition}] @emph{read-argument}[,...@emph{read-argument}]
2851: @end example
2852:
2853: Each @emph{read-argument} may be one of the following:
2854:
2855: @table @asis
2856:
2857: @item String Literal
2858: String literal @emph{read-argument}s will be output to @code{$IO} unmodified.
2859:
2860: @item Format Specifier
2861: One or more of the following:
2862:
2863: @table @asis
2864: @item @code{!} (newline)
2865: Advances the cursor down by one line and returns it to the first column.
2866:
2867: @item @code{#} (form-feed)
2868: Advances the screen down by @code{$ZROWS} and moves the cursor to the upper-left corner of the screen.
2869:
2870: @item @code{?@emph{n}} (position)
2871: Advances the cursor and @code{$X} forward to position @emph{n}.
2872:
2873: @end table
2874:
2875: @item Single-Character Read (@code{*@emph{variable-name}[@emph{:timeout}]})
2876: Reads one character into variable @emph{variable-name}. If the optional @emph{timeout} is specified, will wait @emph{timeout} seconds to retrieve one character. If a character is read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{1}. If no character is read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{0}.
2877:
2878: @item Variable-Length Character Read (@code{@emph{variable-name}[@emph{:timeout}]})
2879: Reads characters into @emph{variable-name} until the character or character pair in @code{^$DEVICE(@emph{io-channel},"OPTIONS","TERMINATOR")} is encountered. If the optional @emph{timeout} is specified, will wait @emph{timeout} seconds to retrieve characters. If characters are read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{1}. If no character is read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{0}.
2880:
2881: @item Fixed-Length Character Read (@code{@emph{variable-name}#@emph{count}[@emph{:timeout}]})
2882: Reads @emph{count} characters into @emph{variable-name}. If the optional @emph{timeout} is specified, will wait @emph{timeout} seconds to retrieve characters. If characters are read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{1}. If no character is read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{0}.
2883:
2884: @item Control Mnemonic (@code{/@emph{control-mnemonic}[@emph{(arg1[,...argN])}]})
2885: Outputs X3.64 control mnemonic @emph{control-mnemonic} to @code{$IO}. Please see the appendix on X3.64 Control Mnemonics for more information.
2886:
2887: @end table
2888:
2889: @node SET
2890: @section SET
2891: @cindex SET
2892: @cindex commands, SET
2893:
2894: The @code{SET} command places values into one or more variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2895:
2896: @emph{Syntax}
2897: @example
2898: SET[@emph{:postcondition}] @emph{set-argument}[=@emph{expression} | @emph{postfix-operator}][@emph{,...set-argument}[=@emph{expression} | @emph{postfix-operator}]]
2899: @end example
2900:
2901: Each @emph{set-argument} can be:
2902:
2903: @table @asis
2904: @item @emph{variable-name}
2905: A local variable, global variable, writable intrinsic special variable, or writable structured system variable.
2906:
2907: @item @emph{lhs-function}
2908: @code{$EXTRACT} or @code{$PIECE}.
2909: @end table
2910:
2911: If any grouping of @emph{set-argument}s is surrounded by parentheses, all @emph{set-argument}s in the parenthesized group will be set to the result of @emph{expression}.
2912:
2913: If @emph{postfix-operator} is used instead of @code{=@emph{expression}}, the results of applying @emph{postfix-operator} to the @emph{set-argument} will be stored in @emph{set-argument}. @emph{postfix-operator} may not be used following a parenthesized group of @emph{set-argument}s.
2914:
2915: @emph{Example (postfix-operator)}
2916:
2917: @example
2918: SET A++,B-- ; increments A, decrements B
2919: @end example
2920:
2921: @node TCOMMIT
2922: @section TCOMMIT
2923: @cindex TCOMMIT
2924: @cindex commands, TCOMMIT
2925:
2926: Commits all pending transactions to the data files, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2927:
2928: @emph{Syntax}
2929: @example
2930: TCOMMIT[@emph{:postcondition}]
2931: @end example
2932:
2933: @node THEN
2934: @section THEN
2935: @cindex THEN
2936: @cindex commands, THEN
2937:
2938: Saves the value of @code{$TEST} until the end of the current line, restoring it at the end of the current line or when a @code{QUIT} is encountered. @code{THEN} should be used in all new code in conjunction with @code{IF}.
2939:
2940: @emph{Example}
2941: @example
2942: IF 1 THEN WRITE "HELLO!",!
2943: @end example
2944:
2945: @node TROLLBACK
2946: @section TROLLBACK
2947: @cindex TROLLBACK
2948: @cindex commands, TROLLBACK
2949:
2950: Rolls back all pending transactions for the current process, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2951:
2952: @emph{Syntax}
2953:
2954: @example
2955: TROLLBACK[@emph{:postcondition}]
2956: @end example
2957:
2958: @node TSTART
2959: @section TSTART
2960: @cindex TSTART
2961: @cindex commands, TSTART
2962:
2963: Introduces a new transaction level, incrementing @code{$TLEVEL}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted. Any global data file operations encountered when @code{$TLEVEL} is greater than zero will not be committed to the global data files until @code{TCOMMIT} is encountered.
2964:
2965: If a transaction is restartable, variables in the @emph{variables-list} will be restored to their original values on a restart of the transaction.
2966:
2967: @emph{Syntax}
2968:
2969: @example
2970: TSTART[@emph{:postcondition}] @emph{<variables-list>}:@emph{<transaction-parameters>}
2971: @end example
2972:
2973: @emph{<variables-list>} can be:
2974:
2975: @table @asis
2976:
2977: @item @code{()}
2978: Do not save off any local variables. Makes the transaction non-restartable.
2979:
2980: @item @code{*}
2981: Save off all local variables. Makes the transaction restartable.
2982:
2983: @item @code{@emph{variableName}}
2984: Saves off only one local variable, @emph{variableName}. Makes the transaction restartable.
2985:
2986: @item @code{(@emph{variableName1},...,@emph{variableNameN})}
2987: Saves off all local variables listed. Makes the transaction restartable.
2988:
2989: @end table
2990:
2991: @emph{<transaction-parameters>} can be:
2992:
2993: @table @asis
2994:
2995: @item @code{S[ERIAL]}
2996: Forces ACID properties on the transaction. When @code{SERIAL} is not selected, transactions occur in batch mode, and no attempt is made to guarantee ACID properties.
2997:
2998: @item @code{T[RANSACTIONID]=@emph{transaction-id}}
2999: Sets the ID of the transaction to @emph{transaction-id}
3000:
3001: @end table
3002:
3003: If you are using more than one transaction parameter, surround all of them in parentheses and separate them with commas, e.g.:
3004:
3005: @example
3006: TSTART (FOO,BAR):(SERIAL,TRANSACTIONID="FOO")
3007: @end example
3008:
3009:
3010: @node USE
3011: @section USE
3012: @cindex USE
3013: @cindex commands, USE
3014:
3015: Sets @code{$IO} to a particular FreeM I/O channel, allowing @code{READ}s from and @code{WRITE}s to the associated terminal, sequential file, or network socket. Also sets various device parameters.
3016:
3017: @emph{Syntax (Terminal)}
3018:
3019: @example
3020: USE@emph{:postcondition} @emph{io-channel}[:(@emph{right-margin}:@emph{input-field-length}:@emph{device-status-word}:@emph{position}:@emph{line-terminator}:@emph{break-key})]
3021: @end example
3022:
3023: For terminals, @emph{io-channel} must be 0.
3024:
3025: Semantic and functional description of each device parameter TBA.
3026:
3027: @emph{Syntax (Sequential Files)}
3028:
3029: @example
3030: USE@emph{:postcondition} @emph{io-channel}[:@emph{seek-position}:@emph{terminator}:@emph{nodelay})]
3031: @end example
3032:
3033: For sequential files, @emph{io-channel} must be in the range 1-99.
3034:
3035: Semantic and functional description of each device parameter TBA.
3036:
3037: @emph{Syntax (Network Sockets)}
3038:
3039: @example
3040: USE@emph{:postcondition} @emph{io-channel}
3041: @end example
3042:
3043: The above syntax will set @code{$IO} to @emph{io-channel}, directing successive @code{READ}s and @code{WRITE}s to @emph{io-channel}, provided the optional @emph{postcondition} is @emph{true} or omitted.
3044:
3045: @example
3046: USE@emph{:postcondition} @emph{io-channel}:/CONNECT
3047: @end example
3048:
3049: The above syntax will set @code{$IO} to @emph{io-channel}, as in the prior example, but will also attempt to connect to the host and port specified for @emph{io-channel} when it was @code{OPEN}ed. The @code{/CONNECT} control mnemonic is only valid for socket channels whose connection type is @code{TCP}. Using @code{/CONNECT} on a @code{UDP} socket channel will throw @code{SCKAERR} (error code 55).
3050:
3051: For network sockets, @emph{io-channel} must be in the range 100-255.
3052:
3053: @node VIEW
3054: @section VIEW
3055: @cindex VIEW
3056: @cindex commands, VIEW
3057:
3058: Provides write access to various FreeM internal parameters, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
3059:
3060: @emph{Syntax}
3061: @example
3062: VIEW[@emph{:postcondition}] @emph{view-number}[:@emph{view-argument}[:@emph{view-argument}...]]
3063: @end example
3064:
3065: The @emph{view-number} argument can be one of the following:
3066:
3067: @table @asis
3068:
3069: @item @code{21} - Close All Globals
3070: Closes all global data files open in the current process. Takes no arguments.
3071:
3072: @emph{Syntax}
3073: @example
3074: VIEW 21
3075: @end example
3076:
3077: @item @code{52} - Set G0 Input Translation Table for @code{$IO}
3078:
3079: @emph{Syntax}
3080: @example
3081: VIEW 52:@emph{expr V trantab}
3082: @end example
3083:
3084: @item @code{53} - Set G0 Output Translation Table for @code{$IO}
3085:
3086: @emph{Syntax}
3087: @example
3088: VIEW 53:@emph{expr V trantab}
3089: @end example
3090:
3091: @item @code{54} - Set G1 Input Translation Table for @code{$IO}
3092:
3093: @emph{Syntax}
3094: @example
3095: VIEW 54:@emph{expr V trantab}
3096: @end example
3097:
3098: @item @code{55} - Set G1 Output Translation Table for @code{$IO}
3099:
3100: @emph{Syntax}
3101: @example
3102: VIEW 55:@emph{expr V trantab}
3103: @end example
3104:
3105: @item @code{62} - Set @code{$RANDOM} Seed Number
3106: Sets the seed number used by @code{$RANDOM} to @emph{numexpr}.
3107:
3108: @emph{Syntax}
3109: @example
3110: VIEW 62:@emph{numexpr}
3111: @end example
3112:
3113: @item @code{63} - Set @code{$RANDOM} Parameter A
3114: Sets the number used for @code{$RANDOM} Parameter A to @emph{numexpr}.
3115:
3116: @emph{Syntax}
3117: @example
3118: VIEW 63:@emph{numexpr}
3119: @end example
3120:
3121: @item @code{64} - Set @code{$RANDOM} Parameter B
3122: Sets the number used for @code{$RANDOM} Parameter B to @emph{numexpr}.
3123:
3124: @emph{Syntax}
3125: @example
3126: VIEW 64:@emph{numexpr}
3127: @end example
3128:
3129: @item @code{65} - Set @code{$RANDOM} Parameter C
3130: Sets the number used for @code{$RANDOM} Parameter C to @emph{numexpr}.
3131:
3132: @emph{Syntax}
3133: @example
3134: VIEW 65:@emph{numexpr}
3135: @end example
3136:
3137: @item @code{66} - Set or Clear @code{SIGTERM} Handling Flag
3138: Enables or disables handling of @code{SIGTERM} UNIX signals. If @emph{tvexpr} evaluates to 1 (@emph{true}), @code{SIGTERM} handling will be enabled. Otherwise, @code{SIGTERM} handling will be disabled.
3139:
3140: @emph{Syntax}
3141: @example
3142: VIEW 66:@emph{tvexpr}
3143: @end example
3144:
3145: @item @code{67} - Set or Clear @code{SIGHUP} Handling Flag
3146: Enables or disables handling of @code{SIGHUP} UNIX signals. If @emph{tvexpr} evaluates to 1 (@emph{true}), @code{SIGHUP} handling will be enabled. Otherwise, @code{SIGHUP} handling will be disabled.
3147:
3148: @emph{Syntax}
3149: @example
3150: VIEW 67:@emph{tvexpr}
3151: @end example
3152:
3153: @item @code{70} - Set @code{$ZSORT}/@code{$ZSYNTAX} Flag
3154: Selects whether @code{$ZS} resolves to @code{$ZSORT} or @code{$ZSYNTAX}.
3155:
3156: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZSYNTAX}. Otherwise, selects @code{$ZSORT}.
3157:
3158: @emph{Syntax}
3159: @example
3160: VIEW 70:@emph{tvexpr}
3161: @end example
3162:
3163: @item @code{71} - Set @code{$ZNEXT}/@code{$ZNAME} Flag
3164: Selects whether @code{$ZN} resolves to @code{$ZNEXT} or @code{$ZNAME}.
3165:
3166: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZNAME}. Otherwise, selects @code{$ZNEXT}.
3167:
3168: @emph{Syntax}
3169: @example
3170: VIEW 71:@emph{tvexpr}
3171: @end example
3172:
3173: @item @code{72} - Set @code{$ZPREVIOUS}/@code{$ZPIECE} Flag
3174: Selects whether @code{$ZP} resolves to @code{$ZPREVIOUS} or @code{$ZPIECE}.
3175:
3176: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZPIECE}. Otherwise, selects @code{$ZPREVIOUS}.
3177:
3178: @emph{Syntax}
3179: @example
3180: VIEW 72:@emph{tvexpr}
3181: @end example
3182:
3183: @item @code{73} - Set @code{$ZDATA}/@code{$ZDATE} Flag
3184: Selects whether @code{$ZD} resolves to @code{$ZDATA} or @code{$ZDATE}.
3185:
3186: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZDATE}. Otherwise, selects @code{$ZDATA}.
3187:
3188: @emph{Syntax}
3189: @example
3190: VIEW 73:@emph{tvexpr}
3191: @end example
3192:
3193: @item @code{79} - Set Old @code{ZJOB} vs. New @code{ZJOB} Flag
3194: If @emph{tvexpr} evaluates to @emph{true}, sets the @code{ZJOB} mode to new, otherwise, sets it to old.
3195:
3196: @emph{Syntax}
3197: @example
3198: VIEW 79:@emph{tvexpr}
3199: @end example
3200:
3201: @item @code{80} - Set or Clear 8-Bit Flag
3202: If @emph{tvexpr} evaluates to @emph{true}, sets FreeM to 8-bit mode. Otherwise, sets FreeM to 7-bit mode.
3203:
3204: @emph{Syntax}
3205: @example
3206: VIEW 80:@emph{tvexpr}
3207: @end example
3208:
3209: @item @code{81} - Set or Clear PF1 Flag
3210: If @emph{tvexpr} evaluates to @emph{true}, sets the @code{PF1} flag. We do not yet know what this does.
3211:
3212: @emph{Syntax}
3213: @example
3214: VIEW 81:@emph{tvexpr}
3215: @end example
3216:
3217: @item @code{83} - Set or Clear Text in @code{$ZERROR} Flag
3218: If @emph{tvexpr} evaluates to @emph{true}, descriptive error messages will be included in @code{$ZERROR}. Otherwise, only the short error code (i.e. @emph{ZILLFUN}) will be included in @code{$ZERROR}.
3219:
3220: @emph{Syntax}
3221: @example
3222: VIEW 83:@emph{tvexpr}
3223: @end example
3224:
3225: @item @code{92} - Set Type Mismatch Error Flag on @code{EUR2DEM}
3226: If @emph{tvexpr} evaluates to @emph{true}, a type mismatch error will be thrown in @code{EUR2DEM} currency conversions in certain situations that we do not yet understand.
3227:
3228: @emph{Syntax}
3229: @example
3230: VIEW 92:@emph{tvexpr}
3231: @end example
3232:
3233: @item @code{93} - Define @code{ZKEY} Production Rule
3234: We do not know what this does.
3235:
3236: @item @code{96} - Set Global Prefix
3237: Forces global data filenames to be prefixed with the result of @emph{expr}.
3238:
3239: @emph{Syntax}
3240: @example
3241: VIEW 96:@emph{expr V string}
3242: @end example
3243:
3244: @item @code{97} - Set Global Postfix
3245: Forces global data filenames to be postfixed with the result of @emph{expr}.
3246:
3247: @emph{Syntax}
3248: @example
3249: VIEW 97:@emph{expr V string}
3250: @end example
3251:
3252: @item @code{98} - Set Routine Extension
3253: Sets the default extension for M routine filenames to the result of @emph{expr}.
3254:
3255: @emph{Syntax}
3256: @example
3257: VIEW 98:@emph{expr V string}
3258: @end example
3259:
3260: @item @code{101} - Set @code{ierr}
3261: Sets the FreeM internal @code{ierr} value to @emph{intexpr}. Used by some FreeM polyfills (commands or functions implemented in M code).
3262:
3263: @emph{Syntax}
3264: @example
3265: VIEW 101:@emph{intexpr}
3266: @end example
3267:
3268: @item @code{102} - Set @code{ierr} (Deferred)
3269: Sets the FreeM internal @code{ierr} value to @emph{intexpr}, but only after the current process stack level is exited. Used by FreeM polyfills to throw an error that will appear to come from the user's own code rather than the polyfill implementation M code.
3270:
3271: @emph{Syntax}
3272: @example
3273: VIEW 102:@emph{intexpr}
3274: @end example
3275:
3276: @item @code{103} - Signal @code{MERGE} to @code{^$WINDOW} Complete
3277: Signals FreeM's MWAPI implementation that a @code{MERGE} to @code{^$WINDOW} or descendant subscripts thereof has completed.
3278:
3279: @emph{Syntax}
3280: @example
3281: VIEW 103[@emph{:subscript}]
3282: @end example
3283:
3284: @item @code{110} - Set Local @code{$ORDER}/@code{$QUERY} Data Value
3285: Sets the local variable @code{$ORDER}/@code{$QUERY} data value to the result of @emph{expr}. We're not entirely sure what this is.
3286:
3287: @emph{Syntax}
3288: @example
3289: VIEW 110:@emph{expr}
3290: @end example
3291:
3292: @item @code{111} - Set Global @code{$ORDER}/@code{$QUERY} Data Value
3293: Sets the global variable @code{$ORDER}/@code{$QUERY} data value to the result of @emph{expr}. We're not entirely sure what this is.
3294:
3295: @emph{Syntax}
3296: @example
3297: VIEW 111:@emph{expr}
3298: @end example
3299:
3300: @item @code{113} - Set @code{termio} Information
3301: We don't know what this does.
3302:
3303: @item @code{133} - Remember @code{ZLOAD} Directory on @code{ZSAVE}
3304: We don't know what this does, but it takes a @emph{tvexpr}.
3305:
3306: @emph{Syntax}
3307: @example
3308: VIEW 133:@emph{tvexpr}
3309: @end example
3310:
3311: @end table
3312:
3313:
3314:
3315: @node WRITE
3316: @section WRITE
3317: @cindex WRITE
3318: @cindex commands, WRITE
3319:
3320: @node XECUTE
3321: @section XECUTE
3322: @cindex XECUTE
3323: @cindex commands, XECUTE
3324:
3325: @node ZASSERT
3326: @section ZASSERT
3327: @cindex ZASSERT
3328: @cindex commands, ZASSERT
3329: @cindex commands, debugging
3330: @cindex commands, implementation-specific
3331: @cindex commands, non-standard
3332: @emph{FreeM Extension}
3333:
3334: Triggers error @code{ZASSERT} if the supplied truth-valued expression @emph{tvexpr} is @emph{false} (@emph{1} is @emph{true}, and @emph{0} is @emph{false}), and that the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
3335:
3336: The @code{ZASSERT} error is catchable whether using standard-style, FreeM-style, or DSM 2.0-style error processing.
3337:
3338: @emph{Syntax}
3339:
3340: @example
3341: ZASSERT@emph{:postcondition} @emph{<tvexpr>}
3342: @end example
3343:
3344: @emph{Example}
3345:
3346: @example
3347: DEFAULT.USER> SET DEBUG=1
3348:
3349:
3350: DEFAULT.USER> ZASSERT:DEBUG 1=1
3351:
3352:
3353: DEFAULT.USER> ZASSERT:DEBUG 1=0
3354:
3355:
3356: >> Error ZASSERT: programmer assertion failed in SYSTEM::^%SYSINIT [$STACK = 0]
3357: >> ZASSERT:DEBUG 1=0
3358: ^
3359: @end example
3360:
3361: @node ZBREAK
3362: @section ZBREAK
3363: @cindex ZBREAK
3364: @cindex commands, ZBREAK
3365: @cindex commands, debugging
3366: @cindex commands, implementation-specific
3367: @cindex commands, non-standard
3368: @emph{FreeM Extension}
3369:
3370: Sets or clears the @code{ZBREAK} flag@footnote{NOTE: FreeM team needs to investigate how @code{zbreakon} and @code{zbflag} affect program execution.}, based on the result of evaluating @emph{tvexpr}.
