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-rc0), which is a free and open-source implementation of the M programming language.
8:
9:
10: Copyright @copyright{} 2014-2025 Coherent Logic Development LLC
11:
12: @quotation
13: 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.
14: @end quotation
15: @end copying
16:
17: @titlepage
18:
19: @title The FreeM Manual
20: @subtitle @sc{The Official Manual of FreeM}
21: @subtitle Version 0.64.0-rc0
22: @c@vskip 10pt
23: @c@center @image{freem-logo-sm,,,,.png}
24: @author Serena Willis
25: @page
26: @vskip 0pt plus 1filll
27: @insertcopying
28: @end titlepage
29: @contents
30:
31: @ifnottex
32: @node Top
33: @top The FreeM Manual
34:
35: This is the official manual for the FreeM programming language.
36: @end ifnottex
37:
38: @dircategory The FreeM Manual
39: @direntry
40: * FreeM: (freem). The FreeM M programming language.
41: @end direntry
42:
43: @menu
44: * Introduction:: About the FreeM Project, its history, and its goals.
45: * FreeM Invocation:: How to invoke FreeM from the command line.
46: * The FreeM Environment Daemon:: Managing shared resources in the FreeM environment.
47: * The FreeM Direct-Mode Environment:: Executing M programs interactively.
48:
49: * Directives:: Per-Routine Language Directives.
50: * Intrinsic Special Variables:: Intrinsic Special Variables.
51: * Intrinsic Functions:: Intrinsic Functions.
52: * OBJECT Methods:: Methods for OBJECT variables.
53: * STRING Methods:: Methods for STRING variables.
54: * Commands:: Commands.
55: * Structured System Variables:: Structured System Variables.
56: * Operators:: FreeM Operators.
57:
58: * Routines:: The units of M code in FreeM.
59: * Types:: FreeM data types.
60: * Globals:: FreeM persistent sparse arrays.
61: * Concurrency Control:: @code{LOCK}ing and transaction processing.
62: * Local Variables:: In-memory variables.
63: * Scoping:: Scoping in FreeM.
64: * Decision Constructs:: @code{IF}, @code{THEN}, @code{ELSE}, @code{$SELECT}, and postconditionals.
65: * Branch Constructs:: Labels, @code{GOTO}, @code{DO}, and @code{JOB}.
66: * Loop Constructs:: The @code{FOR} loop.
67: * Modular Programming:: Extrinsic functions and subroutines.
68: * Object-Oriented Programming:: Classes and objects in FreeM.
69: * Libraries:: System and user libraries.
70: * Sequential I/O:: Processing sequential files in FreeM.
71: * Network I/O:: Handling network sockets in FreeM.
72: * Extended Global References:: Accessing globals in non-default namespaces.
73: * Global Aliasing:: Defining alternate names for globals.
74: * Global Mappings:: Mapping global names to non-default namespaces.
75:
76: * Transaction Processing:: Transactions in FreeM.
77: * Asynchronous Event Handling:: Handling asynchronous events in FreeM.
78: * Global Triggers:: Responding to global accesses in M code.
79: * Synchronous Event Handling:: Synchronous events in FreeM.
80:
81:
82: * GUI Programming with MWAPI:: Creating graphical interfaces in FreeM.
83:
84: * User-Defined Z Commands:: Adding your own Z commands to FreeM.
85: * User-Defined Z Functions:: Adding your own Z functions to FreeM.
86: * User-Defined SSVNs:: Adding your own SSVNs to FreeM.
87:
88: * Language Dialects:: Controlling FreeM standards compliance.
89:
90: * System Library Routines:: FreeM built-in library of M routines.
91:
92: * Interrupt Handling:: How FreeM handles interrupts.
93: * Error Processing:: How to handle errors in M program code.
94: * FreeM Error Codes:: Explanations of each FreeM error code.
95: * Debugging:: The program development cycle of FreeM.
96:
97: * System Configuration:: Configuring your FreeM installation.
98: * Accessing FreeM from C Programs:: How to use the mlib interface.
99:
100: * FreeM Administrator:: The fmadm system manager tool.
101: * FreeM Legacy Utilities:: FreeM legacy system manager utilities.
102: * FreeM VIEW Commands and Functions:: Getting and setting info about FreeM internals.
103: * Implementation Limits:: FreeM limitations.
104: * US-ASCII Character Set:: The US-ASCII character set.
105: * FreeM Project Coding Standards:: How to write code for submission to the FreeM project.
106:
107: * Index:: Complete index.
108: @end menu
109:
110: @node Introduction
111: @unnumbered Introduction
112:
113: 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 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.
114:
115: 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.
116:
117: 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 product.
118:
119: @section Production Readiness
120:
121: FreeM is not yet production-ready. There are several show-stopping bugs that preclude a general release for public use:
122:
123: @itemize @bullet
124:
125: @item
126: @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.
127:
128: @item
129: Server sockets are not yet implemented.
130:
131: @item
132: There are some situations that can result in segmentation faults and/or lock-ups.
133:
134: @item
135: In spite of our best efforts, this manual is not yet complete.
136:
137: @end itemize
138:
139: @section Contributors
140: Current contributors denoted with a @emph{+} following their name and role.
141: @cindex contributors, ha-Ashkenaz, Shalom
142: @cindex contributors, Best, John
143: @cindex contributors, Diamond, Jon
144: @cindex contributors, Fox, Ronald L.
145: @cindex contributors, Gerum, Winfried
146: @cindex contributors, Kreis, Greg
147: @cindex contributors, Landis, Larry
148: @cindex contributors, Milligan, Lloyd
149: @cindex contributors, Morris, Steve
150: @cindex contributors, Murray, John
151: @cindex contributors, Pastoors, Wilhelm
152: @cindex contributors, Schell, Kate
153: @cindex contributors, Schofield, Lyle
154: @cindex contributors, Stefanik, Jim
155: @cindex contributors, Trocha, Axel
156: @cindex contributors, Walters, Dick
157: @cindex contributors, Whitten, David
158: @cindex contributors, Wicksell, David
159: @cindex contributors, Willis, Serena
160: @cindex contributors, Zeck, Steve
161:
162: @itemize @bullet
163:
164: @item
165: Shalom ha-Ashkenaz (Original Implementer)
166:
167: @item
168: John Best (IBM i and OS/400)
169:
170: @item
171: Jon Diamond (Library, Utilities, Conformance)
172:
173: @item
174: Ronald L. Fox (Initial port to Red Hat 5/libc-6)
175:
176: @item
177: Winfried Gerum (Code, Advice, MTA coordination)
178:
179: @item
180: Greg Kreis (Hardhats coordination, Dependencies)
181:
182: @item
183: Larry Landis (Coordination, Code, Documentation)
184:
185: @item
186: Rick Marshall (Testing, MDC Conformance) @emph{+}
187:
188: @item
189: Lloyd Milligan (Code, Testing, Documentation)
190:
191: @item
192: Steve Morris (Code, Microsoft)
193:
194: @item
195: John Murray (Code, Conformance)
196:
197: @item
198: Wilhelm Pastoors (Testing, Documentation)
199:
200: @item
201: Kate Schell (Coordination, Conformance, MTA, MDC, Advice)
202:
203: @item
204: Lyle Schofield (Advice, Prioritization, Tracking, Project Management)
205:
206: @item
207: Jim Stefanik (GNU/Linux on s390x, IBM AIX, IBM z/OS)
208:
209: @item
210: Axel Trocha (Code, Utilities)
211:
212: @item
213: Dick Walters (Project Lead, Chief Coordinator, MTA)
214:
215: @item
216: David Whitten (QA Test Suite, MDC, Advice) @emph{+}
217:
218: @item
219: David Wicksell (Debugging, Code, Testing) @emph{+}
220:
221: @item
222: Serena Willis (Current Maintainer and Project Lead) @emph{+}
223:
224: @item
225: Steve Zeck (Code)
226:
227: @end itemize
228: @node FreeM Invocation
229: @chapter FreeM Invocation
230: @cindex invocation, command-line
231: @cindex options, command-line
232:
233: @section Synopsis
234: @example
235: $ @command{./freem} [@emph{OPTIONS}...] [[-r <entryref>] | [--routine=<entryref>]]
236: @end example
237:
238: When FreeM loads, it searches the @code{SYSTEM} namespace for the @code{^%SYSINIT} routine, and begins executing it.