3371:
3372: @emph{Syntax}
3373:
3374: @example
3375: ZBREAK @emph{tvexpr}
3376: @end example
3377:
3378: @node ZCONST
3379: @section ZCONST
3380: @cindex ZCONST
3381: @cindex commands, ZCONST
3382: @cindex commands, non-standard
3383: @emph{FreeM Extension}
3384:
3385: Defines a local @emph{constant}, or variable that cannot be altered after its initial definition, provided the optional @emph{postcondition} is @emph{true} or omitted.
3386:
3387: Constants must only be locals, and globals are not supported.
3388:
3389: @emph{Syntax}
3390:
3391: @example
3392: @code{ZCONST@emph{:postcondition} @emph{mref1}=@emph{initial-value1},...,@emph{mrefN}=@emph{initial-valueN}}
3393: @end example
3394:
3395: @node ZGOTO
3396: @section ZGOTO
3397: @cindex ZGOTO
3398: @cindex commands, ZGOTO
3399: @cindex commands, implementation-specific
3400: @cindex commands, non-standard
3401: @emph{FreeM Extension}
3402:
3403: In its argumented form, enables @code{BREAK} mode and branches unconditionally to @emph{entryref}.
3404:
3405: @emph{Syntax}
3406:
3407: @example
3408: ZGOTO @emph{entryref}
3409: @end example
3410:
3411: In its argumented form, resumes execution after a @code{BREAK}.
3412:
3413: @emph{Syntax}
3414:
3415: @example
3416: ZGOTO
3417: @end example
3418:
3419: @node ZHALT
3420: @section ZHALT
3421: @cindex ZHALT
3422: @cindex commands, ZHALT
3423: @cindex commands, implementation-specific
3424: @cindex commands, non-standard
3425: @emph{FreeM Extension}
3426:
3427: In its single-argumented form, @code{ZHALT} command is used to exit the FreeM process with a specific return value @emph{intexpr}.
3428:
3429: @emph{Syntax}
3430:
3431: @example
3432: ZHALT @emph{intexpr}
3433: @end example
3434:
3435: In its argumentless form, @code{ZHALT} is synonymous with @code{HALT}.
3436:
3437: @emph{Syntax}
3438:
3439: @example
3440: ZHALT
3441: @end example
3442:
3443: @node ZINSERT
3444: @section ZINSERT
3445: @cindex ZINSERT
3446: @cindex commands, ZINSERT
3447: @cindex commands, implementation-specific
3448: @cindex commands, non-standard
3449: @emph{FreeM Extension}
3450:
3451: @node ZJOB
3452: @section ZJOB
3453: @cindex ZJOB
3454: @cindex commands, ZJOB
3455: @cindex commands, implementation-specific
3456: @cindex commands, non-standard
3457: @emph{FreeM Extension}
3458:
3459: When @code{ZJOB} is used, the semantics are identical to @code{JOB}, with the exception that the @emph{timeout} is forced to be @code{0}, regardless of what the user specifies.
3460:
3461: For more information, see @code{JOB}.
3462:
3463: @node ZLOAD
3464: @section ZLOAD
3465: @cindex ZLOAD
3466: @cindex commands, ZLOAD
3467: @cindex commands, implementation-specific
3468: @cindex commands, non-standard
3469: @emph{FreeM Extension}
3470:
3471: Loads routine @emph{<routine-name>} into FreeM's routine buffer, provided the optional @emph{postcondition} is @emph{true} or omitted.
3472:
3473: @emph{Syntax}
3474:
3475: @example
3476: ZLOAD@emph{:postcondition} @emph{<routine-name>}
3477: @end example
3478:
3479:
3480: @node ZMAP
3481: @section ZMAP
3482: @cindex ZMAP
3483: @cindex commands, ZMAP
3484: @cindex commands, implementation-specific
3485: @cindex commands, non-standard
3486:
3487: Maps global name @code{gvn} to be mapped to the non-default namespace @emph{expr V namespace}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
3488:
3489: @emph{Syntax}
3490:
3491: @example
3492: ZMAP[@emph{:postcondition}] GLOBAL @emph{gvn}=@emph{expr V namespace}
3493: @end example
3494:
3495: @node ZNEW
3496: @section ZNEW
3497: @cindex ZNEW
3498: @cindex commands, ZNEW
3499: @cindex commands, implementation-specific
3500: @cindex commands, non-standard
3501: @emph{FreeM Extension}
3502:
3503: @node ZPRINT
3504: @section ZPRINT
3505: @cindex ZPRINT
3506: @cindex commands, ZPRINT
3507: @cindex commands, implementation-specific
3508: @cindex commands, non-standard
3509: @emph{FreeM Extension}
3510:
3511: Prints the contents of the current routine buffer, provided the optional @emph{postcondition} is @emph{true} or omitted.
3512:
3513: @emph{Syntax}
3514:
3515: @example
3516: ZPRINT@emph{:postcondition}
3517: @end example
3518:
3519: @node ZQUIT
3520: @section ZQUIT
3521: @cindex ZQUIT
3522: @cindex commands, ZQUIT
3523: @cindex commands, implementation-specific
3524: @cindex commands, non-standard
3525: @emph{FreeM Extension}
3526:
3527: In its single-argument form, quits from @emph{levels} levels of the stack, provided the optional @emph{postcondition} is @emph{true} or omitted.
3528:
3529: In its argumentless form, quits from @code{$STACK} levels of the stack, provided the optional @emph{postcondition} is @emph{true} or omitted.
3530:
3531: @emph{Syntax}
3532:
3533: @example
3534: @code{ZQUIT@emph{:postcondition} [@emph{levels}]}
3535: @end example
3536:
3537: @node ZREMOVE
3538: @section ZREMOVE
3539: @cindex ZREMOVE
3540: @cindex commands, ZREMOVE
3541: @cindex commands, implementation-specific
3542: @cindex commands, non-standard
3543: @emph{FreeM Extension}
3544:
3545: @node ZSAVE
3546: @section ZSAVE
3547: @cindex ZSAVE
3548: @cindex commands, ZSAVE
3549: @cindex commands, implementation-specific
3550: @cindex commands, non-standard
3551: @emph{FreeM Extension}
3552:
3553:
3554: @node ZTHROW
3555: @section ZTHROW
3556: @cindex ZTHROW
3557: @cindex commands, ZTHROW
3558: @cindex commands, non-standard
3559: @emph{FreeM Extension}
3560:
3561: Raises an error condition as long as the optional @emph{postcondition} is @emph{true} or omitted.
3562:
3563: @emph{Syntax}
3564:
3565: @example
3566: @code{ZTHROW@emph{:postcondition} @emph{expr V error-code}}
3567: @end example
3568:
3569: @emph{Example}
3570:
3571: @example
3572: @code{ZTHROW "M102"}
3573: @end example
3574:
3575: @node ZTRAP
3576: @section ZTRAP
3577: @cindex ZTRAP
3578: @cindex commands, ZTRAP
3579: @cindex commands, debugging
3580: @cindex commands, implementation-specific
3581: @cindex commands, non-standard
3582: @emph{FreeM Extension}
3583:
3584: Synonymous with @ref{ZTHROW}.
3585:
3586: @node ZUNMAP
3587: @section ZUNMAP
3588: @cindex ZUNMAP
3589: @cindex commands, ZUNMAP
3590: @cindex commands, implementation-specific
3591: @cindex commands, non-standard
3592:
3593: Removes any mapping connecting @emph{gvn} to a non-default namespace, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
3594:
3595: @emph{Syntax}
3596:
3597: @example
3598: ZUNMAP GLOBAL @emph{gvn}
3599: @end example
3600:
3601: @node ZWATCH
3602: @section ZWATCH
3603: @cindex ZWATCH
3604: @cindex commands, ZWATCH
3605: @cindex commands, debugging
3606: @cindex commands, implementation-specific
3607: @cindex commands, non-standard
3608: @emph{FreeM Extension}
3609:
3610: Sets a watchpoint on a global, local, or SSVN node.
3611:
3612: @emph{Syntax}
3613:
3614:
3615: In its @emph{argumentless} form, @code{ZWATCH} toggles watchpoints on and off, provided the optional @emph{postcondition} is @emph{true} or omitted.
3616:
3617: @example
3618: ZWATCH[@emph{:postcondition}]
3619: @end example
3620:
3621: In its @emph{inclusive} form, @code{ZWATCH} adds, removes, or examines watchpoints, provided the optional @emph{postcondition} is @emph{true} or omitted.
3622:
3623: A @code{+} adds a new watchpoint to the following variable.
3624:
3625: A @code{-} removes an existing watchpoint for the following variable.
3626:
3627: A @code{?} examines the status of a watchpoint for the following variable.
3628:
3629: @example
3630: ZWATCH[@emph{:postcondition}] [+|-|?]@emph{var1}...,[+|-|?]@emph{varN}
3631: @end example
3632:
3633:
3634: The following example demonstrates turning watchpoint processing on and adding a watchpoint for global variable @code{^snw(1)}. It then changes the value of @code{^snw(1)}.
3635:
3636: @example
3637: DEFAULT.USER> ZWATCH
3638:
3639: Watchpoints enabled.
3640:
3641: DEFAULT.USER> ZWATCH +^SNW(1)
3642:
3643: Added '^SNW("1")' to the watchlist.
3644:
3645: DEFAULT.USER> SET ^SNW(1)="new value"
3646:
3647: >> WATCHPOINT: ^SNW("1") => 'new value' (changed 1 times)
3648:
3649: @end example
3650:
3651: The following example will remove that watchpoint:
3652:
3653: @example
3654: DEFAULT.USER> ZWATCH -^SNW(1)
3655:
3656: Removed '^SNW("1")' from the watchlist.
3657:
3658: DEFAULT.USER> ZWATCH ?^SNW(1)
3659:
3660: '^SNW("1")' is not being watched.
3661: @end example
3662:
3663: @node ZWITH
3664: @section ZWITH
3665: @cindex ZWITH
3666: @cindex commands, ZWITH
3667: @cindex commands, non-standard
3668: @emph{FreeM Extension}
3669:
3670: NOTE: This command may be deprecated and removed in future FreeM releases.
3671:
3672: Sets a prefix to be applied to all subsequent local variable or constant references.
3673:
3674: @emph{Syntax}
3675:
3676: @example
3677: @code{ZWITH@emph{:postcondition} @emph{var-prefix}}
3678: @end example
3679:
3680: In the above single-argument form, sets the @code{$WITH} prefix to @emph{var-prefix}, provided that the optional @emph{postcondition} is either @emph{true} or omitted.
3681:
3682: The @emph{var-prefix} argument may be a string literal or any valid FreeM expression.
3683:
3684: @example
3685: @code{ZWITH@emph{:postcondition}}
3686: @end example
3687:
3688: In the above argumentless form, clears the @code{$WITH} prefix, provided the optional @emph{postcondition} is either @emph{true} or omitted. Equivalent to @code{ZWITH ""}.
3689:
3690:
3691:
3692:
3693:
3694:
3695:
3696:
3697: @node ZWRITE
3698: @section ZWRITE
3699: @cindex ZWRITE
3700: @cindex commands, ZWRITE
3701: @cindex commands, implementation-specific
3702: @cindex commands, non-standard
3703: @emph{FreeM Extension}
3704:
3705: Writes the names and values of M variables to @code{$IO}.
3706:
3707: @emph{Syntax}
3708:
3709: @example
3710: ZWRITE@emph{:postcondition}
3711: @end example
3712:
3713: In the argumentless form, writes the names and values of all local variables to @code{$IO} if the optional @emph{postcondition} is @emph{true} or omitted.
3714:
3715: @example
3716: ZWRITE@emph{:postcondition} @emph{ArrayName},@dots{}
3717: @end example
3718:
3719: In the inclusive form, writes the names and values of all local, global, or structured system variables specified in the list of @emph{ArrayName}s to @code{$IO} if the optional @emph{postcondition} is @emph{true} or omitted.
3720:
3721: @example
3722: ZWRITE@emph{:postcondition} (@emph{ArrayName},@dots{})
3723: @end example
3724:
3725: In the exclusive form, writes all local variables @emph{except} those specified in the list of @emph{ArrayName}s to @code{$IO} if the optional @emph{postcondition} is @emph{true} or omitted.
3726:
3727:
3728: @node Structured System Variables
3729: @chapter Structured System Variables
3730: @cindex variables, structured system
3731: @cindex structured system variables
3732: @cindex SSVNs
3733:
3734: @menu
3735: * ^$CHARACTER:: Character set information.
3736: * ^$DEVICE:: Device information.
3737: * ^$DISPLAY:: Information about graphic display.
3738: * ^$EVENT:: Information supplied about a synchronous or asynchronous event.
3739: * ^$GLOBAL:: Information about M globals.
3740: * ^$JOB:: Information about and control of FreeM jobs.
3741: * ^$LOCK:: Information about the FreeM lock table.
3742: * ^$OBJECT:: Information about FreeM objects.
3743: * ^$ROUTINE:: Information about FreeM routines.
3744: * ^$SYSTEM:: Information about the running system.
3745: * ^$WINDOW:: Configuration of MWAPI windows.
3746: * ^$ZPROCESS:: Information about and control of system processes.
3747: * ^$ZRPI:: Information about and control of Raspberry Pi GPIO pins.
3748: @end menu
3749:
3750: SSVN subscripts are each described in the following format:
3751:
3752: @table @asis
3753: @item @code{@emph{<ssvn-subscript-name>}} +/-R +/-U +/-D
3754: @end table
3755:
3756: The R, U, and D flags represent Read, Update, and Delete. A minus sign indicates that the given operation is @emph{not} allowed, and a plus sign indicates that the given operation @emph{is} allowed.
3757:
3758: @node ^$CHARACTER
3759: @section ^$CHARACTER
3760: @cindex ^$CHARACTER
3761: @cindex structured system variables, ^$CHARACTER
3762:
3763: Exposes character set information. As FreeM currently only supports the @code{M} character set, the first subscript of @code{^$CHARACTER} must always be @code{"M"}.
3764:
3765: The following values for the second subscript are supported:
3766:
3767: @table @asis
3768:
3769: @item @code{IDENT} +R -U -D
3770: Returns the empty string.
3771:
3772: @item @code{COLLATE} +R -U -D
3773: Returns the empty string.
3774:
3775: @item @code{INPUT} +R -U -D
3776: Returns the empty string if the third subscript is @code{M}, otherwise, raises error @code{M38}.
3777:
3778: @item @code{OUTPUT} +R -U -D
3779: Returns the empty string if the third subscript is @code{M}, otherwise, raises error @code{M38}.
3780:
3781: @end table
3782:
3783: @node ^$DEVICE
3784: @section ^$DEVICE
3785: @cindex ^$DEVICE
3786: @cindex structured system variables, ^$DEVICE
3787:
3788: FreeM implements several important pieces of functionality in the @code{^$DEVICE} SSVN.
3789:
3790: The first subscript of @code{^$DEVICE} represents the I/O channel of an @code{OPEN}ed device.
3791:
3792: The following values for the second subscript are supported:
3793:
3794: @table @asis
3795:
3796: @item @code{$DEVICE}
3797: Returns the value of @code{$DEVICE} for the specified I/O channel.
3798:
3799: @item @code{$X} +R -U -D
3800: Returns the horizontal cursor position of a terminal device. Only valid if the I/O channel is @code{0}.
3801:
3802: @item @code{$Y} +R -U -D
3803: Returns the vertical cursor position of a terminal device. Only valid if the I/O channel is @code{0}.
3804:
3805: @item @code{ROWS} +R -U -D
3806: Returns the number of character rows on the terminal device. Only valid if the I/O channel is @code{0}.
3807:
3808: @item @code{COLUMNS} +R -U -D
3809: Returns the number of character columns on the terminal device. Only valid if the I/O channel is @code{0}.
3810:
3811: @item @code{CHARACTER} +R -U -D
3812: Returns the character set of the specified I/O channel; always @code{M} in the current implementation.
3813:
3814: @item @code{INPUT_BUFFER} +R +U -D
3815: Returns or sets the contents of the input buffer for the specified I/O channel. Data populated in this node will remain in the buffer until subsequent @code{READ} command(s) remove it. This can be used to perform input buffer stuffing, i.e., to fill out an interactive form programmatically.
3816:
3817: @item @code{NAME} +R -U -D
3818: Returns the operating system's name for the file, device, or socket attached to the specified I/O channel.
3819:
3820: @item @code{FD} +R -U -D
3821: Returns the UNIX file descriptor of the specified I/O channel.
3822:
3823: @item @code{MODE} +R -U -D
3824: Returns one of @code{READ}, @code{WRITE}, @code{READWRITE}, or @code{APPEND}, depending on the mode in which the specified I/O channel was opened.
3825:
3826: @item @code{EOF} +R -U -D
3827: Returns @code{1} if the I/O channel has encountered an end-of-file condition; @code{0} otherwise. Only valid if the I/O channel is connected to a sequential file.
3828:
3829: @item @code{LENGTH} +R -U -D
3830: Returns the length of the file connected to the I/O channel. Only valid if the I/O channel is connected to a sequential file.
3831:
3832: @item @code{NAMESPACE} +R -U -D
3833: Returns the current @emph{mnemonic-space} in use for the referenced I/O channel. Always @code{X364} for terminals and blank for sequential files.
3834:
3835: @item @code{TYPE} +R -U -D
3836: Returns either @code{1,FILE}, @code{2,SOCKET}, or @code{4,TERMINAL}, depending on the device type associated with the specified I/O channel.
3837:
3838: @item @code{OPTIONS} -R -U -D
3839: The following subscripts reside beneath @code{^$DEVICE(<io-channel>,"OPTIONS")}, and this subscript may not be accessed without one of the following third-level subscripts being specified:
3840:
3841: @table @asis
3842:
3843: @item @code{DSW} +R +U -D
3844: Sets or returns the current @emph{Device Status Word} controlling terminal characteristics. Only valid for I/O channel 0.
3845:
3846: @item @code{TERMINATOR} +R +U -D
3847: Sets or returns the @code{READ} terminator for the specified I/O channel. Must be either @code{$C(13,10)} or @code{$C(10)}. Currently only supported for socket devices (those having an I/O channel of 100-255).
3848:
3849: @item @code{TERMID} +R -U -D
3850: Returns the type of terminal connected to channel 0. Only valid for I/O channel 0.
3851:
3852: @item @code{ECHO} +R +U -D
3853: Enables or disables local echo of characters typed in a @code{READ} command. Only valid for I/O channel 0. Corresponds to bit 0 of the Device Status Word.
3854:
3855: @item @code{DELMODE} +R +U -D
3856: Enables or disables visual backspace during a @code{READ} command. Only valid for I/O channel 0. Corresponds to bit 2 of the Device Status Word.
3857:
3858: @item @code{ESCAPE} +R +U -D
3859: Enables or disables escape sequence processing during a @code{READ} command. Only valid for I/O channel 0. Corresponds to bit 6 of the Device Status Word.
3860:
3861: @item @code{CONVUPPER} +R +U -D
3862: Enables or disables automatic conversion to uppercase of alphabetical characters during a @code{READ} command. Only valid for I/O channel 0. Corresponds to bit 14 of the Device Status Word.
3863:
3864: @item @code{DELEMPTY} +R +U -D
3865: Enables or disables the automatic deletion of empty strings supplied to a @code{READ} command. Only valid for I/O channel 0. Corresponds to bit 19 of the Device Status Word.
3866:
3867: @item @code{NOCTRLS} +R +U -D
3868: TBD. Only valid for I/O channel 0. Corresponds to bit 20 of the Device Status Word.
3869:
3870: @item @code{CTRLOPROC} +R +U -D
3871: Enables or disables @emph{Ctrl-O} processing during @code{READ} commands. Only valid for I/O channel 0. Corresponds to bit 21 of the Device Status Word.
3872:
3873: @item @code{NOTYPEAHEAD} +R +U -D
3874: Enables or disables typeahead buffering during @code{READ} commands. Only valid for I/O channel 0. Corresponds to bit 25 of the Device Status Word.
3875: @end table
3876: @end table
3877:
3878: @emph{Example}
3879:
3880: The following example M code opens @code{/etc/freem.conf} and reads its contents line-by-line until the end of the file is reached.
3881:
3882: @example
3883: SET ^$JOB($JOB,"IOPATH")="/etc" ; set I/O path to /etc
3884: OPEN 1:"freem.conf/r" ; open freem.conf for reading
3885: ;
3886: ; read until we run out of lines
3887: ;
3888: FOR USE 1 READ LINE USE 0 QUIT:^$DEVICE(1,"EOF") D
3889: . WRITE LINE,!
3890: ;
3891: CLOSE 1
3892: QUIT
3893: @end example
3894:
3895: @node ^$DISPLAY
3896: @section ^$DISPLAY
3897: @cindex ^$DISPLAY
3898: @cindex structured system variables, ^$DISPLAY
3899:
3900: Provides information about the specified graphical display. The first subscript corresponds to a display number, which is an integer value, often corresponding to the current value of the @code{$PDISPLAY} ISV.
3901:
3902: The following second-level subscripts and specified descendant subscripts are supported:
3903:
3904: @table @asis
3905:
3906: @item @code{CLIPBOARD} +R +U +D
3907: Retrieves, sets, or erases the contents of the system clipboard.