239:
240: 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.
241:
242: @section %SYSINIT Routine
243:
244: 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}.
245:
246: 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.
247:
248: @section Command-Line Options
249: @cindex options, command-line
250:
251: @table @asis
252:
253: @item @option{-d}, @option{--daemon}
254: 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.
255:
256: @item @option{-e}, @option{--environment}
257: Selects the environment to be used. If no environment is specified, @code{DEFAULT} is used.
258:
259: @item @option{-k}, @option{--nofork}
260: When used with @option{-d} or @option{--daemon}, causes the FreeM environment daemon to run instead in the foreground. Useful for debugging.
261:
262: @item @option{-S}, @option{--shmsize}
263: 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.
264:
265: @item @option{-c}, @option{--config}
266: Specify a configuration file other than @code{$PREFIX/etc/freem.conf}.
267:
268: @item @option{-h}, @option{--help}
269: Display a help message showing valid FreeM options.
270:
271: @item @option{-i}, @option{--import}
272: Causes your UNIX environment variables to be imported into FreeM's local symbol table.
273:
274: @item @option{-f}, @option{--filter}
275: Allows your M routines to be used as UNIX filters.
276:
277: @item @option{-n @emph{<namespace-name>}}, @option{--namespace=@emph{<namespace-name>}}
278: Selects the FreeM namespace to be entered on startup. Must be defined in @file{/etc/<environment>/freem.conf}.
279:
280: @item @option{-r @emph{<entryref>}}, @option{--routine=@emph{<entryref>}}
281: Causes @code{<entryref>} to be executed at load, instead of @code{^%SYSINIT}.
282:
283: @item @option{--standard=@emph{<standard>}}
284: Sets the default FreeM dialect to use for new routine buffers.
285:
286: Valid values for @code{@emph{<standard>}} are as follows:
287:
288: @table @code
289: @item @code{M77}
290: Restricts FreeM to use only features specified by the 1977 M standard.
291: @item @code{M84}
292: Restricts FreeM to use only features specified by the 1984 M standard.
293: @item @code{M90}
294: Restricts FreeM to use only features specified by the 1990 M standard.
295: @item @code{M95}
296: Restricts FreeM to use only features specified by the 1995 M standard.
297: @item @code{MDS}
298: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
299: @item @code{M5}
300: Restricts FreeM to use only features proposed by the upcoming M5 standard.
301: @item @code{FREEM}, @code{EXTENDED}
302: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{$DIALECT}.
303: @end table
304:
305: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{@emph{<standard>}}.
306:
307: @item @option{-v}, @option{--version}
308: Displays FreeM version information.
309:
310: @item @option{-x @emph{<mcode>}}, @option{--execute=@emph{<mcode>}}
311: Executes M code @code{<mcode>} at startup.
312:
313: @end table
314:
315: @section Using FreeM for Shell Scripting
316: @cindex routines, as shell scripts
317: @cindex shebang line
318: @cindex shell scripting
319:
320: 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.
321: The following example presumes that FreeM is installed at @file{/usr/local/bin/freem} and uses the @code{USER} namespace:
322:
323: @example
324: #!/usr/local/bin/freem
325: MYSCRIPT ;
326: SET ^$JOB($JOB,"NAMESPACE")="USER"
327: WRITE "This is output from an M routine used as a shell script.",!
328: Q
329: @end example
330:
331: 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.
332:
333: You will also need to set the script's permissions to @emph{executable} in order for this to work:
334:
335: @example
336: $ chmod +x @emph{myscript.m}
337: @end example
338:
339: @node The FreeM Environment Daemon
340: @chapter The FreeM Environment Daemon
341: @cindex daemon, freem
342:
343: 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.
344:
345: One daemon process is required per FreeM environment, and can be started in the following ways, in order of preference:
346:
347: @example
348: $ sudo fmadm start environment [-e=<environment-name>]
349: @end example
350:
351: @example
352: $ freem --daemon [--nofork] [--environment=<environment-name>] [--shmsize=<bytes>]
353: @end example
354:
355: 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.
356:
357: 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.
358:
359: 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.
360:
361: Attempting to start a FreeM interpreter process without a daemon running with the same environment name will result in an error.
362:
363: @node The FreeM Direct-Mode Environment
364: @chapter The FreeM Direct-Mode Environment
365: @cindex command line interface
366: @cindex direct mode
367: @cindex execution, interactive
368: @cindex modes, programmer
369:
370:
371: 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>}}:
372:
373: @example
374: Coherent Logic Development FreeM version 0.64.0-rc0 (x86_64-pc-linux-gnu)
375: Copyright (C) 2014, 2020, 2021 Coherent Logic Development LLC
376:
377:
378: USER>
379: @end example
380:
381: 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{$TLEVEL}}:
382:
383: @example
384: TL1:DEFAULT.USER>
385: @end example
386:
387: In the above example, @code{TL1} indicates that @code{@ref{$TLEVEL}} is currently @emph{1}.
388:
389: @section Direct-Mode Commands
390:
391: When you are in direct mode, in addition to M commands, a number of internal commands are available to help developers be more productive:
392:
393: @table @asis
394:
395: @item @command{?}
396: Accesses FreeM online help. Requires GNU @command{info(1)} to be installed on your local system.
397:
398: @item @command{events}
399: Writes a list of @emph{event classes} and their @code{ABLOCK} counts:
400:
401: @example
402: DEFAULT.USER> events
403:
404: Event Class Processing Mode ABLOCK Count
405: ----------- --------------- ------------
406: COMM Disabled 0
407: HALT Disabled 0
408: IPC Disabled 0
409: INTERRUPT Disabled 0
410: POWER Disabled 0
411: TIMER Disabled 0
412: USER Disabled 0
413: WAPI Disabled 0
414: TRIGGER Disabled 0
415: @end example
416:
417:
418: @anchor{trantab}
419: @item @command{trantab}
420: Displays information about any uncommitted transactions currently in-flight for this process.
421:
422: @anchor{glstat}
423: @item @command{trantab}
424: Displays statistics about globals that have been opened in the current FreeM process.
425:
426: @anchor{jobtab}
427: @item @command{jobtab}
428: Displays a summary of the FreeM job table.
429:
430: @anchor{locktab}
431: @item @command{locktab}
432: Displays a list of @code{LOCK}s held in the current environment.
433:
434: @anchor{rbuf}
435: @item @command{rbuf}
436: Lists the status of all FreeM routine buffers.
437:
438: @anchor{dbstats}
439: @item @command{dbstats}
440: Shows statistics for the BerkeleyDB global handler.
441:
442: @anchor{wh}
443: @item @command{wh}
444: Forces an immediate flush of this process's @code{readline} history buffer to disk.
445:
446: @anchor{shmstat}
447: @item @command{shmstat}
448: Displays the configuration of FreeM shared memory. Intended only for advanced debugging of the FreeM environment.
449:
450: @anchor{shmpages}
451: @item @command{shmpages}
452: Lists the status of each FreeM shared memory page. Intended only for advanced debugging of the FreeM environment.
453:
454: @anchor{history}
455: @item @command{history}
456: Prints a list of all the direct-mode commands you have entered across all sessions.
457:
458: @anchor{rcl}
459: @item @command{rcl @emph{<history-index>}}
460: 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.
461:
462: @item @command{!!}
463: Launches a subshell within the FreeM direct mode, allowing the user to run operating system commands.
464:
465: @example
466: DEFAULT.USER> !!
467:
468: Type Ctrl-D to exit from the shell
469: $ uname -a
470: Linux hesperos 4.19.0-17-amd64 #1 SMP Debian 4.19.194-3 (2021-07-18) x86_64 GNU/Linux
471: $ exit
472:
473: DEFAULT.USER>
474: @end example
475:
476: @item @command{!@emph{<external-command>}}
477: 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}.
478:
479: 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>}.
480:
481: 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")}.
482:
483: 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}.
484:
485: @end table
486:
487: @cindex HALT, in direct-mode
488: 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:
489:
490: @example
491: DEFAULT.USER> TSTART
492:
493:
494: TL1:DEFAULT.USER> SET ^MYGLOBAL=1
495:
496:
497: TL1:DEFAULT.USER> HALT
498:
499: UNCOMMITTED TRANSACTIONS EXIST:
500:
501: $TLEVEL 1*
502: Operations for Transaction ID: k8xj1de
503: 1: action = 0 key = ^MYGLOBAL data = 1
504:
505: Would you like to c)ommit or r)ollback the above transactions and their operations? ($TLEVEL = 1) r
506:
507:
508: Transactions have been rolled back.
509: @end example
510:
511: In the above example, the user selected @code{r} to rollback the single pending transaction.
512:
513: @section REPL Functionality
514: @cindex REPL, direct-mode
515:
516: FreeM direct mode allows you to enter M expressions directly from the direct-mode prompt, as long as they begin with a number:
517:
518: @example
519: DEFAULT.USER> S DENOM=10
520:
521:
522: DEFAULT.USER> 100/DENOM
523:
524: 10
525: DEFAULT.USER>
526: @end example
527:
528: Such expressions will be immediately evaluated, and the result printed on @code{@ref{$IO}}.
529:
530: @node Directives
531: @chapter Directives
532: @cindex directives
533:
534: In FreeM, a directive is an instruction embedded in an M comment, and passed to the interpreter to affect a change that is specific to the current routine only.
535:
536: The format of a directive is @code{;%@emph{<directive-name>}}, where @code{@emph{<directive-name>}} is one of the directives listed below.
537:
538: @menu
539: * %DIALECT:: Sets the M dialect in effect.
540: @end menu
541:
542: @anchor{%DIALECT}
543: @section %DIALECT
544: @cindex %DIALECT
545: @cindex directives, %DIALECT
546:
547: Sets the M dialect in effect for the current routine buffer; also sets the @code{$DIALECT} special variable to match. See also @ref{$DIALECT}.
548:
549: @emph{Syntax}
550:
551: @example
552: ;%DIALECT @emph{<dialect>}
553: @end example
554:
555: Valid values for @code{@emph{<dialect>}} are as follows:
556:
557: @table @code
558: @item @code{M77}
559: Restricts FreeM to use only features specified by the 1977 M standard.
560: @item @code{M84}
561: Restricts FreeM to use only features specified by the 1984 M standard.
562: @item @code{M90}
563: Restricts FreeM to use only features specified by the 1990 M standard.
564: @item @code{M95}
565: Restricts FreeM to use only features specified by the 1995 M standard.
566: @item @code{MDS}
567: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
568: @item @code{M5}
569: Restricts FreeM to use only features proposed by the upcoming M5 standard.
570: @item @code{FREEM}, @code{EXTENDED}
571: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{%DIALECT}.
572: @end table
573:
574: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{%DIALECT}.
575:
576:
577: @node Intrinsic Special Variables
578: @chapter Intrinsic Special Variables
579: @cindex variables, intrinsic special
580:
581: @menu
582: * $DEVICE:: $IO device status.
583: * $DIALECT:: Current M dialect.
584: * $ECODE:: Latest M error code.
585: * $ESTACK:: Error stack info.
586: * $ETRAP:: Standard error handler code.
587: * $HOROLOG:: Current date and time.
588: * $IO:: Current I/O device.
589: * $JOB:: PID of current process.
590: * $KEY:: Characters terminating last @code{READ} command.
591: * $PDISPLAY:: Current primary MWAPI display.
592: * $PRINCIPAL:: I/O channel of terminal.
593: * $REFERENCE:: Most recent global reference.
594: * $QUIT:: Whether a @code{QUIT} command requires an argument in the current execution context.
595: * $STACK:: Current program execution stack level.
596: * $STORAGE:: Number of bytes available in the heap.
597: * $SYSTEM:: MDC system ID of FreeM.
598: * $TEST:: Truth value of last conditional expression or result of certain @code{LOCK} operations.
599: * $TLEVEL:: Current level of transaction nesting.
600: * $WITH:: Current variable prefix set by @code{WITH} command.
601: * $X:: Current horizontal screen position.
602: * $Y:: Current vertical screen position.
603: * $ZA:: Current position of file on @code{$IO}.
604: * $ZB:: Most recent keystroke.
605: * $ZCONTROLC:: Control-C handling flag.
606: * $ZDATE:: Current date in locale-specific representation.
607: * $ZERROR:: Last error message.
608: * $ZHOROLOG:: Date and time, including milliseconds.
609: * $ZINRPT:: State of the interrupt enable/disable flag.
610: * $ZJOB:: PID of parent process, if applicable.
611: * $ZLOCAL:: Last local variable reference.