3908:
3909: @item @code{PLATFORM} +R -U -D
3910: Retrieves the name and version of the underlying window system platform.
3911:
3912: @item @code{SIZE} +R -U -D
3913: Retrieves the display resolution of the specified graphical display. For instance, a 1080p display would have a @code{SIZE} value of @code{1920,1080}.
3914:
3915: @item @code{SPECTRUM} +R -U -D
3916: Retrieves the color depth (number of colors supported) of the specified graphical display.
3917:
3918: @item @code{COLORTYPE} +R -U -D
3919: Always returns @code{COLOR}, as monochrome and grayscale displays are not yet supported in FreeM.
3920:
3921: @item @code{UNITS} +R -U -D
3922: Returns the measurement unit of the specified display, i.e., @code{PIXEL}.
3923:
3924: @item @code{TYPEFACE} +R -U -D
3925: The third-level subscripts beneath this subscript represent a list of font families available on this display. The fourth level subscript is a list of sizes supported for the specified typeface, or @code{0} for vector typefaces, such as TrueType, OpenType, and Adobe Type 1 fonts.
3926:
3927: @end table
3928:
3929: @node ^$EVENT
3930: @section ^$EVENT
3931: @cindex ^$EVENT
3932: @cindex structured system variables, ^$EVENT
3933:
3934: The @code{^$EVENT} SSVN is not yet implemented.
3935:
3936: @node ^$GLOBAL
3937: @section ^$GLOBAL
3938: @cindex ^$GLOBAL
3939: @cindex structured system variables, ^$GLOBAL
3940:
3941: The @code{^$GLOBAL} structured system variable provides information about M globals. The first-level subscript is a global name, sans the leading caret symbol.
3942:
3943: The following second-level subscripts are supported:
3944:
3945: @table @asis
3946:
3947: @item @code{BYTES} +R -U -D
3948: Returns the number of bytes this global occupies in fixed storage.
3949:
3950: @item @code{BLOCKS} +R -U -D
3951: Returns the number of blocks contained in this global.
3952:
3953: @item @code{BLOCKSIZE} +R -U -D
3954: Returns the size of data blocks for this global. Currently, FreeM only supports 1024-byte blocks.
3955:
3956: @item @code{FILE} +R -U -D
3957: Returns the full filesystem path to the data file where this global resides in fixed storage.
3958:
3959: @item @code{NAMESPACE} +R +U +D
3960: Returns or sets the name of the FreeM namespace to which this global belongs. @code{SET}ting this node creates a mapping for the specified global name to a non-default namespace. @code{KILL}ing this node restores the mapping configuration for the specified global to the default.
3961:
3962: @end table
3963:
3964: @node ^$JOB
3965: @section ^$JOB
3966: @cindex ^$JOB
3967: @cindex structured system variables, ^$JOB
3968:
3969: FreeM fully implements @code{^$JOB} per ANSI X11.1-1995, as well as several extensions proposed in the M Millennium Draft Standard.
3970:
3971: The first subscript of @code{^$JOB} represents the @code{$JOB} of the process.
3972:
3973: If you @code{KILL} a first-level subscript of @code{^$JOB}, the @code{SIGTERM} signal will be sent to the corresponding UNIX process, causing pending transactions to be rolled back and the process to be terminated. If the targeted process is in direct mode, the user will be prompted with options of either rolling back or committing any pending transactions.
3974:
3975: The following subscripts are supported:
3976:
3977: @table @asis
3978:
3979: @item @code{GVNDEFAULT} +R +U +D
3980: Contains a default expression to be evaluated if a global variable access attempt results in an @code{M7} error.
3981:
3982: Equivalent to wrapping all global accesses in @code{$GET(@emph{global-name},@emph{string-expr})}.
3983:
3984: @item @code{LVNDEFAULT} +R +U +D
3985: Contains a default expression to be evaluated if a local variable access attempt results in an @code{M6} error.
3986:
3987: Equivalent to wrapping all local accesses in @code{$GET(@emph{global-name},@emph{string-expr})}.
3988:
3989: @item @code{LVNQOVAL} +R +U +D
3990: Contains the data value (if any) at the subscripted local variable reference from the most recent @code{$ORDER} or @code{$QUERY} operation.
3991:
3992: This node is useful for code that uses @code{$ORDER} or @code{$QUERY} heavily in loops that retrieve successive data values, as it will prevent an additional symbol table scan that would result from retrieving the data value in the usual way, thus improving application performance. However, this optimization comes at the cost of compatibility with other M implementations.
3993:
3994: @item @code{GVNQOVAL} +R +U +D
3995: Contains the data value (if any) at the subscripted global variable reference from the most recent @code{$ORDER} or @code{$QUERY} operation.
3996:
3997: This node is useful for code that uses @code{$ORDER} or @code{$QUERY} heavily in loops that retrieve successive data values, as it will prevent an additional data file scan that would result from retrieving the data value in the usual way, thus improving application performance. However, this optimization comes at the cost of compatibility with other M implementations.
3998:
3999: @item @code{ZCOMMANDS} +R +U -D
4000: Contains a space-delimited list of @code{Z}-commands to be treated as intrinsic. Any @code{Z}-command not appearing in this list will be treated as a user-defined command.
4001:
4002: For instance, if command @code{ZFOO} does @emph{not} appear in this list, FreeM will attempt to run @code{^%ZFOO} as a subroutine when the @code{ZFOO} command is encountered in program code.
4003:
4004: If you remove a command from this list, you may provide your own private M implementation of the command in the manner described above.
4005:
4006: If an argument is passed to a @code{Z}-command you implement in M, it is made available to your M code in a variable whose name is specified in @code{^$JOB($JOB,"ZCOMMAND_ARGUMENT_NAME")}, which defaults to @code{%}.
4007:
4008: @item @code{PIPE_GLVN} +R +U -D
4009: Contains an M local or global variable to be used as standard input or standard output for the external shell commands run by @code{!<} and @code{!>}.
4010:
4011: @item @code{ZCOMMAND_ARGUMENT_NAME} +R +U -D
4012: Returns or sets the variable name in which arguments to user-defined @code{Z}-commands are passed. Defaults to @code{%}.
4013:
4014: @item @code{ZFUNCTIONS} +R +U -D
4015: Contains a space-delimited list of @code{Z} functions to be treated as intrinsic. Any @code{Z} function not appearing in this list will be treated as a user-defined extrinsic function.
4016:
4017: For instance, if function @code{$ZFOO} does @emph{not} appear in this list, FreeM will attempt to return the value of @code{$$^%ZFOO} called as an extrinsic function.
4018:
4019: If you remove a function from this list, you may provide your own private M implementation of the function in the manner described above.
4020:
4021: @item @code{ZSVS} +R +U -D
4022: Contains a space-delimited list of @code{Z} special variables to be treated as intrinsic. Any @code{Z} special variable not appearing in this list will be treated as a user-defined extrinsic function taking no arguments.
4023:
4024: For instance, if the special variable @code{$ZFOO} does @emph{not} appear in this list, FreeM will attempt to return the value of @code{$$^%ZFOO} called as an extrinsic function.
4025:
4026: If you remove a built-in special variable from this list, you may provide your own private M implementation of the special variable in the manner described above.
4027:
4028: @item @code{BREAK_HANDLER} +R +U -D
4029: Contains M code to be executed when the @code{BREAK} command is run.
4030:
4031: @item @code{ROUTINE_BUFFER_SIZE} +R +U -D
4032: Returns or sets the number of bytes allocated to each routine buffer. If @code{ROUTINE_BUFFER_AUTO_ADJUST} is set to @code{0}, this determines the maximum size of routines that FreeM will execute.
4033:
4034: @item @code{ROUTINE_BUFFER_COUNT} +R +U -D
4035: Returns or sets the number of routine buffers that FreeM will store in memory concurrently. Raising this value will increase memory usage, but will also increase performance if your applications call many different routines repeatedly.
4036:
4037: @item @code{ROUTINE_BUFFER_AUTO_ADJUST} +R +U -D
4038: Determines whether or not the size of routine buffers will be automatically adjusted at runtime. If set to @code{0}, routine buffers will be fixed to the byte size specified in @code{ROUTINE_BUFFER_SIZE} and may be manually resized using @code{ROUTINE_BUFFER_SIZE}. If set to @code{1}, routine buffers will grow automatically as necessary.
4039:
4040: @item @code{SYMBOL_TABLE_SIZE} +R +U -D
4041: Returns or sets the number of bytes allocated to each of the two FreeM symbol tables. If @code{SYMBOL_TABLE_AUTO_ADJUST} is @code{1}, this value is treated as a default, initial size. If @code{SYMBOL_TABLE_AUTO_ADJUST} is @code{0}, this value controls the fixed size of the two symbol tables.
4042:
4043: @item @code{SYMBOL_TABLE_AUTO_ADJUST} +R +U -D
4044: Determines whether or not the size of the two FreeM symbol tables will be automatically adjusted at runtime. If set to @code{0}, the symbol table will be fixed to the byte size specified in @code{SYMBOL_TABLE_SIZE} and may be manually resized by modifying @code{SYMBOL_TABLE_SIZE}. If set to @code{1}, the two symbol tables will grow automatically as necessary.
4045:
4046:
4047: @item @code{USER_DEFINED_ISV_TABLE_SIZE} +R +U -D
4048: Returns or sets the number of bytes allocated to the FreeM user-defined intrinsic special variable table. If @code{USER_DEFINED_ISV_TABLE_AUTO_ADJUST} is @code{1}, this value is treated as a default, initial size. If @code{USER_DEFINED_ISV_TABLE_AUTO_ADJUST} is @code{0}, this value controls the fixed byte size of the user-defined intrinsic special variable table.
4049:
4050: @item @code{USER_DEFINED_ISV_TABLE_AUTO_ADJUST} +R +U -D
4051: Determines whether or not the size of the FreeM user-defined intrinsic special variable table will be automatically adjusted at runtime. If set to @code{0}, the user-defined ISV table will be fixed to the byte size specified in @code{USER_DEFINED_ISV_TABLE_SIZE} and may be manually resized by modifying @code{USER_DEFINED_ISV_TABLE_SIZE}. If set to @code{1}, the user-defined ISV table will grow automatically as necessary.
4052:
4053: @item @code{GVN_UNIQUE_CHARS} +R +U -D
4054: Returns or sets the number of characters of a global name that make it unique, from 1 to 255.
4055:
4056: @item @code{GVN_CASE_SENSITIVE} +R +U -D
4057: Returns or sets the case sensitivity of global names. If set to @code{0}, global names are case-insensitive. If set to @code{1}, global names are case-sensitive.
4058:
4059: @item @code{GVN_NAME_SUB_LENGTH} +R +U -D
4060: Returns or sets the maximum number of characters of a global name plus all of its subscripts, from 1-255.
4061:
4062: @item @code{GVN_SUB_LENGTH} +R +U -D
4063: Returns or sets the maximum number of characters of a single global subscript, from 1-255.
4064:
4065: @item @code{SINGLE_USER} +R +U -D
4066: If set to @code{1}, FreeM will skip all file locking operations on globals. If set to @code{0}, FreeM will enforce file locking on both.
4067:
4068: Setting @code{SINGLE_USER} to @code{1} will improve FreeM performance, but you must @emph{ONLY} use this on systems where you are absolutely sure that only one FreeM process will run at any given time, as running multiple instances of FreeM concurrently when any of them are set to @code{SINGLE_USER} mode @emph{will} cause global data corruption.
4069:
4070: @item @code{CHARACTER} +R -U -D
4071: Returns the character set of the job.
4072:
4073: @item @code{CWD} +R +U -D
4074: Returns or sets the current working directory of the job.
4075:
4076: @item @code{OPEN} +R -U -D
4077: The @code{^$JOB($JOB,"OPEN",<channel>} subscripts list the open I/O channels in the specified job.
4078:
4079: @item @code{BERKELEYDB,FLUSH_THRESHOLD} +R +U -D
4080: Returns or sets the number of write operations that will be cached in the BerkeleyDB global handler prior to flushing BerkeleyDB's cache to disk.
4081:
4082: @item @code{EVENT} +R +U +D
4083: The subtree contained under @code{^$JOB($J,"EVENT")} defines asynchronous event handlers for the current job. Please see @emph{Asynchronous Event Handling} for more information.
4084:
4085: @item @code{GLOBAL} +R -U -D
4086: Returns the global environment of the job.
4087:
4088: @item @code{IOPATH} +R +U -D
4089: Returns or sets the @emph{I/O path} to be used by the @code{OPEN} command.
4090:
4091: @item @code{PRIORITY} +R +U -D
4092: Returns or sets the @emph{nice} value of the FreeM job.
4093:
4094: @item @code{REVSTR} +R +U -D
4095: When set to 1, allows @code{$EXTRACT} to accept negative values.
4096:
4097: @item @code{ROUTINE} +R -U -D
4098: Returns the name of the routine currently being executed by the job.
4099:
4100: @item @code{SYMTAB} +R +U -D
4101: Returns or sets the current local variable symbol table in use.
4102:
4103: FreeM supports two unique and independent symbol tables, allowing FreeM programs to maintain two independent sets of identically- or differently-named local variables per process.
4104:
4105: The default symbol table is @code{0}, and the alternate symbol table is @code{1}, corresponding to the valid values for @code{^$JOB($JOB,"SYMTAB")}.
4106:
4107: Setting this subscript to values other than @code{0} or @code{1} will result in a @code{ZINVEXPR} error.
4108:
4109: @item @code{$PDISPLAY} +R -U -D
4110: Returns the value of @code{$PDISPLAY} for the job.
4111:
4112: @item @code{$PRINCIPAL} +R -U -D
4113: Returns the value of @code{$PRINCIPAL} for the job.
4114:
4115: @item @code{$TLEVEL} +R -U -D
4116: Returns the current transaction level (value of @code{$TLEVEL} for the job.
4117:
4118: @item @code{$IO} +R -U -D
4119: Returns the current value of @code{$IO} for the job.
4120:
4121: @item @code{USER} +R -U -D
4122: Returns the UID of the user owning the job.
4123:
4124: @item @code{GROUP} +R -U -D
4125: Returns the GID of the group owning the job.
4126:
4127: @item @code{NAMESPACE} +R +U -D
4128: Returns or sets the name of the job's currently-active namespace.
4129:
4130: @item @code{MATH} +R +U -D
4131: Returns or sets the mode in which decimal comparisons and arithmetic calculations are conducted. Valid values are @code{FIXED}, for fixed-point decimals having up to 20,000 digits of precision, as determined by the @code{$ZPRECISION} intrinsic special variable, and @code{IEEE754}, to use IEEE 754 floating-point decimals. When in @code{IEEE754} mode, floating-point numbers support up to 16 digits of numeric precision.
4132:
4133: @code{IEEE754} mode will make mathematical calculations significantly faster, especially when accelerated by a floating-point processor, at the expense of precision and accuracy.
4134:
4135: @code{FIXED} mode is recommended for financial calculations, or where precision and accuracy are valued over performance. @code{FIXED} is the default mode of FreeM operation.
4136:
4137: Attempting to @code{SET} this node to values other than @code{FIXED} or @code{IEEE754} will set @code{$ECODE} to @code{M29}.
4138:
4139: @end table
4140:
4141: @node ^$LOCK
4142: @section ^$LOCK
4143: @cindex ^$LOCK
4144: @cindex structured system variables, ^$LOCK
4145:
4146: The first-level subscript of @code{^$LOCK} is a lock name. The value at each node is the PID which owns the lock, a comma, and the lock counter for the locked resource.
4147:
4148: Attempting to @code{SET} or @code{KILL} any node in @code{^$LOCK} will raise error @code{M29}.
4149:
4150: @node ^$OBJECT
4151: @section ^$OBJECT
4152: @cindex ^$OBJECT
4153: @cindex structured system variables, ^$OBJECT
4154:
4155: @node ^$ROUTINE
4156: @section ^$ROUTINE
4157: @cindex ^$ROUTINE
4158: @cindex structured system variables, ^$ROUTINE
4159:
4160: The @code{^$ROUTINE} SSVN exposes a list of routines available in the current FreeM namespace, as well as additional attributes further describing each routine.
4161:
4162: The first-level subscript is the name of a FreeM routine minus the leading caret symbol.
4163:
4164: The following second-level subscripts are supported:
4165:
4166: @table @asis
4167:
4168: @item @code{CHARACTER} +R -U -D
4169: Returns the character set of the routine.
4170:
4171: @item @code{NAMESPACE} +R -U -D
4172: Returns the name of the FreeM namespace in which the routine resides.
4173:
4174: @item @code{PATH} +R -U -D
4175: Returns the full filesystem path to the routine in fixed storage.
4176:
4177: @end table
4178:
4179: @node ^$SYSTEM
4180: @section ^$SYSTEM
4181: @cindex ^$SYSTEM
4182: @cindex structured system variables, ^$SYSTEM
4183:
4184: The @code{^$SYSTEM} SSVN exposes system-level implementation details.
4185:
4186: The following first-level subscripts are supported:
4187:
4188: @table @asis
4189:
4190: @item @code{DEFPSIZE} +R -U -D
4191: Returns the default size in bytes of the symbol table and routine buffer memory partition.
4192:
4193: @item @code{DEFUDFSVSIZ} +R -U -D
4194: Returns the default size in bytes of the user-defined intrinsic special variable table.
4195:
4196: @item @code{DEFNSIZE} +R -U -D
4197: Returns the default size of the @code{NEW} stack, in number of entries.
4198:
4199: @item @code{MAXNO_OF_RBUF} +R -U -D
4200: Returns the maximum number of routine buffers.
4201:
4202: @item @code{DEFNO_OF_RBUF} +R -U -D
4203: Returns the default number of routine buffers.
4204:
4205: @item @code{DEFPSIZE0} +R -U -D
4206: Returns the default size in bytes of each routine buffer.
4207:
4208: @item @code{NO_GLOBLS} +R -U -D
4209: Returns the maximum number of globals that can be concurrently opened.
4210:
4211: @item @code{NO_OF_GBUF} +R -U -D
4212: Returns the number of global buffers.
4213:
4214: @item @code{NESTLEVLS} +R -U -D
4215: Returns the depth of the @code{DO}, @code{FOR}, @code{XECUTE} stack.
4216:
4217: @item @code{PARDEPTH} +R -U -D
4218: Returns the maximum depth of the parser's parameter stack.
4219:
4220: @item @code{PATDEPTH} +R -U -D
4221: Returns the maximum number of @emph{patatom}s in each pattern.
4222:
4223: @item @code{TRLIM} +R -U -D
4224: Returns the trace limit of the @code{BUILTIN} global handler.
4225:
4226: @item @code{ARGS_IN_ESC} +R -U -D
4227: Returns the maximum number of arguments in a terminal escape sequence.
4228:
4229: @item @code{ZTLEN} +R -U -D
4230: Returns the maximum length of @code{$ZTRAP}.
4231:
4232: @item @code{FUNLEN} +R -U -D
4233: Returns the maximum length of the @code{$ZF} (function key) variable.
4234:
4235: @item @code{NAME_LENGTH} +R -U -D
4236: Returns the maximum length of variable names in the current FreeM build. Compatible with the same SSVN node in @emph{Reference Standard M}
4237:
4238: @item @code{STRING_MAX} +R -U -D
4239: Returns the maximum length of character strings in the current FreeM build. Compatible with the same SSVN node in @emph{Reference Standard M}
4240:
4241: @item @code{$NEXTOK} +R -U -D
4242: Returns a value indicating whether or not the @code{$NEXT} intrinsic function is allowed. In FreeM, @code{$NEXT} is always enabled, and this SSVN is provided solely for compatibility with @emph{Reference Standard M}. Thus, this SSVN node always returns @code{1}.
4243:
4244: @item @code{EOK} +R -U -D
4245: Returns a value indicating whether or not @code{E} notation for exponents is allowed. In FreeM, this feature is always enabled, and this SSVN is provided solely for compatibility with @emph{Reference Standard M}. Thus, this SSVN node always returns @code{1}.
4246:
4247: @item @code{OFFOK} +R -U -D
4248: Returns a value indicating whether or not offsets are allowed in @code{DO} and @code{GOTO}. In FreeM, this feature is always enabled, and this SSVN is provided solely for compatibility with @emph{Reference Standard M}. Thus, this SSVN node always returns @code{1}.
4249:
4250: @item @code{BIG_ENDIAN} +R -U -D
4251: Returns a 1 if FreeM is running on a big-endian platform, or a 0 otherwise. Compatible with the same SSVN node in @emph{Reference Standard M}.
4252:
4253: @item @code{NAMESPACE} +R -U -D
4254: The descendant subscripts of this node list each namespace in the current FreeM environment.
4255:
4256: @item @code{MAPPINGS,GLOBAL} +R -U -D
4257: Descendant subscripts of this node represent global name mappings set in @code{^$GLOBAL(@emph{gvn},"NAMESPACE")}
4258:
4259: @end table
4260:
4261: @node ^$WINDOW
4262: @section ^$WINDOW
4263: @cindex ^$WINDOW
4264: @cindex structured system variables, ^$WINDOW
4265:
4266: The @code{^$WINDOW} SSVN has no nodes yet defined. However, completing a @code{MERGE} to this SSVN will cause MWAPI-ish things to happen, and further work is proceeding on MWAPI implementation.