612: * $ZNAME:: Name of current M routine.
613: * $ZPRECISION:: Digits of arithmetical precision.
614: * $ZREFERENCE:: Last gvn referenced.
615: * $ZSYSTEM:: Return value of last external command.
616: * $ZTIME:: Current time in locale-specific representation.
617: * $ZTRAP:: Entryref to be executed on error condition.
618: * $ZUT:: Microseconds since the UNIX epoch.
619: * $ZVERSION:: Version of FreeM and GNU host triplet.
620: @end menu
621:
622: @node $DEVICE
623: @section $DEVICE
624: @cindex $DEVICE
625: @cindex intrinsic special variables, $DEVICE
626:
627: Returns the status of the device currently in use.
628:
629: If @code{$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.
630:
631: @node $DIALECT
632: @section $DIALECT
633: @cindex $DIALECT
634: @cindex intrinsic special variables, $DIALECT
635:
636: Returns or sets the language dialect of the current routine.
637:
638: Valid values for @code{$DIALECT} are as follows:
639:
640: @table @code
641: @item @code{M77}
642: Restricts FreeM to use only features specified by the 1977 M standard.
643: @item @code{M84}
644: Restricts FreeM to use only features specified by the 1984 M standard.
645: @item @code{M90}
646: Restricts FreeM to use only features specified by the 1990 M standard.
647: @item @code{M95}
648: Restricts FreeM to use only features specified by the 1995 M standard.
649: @item @code{MDS}
650: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
651: @item @code{M5}
652: Restricts FreeM to use only features proposed by the upcoming M5 standard.
653: @item @code{FREEM}, @code{EXTENDED}
654: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{$DIALECT}.
655: @end table
656:
657: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{$DIALECT}.
658:
659: @node $ECODE
660: @section $ECODE
661: @cindex $ECODE
662: @cindex intrinsic special variables, $ECODE
663:
664: Returns a comma-delimited list of error conditions currently present, and is writable. An empty @code{$ECODE} indicates no errors.
665:
666: @node $ESTACK
667: @section $ESTACK
668: @cindex $ESTACK
669: @cindex intrinsic special variables, $ESTACK
670:
671: Returns the depth of the program execution stack since the last time @code{$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.
672:
673: @node $ETRAP
674: @section $ETRAP
675: @cindex $ETRAP
676: @cindex intrinsic special variables, $ETRAP
677:
678: Sets or retrieves the M code that is run when an error is encountered or @code{@ref{$ECODE}} is set to a non-blank value. @code{$ETRAP} code executes when @code{$ECODE} becomes non-blank.
679:
680:
681: @node $HOROLOG
682: @section $HOROLOG
683: @cindex $HOROLOG
684: @cindex intrinsic special variables, $HOROLOG
685:
686: Returns a string containing the current date and time as @code{<days>,<seconds>}, where @code{<days>} represents the number of days since the M epoch (midnight on 31 December 1840),
687: and @code{<seconds>} represents the number of seconds since the most recent midnight.
688:
689: @cartouche
690: @quotation
691: @emph{FreeM Extension}
692:
693: In FreeM, @code{$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.
694: @end quotation
695: @end cartouche
696:
697: @node $IO
698: @section $IO
699: @cindex $IO
700: @cindex intrinsic special variables, $IO
701:
702: Represents the current input/output device. Read-only.
703:
704: @node $JOB
705: @section $JOB
706: @cindex $JOB
707: @cindex intrinsic special variables, $JOB
708:
709: Represents the process ID of the FreeM instance currently in use.
710:
711: @node $KEY
712: @section $KEY
713: @cindex $KEY
714: @cindex intrinsic special variables, $KEY
715:
716: Represents the sequence of control characters that terminated the last @code{@ref{READ}} command on @code{@ref{$IO}}.
717:
718: @node $PDISPLAY
719: @section $PDISPLAY
720: @cindex $PDISPLAY
721: @cindex intrinsic special variables, $PDISPLAY
722:
723: Represents the current principal display for M Windowing API operations. Commonly used as an index into the @code{@ref{^$DISPLAY}} structured system variable.
724:
725: @node $PRINCIPAL
726: @section $PRINCIPAL
727: @cindex $PRINCIPAL
728: @cindex intrinsic special variables, $PRINCIPAL
729:
730: Represents the primary input/output device. Usually a terminal or virtual terminal.
731:
732: @node $REFERENCE
733: @section $REFERENCE
734: @cindex $REFERENCE
735: @cindex intrinsic special variables, $REFERENCE
736:
737: Returns the last @emph{glvn} referenced. Can be @code{@ref{SET}}, and also stacked with @code{@ref{NEW}}.
738:
739: @node $QUIT
740: @section $QUIT
741: @cindex $QUIT
742: @cindex intrinsic special variables, $QUIT
743:
744: If the current execution context was invoked as an extrinsic function, @code{$QUIT} returns @emph{1}. Otherwise, returns @emph{0}.
745:
746: When @code{$QUIT} returns @emph{1}, a subsequent @code{@ref{QUIT}} command must have an argument.
747:
748: @node $STACK
749: @section $STACK
750: @cindex $STACK
751: @cindex intrinsic special variables, $STACK
752:
753: Represents the current stack level.
754:
755: @node $STORAGE
756: @section $STORAGE
757: @cindex $STORAGE
758: @cindex intrinsic special variables, $STORAGE
759:
760: Represents the number of bytes of free space available in FreeM's heap.
761:
762: @node $SYSTEM
763: @section $SYSTEM
764: @cindex $SYSTEM
765: @cindex intrinsic special variables, $SYSTEM
766:
767: Returns the MDC system ID of FreeM, as well as the environment ID of the current environment.
768:
769: @node $TEST
770: @section $TEST
771: @cindex $TEST
772: @cindex intrinsic special variables, $TEST
773:
774: @code{$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}.
775:
776: @code{$TEST} is implicitly @code{NEW}ed when entering a new stack frame for extrinsic functions and argumentless @code{@ref{DO}}. @code{$TEST}
777: is @emph{not} implicitly @code{NEW}ed when a new stack frame is entered with an argumented @code{DO}.
778:
779: 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.
780:
781: @node $TLEVEL
782: @section $TLEVEL
783: @cindex $TLEVEL
784: @cindex intrinsic special variables, $TLEVEL
785:
786: Returns a numeric value indicating the current level of transaction nesting in the process. When @code{$TLEVEL} is greater than @emph{0},
787: uncommitted transactions exist.
788:
789: @node $WITH
790: @section $WITH
791: @cindex $WITH
792: @cindex intrinsic special variables, $WITH
793:
794: Returns the variable prefix set by the @code{@ref{WITH}} command.
795:
796: @node $X
797: @section $X
798: @cindex $X
799: @cindex intrinsic special variables, $X
800:
801: Represents the current column position of the FreeM cursor.
802:
803: @cartouche
804: @quotation
805: In FreeM, setting @code{$X} will move the FreeM cursor.