4267:
4268: @node ^$ZPROCESS
4269: @section ^$ZPROCESS
4270: @cindex ^$ZPROCESS
4271: @cindex structured system variables, ^$ZPROCESS
4272:
4273: Provides access to @code{procfs}, which is a filesystem-like abstraction for UNIX process metadata contained in @code{/proc}, as well as features for examining and controlling the state of processes external to the FreeM interpreter.
4274:
4275: The first subscript always represents the @emph{process ID} of the external process being acted upon.
4276:
4277: The following values for the second subscript are supported:
4278:
4279:
4280: @table @asis
4281:
4282: @item @code{EXISTS} +R -U -D
4283: Returns 1 if the referenced process exists; 0 otherwise.
4284:
4285: @item @code{ATTRIBUTE} +R -U -D
4286: Exposes the @code{/proc} files as descendant subscripts, i.e., @code{WRITE ^$ZPROCESS(2900,"ATTRIBUTE","cmdline"),!} would print the initial command line used to invoke process ID 2900. Note that the third subscript (the immediate descendant of the @code{ATTRIBUTE} subscript) is case sensitive.
4287:
4288: @item @code{SIGNAL} -R +U -D
4289: Allows signals to be sent to the referenced process. The following subscript is an integer value corresponding to the desired signal number. You may obtain a list of signal numbers on most UNIX systems with the command @code{kill -l}.
4290:
4291: The constants @code{%SYS.SIGNAL.HUP}, @code{%SYS.SIGNAL.INT}, @code{%SYS.SIGNAL.KILL}, and @code{%SYS.SIGNAL.TERM} are provided for convenient use of this SSVN subscript.
4292:
4293: @end table
4294:
4295: @node ^$ZRPI
4296: @section ^$ZRPI
4297: @cindex ^$ZRPI
4298: @cindex structured system variables, ^$ZRPI
4299:
4300: The @code{^$ZRPI} structured system variable provides easy access to general-purpose input/output (GPIO) pins on Raspberry Pi single-board computers.
4301:
4302: To initialize the GPIO subsystem, @code{SET ^$ZRPI("INITIALIZE")=1}.
4303:
4304: Individual pins are accessed through @code{^$ZRPI("GPIO",<pin>,...)}, where @code{<pin>} represents the desired pin number. Descendant subscripts of @code{^$ZRPI("GPIO",<pin>)} are as follows:
4305:
4306: @table @asis
4307:
4308: @item @code{MODE} +R +U -D
4309: Represents the operating mode of the selected pin. One of @code{INPUT}, @code{OUTPUT}, @code{PWM_OUTPUT}, or @code{GPIO_CLOCK}.
4310:
4311: @item @code{DIGITAL} +R +U -D
4312: Reads or writes the selected pin digitally. The value is limited to @code{1} or @code{0}.
4313:
4314: @item @code{ANALOG} +R +U -D
4315: Reads or writes the selected pin in an analog fashion. The value represents analog voltage.
4316:
4317: @end table
4318:
4319: @node Operators
4320: @chapter Operators
4321:
4322: @menu
4323: * Unary +:: Force a value to positive.
4324: * Unary -:: Force a value to negative.
4325: * +:: Add.
4326: * +=:: Add and assign.
4327: * ++:: Postfix increment.
4328: * -:: Subtract.
4329: * -=:: Subtract and assign.
4330: * --:: Postfix decrement.
4331: * *:: Multiply.
4332: * *=:: Multiply and assign.
4333: * /:: Divide.
4334: * /=:: Divide and assign.
4335: * \:: Integer divide.
4336: * \=:: Integer divide and assign.
4337: * #:: Modulo.
4338: * #=:: Modulo and assign.
4339: * **:: Exponentiate.
4340: * **=:: Exponentiate and assign.
4341: * <:: Less than.
4342: * <=:: Less than or equal to.
4343: * >:: Greater than.
4344: * >=:: Greater than or equal to.
4345: * _:: Concatenate.
4346: * _=:: Concatenate and assign.
4347: * =:: Equals.
4348: * [:: Contains.
4349: * ]:: Follows.
4350: * ]]:: Sorts after.
4351: * ?:: Pattern match.
4352: * &:: Logical AND.
4353: * ! (Operator):: Logical OR.
4354: * ':: Logical NOT.
4355: * @@ (Operator):: Indirect
4356: @end menu
4357:
4358: @node Unary +
4359: @section Unary +
4360: @cindex operators, unary +
4361:
4362: Forces a number to positive, whether positive or negative. Also forces numeric coercion of strings.
4363:
4364: @node Unary -
4365: @section Unary -
4366: @cindex operators, unary -
4367:
4368: Forces a number to negative, whether positive or negative. Also forces numeric coercion of strings.
4369:
4370: @node +
4371: @section + (Add)
4372: @cindex operators, +
4373:
4374: @emph{Syntax}
4375:
4376: @example
4377: S X=1+2 ; => 3
4378: @end example
4379:
4380: Adds numbers together.
4381:
4382: @node +=
4383: @section += (Add/Assign)
4384: @cindex operators, +=
4385:
4386: @emph{Syntax}
4387:
4388: @example
4389: S X=5
4390: S X+=3 ; => 8
4391: @end example
4392:
4393: Increments the variable on the LHS by the value on the RHS.
4394:
4395: @node ++
4396: @section ++ (Postfix Increment)
4397: @cindex operators, ++
4398:
4399: Increments a variable by 1.
4400:
4401: @node -
4402: @section - (Subtract)
4403: @cindex operators, -
4404:
4405: Subtracts one number from another.
4406:
4407: @node -=
4408: @section -= (Subtract/Assign)
4409: @cindex operators, -=
4410:
4411: @emph{Syntax}
4412:
4413: @example
4414: S X=5
4415: S X-=3 ; => 2
4416: @end example
4417:
4418: Decrements the variable on the LHS by the value on the RHS.
4419:
4420: @node --
4421: @section -- (Postfix Decrement)
4422: @cindex operators, --
4423:
4424: Decrements the variable by one.
4425:
4426: @node *
4427: @section * (Multiply)
4428: @cindex operators, *
4429:
4430: Multiplies one number by another.
4431:
4432: @node *=
4433: @section *= (Multiply/Assign)
4434: @cindex operators, *=
4435:
4436:
4437:
4438: @node /
4439: @section / (Divide)
4440: @cindex operators, /
4441:
4442: @node /=
4443: @section /= (Divide/Assign)
4444: @cindex operators, /=
4445:
4446: @node \
4447: @section \ (Integer Divide)
4448: @cindex operators, \
4449:
4450: @node \=
4451: @section \= (Integer Divide/Assign)
4452: @cindex operators, \=
4453:
4454: @node #
4455: @section # (Modulo)
4456: @cindex operators, #
4457:
4458: @node #=
4459: @section #= (Modulo/Assign)
4460: @cindex operators, #=
4461:
4462: @node **
4463: @section ** (Exponentiate)
4464: @cindex operators, **
4465:
4466: @node **=
4467: @section **= (Exponentiate/Assign)
4468: @cindex operators, **=
4469:
4470: @node <
4471: @section < (Less Than)
4472: @cindex operators, <
4473:
4474: @node <=
4475: @section <= (Less Than or Equal To)
4476: @cindex operators, <=
4477:
4478: @node >
4479: @section > (Greater Than)
4480: @cindex operators, >
4481:
4482: @node >=
4483: @section >= (Greater Than or Equal To)
4484: @cindex operators, >=
4485:
4486: @node _
4487: @section _ (Concatenate)
4488: @cindex operators, _
4489:
4490: @node _=
4491: @section _= (Concatenate/Assign)
4492: @cindex operators, _=
4493:
4494: @node =
4495: @section = (Equals)
4496: @cindex operators, =
4497:
4498: @node [
4499: @section [ (Contains)
4500: @cindex operators, [
4501:
4502: @node ]
4503: @section ] (Follows)
4504: @cindex operators, ]
4505:
4506: @node ]]
4507: @section ]] (Sorts After)
4508: @cindex operators, ]]
4509:
4510: @node ?
4511: @section ? (Pattern Match)
4512: @cindex operators, ?
4513:
4514: @node &
4515: @section & (Logical AND)
4516: @cindex operators, &
4517:
4518: @node ! (Operator)
4519: @section ! (Logical OR)
4520: @cindex operators, !
4521:
4522: @node '
4523: @section ' (Logical NOT)
4524: @cindex operators, '
4525:
4526: @node @@ (Operator)
4527: @section @@ (Indirect)
4528: @cindex operators, @@
4529:
4530: @node Routines
4531: @chapter Routines
4532: @cindex routines
4533:
4534: A @emph{routine} is a file containing M source code to be processed by FreeM.
4535:
4536: Routines exist within a @emph{namespace} (such as @code{SYSTEM} or @code{USER}), which in turn exist within an @emph{environment} (such as @code{DEFAULT}).
4537:
4538: @menu
4539: * Routine Naming:: Requirements and conventions for routine names.
4540: @end menu
4541:
4542:
4543: @node Routine Naming
4544: @section Routine Naming
4545: The routine's filename follows the format @code{NAME.m}, where @code{NAME} is the name of the routine, and @code{.m} is the filename extension.
4546:
4547: Routine naming rules are as follows:
4548:
4549: @itemize @bullet
4550: @item Routine names must begin with an upper- or lower-case letter, or a @code{%} sign
4551: @item Within the routine name, you may have upper-case or lower-case letters or digits
4552: @item The entire routine name must not be longer than 255 characters
4553: @end itemize
4554:
4555: Routines whose names begin with @code{%} must be located in the @code{SYSTEM} namespace. Other routines may be located in any namespace.
4556:
4557: @node Types
4558: @chapter Types
4559: @cindex types
4560: @cindex data types
4561:
4562: FreeM supports all @emph{libdatatype} types defined in the former MDC's @emph{Millennium Draft Standard}, with the exception of @code{MATRIX}, and with extensions supporting object-oriented programming. A notable enhancement in FreeM is that the library data types can be used in the @emph{formallist} of any extrinsic function or subroutine; not only in @emph{libraryelement}s.
4563:
4564: @menu
4565: * BOOLEAN:: Truth values.
4566: * COMPLEX:: Numbers with real and imaginary parts.
4567: * INTEGER:: Numbers with no decimal part.
4568: * REAL:: Numbers with a decimal part.
4569: * STRING:: Arbitrary strings of characters.
4570: * Custom Types (Classes):: User-defined, object-oriented types.
4571: @end menu
4572:
4573: @node BOOLEAN
4574: @section BOOLEAN
4575: @cindex data types, BOOLEAN
4576: @cindex types, BOOLEAN
4577:
4578: The @code{BOOLEAN} type represents any M value that can be interpreted as a truth-value.
4579:
4580: @node COMPLEX
4581: @section COMPLEX
4582: @cindex data types, COMPLEX
4583: @cindex types, COMPLEX
4584:
4585: The @code{COMPLEX} type is a complex number represented as a string in the format @code{@emph{<real-part>}%@emph{<imaginary-part>}}, where @emph{real-part} and @emph{imaginary-part} are both @code{REAL} numbers. See @ref{REAL} for more information.
4586:
4587: FreeM will attempt to interpret any @code{COMPLEX} value according to the usual rules for M canonical numbers, i.e., the string @code{sabc123.345%fbd3.1} would be interpreted as a complex number with the real part being @code{123.345} and the imaginary part being @code{3.1}.
4588:
4589: @node INTEGER
4590: @section INTEGER
4591: @cindex data types, INTEGER
4592: @cindex types, INTEGER
4593:
4594: An @code{INTEGER} is an interpretation of numeric data with any fractional part removed.
4595:
4596: @node REAL
4597: @section REAL
4598: @cindex data types, REAL
4599: @cindex types, REAL
4600:
4601: A @code{REAL} is a numeric interpretation of data including a fractional part.
4602:
4603: @node STRING
4604: @section STRING
4605: @cindex data types, STRING
4606: @cindex types, STRING
4607:
4608: The @code{STRING} is the fundamental FreeM data type. Other types are inferred from the context of their usage.
4609:
4610: @subsection String Rules
4611:
4612: The following rules apply to all FreeM strings:
4613:
4614: @itemize
4615: @item Must not exceed 255 characters
4616: @item Must not contain @code{$C(0)}, @code{$C(201)}, or @code{$C(202)}
4617: @end itemize
4618:
4619: @subsection String Quoting Rules
4620: Strings in FreeM must be surrounded in double quotes:
4621:
4622: @example
4623: SET MYSTRING="This is a string literal"
4624: @end example
4625:
4626: If you want to include double quotes inside of a string, simply double them:
4627:
4628: @example
4629: SET MYSTRING="This is a ""string literal"" with embedded double quotes"
4630: @end example
4631:
4632:
4633: @node Custom Types (Classes)
4634: @section Custom Types (Classes)
4635: @cindex data types, custom
4636: @cindex types, custom
4637: @cindex classes
4638:
4639: See @ref{Object-Oriented Programming}.
4640:
4641: @node Globals
4642: @chapter Globals
4643: @cindex globals
4644: @cindex variables, global
4645: @cindex data
4646:
4647: @menu
4648: * Globals Overview:: Basics of FreeM persistent storage.
4649: * Creating Globals:: How to create globals.
4650: * Removing Globals:: How to remove globals.
4651: * Global Storage:: How globals are stored.
4652: @end menu
4653:
4654: @node Globals Overview
4655: @section Globals Overview
4656:
4657: FreeM supports typical M globals, which are often described as persistent, hierachical sparse arrays. Globals make it relatively simple to include persistent data in an application without requiring the developer to use an external database management system, and offer syntax and semantics so similar to M local variables and structured system variables that moving from one to the other is seamless.
4658:
4659: Each global comprises three elements:
4660:
4661: @itemize @bullet
4662: @item
4663: An alphabetic name beginning with a caret (@code{^}) or a caret and a percent sign (@code{^%})
4664: @item
4665: Optionally, one or more comma-delimited subscripts, enclosed in parentheses
4666: @item
4667: A value of up to 255 characters in length
4668: @end itemize
4669:
4670: A leading percent sign in the global name will force the named global into the @code{SYSTEM} namespace of the current FreeM environment.
4671:
4672: @node Creating Globals
4673: @section Creating Globals
4674: @cindex globals, creating
4675:
4676: To create a global, you can use the @code{SET} command:
4677:
4678: @example
4679: SET ^MYGLOBAL("foo","bar")="this is the data value"
4680: @end example
4681:
4682: @node Removing Globals
4683: @section Removing Globals
4684: @cindex globals, removing
4685:
4686: To remove an entire global, you can use the @code{KILL} command with the unsubscripted name of the global:
4687:
4688: @example
4689: KILL ^MYGLOBAL
4690: @end example
4691:
4692: If you only want to remove part of a global, i.e., beginning at a certain subscript level, use the @code{KILL} command with a subscripted name:
4693:
4694: @example
4695: KILL ^MYGLOBAL("foo")
4696: @end example
4697:
4698: This will remove only the @code{"foo"} subscript and all of its children.
4699:
4700: If you only want to remove the data value at a specific subscript level, leaving the subscript itself intact, use @code{KVALUE}:
4701:
4702: @example
4703: KVALUE ^MYGLOBAL("foo")
4704: @end example
4705:
4706: @node Global Storage
4707: @section Global Storage
4708: @cindex globals, storage
4709:
4710: FreeM globals are stored in @code{$PREFIX/var/freem/@emph{<environment-name>}/@emph{<namespace-name>}/globals} in a binary format.
4711:
4712: Global files have a header of the following format:
4713:
4714: @verbatim
4715: typedef struct global_header {
4716:
4717: char magic[5]; /* FRMGL */
4718: int format_version;
4719: char host_triplet[40];
4720: char host_id[256];
4721:
4722: unsigned long block_size;
4723: unsigned long last_transaction_id;
4724:
4725: long created;
4726: long last_backup;
4727:
4728: } global_header;
4729: @end verbatim
4730:
4731: @node Concurrency Control
4732: @chapter Concurrency Control
4733: @cindex concurrency control
4734: @cindex locking
4735: @cindex transaction processing
4736:
4737: @menu
4738: * Concurrency Control Overview:: Basics of concurrency control.
4739: * Advisory Locks:: Coordinating access voluntarily.
4740: * Transaction Processing:: Ensuring logical consistency.
4741: @end menu
4742:
4743: @node Concurrency Control Overview
4744: @section Concurrency Control Overview
4745:
4746: Multitasking, multi-user FreeM applications must concern themselves with conscientious management of concurrent access to globals in order to maintain logical consistency and prevent concurrent reads and writes from conflicting with each other.
4747:
4748: In FreeM, there are two mechanisms provided for managing concurrent global access: @emph{advisory locks}, and @emph{transaction processing}.
4749:
4750: Advisory locks allow applications to voluntarily coordinate concurrent access to globals with the @code{LOCK} command, and require each application to check the @code{LOCK} status prior to accessing a global.
4751:
4752: Transaction processing allows applications to delineate sets of global operations (sets, kills, etc.) as being part of a transaction, in which no operations are performed against the globals contained within the transaction until the transaction is committed. In addition, processes other than the one running the transaction will be forced to wait to access globals for either the duration of the commit phase (@emph{batch mode}), or for the entire duration of the transaction (@emph{serial mode}).
4753:
4754: @node Advisory Locks
4755: @section Advisory Locks
4756:
4757: @node Transaction Processing
4758: @section Transaction Processing
4759: @cindex transaction processing
4760:
4761: FreeM implements a significant subset of the transaction processing features from @emph{ANSI X11.1-1995}. This allows a series of global operations to be conducted all at once, either in batch mode (where concurrent operation is not interrupted until the last possible moment), or in serial mode (where writes are guaranteed to be atomic, consistent, isolated, and durable).
4762:
4763: @subsection Theory of Operation
4764:
4765: FreeM uses a pessimistic concurrency control mechanism for @code{SERIAL} transactions, meaning that any @code{TSTART} command that includes the @code{SERIAL} transaction parameter will cause the process to acquire the transaction processing mutex, which prevents any process but the one holding the mutex from performing any data access (read or write) until either @code{TCOMMIT} or @code{TROLLBACK} is called, either committing or rolling back the transaction, respectively.
4766:
4767: Any transaction in between its @code{TSTART} and @code{TCOMMIT}/@code{TROLLBACK} is said to be @emph{in-flight}. During the in-flight stage, pending global operations are held only in memory and after-image journals.
4768:
4769: FreeM maintains a list of all globals affected during a transaction in-flight. When a @code{TCOMMIT} is reached, FreeM will generate a @emph{checkpoint} of each global data file to be changed by the transaction. These checkpoints allow all FreeM globals to be restored to their pre-transaction state if a @code{TCOMMIT} should fail part of the way through its operation.
4770:
4771: Checkpoints can have one of two modes:
4772:
4773: @table @asis
4774:
4775: @item @code{CP_REMOVE}
4776: Used for globals that did not exist prior to the beginning of this transaction. Simply marks the entire global data file for deletion in case of @code{TCOMMIT} failure.
4777:
4778: @item @code{CP_RESTORE}
4779: Used for globals that @emph{did} exist prior to the beginning of this transaction. In this case, the entire global data file is copied to a new file with a @code{.chk} extension. In cases of @code{TCOMMIT} failure, @code{CP_RESTORE} checkpoint files will be restored over the partially-modified live data file.
4780:
4781: @end table
4782:
4783: The below example shows a few global operations and checkpoints for a transaction in-flight using the @code{trantab} direct-mode command:
4784:
4785: @verbatim
4786: TL1:DEFAULT.USER> trantab
4787: $TLEVEL 1*
4788: Operations for Transaction ID: 6ea14aad-b8f1-47f9-9f52-4f513f892bc0 [RESTARTABLE SERIAL]
4789:
4790: OP. NO. ACTION KEY/DATA
4791: ------- ------ --------
4792: 1 SET ^FOO=3
4793: 2 KILL ^FOO
4794: 3 SET ^snw=10
4795: 4 SET ^BRANDNEW=6
4796:
4797: Global checkpoints:
4798:
4799: GLOBAL MODE FILES
4800: ------ ---- -----
4801: ^BRANDNEW CP_REMOVE IN: /usr/local/var/freem/USER/globals/^BRANDNEW
4802: ^snw CP_RESTORE IN: /usr/local/var/freem/USER/globals/^snw
4803: OUT: /usr/local/var/freem/USER/globals/^snw.23390.1.chk
4804: ^FOO CP_RESTORE IN: /usr/local/var/freem/USER/globals/^FOO
4805: OUT: /usr/local/var/freem/USER/globals/^FOO.23390.1.chk
4806: @end verbatim
4807:
4808: In the above example, @code{IN} files are the live data file that will be overwritten or removed, and @code{OUT} files are the checkpoints themselves. Note that @code{OUT} files are only used for @code{CP_RESTORE} checkpoints.
4809:
4810: @subsection Using Transaction Processing
4811:
4812: To use transactions in FreeM, you need to be familiar with three commands:
4813:
4814: @itemize @bullet
4815: @item
4816: @code{TSTART}
4817: @item
4818: @code{TCOMMIT}
4819: @item
4820: @code{TROLLBACK}
4821: @end itemize
4822:
4823: With transaction processing, global variable operations occurring between @code{TSTART} and @code{TCOMMIT} commands will be contained within the transaction.