806: @end quotation
807: @end cartouche
808:
809:
810: @node $Y
811: @section $Y
812: @cindex $Y
813: @cindex intrinsic special variables, $Y
814:
815: Represents the current row position of the FreeM cursor.
816:
817: @cartouche
818: @quotation
819: In FreeM, setting @code{$Y} will move the FreeM cursor.
820: @end quotation
821: @end cartouche
822:
823:
824: @node $ZA
825: @section $ZA
826: @cindex $ZA
827: @cindex intrinsic special variables, $ZA
828: @cindex intrinsic special variables, implementation-specific
829:
830: On the @code{HOME} device, always @code{0}. On other devices, returns the current position of the file opened on I/O channel @code{@ref{$IO}}.
831:
832: @node $ZB
833: @section $ZB
834: @cindex $ZB
835: @cindex intrinsic special variables, $ZB
836: @cindex intrinsic special variables, implementation-specific
837:
838: Represents the last keystroke.
839:
840: @node $ZCONTROLC
841: @section $ZCONTROLC
842: @cindex $ZCONTROLC
843: @cindex intrinsic special variables, $ZCONTROLC
844: @cindex intrinsic special variables, implementation-specific
845:
846: Returns the status of the Ctrl-C flag and resets it to @emph{false}.
847:
848: @node $ZDATE
849: @section $ZDATE
850: @cindex $ZDATE
851: @cindex intrinsic special variables, $ZDATE
852: @cindex intrinsic special variables, implementation-specific
853:
854: Returns the current date, in the preferred representation for the current system locale.
855:
856: @node $ZERROR
857: @section $ZERROR
858: @cindex $ZERROR
859: @cindex intrinsic special variables, $ZERROR
860: @cindex intrinsic special variables, implementation-specific
861:
862: Returns the last error message.
863:
864: @node $ZHOROLOG
865: @section $ZHOROLOG
866: @cindex $ZHOROLOG
867: @cindex intrinsic special variables, $ZHOROLOG
868: @cindex intrinsic special variables, implementation-specific
869:
870: Output @code{@ref{$HOROLOG}}-style time, with the addition of milliseconds.
871:
872: @node $ZINRPT
873: @section $ZINRPT
874: @cindex $ZINRPT
875: @cindex intrinsic special variables, $ZINRPT
876: @cindex intrinsic special variables, implementation-specific
877:
878: Gets or sets the interrupt enable/disable flag.
879:
880: @node $ZJOB
881: @section $ZJOB
882: @cindex $ZJOB
883: @cindex intrinsic special variables, $ZJOB
884: @cindex intrinsic special variables, implementation-specific
885:
886: Returns the @code{@ref{$JOB}} value of the parent process if the current process was started by a @code{@ref{JOB}} command. Otherwise, returns an empty string.
887:
888: @node $ZLOCAL
889: @section $ZLOCAL
890: @cindex $ZLOCAL
891: @cindex intrinsic special variables, $ZLOCAL
892: @cindex intrinsic special variables, implementation-specific
893:
894: Returns the last local variable referenced.
895:
896: @node $ZNAME
897: @section $ZNAME
898: @cindex $ZNAME
899: @cindex intrinsic special variables, $ZNAME
900: @cindex intrinsic special variables, implementation-specific
901:
902: Returns the name of the current routine.
903:
904: @node $ZPRECISION
905: @section $ZPRECISION
906: @cindex $ZPRECISION
907: @cindex intrinsic special variables, $ZPRECISION
908: @cindex intrinsic special variables, implementation-specific
909:
910: Gets or sets the number of digits of numeric precision used for fixed-point decimal arithmetic. If @code{^$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{$ZPRECISION} defaults to 100 digits, with a maximum of 20,000 digits.
911:
912: @xref{^$JOB}.
913:
914: @node $ZREFERENCE
915: @section $ZREFERENCE
916: @cindex $ZREFERENCE
917: @cindex intrinsic special variables, $ZREFERENCE
918: @cindex intrinsic special variables, implementation-specific
919:
920: Returns the last @emph{gvn} referenced.
921:
922: @node $ZSYSTEM
923: @section $ZSYSTEM
924: @cindex $ZSYSTEM
925: @cindex intrinsic special variables, $ZSYSTEM
926: @cindex intrinsic special variables, implementation-specific
927:
928: Represents the return value of the last external command run with @code{!}.
929:
930: @node $ZTIME
931: @section $ZTIME
932: @cindex $ZTIME
933: @cindex intrinsic special variables, $ZTIME
934: @cindex intrinsic special variables, implementation-specific
935:
936: Returns the system time in the preferred representation for the current system locale.
937:
938: @node $ZTRAP
939: @section $ZTRAP
940: @cindex $ZTRAP
941: @cindex intrinsic special variables, $ZTRAP
942: @cindex intrinsic special variables, implementation-specific
943:
944: Sets or retrieves the entryref to be executed when an M program execution error occurs under FreeM-style or DSM 2.0-style error processing.
945:
946: In FreeM-style error processing, @code{$ZTRAP} is specific to each program execution stack level.
947:
948: In DSM 2.0-style error processing, @code{$ZTRAP} is the same for all program execution stack levels.
949:
950: When FreeM encounters an error, if @code{$ZTRAP} is nonempty and @code{$ETRAP} is empty, FreeM will perform an implicit @code{@ref{GOTO}} to the entryref indicated in @code{$ZTRAP}.
951:
952: 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.
953:
954: @node $ZUT
955: @section $ZUT
956: @cindex $ZUT
957: @cindex intrinsic special variables, $ZUT
958: @cindex intrinsic special variables, implementation-specific
959:
960: Returns the number of microseconds elapsed since the UNIX epoch (Jan 1, 1970 0:00:00).
961:
962: @node $ZVERSION
963: @section $ZVERSION
964: @cindex $ZVERSION
965: @cindex intrinsic special variables, $ZVERSION
966: @cindex intrinsic special variables, implementation-specific
967:
968: Returns the version of FreeM in use, as well as the GNU host triplet for the current FreeM build.
969:
970: See @emph{https://wiki.osdev.org/Target_Triplet}.
971:
972: @node Intrinsic Functions
973: @chapter Intrinsic Functions
974:
975: @menu
976: * $ASCII():: Return ASCII code for character in string.
977: * $CHAR():: Return character for one or more ASCII codes.
978: * $DATA():: Retrieve definition and characteristics of array node.
979: * $EXTRACT():: Return a substring of a string.
980: * $FIND():: Find position of substring within string.
981: * $FNUMBER():: Format a number according to formatting codes.
982: * $GET():: Return value of glvn or a default if undefined.
983: * $INSTANCEOF():: Determine if lvn is an instance of a class.
984: * $JUSTIFY():: Right-justify a string based on specified length.
985: * $LENGTH():: Return length or delimiter-based piece count of string.
986: * $NAME():: Return canonical name from string representation of glvn.
987: * $NEXT():: Return next numeric subscript following given glvn.
988: * $ORDER():: Return next subscript at same level of specified glvn.
989: * $PIECE():: Return one or more delimited pieces of a string.
990: * $QLENGTH():: Return subscript count of glvn.
991: * $QSUBSCRIPT():: Return a specified subscript from glvn.
992: * $QUERY():: Return next subscript of specified glvn.
993: * $RANDOM():: Return pseudorandom integer up to a maximum value.
994: * $REVERSE():: Reverse a string.
995: * $SELECT():: Return value from first true condition in list of expressions.
996: * $STACK():: Return information about the program stack.
997: * $TEXT():: Return line of code from a routine.
998: * $TRANSLATE():: Substitute specified characters in a string.
999: * $TYPE():: Return class of the specified lvn.
1000: * $VIEW():: Retrieve implementation-specific information.
1001: * $ZBOOLEAN():: Perform boolean operations on numeric arguments.
1002: * $ZCALL():: Unknown.
1003: * $ZCRC():: Generate checksum of a string argument.
1004: * $ZDATA():: Unknown.
1005: * $ZDATE():: Convert @code{@ref{$HOROLOG}} string into human-readable date.
1006: * $ZEDIT():: Unknown.
1007: * $ZHOROLOG():: Convert date/time values to @code{@ref{$HOROLOG}} format.
1008: * $ZKEY():: Unknown.
1009: * $ZLENGTH():: Unknown.
1010: * $ZLSD():: Compute Levenshtein distance between two arguments.
1011: * $ZM():: Unknown.
1012: * $ZNAME():: Unknown.
1013: * $ZNEXT():: Unknown.
1014: * $ZORDER():: Unknown.
1015: * $ZPIECE():: Unknown.
1016: * $ZPREVIOUS():: Unknown.
1017: * $ZREPLACE():: Replace all instances of a substring within a string.
1018: * $ZSYNTAX():: Perform syntax check on string argument.
1019: * $ZTIME():: Convert a @code{@ref{$HOROLOG}} string into human-readable time.
1020: @end menu
1021:
1022: @node $ASCII()
1023: @section $ASCII
1024: @cindex $ASCII
1025: @cindex intrinsic functions, $ASCII
1026:
1027: Returns the ASCII code (in decimal) for one character in a string.
1028:
1029: @example
1030: SET RESULT=$ASCII(@emph{<string>}[,@emph{<index>}])
1031: @end example
1032:
1033:
1034: 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>}.
1035:
1036: @node $CHAR()
1037: @section $CHAR
1038: @cindex $CHAR
1039: @cindex intrinsic functions, $CHAR
1040:
1041: Returns a string of characters corresponding to a list of ASCII codes.
1042:
1043: @example
1044: SET RESULT=$CHAR(@emph{<ascii-code>}[,@emph{<ascii-code>},...])
1045: @end example
1046:
1047: @node $DATA()
1048: @section $DATA
1049: @cindex $DATA
1050: @cindex intrinsic functions, $DATA
1051:
1052: Returns a numeric value 0, 1, 10, or 11, depending on whether a referenced node is defined, has data, or has children:
1053:
1054: @example
1055: SET RESULT=$DATA(@emph{<node>})
1056: @end example
1057:
1058: The return values are as follows:
1059:
1060: @example
1061: 0: @emph{<node>} is undefined
1062: 1: @emph{<node>} has data but no children
1063: 10: @emph{<node>} has children but no data
1064: 11: @emph{<node>} has children and data
1065: @end example
1066:
1067: @node $EXTRACT()
1068: @section $EXTRACT
1069: @cindex $EXTRACT
1070: @cindex intrinsic functions, $EXTRACT
1071:
1072: Extracts a substring of a string.
1073:
1074: The first argument is the source string.
1075:
1076: The optional second argument specifies the starting position of the substring to extract, and defaults to @code{1}.
1077:
1078: The optional third argument specifies the ending position of the substring to extract, and defaults to the value of the second argument, or @code{1}.
1079:
1080: This example will extract the string @emph{FreeM} into the local variable @code{M}.
1081:
1082: @example
1083: SET NAME="FreeM is the best!"
1084: SET M=$EXTRACT(NAME,1,5)
1085: @end example
1086:
1087: It is also possible to use @code{$EXTRACT} on the left-hand side of a @code{SET} assignment in order to modify a substring:
1088:
1089: @example
1090: DEFAULT.USER> SET FOO="ABCDEFG"
1091:
1092:
1093: DEFAULT.USER> SET $EXTRACT(FOO,1,3)="XYZ"
1094:
1095:
1096: DEFAULT.USER> WRITE FOO
1097:
1098: XYZDEFG
1099: @end example
1100:
1101: @node $FIND()
1102: @section $FIND
1103: @cindex $FIND
1104: @cindex intrinsic functions, $FIND
1105:
1106: Finds the character immediately following the first occurence of a substring within a string.
1107:
1108: The first argument is the source string.
1109:
1110: The second argument is the substring to be located.
1111:
1112: The optional third argument indicates the position within the source string at which to begin searching.
1113:
1114: @node $FNUMBER()
1115: @section $FNUMBER
1116: @cindex $FNUMBER
1117: @cindex intrinsic functions, $FNUMBER
1118:
1119: Formats a number according to a particular set of formatting codes.
1120:
1121: The first argument is the number to format.
1122:
1123: The second argument is the series of formatting codes:
1124:
1125: @table @asis
1126: @item 'P' or 'p'
1127: Will display negative numbers within parentheses instead of showing a minus sign.
1128: @item , (comma)
1129: Will add commas as thousands separators.
1130: @item +
1131: Will include a plus sign for positive numbers. Not compatible with 'P' or 'p'.
1132: @item -
1133: Will remove the minus sign from negative numbers. Not compatible with 'p' or 'P'.
1134: @item 't' or 'T'
1135: Will place the sign after the number instead of before the number.
1136: @end table
1137:
1138: The optional third argument is a number indicating how many digits to which the fractional part of the number will be zero-padded.
1139:
1140: @node $GET()
1141: @section $GET
1142: @cindex $GET
1143: @cindex intrinsic functions, $GET
1144:
1145: Returns the value of a local, global, or SSVN if the specified item is defined, or a default value otherwise.
1146:
1147: The first argument is the local, global, or SSVN to be examined.
1148:
1149: The optional second argument is the default value to be returned if the referenced item is undefined, and defaults to the empty string.
1150:
1151: @node $INSTANCEOF()
1152: @section $INSTANCEOF
1153: @cindex $INSTANCEOF
1154: @cindex intrinsic functions, $INSTANCEOF
1155: @cindex object functions, $INSTANCEOF
1156:
1157: Returns @code{1} if the specified @emph{lvn} is an instance of class @emph{class}, or @code{0} otherwise.
1158:
1159: The first argument is a string representing a valid FreeM local variable.
1160:
1161: The second argument is a string representing a valid FreeM class.
1162:
1163: @example
1164: DEFAULT.USER> N STR=$$^%STRING
1165:
1166: DEFAULT.USER> W $INSTANCEOF("STR","^%STRING")
1167: 1
1168: @end example
1169:
1170: @node $JUSTIFY()
1171: @section $JUSTIFY
1172: @cindex $JUSTIFY
1173: @cindex intrinsic functions, $JUSTIFY
1174:
1175: Right-justifies a string based on a specified fixed length.