4824:
4825: The atomicity, consistency, isolation, and durability facets of FreeM transaction hinge on the transaction mode.
4826:
4827: @subsubsection BATCH Transactions
4828: @code{BATCH} transactions offer higher performance, and allow other applications aside from the one doing the transaction to continue normal operations until the transaction is committed with @code{TCOMMIT}. In batch mode, other processes are only locked out of normal operation during the commit phase of the transaction.
4829:
4830: The effect of this is that the operations within the batch transaction will not be interleaved with global writes from other applications, but the entire lifetime of the transaction is not guaranteed to be serialized with respect to the transaction processing activities of other running applications in the environment.
4831:
4832: @subsubsection SERIAL Transactions
4833: @code{SERIAL} transactions offer full ACID compliance at the expense of multiprocessing performance. In serial mode, a @code{TSTART} blocks all activity from all other FreeM processes in the environment, and this blocking effect is not released until the transaction is committed with @code{TCOMMIT} or rolled back with @code{TROLLBACK} (or due to abnormal conditions in the environment that preclude the successful completion of the transaction).
4834:
4835: @node Local Variables
4836: @chapter Local Variables
4837: @cindex variables, local
4838: @cindex local variables
4839:
4840: @menu
4841: * Local Variables Overview:: The basics of locals.
4842: * Creating Local Variables:: Creating locals with SET.
4843: * Removing Local Variables:: Removing locals with KILL.
4844: @end menu
4845:
4846: @node Local Variables Overview
4847: @section Local Variables Overview
4848:
4849: FreeM @emph{local variables} have the same data structure as global variables, but are scoped to a single FreeM process, and stored in memory.
4850:
4851: Each local comprises three elements:
4852:
4853: @itemize @bullet
4854: @item
4855: An alphabetic name beginning with a letter or a percent sign (@code{%})
4856: @item
4857: Optionally, one or more comma-delimited subscripts, enclosed in parentheses
4858: @item
4859: A value of up to 255 characters in length
4860: @end itemize
4861:
4862: @node Creating Local Variables
4863: @section Creating Local Variables
4864: @cindex local variables, creating
4865:
4866: To create a local variable, use the @code{SET} command:
4867:
4868: @example
4869: SET MYLOCAL("foo","bar")="this is the data value"
4870: @end example
4871:
4872: @node Removing Local Variables
4873: @section Removing Local Variables
4874: @cindex local variables, removing
4875:
4876: To remove an entire local variable, you can use the @code{KILL} command with the unsubscripted name of the variable:
4877:
4878: @example
4879: KILL MYLOCAL
4880: @end example
4881:
4882: If you only want to remove part of a local variable, i.e., beginning at a certain subscript level, use the @code{KILL} command with a subscripted name:
4883:
4884: @example
4885: KILL MYLOCAL("foo")
4886: @end example
4887:
4888: This will remove only the @code{"foo"} subscript and all of its children.
4889:
4890: If you only want to remove the data value at a specific subscript level, leaving the subscript itself intact, use @code{KVALUE}:
4891:
4892: @example
4893: KVALUE MYLOCAL("foo")
4894: @end example
4895:
4896: @node Scoping
4897: @chapter Scoping
4898: @cindex scoping
4899:
4900: By default, FreeM local variables and their values are scoped to the entire process, meaning that any function or subroutine can access and modify their values. This can lead to pernicious bugs.
4901:
4902: M provides the @code{NEW} command to work around these issues. When @code{NEW} is called with a local variable as its argument, FreeM will scope the variable to the process stack frame in which the @code{NEW} command occured. When exiting the stack frame (i.e. with the @code{QUIT} command), FreeM will restore the variable to its value prior to being @code{NEW}ed.
4903:
4904: @emph{Example}
4905:
4906: @example
4907: MYRTN ;
4908: S J=1 ; set local variable J to 1
4909: W J,! ; this will output "1"
4910: D X ; execute subroutine X
4911: W J,! ; this will output "1", as the value of J was restored
4912: Q
4913: ;;
4914: X ;
4915: N J ; stack J
4916: S J=6 ; set its value to 6
4917: W J,! ; this will output "6"
4918: Q ; quit from the subroutine, destroying its stack frame
4919: ;;
4920: @end example
4921:
4922: @section Scoping Considerations for $TEST
4923:
4924: In M, the truth value of comparisons, logic operations, and certain forms of @code{LOCK} is stored in the @code{$TEST} intrinsic special variable, which follows the same rules as any M local variable.
4925:
4926: This is probably the most significant design flaw of the language, as the side effects of logic on @code{$TEST} lead to incredibly difficult bugs. However, M allows @code{$TEST} to be @code{NEW}ed, and FreeM provides the @code{THEN} command@footnote{From MDC Type A extension X11/1998-31} to help in the case of conditionals. @code{THEN} stacks @code{$TEST} to the end of the line.
4927:
4928: When writing new M code in FreeM, we strongly suggest using @code{THEN} as follows:
4929:
4930: @example
4931: MYRTN ;
4932: IF MYVAR=1 THEN DO SUBRT
4933: @end example
4934:
4935: This is instead of the traditional form:
4936:
4937: @example
4938: MYRTN ;
4939: IF MYVAR=1 DO SUBR
4940: @end example
4941:
4942: @cartouche
4943: @quotation
4944: @emph{Style Recommendation}
4945:
4946: Note that @code{THEN} is not in any currently published version of the @emph{Standard}, but is part of MDC Type A extension X11/1998-31. However, we recommend using @code{THEN} instead of favoring portability, as there is no defensible reason for this incredibly simple feature @emph{not} to be ubiquitous.
4947:
4948: If you use other M implementations, you should bug the implementers to implement @code{THEN}, as it at least partially mitigates an inexcusable flaw in the design of M.
4949: @end quotation
4950: @end cartouche
4951:
4952: @node Decision Constructs
4953: @chapter Decision Constructs
4954: @cindex decision constructs
4955: @cindex IF
4956: @cindex ELSE
4957: @cindex THEN
4958: @cindex postconditionals
4959:
4960: @node Branch Constructs
4961: @chapter Branch Constructs
4962: @cindex branch constructs
4963: @cindex DO
4964: @cindex GOTO
4965: @cindex JOB
4966:
4967: @node Loop Constructs
4968: @chapter Loop Constructs
4969: @cindex loop constructs
4970: @cindex FOR
4971:
4972: @node Modular Programming
4973: @chapter Modular Programming
4974: @cindex modular programming
4975: @cindex functions, extrinsic
4976: @cindex subroutines
4977:
4978: @menu
4979: * Subroutines:: Making sections of code reusable.
4980: * Extrinsic Functions:: Reusable code that returns a value.
4981: @end menu
4982:
4983: @node Subroutines
4984: @section Subroutines
4985:
4986: @node Extrinsic Functions
4987: @section Extrinsic Functions
4988:
4989: @node Object-Oriented Programming
4990: @chapter Object-Oriented Programming
4991: @cindex object-oriented programming
4992: @cindex programming, object-oriented
4993:
4994: @menu
4995: * Classes:: The organizing concept of object-oriented programming.
4996: * Inheritance:: Making one class derive from another.
4997: * Methods:: Attach code to classes.
4998: * Public and Private Variables:: Determining accessibility.
4999: * Instantiating Objects:: Creating instances of classes.
5000: @end menu
5001:
5002: @node Classes
5003: @section Classes
5004: @subsection Class Overview
5005:
5006: A @emph{class} is the primary organizing concept of FreeM support for object-oriented programming, and in FreeM, is simply an M routine with a few special properties:
5007:
5008: @example
5009: MYCLASS(THIS,INIT):OBJECT ; Constructor for MYCLASS, inherits OBJECT
5010: ; two private variables
5011: S THIS("NUMERATOR"):PRIVATE=$P(INIT,"/",1)
5012: S THIS("DENOMINATOR"):PRIVATE=$P(INIT,"/",2)
5013: Q
5014: ;
5015: DESTROY(THIS) ; This is the destructor
5016: Q
5017: @end example
5018:
5019: The above example demonstrates general class syntax.
5020:
5021: @subsection Constructors
5022:
5023: A @emph{constructor} is an M entry point that is called when a new instance of a class is created.
5024:
5025: A constructor must be the first entry point in a class routine, its tag must match the class/routine name, and it must take two arguments, @code{THIS} and @code{INIT}.
5026:
5027: @code{THIS} represents the instance of the object being accessed, and @code{INIT} represents an initializer that can be used to assign an initial value to the object when instantiating the class.
5028:
5029: A constructor looks like this:
5030:
5031: @example
5032: %FRACTION(THIS,INIT):OBJECT ;
5033: S THIS("NUMERATOR"):PRIVATE=$P(INIT,"/",1)
5034: S THIS("DENOMINATOR"):PRIVATE=$P(INIT,"/",2)
5035: Q
5036: @end example
5037:
5038: @emph{Syntax}
5039: @example
5040: @emph{<class-name>}(THIS,INIT)[:@emph{<superclass>}]
5041: @end example
5042:
5043: In the above example, @emph{<superclass>} represents the name of a class from which this class should inherit. In this case, the @code{FRACTION} class inherits from the @code{OBJECT} class. Note that this is not strictly necessary in this case, as all classes in FreeM automatically inherit from @code{OBJECT}.
5044:
5045: @subsection Destructors
5046: A @code{destructor} is called when you @code{KILL} an instance variable. Its tag must be @code{DESTROY}, and it must take one argument (@code{THIS}).
5047:
5048: The destructor should be used to clean up any resources used by class methods.
5049:
5050: A destructor looks like this:
5051:
5052: @example
5053: DESTROY(THIS) ;
5054: ; free any resources that should be freed at the end of the object's lifetime
5055: Q
5056: @end example
5057:
5058: @node Inheritance
5059: @section Inheritance
5060:
5061: Every class you create will automatically inherit the methods and functionality of the @code{OBJECT} class, supplied with FreeM.
5062:
5063: When attempting to call a method, FreeM will first search the class routine for a matching entry point, and then follow the inheritance chain upwards until a matching entry point is found. If the final class in the chain does not have a matching entry point, FreeM will try to find a matching entry point in the @code{OBJECT} class.
5064:
5065: Inheritance is achieved by specifying the name of the superclass in the constructor:
5066:
5067: @example
5068: CLASS(THIS,INIT):SUPERCLASS
5069: @end example
5070:
5071: @subsection Runtime Polymorphism
5072:
5073: You can achieve runtime polymorphism by subclassing, and defining methods in the subclass that match the names of existing methods in the superclass. Following FreeM inheritance rules, the overridden method in the subclass will be called, and the method in the superclass will not.
5074:
5075: Note that the overridden method in the subclass can take a different set or number of arguments than the @emph{formallist} of the superclass method would specify.
5076:
5077: @node Methods
5078: @section Methods
5079: Class methods are defined as tags with @emph{formallist}s in a class routine, and per the typical FreeM object pattern, must take at least one argument, being @code{THIS} (representing a reference to the object instance being accessed).
5080:
5081: The following class (@code{MYCLASS}) has a constructor, a destructor, and a method called @code{MYMETHOD}:
5082:
5083: @example
5084: %MYCLASS(THIS,INIT) ;
5085: Q THIS
5086: DESTROY(THIS) ;
5087: Q
5088: MYMETHOD(THIS) ;
5089: Q "VALUE"
5090: @end example
5091:
5092: The dot operator is used to invoke class methods:
5093:
5094: @example
5095: DEFAULT.USER> N MYOBJ=$#^%MYCLASS("")
5096: DEFAULT.USER> W MYOBJ.MYMETHOD()
5097: VALUE
5098: @end example
5099:
5100: @node Public and Private Variables
5101: @section Public and Private Variables
5102:
5103: FreeM supports private fields with the @code{:PRIVATE} specifier in the @code{SET} command, enforcing classical object-oriented data encapsulation. The @code{:PUBLIC} specifier is provided for completeness, and is the default.
5104:
5105: The below constructor for a @code{FRACTION} class defines two private fields:
5106:
5107: @example
5108: %FRACTION(THIS,INIT):OBJECT ;
5109: S THIS("NUMERATOR"):PRIVATE=$P(INIT,"/",1)
5110: S THIS("DENOMINATOR"):PRIVATE=$P(INIT,"/",2)
5111: Q
5112: @end example
5113:
5114: Either of the following commands will create a public field:
5115:
5116: @example
5117: S THIS("VARNAM")="Initial Value"
5118: S THIS("VARNAM"):PUBLIC="Initial Value"
5119: @end example
5120:
5121: Attempting to access private fields from outside of the class will raise error condition @code{ZOBJFLDACCV}.
5122:
5123: @node Instantiating Objects
5124: @section Instantiating Objects
5125:
5126: To instantiate an object (i.e., create an object from a certain class), you will use the @code{NEW} command as follows:
5127:
5128: @example
5129: NEW MYSTR=$#^%STRING("myString")
5130: @end example
5131:
5132: This will create a local variable called MYSTR of type STRING, and initialize it with the value myString.
5133:
5134: @subsection Determining Object Class
5135:
5136: To determine the class of any FreeM local variable, you will use the @code{$$TYPE()} method:
5137:
5138: @example
5139: USER> W MYSTR.$$TYPE()
5140: ^%STRING
5141: @end example
5142:
5143: The @code{$$TYPE()} method is a member of the @code{OBJECT} class.
5144:
5145: @node Libraries
5146: @chapter Libraries
5147: @cindex libraries
5148:
5149: @node Sequential I/O
5150: @chapter Sequential I/O
5151:
5152: @node Network I/O
5153: @chapter Network I/O
5154: @cindex networks, input and output
5155:
5156: Network I/O in FreeM is supplied through I/O channels 100-255. The normal @code{READ} and @code{WRITE} syntax will work with network sockets, with a few exceptions.
5157:
5158: @section Opening and Connecting a Client Socket
5159: @cindex networks, opening and connecting client sockets
5160:
5161: To open a client socket and connect to it, you will need to call the @code{OPEN} command and the @code{USE} command:
5162:
5163: @example
5164: ;
5165: ; Set socket read terminator to LF
5166: ;
5167: SET ^$DEVICE(100,"OPTIONS","TERMINATOR")=$C(10)
5168: ;
5169: ; Open an IPv4 TCP socket to mail.mydomain.com on port 25 (SMTP)
5170: ; and connect to it
5171: ;
5172: OPEN 100:"mail.mydomain.com:25:IPV4:TCP"
5173: USE 100:/CONNECT
5174: ;
5175: ; Read a line of input from the remote host and write it to the terminal
5176: ;
5177: NEW LINE
5178: READ LINE
5179: USE 0
5180: WRITE LINE,!
5181: ;
5182: ; CLOSE the socket and disconnect
5183: ;
5184: CLOSE 100
5185: QUIT
5186: @end example
5187:
5188: @node Extended Global References
5189: @chapter Extended Global References
5190: @cindex global references, extended
5191: @cindex extended global references
5192:
5193: @section Standard Extended Global References
5194: @cindex extended global references, standard
5195:
5196: FreeM supports extended global references, allowing the user to access globals in namespaces other than the current default namespace and the @code{SYSTEM} namespace, without switching to the other namespace.
5197:
5198: For example, if you are in the @code{USER} namespace, the following code will print the value of @code{^VA(200,0)} in the @code{VISTA} namespace:
5199:
5200: @example
5201: WRITE ^|"VISTA"|VA(200,0),!
5202: @end example
5203:
5204: You may also use an expression that resolves to a string containing a valid namespace name:
5205:
5206: @example
5207: SET NS="VISTA"
5208: WRITE ^|NS|VA(200,0),!
5209: @end example
5210:
5211: @node Global Aliasing
5212: @chapter Global Aliasing
5213: @cindex aliasing, global
5214: @cindex globals, aliasing
5215:
5216: FreeM provides the ability to set alternative names for M global variables.
5217:
5218: To create an alias of @code{^FOO} named @code{^BAR}, use the following command:
5219:
5220: @example
5221: SET ^$JOB($JOB,"ALIASES","^BAR")="^FOO"
5222: @end example
5223:
5224: If such an alias is set, any reference to global variable @code{^BAR} will affect @code{^FOO} instead of @code{^BAR} until @code{^$JOB($JOB,"ALIASES","^BAR")} is @code{KILL}ed. If @code{^BAR} existed prior to the definition of this alias, its data will be unavailable to and unaffected by application code.
5225:
5226: @node Global Mappings
5227: @chapter Global Mappings
5228: @cindex mappings, global
5229: @cindex globals, mapping
5230:
5231: FreeM supports creating persistent mappings through which arbitrary global names may be mapped to specific namespaces. This allows non-@code{%} globals to be stored in the @code{SYSTEM} namespace, or @code{%} globals to be stored in non-@code{SYSTEM} namespaces.
5232:
5233: To map the @code{^FOO} global to the @code{SYSTEM} namespace, any of the following will work:
5234:
5235: @example
5236: MAP GLOBAL ^FOO="SYSTEM"
5237: SET ^$GLOBAL("FOO","NAMESPACE")="SYSTEM"
5238: SET ^$SYSTEM("MAPPINGS","GLOBAL","^FOO")="SYSTEM"
5239: @end example
5240:
5241: There is no functional difference in any of the three approaches; the method you choose is a matter of personal preference.
5242:
5243: To remove the above mapping, any of the following examples will also work:
5244:
5245: @example
5246: UNMAP GLOBAL ^FOO
5247: KILL ^$GLOBAL("FOO","NAMESPACE")
5248: KILL ^$SYSTEM("MAPPINGS","GLOBAL","^FOO")
5249: @end example
5250:
5251:
5252:
5253: @node Asynchronous Event Handling
5254: @chapter Asynchronous Event Handling
5255: @cindex event handling, asynchronous
5256:
5257: Asynchronous event handling in FreeM follows the specifications of the unpublished MDC @emph{Millennium Draft Standard}.
5258:
5259: @section Setting Up Async Event Handlers
5260:
5261: Asynchronous event handlers are configured through the @code{^$JOB} structured system variable for job-specific events, and the @code{^$SYSTEM} structured system variable for system-wide events. In order to become proficient in writing asynchronous event handling code, you need to be aware of several important concepts:
5262:
5263: @table @emph
5264:
5265: @item Event Classes
5266: @emph{Event classes} denote particular categories of events. These include @code{COMM}, @code{HALT}, @code{IPC}, @code{INTERRUPT}, @code{POWER}, @code{TIMER}, @code{TRIGGER}, and @code{USER} event classes. At present, only @code{INTERRUPT} and @code{TRIGGER} event classes are supported.
5267:
5268: @item Event Identifiers
5269: @emph{Event identifiers} denote the precise nature of the event that has occurred. For instance, resizing the terminal window in which a FreeM job is running will send an event of class @code{INTERRUPT} with an event identifier of @code{SIGWINCH} (short for @emph{SIGnal WINdow CHange}).
5270:
5271: @item Event Handlers
5272: @emph{Event handlers} are M routines or subroutines that can be registered to run when an event of a certain event class occurs.
5273:
5274: @item Event Registration
5275: @emph{Event registration} is the process of modifying the @code{^$JOB} or @code{^$SYSTEM} SSVN to associate a particular event class and event identifier with an event handler routine or subroutine.
5276:
5277: @item Event Blocking and Unblocking
5278: @emph{Event blocking} is the means by which asynchronous event handling can be temporarily suspended. For example, asynchronous events are temporarily and implicitly blocked for the duration of event handler execution, unless explicitly un-blocked within the event handler. Event handling can also be blocked and unblocked programatically from M code using the @code{ABLOCK} and @code{AUNBLOCK} commands.
5279:
5280: @end table
5281:
5282: The following sections of this chapter will take you step-by-step through setting up an event handler for @code{SIGWINCH} signal handling.
5283:
5284: @section Registering an Asynchronous Event Handler
5285: @cindex event handlers, registration
5286:
5287: To register a job-specific event handler that will only execute in the current FreeM process, use the following syntax:
5288:
5289: @example
5290: SET ^$JOB($JOB,"EVENT",@emph{event-class},@emph{event-identifier})=@emph{entryref}
5291: @end example
5292:
5293: To register a system-wide event handler that will execute in every FreeM process, use the following syntax:
5294:
5295: @example
5296: SET ^$SYSTEM("EVENT",@emph{event-class},@emph{event-identifier})=@emph{entryref}
5297: @end example
5298:
5299: For example, use the following to register @code{^RESIZE} as an asynchronous event handler for @code{SIGWINCH} events:
5300:
5301: @example
5302: SET ^$JOB($JOB,"EVENT","INTERRUPT","SIGWINCH")="^RESIZE"
5303: @end example
5304:
5305: This by itself will not enable asynchronous event handling, as it merely @emph{registers} an event handler, associating it with event class @code{INTERRUPT} and event identifier @code{SIGWINCH}.
5306:
5307: @section Enabling Asynchronous Event Handling
5308: @cindex event handlers, enabling
5309:
5310: In order to enable asyncronous event handling, the @code{ASTART} command is used. In the following example, we will enable asynchronous event handling for the @code{INTERRUPT} event class:
5311:
5312: @example
5313: ASTART "INTERRUPT"
5314: @end example
5315:
5316: Omitting the @code{"INTERRUPT"} argument will enable asynchronous event handling for @emph{all} event classes. See @code{ASTART} in the commands section for more details.
5317:
5318: Once this is done, any event handlers registered for the @code{INTERRUPT} event class in @code{^$JOB} will be executed asynchronously as appropriate.
5319:
5320: Please note that @code{ASTART "TRIGGER"} is run implicitly at FreeM startup, to ensure consistency in applications depending on business logic contained in system-wide global triggers. To disable this behavior, add @code{ASTOP "TRIGGER"} to the @code{LOCAL.STARTUP} routine in the @code{USER} namespace. If @code{LOCAL.STARTUP} does not yet exist in your environment, you may create it by typing @code{fmadm edit routine USER LOCAL.STARTUP} from your UNIX command-line shell.
5321:
5322: @section Disabling Asynchronous Event Handling
5323: @cindex event handlers, disabling
5324:
5325: To disable asynchronous event handling, the @code{ASTOP} command is used. In the following example, we will disable asynchronous event handling for the @code{INTERRUPT} event class:
5326:
5327: @example
5328: ASTOP "INTERRUPT"
5329: @end example
5330:
5331: Omitting the @code{"INTERRUPT"} argument will disable asynchronous event handling for @emph{all} event classes. See @code{ASTOP} in the commands section for more details.
5332:
5333: You may also disable asynchronous event handling for a specific event identifier by @code{KILL}ing the appropriate node in the @code{^$JOB} SSVN, which unregisters the event handler altogether. The following example will unregister the event handler for the @code{SIGWINCH} event identifier:
5334:
5335: @example
5336: KILL ^$JOB($JOB,"EVENT","INTERRUPT","SIGWINCH")
5337: @end example
5338:
5339: @section Temporarily Blocking Asynchronous Event Handling
5340: @cindex event handlers, blocking
5341:
5342: To temporarily block processing of specific event classes, you will use the @code{ABLOCK} command. @code{ABLOCK} functions incrementally, that is, each successive call to @code{ABLOCK} will increment a counter of blocks held for the specified event class or classes, and each successive call to @code{AUNBLOCK} will decrement that counter. Event handling for the specified event classes will be blocked as long as the @code{ABLOCK} counter for those classes is greater than zero. Thus, event blocking is cumulative, in a manner similar to M incremental locks.
5343:
5344: The following example blocks asynchronous event handling for the @code{INTERRUPT} event class:
5345:
5346: @example
5347: ABLOCK "INTERRUPT"
5348: @end example
5349:
5350: Note that entering an event handler causes an implicit @code{ABLOCK} of @emph{all} event classes, to prevent event handlers from interrupting other event handlers during their execution. This may be overridden by calling @code{AUNBLOCK} for one or more event classes within an event handler. However, unblocking event handling during an event handler should be done with great caution, as this can make the flow of code execution somewhat unpredictable, especially if M globals are modified inside of an event handler routine or subroutine.
5351:
5352: Modifying M globals within event handlers is allowed but strongly discouraged, as doing so can lead to logical corruption of the data. If you must modify an M global within an event handler, guard all such operations with prodigious and careful use of @code{LOCK}s, ensuring that such modifications occur in the desired logical order.
5353:
5354: @node Global Triggers
5355: @chapter Global Triggers
5356: @cindex global triggers
5357: @cindex triggers
5358:
5359: Global triggers use the FreeM asynchronous event handling subsystem to allow a FreeM process to execute arbitrary M code when a particular action occurs on a particular global.
5360:
5361: To set up a global trigger, you must set up an event handler for event class @code{TRIGGER}. The event identifier must be in the format of @code{"<action>:<gvn>"}, where @emph{<gvn>} is a global variable name, and @emph{<action>} is one of the following:
5362:
5363: @table @asis
5364:
5365: @item @code{DATA}
5366: Trigger will fire when the @code{$DATA} intrinsic function is called on @emph{<gvn>}.
5367:
5368: @item @code{GET}
5369: Trigger will fire when @emph{<gvn>} is read from.
5370:
5371: @item @code{INCREMENT}
5372: Trigger will fire when intrinsic function @code{$INCREMENT} is called on @emph{<gvn>}.
5373:
5374: @item @code{KILL}
5375: Trigger will fire when @emph{<gvn>} is @code{KILL}ed.
5376:
5377: @item @code{NEXT}
5378: Trigger will fire when intrinsic function @code{$NEXT} is called on @emph{<gvn>}.
5379:
5380: @item @code{ORDER}
5381: Trigger will fire when intrinsic function @code{$ORDER} is called on @emph{<gvn>}.
5382:
5383: @item @code{QUERY}
5384: Trigger will fire when intrinsic function @code{$QUERY} is called on @emph{<gvn>}.
5385:
5386: @item @code{SET}
5387: Trigger will fire when @code{SET @emph{<gvn>}=@emph{value}} occurs.
5388:
5389: @item @code{ZDATA}
5390: Trigger will fire when intrinsic function @code{ZDATA} is called on @emph{<gvn>}.
5391:
5392: @end table
5393:
5394: When a @code{TRIGGER} event occurs, the @code{"GLOBAL"} node of the @code{^$EVENT} structured system variable will be populated with the global reference that invoked the trigger event.
5395:
5396: If a @code{SET} or @code{KILL} trigger was the source of the @code{TRIGGER} event, the @code{OLD_VALUE} node of @code{^$EVENT} will be populated with original value of @code{^$EVENT("GLOBAL")} prior to the change, and @code{NEW_VALUE} will be populated with the new value. This allows triggers to contain logic to undo global changes. This functionality can also be used to provide auditing of specific global changes.
5397:
5398: The following example shows a trigger implemented for @code{SET} operations on the @code{^DD} global.
5399:
5400: @example
5401: TRIGGER ;
5402: ;
5403: ; Set up a SET trigger on ^DD
5404: ;
5405: SET ^$JOB($JOB,"EVENT","TRIGGER","SET:^DD")="ONSET^TRIGGER"
5406: ;
5407: ; Enable the TRIGGER event class
5408: ;
5409: ASTART "TRIGGER"
5410: ;
5411: ; Try setting a node in ^DD
5412: ;
5413: SET ^DD(1)="Test"
5414: ;
5415: ; Quit
5416: ;
5417: QUIT
5418: ;
5419: ;
5420: ONSET ;
5421: WRITE "The "_^$EVENT("GLOBAL")_" global node was SET.",!
5422: QUIT
5423: @end example
5424:
5425: You can also set up a trigger that applies to all FreeM processes by setting descendant subscripts of @code{^$SYSTEM("EVENT","TRIGGER",...)} instead of using @code{^$JOB($JOB,"EVENT","TRIGGER",...)}.
5426:
5427: @node Synchronous Event Handling
5428: @chapter Synchronous Event Handling
5429:
5430: @node GUI Programming with MWAPI
5431: @chapter GUI Programming with MWAPI
5432:
5433: @node User-Defined Z Commands
5434: @chapter User-Defined Z Commands
5435:
5436: @node User-Defined Z Functions
5437: @chapter User-Defined Z Functions
5438:
5439: @cindex z functions, user-defined
5440:
5441: @node User-Defined SSVNs
5442: @chapter User-Defined SSVNs
5443:
5444: @cindex structured system variables, user-defined
5445: @cindex structured system variables
5446:
5447: @node Language Dialects
5448: @chapter Language Dialects
5449:
5450: @cindex language dialects
5451: @cindex dialects, language
5452:
5453:
5454: @node System Library Routines
5455: @chapter System Library Routines
5456: @cindex system library routines
5457:
5458: @section ^%ZCOLUMNS
5459: @cindex ^%ZCOLUMNS
5460: @cindex system library routines, ^%ZCOLUMNS
5461:
5462: This routine is the implementation of the @code{$ZCOLUMNS} intrinsic special variable.
5463:
5464: @section %SYSINIT
5465: @cindex %SYSINIT
5466: @cindex system library routines, %SYSINIT
5467:
5468: This routine is the default startup routine for FreeM running in direct mode.
5469:
5470: Running @code{DO INFO} from direct mode will use this routine to display information about the current FreeM status and namespace configuration.
5471:
5472: @section ^%ZHELP
5473: @cindex ^%ZHELP
5474: @cindex system library routines, ^%ZHELP
5475:
5476: This routine implements the online help feature of FreeM, invoked by typing @code{?} in direct mode. It simply asks the underlying system to execute the command @command{info freem}.
5477:
5478: @section ^%ZROWS
5479: @cindex ^%ZROWS
5480: @cindex system library routines, ^%ZROWS
5481:
5482: This routine is the implementation of the @code{$ZROWS} intrinsic special variable.
5483:
5484: @node Interrupt Handling
5485: @chapter Interrupt Handling
5486: @cindex interrupt handling
5487:
5488: When FreeM receives the @code{SIGINT} signal, either by pressing @code{Ctrl-C} during program execution, or by external signal from the operating system, the FreeM environment daemon, or another external process, one of two things can happen, depending on the state of the @code{$ZI} special variable:
5489:
5490: @table @asis
5491: @item @code{$ZI} evaluates @emph{true}
5492: In this case, the @code{ZINRPT} error is raised, and normal error handling procedures apply. If neither @code{$ZTRAP} nor @code{$ETRAP} are set, FreeM prints an error diagnostic on the home device and will exit the FreeM process in application mode (i.e., the @code{freem} executable was started with the @code{--routine} or @code{-r} flag), or return to the direct mode prompt otherwise.
5493:
5494: This is the default behavior of FreeM.
5495: @item @code{$ZI} evaluates @emph{false}
5496: In this case, no error is raised, but the @code{$ZCONTROLC} flag is set. In this mode of operation, it is up to program code to check for @code{$ZCONTROLC} and take appropriate action.
5497:
5498: Checking the value of @code{$ZCONTROLC} will reset it to @emph{false}.
5499: @end table
5500:
5501: In either case, if asynchronous event handling is enabled for the @code{INTERRUPT} event class (i.e., @code{ASTART "INTERRUPT"} or @code{ASTART} have been invoked by the current process), an asynchronous event of event class @code{INTERRUPT} and event identifier @code{SIGINT} will be enqueued.
5502:
5503: @node Error Processing
5504: @chapter Error Processing
5505: @cindex error processing
5506:
5507: FreeM exposes three means of processing M program execution errors:
5508:
5509: @table @emph
5510:
5511: @item FreeM-style error processing
5512: FreeM-style error processing exposes a read/write error trap in @code{$ZTRAP}. The contents of @code{$ZTRAP} must be either empty or a valid M entryref, to which FreeM will @code{GOTO} if an error occurs. Each program stack execution level can have its own @code{$ZTRAP} error handler enabled.
5513:
5514: @item DSM 2.0-style error processing
5515: DSM 2.0-style error processing emulates the @code{$ZTRAP} behavior of Digital Standard MUMPS v2. It has the same behavior as FreeM-style error handling, with the exception that in DSM 2.0-style error processing, only one @code{$ZTRAP} error handler is set across all program stack execution levels.
5516:
5517: @item Standard error processing
5518: Standard error processing uses the @code{NEW}-able @code{$ETRAP} variable to store error handler code, which may be any valid M code. The code in @code{$ETRAP} will run when an error occurs or the @code{$ECODE} ISV becomes non-empty. Stack information for standard error handling is provided by the @code{$STACK} ISV, the @code{$STACK()} intrinsic pseudo-function, and the @code{NEW}-able @code{$ESTACK} ISV.
5519:
5520: If @code{$ETRAP} is non-empty when an error condition occurs, @code{$ZTRAP} is ignored, regardless of whether FreeM-style or DSM 2.0-style error processing is enabled at the time of the error.
5521:
5522: @end table
5523:
5524: For further information on switching between FreeM-style and DSM 2.0-style @code{$ZTRAP} error handling, see the documentation for the @code{BREAK} command.
5525:
5526: @node FreeM Error Codes
5527: @chapter FreeM Error Codes
5528: @cindex Error Codes
5529:
5530: @table @asis
5531:
5532: @item @code{ZINRPT} - @emph{interrupt}
5533: Raised when an interrupt signal is received.
5534:
5535: @item @code{ZBKERR} - @emph{BREAK point}
5536: Raised when a @code{BREAK} point is reached.
5537:
5538: @item @code{ZNOSTAND} - @emph{non standard syntax}
5539: Raised when features incompatible with the current value of @code{$DIALECT} are used.
5540:
5541: @item @code{ZUNDEF} - @emph{variable not found}
5542: Raised when an undefined local or global variable is accessed. This error code has been deprecated in favor of standard error codes @code{M6} and @code{M7}.
5543:
5544: @item @code{ZLBLUNDEF} - @emph{label not found}
5545: Raised when a referenced label is not found.
5546:
5547: @item @code{ZMISSOPD} - @emph{missing operand}
5548: Raised when an operand is missing from an expression.
5549:
5550: @item @code{ZMISSOP} - @emph{missing operator}
5551: Raised when an operator is missing from an expression.
5552:
5553: @item @code{ZILLOP} - @emph{unrecognized operator}
5554: Raised when an unrecognized operator is encountered in an expression.
5555:
5556: @item @code{ZQUOTER} - @emph{unmatched quotes}
5557: Raised when unbalanced quotes are encountered.
5558:
5559: @item @code{ZCOMMAER} - @emph{comma expected}
5560: Raised when a comma is expected in program syntax but is not found.
5561:
5562: @item @code{ZASSIGNER} - @emph{equals '=' expected}
5563: Raised when an equals sign is expected in program syntax but is not found.
5564:
5565: @item @code{ZARGER} - @emph{argument not permitted}
5566: Raised when an argument is encountered in a syntactic position where arguments are not permitted.
5567:
5568: @item @code{ZSPACER} - @emph{blank ' ' expected}
5569: Raised when a space character is expected in program syntax but is not found.
5570:
5571: @item @code{ZBRAER} - @emph{unmatched parentheses}
5572: Raised when unbalanced parentheses are detected in program syntax.
5573:
5574: @item @code{ZLVLERR} - @emph{level error}
5575: Raised when a level error occurs.
5576:
5577: @item @code{ZDIVER} - @emph{divide by zero}
5578: Raised when program code attempts to divide by zero. Deprecated in favor of standard error code @code{M9}.
5579:
5580: @item @code{ZILLFUN} - @emph{function not found}
5581: Raised when program code attempts to call intrinsic or extrinsic functions that are not defined.
5582:
5583: @item @code{ZFUNARG} - @emph{wrong number of function arguments}
5584: Raised when an intrinsic or extrinsic function is called with the wrong number of arguments.
5585:
5586: @item @code{ZZTERR} - @emph{ZTRAP error}
5587: Raised when a @code{$ZTRAP} error occurs.
5588:
5589: @item @code{ZNEXTERR} - @emph{$NEXT/$ORDER error}
5590: Raised when an error occurs in @code{$NEXT} or @code{$ORDER}.
5591:
5592: @item @code{ZSELER} - @emph{$SELECT error}
5593: Raised when an error occurs in @code{$SELECT}
5594:
5595: @item @code{ZCMMND} - @emph{illegal command}
5596: Raised when program code attempts to execute an illegal command.
5597:
5598: @item @code{ZARGLIST} - @emph{argument list incorrect}
5599: Raised when the argument list supplied to an M language element does not match that language element's syntactic requirements.
5600:
5601: @item @code{ZINVEXPR} - @emph{invalid expression}
5602: Raised when an invalid expression is encountered.
5603:
5604: @item @code{ZINVREF} - @emph{invalid reference}
5605: Raised when an invalid variable reference is encountered.
5606:
5607: @item @code{ZMXSTR} - @emph{string too long}
5608: Raised when a string is encountered that exceeds @code{^$SYSTEM("STRING_MAX")}.
5609:
5610: @item @code{ZTOOPARA} - @emph{too many parameters}
5611: Raised when too many parameters are passed to a function or subroutine.
5612:
5613: @item @code{ZNOPEN} - @emph{unit not open}
5614: Raised when attempting to access an I/O channel that has not been opened.
5615:
5616: @item @code{ZNODEVICE} - @emph{unit does not exist}
5617: Raised when attempting to access a device that does not exist.
5618:
5619: @item @code{ZPROTECT} - @emph{file protection violation}
5620: Raised when attempting to access a file or device to which you do not have permission.
5621:
5622: @item @code{ZGLOBER} - @emph{global not permitted}
5623: Raised when attempting to use a global in a syntactic element where global variables are not permitted.
5624:
5625: @item @code{ZFILERR} - @emph{file not found}
5626: Raised when attempting to access a file that does not exist.
5627:
5628: @item @code{ZPGMOV} - @emph{program overflow}
5629: Raised when a program overflows the limits of a routine buffer.
5630:
5631: @item @code{ZSTKOV} - @emph{stack overflow}
5632: Raised when @code{DO}, @code{FOR}, or @code{XECUTE} nesting levels exceed the value in @code{^$SYSTEM("NESTLEVLS")}.
5633:
5634: @item @code{ZSTORE} - @emph{symbol table overflow}
5635: Raised when program code attempts to store too much data in the local symbol table. Should not occur unless symbol table auto-adjust is disabled.
5636:
5637: @item @code{ZNOREAD} - @emph{file won't read}
5638: Raised when program code attempts to read from an unreadable file.
5639:
5640: @item @code{ZNOWRITE} - @emph{file won't write}
5641: Raised when program code attempts to write to an unwritable file.
5642:
5643: @item @code{ZNOPGM} - @emph{routine not found}
5644: Raised when an attempt is made to load or execute a routine that does not exist in the current namespace.
5645:
5646: @item @code{ZNAKED} - @emph{illegal naked reference}
5647: Raised when an attempt is made to use an illegal naked reference.
5648:
5649: @item @code{ZSBSCR} - @emph{illegal subscript}
5650: Raised when an illegal subscript access is attempted.
5651:
5652: @item @code{ZISYNTX} - @emph{insert syntax}
5653: Raised when illegal insert syntax is used.
5654:
5655: @item @code{ZDBDGD} - @emph{global data degradation}
5656: Raised when corruption is detected in global data files.
5657:
5658: @item @code{ZKILLER} - @emph{job kill signal}
5659: Raised on a job kill signal.
5660:
5661: @item @code{ZHUPER} - @emph{hangup signal}
5662: Raised on a job hangup signal.
5663:
5664: @item @code{ZMXNUM} - @emph{numeric overflow}
5665: Raised when an assignment or expression result exceeds @code{$ZPRECISION}.
5666:
5667: @item @code{ZNOVAL} - @emph{function returns no value}
5668: Raised when a function does not return a value. Extrinsic functions must @code{QUIT} with a value.
5669:
5670: @item @code{ZTYPEMISMATCH} - @emph{type mismatch}
5671: Raised when a type mismatch occurs.
5672:
5673: @item @code{ZMEMOV} - @emph{out of memory}
5674: Raised when FreeM runs out of heap memory.
5675:
5676: @item @code{ZNAMERES} - @emph{error in name resolution}
5677: Raised when an attempted name resolution fails.
5678:
5679: @item @code{ZSCKCREAT} - @emph{error creating socket}
5680: Raised when an error occurs creating a socket for network I/O.
5681:
5682: @item @code{ZSCKIFAM} - @emph{invalid address family (must be IPV4 or IPV6)}
5683: Raised when the address family specified in an @code{OPEN} command for a socket I/O channel is not IPV4 or IPV6.
5684:
5685: @item @code{ZSCKITYP} - @emph{invalid connection type (must be TCP or UDP)}
5686: Raised when the connection type specified in an @code{OPEN} command for a socket I/O channel is not @code{TCP} or @code{UDP}.
5687:
5688: @item @code{ZSCKIPRT} - @emph{invalid port number}
5689: Raised when the port number specified in an @code{OPEN} command for a socket I/O channel is invalid. Valid TCP and UDP ports are in the range of 1-65535.
5690:
5691: @item @code{ZSCKCERR} - @emph{connection error}
5692: Raised when an error occurs on a @code{USE <channel>:/CONNECT} command.
5693:
5694: @item @code{ZSCKAERR} - @emph{USE action invalid for connection type (possibly CONNECT on UDP socket?)}
5695: Raised when an attempt is made to @code{USE <channel>:/CONNECT} on a UDP socket I/O channel. The UDP protocol is connectionless.
5696:
5697: @item @code{ZSCKACON} - @emph{attempted to CONNECT an already-connected socket}
5698: Raised when an attempt is made to @code{USE <channel>:/CONNECT} on a TCP socket I/O channel that is already connected.
5699:
5700: @item @code{ZSCKNCON} - @emph{attempted to READ from a disconnected TCP socket}
5701: Raised when an attempt is made to @code{READ} a TCP socket that has not yet been connected.
5702:
5703: @item @code{ZSCKEOPT} - @emph{error setting socket options}
5704: Raised when an error is encountered while setting socket options.
5705:
5706: @item @code{ZSCKERCV} - @emph{error in READ from socket}
5707: Raised when an error occurs in a socket I/O channel @code{READ}.
5708:
5709: @item @code{ZSCKESND} - @emph{error in WRITE to socket}
5710: Raised when an error occurs while attempting to @code{WRITE} to a socket I/O channel.
5711:
5712: @item @code{ZNORPI} - @emph{^$ZRPI only supported on Raspberry Pi hardware}
5713: Raised when an attempt is made to use the @code{^$ZRPI} structured system variable on a platform other than the Raspberry Pi single-board computer.