1176:
1177: The first argument is the source string.
1178:
1179: The second argument is the character length of the output.
1180:
1181: 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.
1182:
1183: @node $LENGTH()
1184: @section $LENGTH
1185: @cindex $LENGTH
1186: @cindex intrinsic functions, $LENGTH
1187:
1188: 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()}}).
1189:
1190: The first argument is the source string.
1191:
1192: 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.
1193:
1194: @node $NAME()
1195: @section $NAME
1196: @cindex $NAME
1197: @cindex intrinsic functions, $NAME
1198:
1199: Returns the canonical name reference along with some or all of its subscripts.
1200:
1201: The first argument is the source name.
1202:
1203: The optional second argument indicates the maximum subscript count to be returned, and defaults to the subscript count of the source name.
1204:
1205: @node $NEXT()
1206: @section $NEXT
1207: @cindex $NEXT
1208: @cindex intrinsic functions, $NEXT
1209:
1210: Deprecated. Use @code{$ORDER} instead.
1211:
1212: @node $ORDER()
1213: @section $ORDER
1214: @cindex $ORDER
1215: @cindex intrinsic functions, $ORDER
1216:
1217: Returns the previous subscript or next subscript in a local, global, or a subset of structured system variables.
1218:
1219: The first argument is the subscripted local, global, or SSVN.
1220:
1221: The optional second argument can be @code{1} to retrieve the next subscript, or @code{-1} to return the previous.
1222:
1223: @node $PIECE()
1224: @section $PIECE
1225: @cindex $PIECE
1226: @cindex intrinsic functions, $PIECE
1227:
1228: @emph{Syntax}
1229:
1230: @code{$PIECE(@emph{s},@emph{d}[,@emph{n}[,@emph{end}]])}
1231:
1232: Accesses the @code{n}th through @code{end} @code{d}-delimited pieces of string @code{s}.
1233:
1234: The first argument is the string to be evaluated.
1235:
1236: The second argument is the delimiter to be used.
1237:
1238: The optional third argument is the first @code{d}-delimited piece to access, and defaults to @code{1}.
1239:
1240: The optional fourth argument is the final @code{d}-delimited piece to access, and defaults to the value of the third argument (@code{n}).
1241:
1242: 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:
1243:
1244: @example
1245: ; ^jpw="this^is^a^piece"
1246: SET $PIECE(^jpw,"^",2)="isn't" ; => "this^isn't^a^piece"
1247: @end example
1248:
1249: @node $QLENGTH()
1250: @section $QLENGTH
1251: @cindex $QLENGTH
1252: @cindex intrinsic functions, $QLENGTH
1253:
1254: @emph{Syntax}
1255:
1256: @example
1257: @code{$QLENGTH(@emph{expr V glvn})}
1258: @end example
1259:
1260: Returns the number of subscripts in @emph{glvn}.
1261:
1262: @emph{Example}
1263: @example
1264: @code{SET SUBCT=$QLENGTH("^GBL(1,2,3)") ; => 3}
1265: @end example
1266:
1267: @node $QSUBSCRIPT()
1268: @section $QSUBSCRIPT
1269: @cindex $QSUBSCRIPT
1270: @cindex intrinsic functions, $QSUBSCRIPT
1271:
1272: @emph{Syntax}
1273:
1274: @example
1275: @code{$QSUBSCRIPT(@emph{expr V glvn},@emph{expr V n})}
1276: @end example
1277:
1278: Returns the @emph{n}th subscript of @emph{glvn}.
1279:
1280: @emph{Example}
1281:
1282: @example
1283: @code{SET SUB=$QSUBSCRIPT("^GBL(1,2,3)",2) ; => 2}
1284: @end example
1285:
1286: @node $QUERY()
1287: @section $QUERY
1288: @cindex $QUERY
1289: @cindex intrinsic functions, $QUERY
1290:
1291: Returns the next subscripted reference in a global.
1292:
1293: @emph{Syntax}
1294:
1295: @example
1296: @code{$QUERY(@emph{glvn})}
1297: @end example
1298:
1299: @emph{Example}
1300:
1301: We will assume the following data structure exists:
1302: @example
1303: ^jpw(1)=1
1304: ^jpw(1,2)="foo"
1305: ^jpw(2)=3
1306: ^jpw(3)=""
1307: @end example
1308:
1309: The following code will retrieve the next subscripted name after @code{^jpw(1)}:
1310:
1311: @example
1312: @code{SET NEXTNAM=$QUERY(^jpw(1)) ; => ^jpw(1,2)}
1313: @end example
1314:
1315: @node $RANDOM()
1316: @section $RANDOM
1317: @cindex $RANDOM
1318: @cindex intrinsic functions, $RANDOM
1319:
1320: @emph{Syntax}
1321:
1322: @example
1323: $RANDOM(@emph{max})
1324: @end example
1325:
1326: Returns a pseudo-random integer in the range of @code{0..@emph{max} - 1}
1327:
1328: @node $REVERSE()
1329: @section $REVERSE
1330: @cindex $REVERSE
1331: @cindex intrinsic functions, $REVERSE
1332:
1333: @emph{Syntax}
1334:
1335: @example
1336: $REVERSE(@emph{s})
1337: @end example
1338:
1339: Returns the reverse of string @emph{s}.
1340:
1341: @emph{Example}
1342:
1343: @example
1344: SET FOO=$REVERSE("ABC") ; => CBA
1345: @end example
1346:
1347: @node $SELECT()
1348: @section $SELECT
1349: @cindex $SELECT
1350: @cindex intrinsic functions, $SELECT
1351:
1352: 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.
1353:
1354: @emph{Example}
1355:
1356: @example
1357: SET FOO=$SELECT(1=2:"math is broken",1=1:"the world makes sense") ; => "the world makes sense"
1358: @end example
1359:
1360: @node $STACK()
1361: @section $STACK
1362: @cindex $STACK
1363: @cindex intrinsic functions, $STACK
1364:
1365: Returns information about the program execution stack. The @code{$STACK} intrinsic function has both a one-argument form and a two-argument form.
1366:
1367: @emph{Syntax (One-Argument)}
1368:
1369: @example
1370: $STACK(@emph{<num>})
1371: @end example
1372:
1373: If @emph{num} is @code{0}, returns the command with which this FreeM instance was invoked.
1374:
1375: If @emph{num} is @code{-1}, returns the current program execution stack level.
1376:
1377: 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:
1378:
1379: @table @asis
1380:
1381: @item @code{$$}
1382: If @code{$STACK(@emph{<num>})="$$"}, program execution stack level @code{num} was created as the result of an extrinsic function call
1383:
1384: @item @emph{<m-command>}
1385: 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.
1386:
1387: @end table
1388:
1389: @emph{Syntax (Two-Argument})
1390:
1391: @example
1392: $STACK(@emph{<num>},"[ECODE|MCODE|PLACE]")
1393: @end example
1394:
1395: Returns the error codes, M program code, or entryref applicable to the action that created program execution stack level @emph{num}.