5714:
5715: @item @code{ZCREDEF} - @emph{cannot redefine CONST}
5716: Raised when attempts are made to redefine a @code{CONST} after its initial definition.
5717:
5718: @item @code{ZCMODIFY} - @emph{cannot modify CONST}
5719: Raised when attempts are made to change the value of a @code{CONST}.
5720:
5721: @item @code{ZFILEXWR} - @emph{cannot open existing file for WRITE}
5722: Raised when an attempt is made to open an existing file in write (but not append) mode.
5723:
5724: @item @code{INEWMULT} - @emph{initializing NEW with multiple setarguments not supported}
5725: Raised when you attempt to use multiple setarguments with initializing @code{NEW}, e.g. @code{NEW X=2,Y=3}.
5726:
5727: @item @code{ZECODEINV} - @emph{invalid value for $ECODE}
5728: Raised when attempts are made to set @code{$ECODE} to an invalid error code value. Obsolete and replaced by standard error code @code{M101}.
5729:
5730: @item @code{ZASSERT} - @emph{programmer assertion failed}
5731: Raised when an @code{ZASSERT} expression's result is not true.
5732:
5733: @item @code{ZUSERERR} - @emph{user-defined error}
5734: Raised when program code calls @code{THROW} with an error code argument for which the first character is @code{U}, or when @code{$ECODE} is set to an error code for which the first character is @code{U}.
5735:
5736: Custom error messages for @code{ZUSERERR} may be set in @code{^$JOB($JOB,"USER_ERRORS",<user_error_code>)}, where @code{<user_error_code>} represents the custom error code.
5737:
5738: For example:
5739:
5740: @example
5741: DEFAULT.USER> S ^$JOB($JOB,"USER_ERRORS","UBLACKHOLE")="black hole encountered"
5742:
5743:
5744: DEFAULT.USER> THROW UBLACKHOLE
5745:
5746:
5747: >> Error UBLACKHOLE: black hole encountered in SYSTEM::^%SYSINIT [$STACK = 0]
5748: >> THROW UBLACKHOLE
5749: ^
5750: @end example
5751:
5752: @item @code{ZSYNTERR} - @emph{syntax error}
5753: Raised when a syntax error without a more specific error code is encountered.
5754:
5755: @item @code{ZCTRLB} - @emph{break}
5756: Pseudo-error used by the FreeM debugger. Not visibly raised in normal program operation.
5757:
5758: @item @code{ZASYNC} - @emph{asynchronous interruption}
5759: Pseudo-error used by the FreeM asynchronous events subsystem. Not visibly raised in normal program operation.
5760:
5761: @item @code{M1} - @emph{naked indicator undefined}
5762: Raised when an attempt is made to use a naked reference before the naked indicator is set.
5763:
5764: @item @code{M2} - @emph{invalid combination with $FNUMBER code atom}
5765:
5766:
5767: @item @code{M3} - @emph{$RANDOM seed less than 1}
5768:
5769:
5770: @item @code{M4} - @emph{no true condition in $SELECT}
5771:
5772:
5773: @item @code{M5} - @emph{line reference less than zero}
5774:
5775:
5776: @item @code{M6} - @emph{undefined local variable}
5777:
5778:
5779: @item @code{M7} - @emph{undefined global variable}
5780:
5781:
5782: @item @code{M8} - @emph{undefined intrinsic special variable}
5783:
5784:
5785: @item @code{M9} - @emph{divide by zero}
5786:
5787:
5788: @item @code{M10} - @emph{invalid pattern match range}
5789:
5790:
5791: @item @code{M11} - @emph{no parameters passed}
5792:
5793:
5794: @item @code{M12} - @emph{invalid line reference (negative offset)}
5795:
5796:
5797: @item @code{M13} - @emph{invalid line reference (line not found)}
5798:
5799:
5800: @item @code{M14} - @emph{line level not 1}
5801:
5802:
5803: @item @code{M15} - @emph{undefined index variable}
5804:
5805:
5806: @item @code{M16} - @emph{argumented QUIT not allowed}
5807:
5808:
5809: @item @code{M17} - @emph{argumented QUIT required}
5810:
5811:
5812: @item @code{M18} - @emph{fixed length READ not greater than zero}
5813:
5814:
5815: @item @code{M19} - @emph{cannot copy a tree or subtree onto itself}
5816:
5817:
5818: @item @code{M20} - @emph{line must have a formal parameter list}
5819:
5820:
5821: @item @code{M21} - @emph{algorithm specification invalid}
5822:
5823:
5824: @item @code{M22} - @emph{SET or KILL to ^$GLOBAL when data in global}
5825:
5826:
5827: @item @code{M23} - @emph{SET or KILL to ^$JOB for non-existent job number}
5828:
5829:
5830: @item @code{M24} - @emph{change to collation algorithm while subscripted local variables defined}
5831:
5832:
5833: @item @code{M26} - @emph{non-existent environment}
5834:
5835:
5836: @item @code{M27} - @emph{attempt to rollback a transaction that is not restartable}
5837:
5838:
5839: @item @code{M28} - @emph{mathematical function, parameter out of range}
5840:
5841:
5842: @item @code{M29} - @emph{SET or KILL on structured system variable not allowed by implementation}
5843:
5844:
5845: @item @code{M30} - @emph{reference to global variable with different collating sequence within a collating algorithm}
5846:
5847:
5848: @item @code{M31} - @emph{control mnemonic used for device without a mnemonic space selected}
5849:
5850:
5851: @item @code{M32} - @emph{control mnemonic used in user-defined mnemonic space which has no associated line}
5852:
5853:
5854: @item @code{M33} - @emph{SET or KILL to ^$ROUTINE when routine exists}
5855:
5856:
5857: @item @code{M35} - @emph{device does not support mnemonic space}
5858:
5859:
5860: @item @code{M36} - @emph{incompatible mnemonic spaces}
5861:
5862:
5863: @item @code{M37} - @emph{READ from device identified by empty string}
5864:
5865:
5866: @item @code{M38} - @emph{invalid structured system variable subscript}
5867:
5868:
5869: @item @code{M39} - @emph{invalid $NAME argument}
5870:
5871:
5872: @item @code{M40} - @emph{call-by-reference in JOB actual parameter}
5873:
5874:
5875: @item @code{M41} - @emph{invalid LOCK argument within a transaction}
5876:
5877:
5878: @item @code{M42} - @emph{invalid QUIT within a transaction}
5879:
5880:
5881: @item @code{M43} - @emph{invalid range value ($X, $Y}
5882:
5883:
5884: @item @code{M44} - @emph{invalid command outside of a transaction}
5885:
5886:
5887: @item @code{M45} - @emph{invalid GOTO reference}
5888:
5889:
5890: @item @code{M56} - @emph{identifier exceeds maximum length}
5891:
5892:
5893: @item @code{M57} - @emph{more than one defining occurrence of label in routine}
5894:
5895:
5896: @item @code{M58} - @emph{too few formal parameters}
5897:
5898:
5899: @item @code{M60} - @emph{illegal attempt to use an undefined SSVN}
5900:
5901:
5902: @item @code{M101} - @emph{invalid value for $ECODE}
5903:
5904:
5905: @item @code{M102} - @emph{synchronous and asynchronous event processing cannot be simultaneously enabled for the same event class}
5906:
5907:
5908: @item @code{M103} - @emph{invalid event identifier}
5909:
5910:
5911: @item @code{M104} - @emph{ETRIGGER event identifier for IPC event class does not match job process identifier}
5912:
5913:
5914: @end table
5915:
5916:
5917: @node System Configuration
5918: @chapter System Configuration
5919: @cindex configuration, system
5920:
5921: @section Installing FreeM
5922: @cindex installation
5923:
5924: @subsection Installation Methods
5925:
5926: FreeM allows the following installation methods:
5927: @table @asis
5928: @item Binary Repository
5929: On recent versions the Ubuntu and Debian distributions of GNU/Linux, we provide package repositories from which FreeM may easily be installed. See the @emph{FreeM Wiki} for more information, and @emph{https://packages.coherent-logic.com} for instructions.
5930:
5931: If available, this is the simplest method of installing FreeM.
5932: @item Binary Packages
5933: We provide binary packages of FreeM for @emph{dpkg} and @emph{rpm}-based distributions of GNU/Linux, and @emph{pkgadd} packages for Solaris 8-10. If you cannot use repositories, this is the easiest option.
5934:
5935: See @emph{https://freem.coherent-logic.com/binaries.cfm} for downloads and instructions.
5936: @item Source Archive
5937: If you prefer installing from source, we recommend that you download the latest @emph{.tar.gz} file from @emph{https://freem.coherent-logic.com/downloads.cfm}, and follow these steps:
5938:
5939: @example
5940: $ gunzip freem-@emph{<version>}.tar.gz
5941: $ tar xf freem-@emph{<version>}.tar
5942: $ cd freem
5943: $ ./configure # see the Build Configuration section for optional flags
5944: $ make
5945: $ sudo make install
5946: @end example
5947:
5948: Once this process has been completed, you may proceed to @emph{Initial Configuration}.
5949:
5950: Installation from source archive is the most challenging but flexible supported option for advanced users.
5951: @item CVS Repository
5952: If you wish to try the bleeding-edge development version of FreeM, you may do so by following these steps:
5953:
5954: @verbatim
5955: $ cvs -d :pserver:anonymous@cvs.coherent-logic.com:/home/cvsroot co freem
5956: $ cd freem
5957: $ ./autogen.sh
5958: $ ./configure # see the Build Configuration section for optional flags
5959: $ make
5960: $ sudo make install
5961: @end verbatim
5962:
5963: Once this process has been completed, you may proceed to @emph{Initial Configuration}.
5964:
5965: This installation method is by far the most complicated, and is intended only for those who wish to contribute to FreeM development. It is not intended for end users, and no technical support will be provided.
5966:
5967: See the @emph{Contributor Guide} on the @emph{FreeM Wiki} for more information.
5968: @end table
5969: @subsection Build Configuration
5970: @cindex build configuration
5971:
5972: When configuring FreeM with the supplied @code{configure} script, there are some FreeM-specific options that may be used to compile in optional features, or exclude default ones:
5973:
5974: @table @asis
5975:
5976: @item @code{--enable-mwapi} (EXPERIMENTAL)
5977: Enables experimental support for the M Windowing API (ANSI @emph{X11.6-1995}) using the OSF/Motif widget toolkit. Requires that you have the @code{X11}, @code{Xt}, @code{ICE}, and @code{Xm} libraries, as well as all of their C header files.
5978:
5979: Please consult your operating system's documentation for the correct commands to install the required libraries.
5980:
5981: @emph{Example}
5982:
5983: @example
5984: $ ./configure --enable-mwapi
5985: $ make
5986: $ sudo make install
5987: @end example
5988:
5989: @end table
5990:
5991: @subsection Initial Configuration
5992: Once FreeM is installed, you will need to configure it:
5993:
5994: @enumerate
5995: @item Create a user and group, each named @emph{freem}, under which FreeM will run
5996: @item Add any user accounts that will need to run FreeM to the @emph{freem} group
5997: @item Have all users added in step 2 sign out and sign in for the new group membership to take effect
5998: @item Run @code{fmadm configure} with superuser privileges to create the @code{DEFAULT} environment with @code{SYSTEM} and @code{USER} namespaces and default after-image journal settings, and populate the bundled vendor routines
5999: @item Run @code{fmadm start environment} with superuser privileges to start the @code{DEFAULT} environment
6000: @item Make sure the environment is ready by running @code{fmadm status environment} with superuser privileges
6001: @end enumerate
6002:
6003: @subsubsection Creating Additional Environments
6004: To create additional environments, do the following steps:
6005:
6006: @enumerate
6007: @item Create a new user and group for the environment @emph{(optional)}
6008: @item Run @code{fmadm configure -e=@emph{<environment>} -u=@emph{<username>} -g=@emph{<groupname>} [-E=@emph{true|false}]} @emph{(the @code{-E} flag enables or disables the environment)}
6009: @item Run @code{fmadm start environment -e=@emph{<environment>}} to start the environment
6010: @item Run @code{fmadm status environment} to make sure the environment is healthy
6011: @end enumerate
6012:
6013: @subsubsection Additional Customization
6014:
6015: See the FreeM @emph{environment catalog} at @code{@emph{$PREFIX}/etc/freem/env.conf}, and the @emph{fmadm}(1) @code{man} page for more information.
6016:
6017: @emph{$PREFIX} represents the root location of your FreeM installation. This can be @code{/usr/local}, @code{/}, or others, depending on how FreeM was built and installed.
6018:
6019: @node Accessing FreeM from C Programs
6020: @chapter Accessing FreeM from C Programs
6021:
6022: FreeM provides a library, @file{libfreem.so}, as well as corresponding header file @file{freem.h}, allowing C programmers to write programs that access FreeM globals, locals, structured system variables, subroutines, and extrinsic functions. This functionality can be used to implement language bindings and data access drivers for external systems.
6023:
6024: In order to be used in your C programs, your C programs must link with @file{libfreem.so} and include @file{freem.h}. This will allow your C code access to the function prototypes, data structures, and constants required for calling the @file{libfreem.so} APIs.
6025:
6026: You must exercise caution in developing programs that interface with FreeM through @file{libfreem.so} to ensure that all @file{libfreem.so} API calls are serialized, as FreeM and the @file{libfreem.so} library are neither thread-safe nor reentrant.
6027:
6028: You must also avoid setting signal handlers for @code{SIGALRM}, as FreeM uses @code{SIGALRM} to manage timeouts for @command{LOCK}, @command{READ}, and @command{WRITE}.
6029:
6030: @section freem_ref_t Data Structure
6031: @cindex libfreem, data structures: freem_ref_t
6032:
6033: The @code{libfreem} API uses a @code{struct} of type @code{freem_ref_t} in order to communicate state, pass in values, and return results.
6034:
6035: The data structure, defined in @file{freem.h}, looks like this:
6036:
6037: @verbatim
6038: typedef struct freem_ref_t {
6039:
6040: /*
6041: * The 'reftype' field can be one of:
6042: *
6043: * MREF_RT_LOCAL
6044: * MREF_RT_GLOBAL
6045: * MREF_RT_SSV
6046: */
6047: short reftype;
6048:
6049: /*
6050: * The 'name' field is the name of the local variable,
6051: * global variable, or SSVN (without ^ or ^$).
6052: */
6053: char name[256];
6054:
6055: /*
6056: * Returned data goes in a string, so you've got to figure out the
6057: * whole M canonical number thing yourself. Good luck. :-)
6058: */
6059: char value[STRLEN];
6060:
6061: short status;
6062:
6063: unsigned int subscript_count;
6064: char subscripts[255][256];
6065:
6066: } freem_ref_t;
6067: @end verbatim
6068:
6069: @emph{freem_ref_t Members}
6070:
6071: @table @asis
6072: @cindex libfreem, freem_ref_t.reftype
6073: @item @option{reftype}
6074: The @option{reftype} member determines whether we are operating on a local variable, a global variable, or a structured system variable. It may be set to any of following constants: @code{MREF_RT_LOCAL}, @code{MREF_RT_GLOBAL}, or @code{MREF_RT_SSV}.
6075:
6076: @cindex libfreem, freem_ref_t.name
6077: @item @option{name}
6078: The @option{name} member contains the name of the global, local, or SSVN to be accessed. You @emph{must not} include leading characters, such as @code{^} or @code{^$}.
6079:
6080: @cindex libfreem, freem_ref_t.value
6081: @item @option{value}
6082: This member contains the value read from or the value to be written to the global, local, or SSVN.
6083:
6084: @cindex libfreem, freem_ref_t.status
6085: @item @option{status}
6086: This member gives us various API status values after the API call returns. In general, this value is also returned by each API function.
6087:
6088: @cindex libfreem, freem_ref_t.subscript_count
6089: @item @option{subscript_count}
6090: The number of subscripts to be passed into the API function being called. This value represents the maximum index into the first dimension of the @code{subscripts} array.
6091:
6092: @cindex libfreem, freem_ref_t.subscripts
6093: @item @option{subscripts}
6094: A two-dimensional array containing the subscripts to which we are referring in this API call.
6095:
6096: @end table
6097:
6098: @section freem_ent_t Data Structure
6099: @cindex libfreem, data structures: freem_ent_t
6100:
6101: The @code{freem_function()} and @code{freem_procedure()} APIs in @code{libfreem} use the @code{freem_ent_t} struct in order to indicate the name of the entry point being called, any arguments being passed to it, and the return value of the called function (not used for @code{freem_procedure()}).
6102:
6103: The data structure, defined in @file{freem.h}, looks like this:
6104:
6105: @verbatim
6106: typedef struct freem_ent_t {
6107:
6108: /* name of function or procedure entry point */
6109: char name[256];
6110:
6111: /* return value */
6112: char value[STRLEN];
6113:
6114: /* value of ierr on return */
6115: short status;
6116:
6117: /* argument count and array */
6118: unsigned int argument_count;
6119: char arguments[255][256];
6120:
6121: } freem_ent_t;
6122: @end verbatim
6123:
6124: @emph{freem_ent_t Members}
6125:
6126: @table @asis
6127:
6128: @item @option{name}
6129: @cindex libfreem, freem_ent_t.name
6130: The @option{name} member contains the name of the extrinsic function or procedure to be called.
6131:
6132: @cindex libfreem, freem_ent_t.value
6133: @item @option{value}
6134: This member contains the value returned by the function called. Not used by @code{freem_procedure()}.
6135:
6136: @cindex libfreem, freem_ent_t.status
6137: @item @option{status}
6138: This member gives us the value of @code{ierr} after the function or procedure call returns. The possible values of @code{ierr} are listed in @code{merr.h}.
6139:
6140: @cindex libfreem, freem_ent_t.argument_count
6141: @item @option{argument_count}
6142: The number of arguments to be passed into the extrinsic function or procedure being called. This value represents the maximum index into the first dimension of the @code{arguments} array.
6143:
6144: @cindex libfreem, freem_ent_t.arguments
6145: @item @option{arguments}
6146: A two-dimensional array containing the arguments to be passed into the extrinsic function or procedure being called.
6147:
6148: @end table
6149:
6150: @section freem_init()
6151: @cindex libfreem, freem_init()
6152:
6153: Initializes @code{libfreem} in preparation for calling other APIs.
6154:
6155: @emph{Synopsis}
6156:
6157: @code{pid_t freem_init(char *environment_name, char *namespace_name);}
6158:
6159: @emph{Parameters}
6160:
6161: @table @asis
6162: @item @code{environment_name}
6163: Specifies the environment to use.
6164: @item @code{namespace_name}
6165: Specifies the namespace to use.
6166: @end table
6167:
6168: @emph{Return Values}
6169:
6170: Returns the process ID of the @code{libfreem} process on success, or @code{-1} on failure.
6171:
6172: @emph{Example}
6173:
6174: This example prompts the user to enter a FreeM namespace and then attempts to initialize @code{libfreem} to use the selected namespace.
6175:
6176: @verbatim
6177: #include <stdio.h>
6178: #include <string.h>
6179: #include <freem.h>
6180:
6181: int main(int argc, char **argv, char **envp)
6182: {
6183: char namespace[256];
6184:
6185: /* get the namespace name to use */
6186: printf("Enter FreeM namespace to use: ");
6187: fgets(namespace, 255, stdin);
6188:
6189: /* remove the trailing newline */
6190: namespace[strcspn(buffer, "\n")] = '\0';
6191:
6192: /* initialize libfreem using the provided namespace */
6193: if(freem_init("DEFAULT", namespace) == TRUE) {
6194: printf("\nSuccess\n");
6195: }
6196: else {
6197: printf("\nFailure\n");
6198: }
6199:
6200: return 0;
6201: }
6202: @end verbatim
6203:
6204: @section freem_version()
6205: @cindex libfreem, freem_version()
6206:
6207: Returns the version of FreeM in use.
6208:
6209: @emph{Synopsis}
6210:
6211: @code{short freem_version(char *result);}
6212:
6213: @emph{Parameters}
6214:
6215: @table @asis
6216: @item @code{result}
6217: The @code{result} parameter is a pointer to a buffer in which the FreeM version information will be returned. The caller must allocate memory for this buffer prior to calling this API. It should be at least 20 bytes in length.
6218: @end table
6219:
6220: @emph{Return Value}
6221:
6222: Returns @code{0}.
6223:
6224: @emph{Example}
6225:
6226: This example will display the FreeM version on standard output.
6227:
6228: @verbatim
6229: #include <stdio.h>
6230: #include <string.h>
6231: #include <freem.h>
6232:
6233: int main(int argc, char **argv, char **envp)
6234: {
6235: char version[20] = {0};
6236:
6237: freem_init(``USER'');
6238: freem_version(version);
6239:
6240: printf(``FreeM version: %s\n'', version);
6241:
6242: }
6243: @end verbatim
6244:
6245: @section freem_set()
6246: @cindex libfreem, freem_set()
6247:
6248: Sets a FreeM local node, global node, or writable SSVN node.
6249:
6250: @emph{Synopsis}
6251:
6252: @code{short freem_set(freem_ref_t *ref);}
6253:
6254: @emph{Parameters}
6255:
6256: @table @asis
6257: @item @code{freem_ref_t}
6258: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
6259: @end table
6260:
6261: @emph{Return Value}
6262:
6263: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
6264:
6265: @emph{Example}
6266:
6267: This example sets the value @code{blue} into global node @code{^car("color")}.
6268:
6269: @verbatim
6270: #include <stdio.h>
6271: #include <string.h>
6272: #include <freem.h>
6273:
6274: int main(int argc, char **argv, char **envp)
6275: {
6276: freem_ref_t ref;
6277:
6278: /* we're setting a global */
6279: ref.reftype = MREF_RT_GLOBAL;
6280:
6281: /* access global "car" */
6282: strcpy(ref.name, "car");
6283:
6284: /* set up the subscripts */
6285: ref.subscript_count = 1;
6286: strcpy(ref.subscripts[0], "color");
6287:
6288:
6289: /* use the USER namespace */
6290: freem_init("USER");
6291:
6292: /* write the data out */
6293: freem_set(&ref);
6294:
6295: }
6296: @end verbatim
6297:
6298: @section freem_get()
6299: @cindex libfreem, freem_get()
6300:
6301: Retrieves a FreeM local node, global node, or writable SSVN node.
6302:
6303: @emph{Synopsis}
6304:
6305: @code{short freem_get(freem_ref_t *ref);}
6306:
6307: @emph{Parameters}
6308:
6309: @table @asis
6310: @item @code{freem_ref_t}
6311: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
6312: @end table
6313:
6314: @emph{Return Value}
6315:
6316: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
6317:
6318: @emph{Example}
6319:
6320: This example retrieves the character set of the current process.
6321:
6322: @verbatim
6323: #include <stdio.h>
6324: #include <sys/types.h>
6325: #include <unistd.h>
6326: #include <string.h>
6327: #include <freem.h>
6328:
6329: int main(int argc, char **argv, char)
6330: {
6331: pid_t pid;
6332: freem_ref_t ref;
6333:
6334: /* get the PID of this process */
6335: pid = getpid();
6336:
6337: /* we want to access an SSVN */
6338: ref.reftype = MREF_RT_SSV;
6339:
6340: /* set up the name and subscripts */
6341: strcpy(ref.name, "JOB");
6342:
6343: ref.subscript_count = 2;
6344: sprintf(ref.subscripts[0], "%d", pid);
6345: strcpy(ref.subscripts[1], "CHARACTER");
6346:
6347: /* initialize libfreem, using the USER namespace */
6348: freem_init("USER");
6349:
6350: /* call libfreem API */
6351: freem_get(&ref);
6352:
6353: /* output the character set info */
6354: printf("PID %d character set is '%s'\n", pid, ref.value);
6355: }
6356: @end verbatim
6357:
6358: @section freem_kill()
6359: @cindex libfreem, freem_kill()
6360:
6361: Deletes a FreeM local node, global node, or killable SSVN node, as well as all of its children.
6362:
6363: @emph{short freem_kill(freem_ref_t *ref);}
6364:
6365: @emph{Parameters}
6366:
6367: @table @asis
6368: @item @code{freem_ref_t}
6369: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
6370: @end table
6371:
6372: @emph{Return Value}
6373:
6374: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
6375:
6376: @emph{Example}
6377:
6378: @verbatim
6379: #include <stdio.h>
6380: #include <string.h>
6381: #include <freem.h>
6382:
6383: int main(int argc, char **argv, char **envp)
6384: {
6385: freem_ref_t ref;
6386:
6387: /* we're killing a global node */
6388: ref.reftype = MREF_RT_GLOBAL;
6389:
6390: /* access global "car" */
6391: strcpy(ref.name, "car");
6392:
6393: /* set up the subscripts */
6394: ref.subscript_count = 0;
6395:
6396: /* use the USER namespace */
6397: freem_init("USER");
6398:
6399: /* kill the global and all its descendant subscripts */
6400: freem_kill(&ref);
6401: }
6402: @end verbatim
6403:
6404: @section freem_data()
6405: @cindex libfreem, freem_data()
6406:
6407: @section freem_order()
6408: @cindex libfreem, freem_order()
6409:
6410: @section freem_query()
6411: @cindex libfreem, freem_query()
6412:
6413: @section freem_lock()
6414: @cindex libfreem, freem_lock()
6415:
6416: @section freem_unlock()
6417: @cindex libfreem, freem_unlock()
6418:
6419: @section freem_tstart()
6420: @cindex libfreem, freem_tstart()
6421:
6422: @section freem_trestart()
6423: @cindex libfreem, freem_trestart()
6424:
6425: @section freem_trollback()
6426: @cindex libfreem, freem_trollback()
6427:
6428: @section freem_tlevel()
6429: @cindex libfreem, freem_tlevel()
6430:
6431: @section freem_tcommit()
6432: @cindex libfreem, freem_tcommit()
6433:
6434: @section freem_function()
6435: @cindex libfreem, freem_function()
6436:
6437: @section freem_procedure()
6438: @cindex libfreem, freem_procedure()
6439:
6440: @node FreeM Administrator
6441: @appendix FreeM Administrator
6442: @cindex utilities, system management
6443: @cindex utilities, fmadm
6444: @cindex fmadm
6445:
6446: The @code{fmadm} utility is the preferred method of managing a FreeM installation, and will eventually replace all of the existing utilities.
6447: Unlike the existing, legacy utilities, @code{fmadm} presents a consistent, simple interface for all FreeM management tasks, and is namespace-aware.
6448: This appendix will document each @code{fmadm} facility as it is implemented, until all of the legacy utilities have been replaced.
6449:
6450: The @code{fmadm} utility's functions all follow the below, consistent syntax:
6451:
6452: @example
6453: usage: fmadm <action> <object> <namespace> [OPTIONS]
6454: @end example
6455:
6456: The @emph{action} keyword can be one of the following:
6457:
6458: @table @emph
6459:
6460: @item list
6461: Lists instances of @emph{object}
6462:
6463: @item examine
6464: Examines a single instance of @emph{object}
6465:
6466: @item verify
6467: Verifies the integrity of @emph{object}
6468:
6469: @item compact
6470: Compacts @emph{object}
6471:
6472: @item repair
6473: Repairs integrity problems in @emph{object}
6474:
6475: @item create
6476: Creates an instance of @emph{object}
6477:
6478: @item remove
6479: Removes an instance of @emph{object}
6480:
6481: @item import
6482: Imports an @emph{object}
6483:
6484: @item export
6485: Exports an @emph{object}
6486:
6487: @item backup
6488: Creates a backup of @emph{object}
6489:
6490: @item restore
6491: Restores a backup of @emph{object}
6492:
6493: @item migrate
6494: Migrates an instance of @emph{object} from an older FreeM version to the current version
6495:
6496: @item edit
6497: Edits an instance of @emph{object}
6498:
6499: @end table
6500:
6501: The @emph{object} keyword can be one of the following:
6502:
6503: @table @emph
6504:
6505: @item lock
6506: The FreeM @code{LOCK} table.
6507:
6508: Supported actions are @code{list} and @code{remove}.
6509:
6510: @item journal
6511: FreeM after-image journaling.
6512:
6513: Supported actions are @code{examine} and @code{restore}.
6514:
6515: The @code{examine} action will dump the after-image journal entries for the selected namespace in human-readable format.
6516:
6517: The @code{restore} action will play after-image journals forward for the selected namespace.
6518:
6519: @item namespace
6520: FreeM namespaces (collections of M routines and globals).
6521:
6522: No actions yet implemented.
6523:
6524: @item global
6525: The data files representing each FreeM @emph{global}.
6526:
6527: Supported actions are @code{list}, @code{examine}, @code{remove}, and @code{verify}.
6528:
6529: @item routine
6530: An M routine, stored as a @code{.m} file.
6531:
6532: Supported actions are @code{list}, @code{examine}, @code{remove}, @code{import}, @code{export}, @code{backup}, and @code{edit}.
6533:
6534: @item job
6535: A UNIX process representing an instance of the FreeM runtime.
6536:
6537: Supported actions are @code{list} and @code{examine}.
6538:
6539: @end table
6540:
6541:
6542: @node FreeM Legacy Utilities
6543: @appendix FreeM Legacy Utilities
6544: @cindex utilities, legacy
6545:
6546: @section Global Compactor (gcompact)
6547: @cindex utilities, legacy, gcompact
6548:
6549: Compacts the specified global in place.
6550:
6551: @emph{Syntax}
6552:
6553: @example
6554: gcompact @emph{/path/to/global/file}
6555: @end example
6556:
6557: @section Block Examiner (gfix)
6558: @cindex utilities, gfix
6559:
6560: The @emph{gfix} interactive utility program permits navigation of the B-tree structure of the specified global a block at a time.
6561:
6562: @emph{Syntax}
6563:
6564: @example
6565: gfix @emph{</path/to/global/file>}
6566: @end example
6567:
6568: @section Global Repair Tool (grestore)
6569: @cindex utilities, legacy, grestore
6570:
6571: This utility will fix problems with the specified global.
6572:
6573: @emph{Syntax}
6574:
6575: @example
6576: grestore @emph{</path/to/global/file>}
6577: @end example
6578:
6579: @node FreeM VIEW Commands and Functions
6580: @appendix FreeM VIEW Commands and Functions
6581:
6582: @section VIEW 16: Total Count of Error Messages/View Single Error Message
6583: @cindex VIEW commands/functions, 16, total count of error messages/view single error message
6584:
6585: Unknown semantics
6586:
6587: @section VIEW 17: Intrinsic Z-Commands
6588: @cindex VIEW commands/functions, 17, intrinsic Z-commands
6589:
6590: Allows the user to retrieve or specify the list of intrinsic Z-commands that FreeM will attempt to run internally, allowing intrinsic Z-commands implemented internally to be replaced with M equivalents implemented as %-routines in the @code{SYSTEM} namespace.
6591:
6592: @section VIEW 18: Intrinsic Z-Functions
6593: @cindex VIEW commands/functions, 18, intrinsic Z-functions
6594:
6595: Allows the user to retrieve or specify the list of intrinsic Z-functions that FreeM will attempt to run internally, allowing intrinsic Z-functions implemented internally to be replaced with M equivalents implemented as %-routines in the @code{SYSTEM} namespace.
6596:
6597: @section VIEW 19: Intrinsic Special Variables
6598: @cindex VIEW commands/functions, 19, intrinsic special variables
6599:
6600: Allows the user to retrieve or specify which special variables are implemented internally.
6601:
6602: @section VIEW 20: Break Service Code
6603: @cindex VIEW commands/functions, 20, break service code
6604:
6605: Allows the user to view or specify the code that will be run when a @code{BREAK} is encountered.
6606:
6607: @section VIEW 21: View Size of Last Global
6608: @cindex VIEW commands/functions, 21, view size of last global
6609:
6610: Allows the user to view the size of the last referenced global.
6611:
6612: @section VIEW 22: Count VIEW 22 Aliases
6613: @cindex VIEW commands/functions, 22, count VIEW 22 aliases
6614:
6615: Retrieves the number of VIEW 22 aliases in effect.
6616:
6617: @section VIEW 23: View Contents of Input Buffer
6618: @cindex VIEW commands/functions, 23, input buffer contents
6619:
6620: Retrieves the contents of the I/O input buffer.
6621:
6622: @section VIEW 24: Maximum Number of Screen Rows
6623: @cindex VIEW commands/functions, 24, maximum number of screen rows
6624:
6625: Retrieves the maximum number of screen rows supported in the current FreeM build.
6626:
6627: @section VIEW 25: Maximum Number of Screen Columns
6628: @cindex VIEW commands/functions, 25, maximum number of screen columns
6629:
6630: Retrieves the maximum number of screen columns supported in the current FreeM build.
6631:
6632: @section VIEW 26: DO/FOR/XECUTE Stack Pointer
6633: @cindex VIEW commands/functions, 26, DO/FOR/XECUTE stack pointer
6634:
6635: Retrieves the @code{DO}, @code{FOR}, and @code{XECUTE} stack pointer.
6636:
6637: @section VIEW 27: DO/FOR/XECUTE Stack Pointer (On Error)
6638: @cindex VIEW commands/functions, 27, DO/FOR/XECUTE stack pointer, on error
6639:
6640: Retrieves the @code{DO}, @code{FOR}, and @code{XECUTE} stack pointer (on error).
6641:
6642: @section VIEW 29: Copy Symbol Table
6643: @cindex VIEW commands/functions, 29, copy symbol table
6644:
6645: Copies the symbol table? We aren't currently aware of what this means.
6646:
6647: @section VIEW 30: Inspect Arguments
6648: @cindex VIEW commands/functions, 30, inspect arguments
6649:
6650: Retrieves the arguments passed to the @code{freem} executable.
6651:
6652: @section VIEW 31: Count Environment Variables
6653: @cindex VIEW commands/functions, 31, count environment variables
6654:
6655: Allows the user to inspect the number of variables in the process environment table.
6656:
6657: @emph{Syntax}
6658:
6659: @example
6660: WRITE $VIEW(31),!
6661: @end example
6662:
6663: @node Implementation Limits
6664: @appendix Implementation Limits
6665:
6666: @cindex limitations, memory
6667: @cindex maximum size, routine
6668: @cindex maximum size, global
6669: @cindex maximum size, string
6670:
6671: @node US-ASCII Character Set
6672: @appendix US-ASCII Character Set
6673:
6674: @multitable {Code} {Character}
6675: @item Code @tab Character
6676: @item 000 @tab @code{<NUL>}
6677: @item 001 @tab @code{<SOH>}
6678: @item 002 @tab @code{<STX>}
6679: @item 003 @tab @code{<ETX>}
6680: @item 004 @tab @code{<EOT>}
6681: @item 005 @tab @code{<ENQ>}
6682: @item 006 @tab @code{<ACK>}
6683: @item 007 @tab @code{<BEL>}
6684: @item 008 @tab @code{<BS>}
6685: @item 009 @tab @code{<HT>}
6686: @item 010 @tab @code{<LF>}
6687: @item 011 @tab @code{<VT>}
6688: @item 012 @tab @code{<FF>}
6689: @item 013 @tab @code{<CR>}
6690: @item 014 @tab @code{<SO>}
6691: @item 015 @tab @code{<SI>}
6692: @item 016 @tab @code{<DLE>}
6693: @item 017 @tab @code{<DC1>}
6694: @item 018 @tab @code{<DC2>}
6695: @item 019 @tab @code{<DC3>}
6696: @item 020 @tab @code{<DC4>}
6697: @item 021 @tab @code{<NAK>}
6698: @item 022 @tab @code{<SYN>}
6699: @item 023 @tab @code{<ETB>}
6700: @item 024 @tab @code{<CAN>}
6701: @item 025 @tab @code{<EM>}
6702: @item 026 @tab @code{<SUB>}
6703: @item 027 @tab @code{<ESC>}
6704: @item 028 @tab @code{<FS>}
6705: @item 029 @tab @code{<GS>}
6706: @item 030 @tab @code{<RS>}
6707: @item 031 @tab @code{<US>}
6708: @item 032 @tab @code{<space>}
6709: @item 033 @tab !
6710: @item 034 @tab ``
6711: @item 035 @tab #
6712:
6713:
6714: @end multitable
6715:
6716: @node FreeM Project Coding Standards
6717: @appendix FreeM Project Coding Standards
6718:
6719: @section Module Headers
6720: @cindex coding standards, module headers
6721:
6722: Module headers should adhere to the following format (where @code{Dollar} should be replaced with a dollar sign):
6723:
6724: @verbatim
6725: /*
6726: * DollarIdDollar
6727: * Function prototypes, structs, and macros for FreeM
6728: * binding library
6729: *
6730: *
6731: * Author: Serena Willis <snw@coherent-logic.com>
6732: * Copyright (C) 1998 MUG Deutschland
6733: * Copyright (C) <Year> Coherent Logic Development LLC
6734: *
6735: * This file is part of FreeM.
6736: *
6737: * FreeM is free software: you can redistribute it and/or modify
6738: * it under the terms of the GNU Affero Public License as published by
6739: * the Free Software Foundation, either version 3 of the License, or
6740: * (at your option) any later version.
6741: *
6742: * FreeM is distributed in the hope that it will be useful,
6743: * but WITHOUT ANY WARRANTY; without even the implied warranty of
6744: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
6745: * GNU Affero Public License for more details.
6746: *
6747: * You should have received a copy of the GNU Affero Public License
6748: * along with FreeM. If not, see <https://www.gnu.org/licenses/>.
6749: *
6750: * DollarLogDollar
6751: *
6752: * SPDX-FileCopyrightText: (C) 2025 Coherent Logic Development LLC
6753: * SPDX-License-Identifier: AGPL-3.0-or-later
6754: **/
6755: @end verbatim
6756:
6757: @section Variable Naming
6758: @cindex coding standards, variable naming
6759:
6760: Variables should be named in all lowercase letters, and words within them delimited by underscores, such as @code{my_useful_variable}. @code{PascalCase} and @code{camelCase} are not to be used in this codebase under any circumstances.
6761:
6762: Constants defined via the C preprocessor should be in all uppercase letters, with words within them likewise delimited by underscores, such as:
6763:
6764: @verbatim
6765: #define MY_USEFUL_CONSTANT 1
6766: @end verbatim
6767:
6768: @section Indentation and General Layout
6769: @cindex coding standards, indentation
6770: @cindex coding standards, layout
6771:
6772: This project uses four spaces for indentation. Tabs are not to be used under any circumstances, and all source files must use a linefeed character to delineate lines. If you are working on a Windows machine, you must take care to follow this, as Windows will use a carriage return followed by a linefeed by default.
6773:
6774: This project follows a modified version of what is known as the Stroustrup indentation style.
6775:
6776: @section Brace Placement (Functions)
6777: @cindex coding standards, brace placement, functions
6778:
6779: We use modern, ANSI-style function prototypes, with the type specifier on the same line as the function name. You may encounter other styles in the code, but we are transitioning to the new style as time permits.
6780:
6781: Below is a correct example:
6782:
6783: @verbatim
6784: int main(int argc, char **argv, char **envp)
6785: {
6786:
6787: }
6788: @end verbatim
6789:
6790: @section Brace Placement (if-for-while-do)
6791: @cindex coding standards, brace placement, if-for-while-do
6792:
6793: The @code{if} keyword should be followed by one space, then the opening paren and conditional expression. We also use Stroustrup-style @code{else} blocks, rather than the K&R 'cuddled' @code{else}:
6794:
6795: @verbatim
6796: if (x) {
6797: ...
6798: }
6799: else {
6800: ...
6801: }
6802:
6803: while (1) {
6804: ...
6805: }
6806:
6807: for (i = 1; i < 10; i++) {
6808: ...
6809: }
6810:
6811: do {
6812: ...
6813: } while (x);
6814: @end verbatim
6815:
6816: Single-statement if blocks should be isolated to a single line:
6817:
6818: @verbatim
6819: if (x) stmt();
6820: @end verbatim
6821:
6822: not:
6823:
6824: @verbatim
6825: if (x)
6826: stmt ();
6827: @end verbatim
6828:
6829: Notice that there is a space between @code{if} and @code{(x)}, and also between @code{stmt} and @code{()}. This should be followed throughout the code.
6830:
6831: If an @code{if} block has an @code{else if} or @code{else}, all parts of the construct must be bracketed, even if one or more of them contain only one statement:
6832:
6833: @verbatim
6834: if (x) {
6835: foo();
6836: }
6837: else if (y) {
6838: bar();
6839: }
6840: else {
6841: bas();
6842: }
6843: @end verbatim
6844:
6845: @section Labels and goto
6846: @cindex coding standards, labels
6847: @cindex coding standards, goto
6848:
6849: Labels must begin in column 1, and have two lines of vertical space above and one beneath.
6850:
6851: @section Preprocessor Conditionals
6852: @section coding standards, preprocessor conditionals
6853:
6854: I have struggled with this, but have settled upon the standard practice of keeping them in column 1.
6855:
6856: @section Overall Program Spacing
6857: @cindex coding standards, spacing of programs
6858:
6859: @itemize @bullet
6860: @item
6861: Variable declarations fall immediately beneath the opening curly brace, and should initialize the variable right there whenever initialization is used.
6862:
6863: @item
6864: One line between the last variable declaration and the first line of real code.
6865:
6866: @item
6867: The @code{return} statement of a function (when used as the last line of a function) should have one blank line above it and none below it.
6868:
6869: @item
6870: Really long functions (those whose entire body is longer than 24 lines) should have a comment immediately following the closing curly brace of the function, telling you what function the closing brace terminates.
6871: @end itemize
6872:
6873: @section The switch() Statement
6874: @cindex coding standards, switch()
6875:
6876: We indent @code{case} one level beneath @code{switch()}, and the code within each @code{case} beneath the @code{case}. Each @code{case} should have one line of vertical whitespace above it:
6877:
6878: @verbatim
6879: switch(foo) {
6880:
6881: case some_const:
6882: foo();
6883:
6884: break;
6885:
6886: case some_other_const:
6887: bar();
6888:
6889: break;
6890:
6891: default:
6892: exit(1);
6893:
6894: break;
6895: }
6896: @end verbatim
6897:
6898: @section Comments
6899: @cindex coding standards, comments
6900:
6901: We use C-style comments (@code{/* comment */}) exclusively, even on single-line comments. C++ comments (@code{// comment}) are not permitted.
6902:
6903: @node Index
6904: @unnumbered Index
6905:
6906: @printindex cp
6907:
6908: @bye
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