1396:
1397: @node $TEXT()
1398: @section $TEXT
1399: @cindex $TEXT
1400: @cindex intrinsic functions, $TEXT
1401:
1402: Returns a line of code from a routine.
1403:
1404: @node $TRANSLATE()
1405: @section $TRANSLATE
1406: @cindex $TRANSLATE
1407: @cindex intrinsic functions, $TRANSLATE
1408:
1409: Replaces characters in a string.
1410:
1411: The first argument is a string expression representing the text to be changed.
1412:
1413: The second argument is a list of characters to replace.
1414:
1415: The third argument is a list of characters to use as the replacements for the characters in the second argument.
1416:
1417: @emph{Example}
1418:
1419: @example
1420: DEFAULT.USER> W $TRANSLATE("twig","wt","rb")
1421: brig
1422: @end example
1423:
1424: @node $TYPE()
1425: @section $TYPE
1426: @cindex $TYPE
1427: @cindex intrinsic functions, $TYPE
1428: @cindex object functions, $TYPE
1429:
1430: Returns a string giving the class of the object specified in the parameter.
1431:
1432: @xref{Object-Oriented Programming}
1433:
1434: @node $VIEW()
1435: @section $VIEW
1436: @cindex $VIEW
1437: @cindex intrinsic functions, $VIEW
1438:
1439: @node $ZBOOLEAN()
1440: @section $ZBOOLEAN
1441: @cindex $ZBOOLEAN
1442: @cindex intrinsic functions, $ZBOOLEAN
1443: @cindex intrinsic functions, implementation-specific
1444:
1445:
1446: Performs @emph{boolean-operation} on numeric arguments @emph{A} and @emph{B}.
1447:
1448: @emph{Syntax}
1449:
1450: @example
1451: SET RESULT=$ZBOOLEAN(@emph{A},@emph{B},@emph{boolean-operation})
1452: @end example
1453:
1454: @code{$ZBOOLEAN} Operations (@emph{boolean-operation} values)
1455:
1456: @table @code
1457: @item 0
1458: Always @emph{false}
1459: @item 1
1460: @code{A AND B}
1461: @item 2
1462: @code{A AND NOT B}
1463: @item 3
1464: @code{A}
1465: @item 4
1466: @code{NOT A AND B}
1467: @item 5
1468: @code{B}
1469: @item 6
1470: @code{A XOR B}
1471: @item 7
1472: @code{A OR B}
1473: @item 8
1474: @code{A NOR B}
1475: @item 9
1476: @code{A EQUALS B}
1477: @item 10
1478: @code{NOT B}
1479: @item 11
1480: @code{A OR NOT B}
1481: @item 12
1482: @code{NOT A}
1483: @item 13
1484: @code{NOT A OR B}
1485: @item 14
1486: @code{A NAND B}
1487: @item 15
1488: Always @emph{true}
1489: @end table
1490:
1491: @node $ZCALL()
1492: @section $ZCALL
1493: @cindex $ZCALL
1494: @cindex intrinsic functions, $ZCALL
1495: @cindex intrinsic functions, implementation-specific
1496:
1497: Purpose unknown.
1498:
1499: @node $ZCRC()
1500: @section $ZCRC
1501: @cindex $ZCRC
1502: @cindex intrinsic functions, $ZCRC
1503: @cindex intrinsic functions, implementation-specific
1504:
1505: Returns a checksum of @code{arg1}.
1506:
1507: @emph{Syntax}
1508:
1509: @code{$ZCRC(@emph{arg1})}
1510:
1511: @code{SET VAR=$ZCRC("MUMPS") ; => 86}
1512:
1513: @node $ZDATA()
1514: @section $ZDATA
1515: @cindex $ZDATA
1516: @cindex intrinsic functions, $ZDATA
1517: @cindex intrinsic functions, implementation-specific
1518:
1519: Purpose unknown.
1520:
1521: @node $ZDATE()
1522: @section $ZDATE
1523: @cindex $ZDATE
1524: @cindex intrinsic functions, $ZDATE
1525: @cindex intrinsic functions, implementation-specific
1526:
1527: Converts a @code{@ref{$HOROLOG}} string into a human-readable date.
1528:
1529: @emph{Syntax}
1530:
1531: @example
1532: SET VAR=$ZDATE($H[,@emph{<format-string>}])
1533: @end example
1534:
1535: 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}).
1536:
1537: @xref{^$SYSTEM}
1538:
1539: @node $ZEDIT()
1540: @section $ZEDIT
1541: @cindex $ZEDIT
1542: @cindex intrinsic functions, $ZEDIT
1543: @cindex intrinsic functions, implementation-specific
1544:
1545: Purpose unknown.
1546:
1547: @node $ZHOROLOG()
1548: @section $ZHOROLOG
1549: @cindex $ZHOROLOG
1550: @cindex intrinsic functions, $ZHOROLOG
1551: @cindex intrinsic functions, implementation-specific
1552:
1553: Converts date and/or time values producible by @code{@ref{$ZDATE()}} or @code{@ref{$ZTIME()}} to @code{@ref{$HOROLOG}} format.
1554:
1555: @emph{Syntax}
1556:
1557: @example
1558: $ZHOROLOG(@emph{<date-value>},@emph{<format-string>})
1559: @end example
1560:
1561: @emph{<date-value>} is a date or time string compatible with the formats from @code{@ref{$ZDATE()}} or @code{@ref{$ZTIME}}.
1562:
1563: @emph{<format-string>} is a format string of the same format as used by the @code{strptime(3)} UNIX function.
1564:
1565: @node $ZKEY()
1566: @section $ZKEY
1567: @cindex $ZKEY
1568: @cindex intrinsic functions, $ZKEY
1569: @cindex intrinsic functions, implementation-specific
1570:
1571: Purpose unknown.
1572:
1573: @node $ZLENGTH()
1574: @section $ZLENGTH
1575: @cindex $ZLENGTH
1576: @cindex intrinsic functions, $ZLENGTH
1577: @cindex intrinsic functions, implementation-specific
1578:
1579: Purpose unknown.
1580:
1581: @node $ZLSD()
1582: @section $ZLSD
1583: @cindex $ZLSD
1584: @cindex intrinsic functions, $ZLSD
1585: @cindex intrinsic functions, implementation-specific
1586:
1587: 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.
1588:
1589: @emph{Syntax}
1590:
1591: @code{SET VAR=$ZLSD(@emph{arg1},@emph{arg2})}
1592:
1593: @emph{Example}
1594:
1595: @code{SET VAR=$ZLSD("KITTENS","MITTENS") ; => 1}
1596:
1597: @node $ZM()
1598: @section $ZM
1599: @cindex $ZM
1600: @cindex intrinsic functions, $ZM
1601: @cindex intrinsic functions, implementation-specific
1602:
1603: @node $ZNAME()
1604: @section $ZNAME
1605: @cindex $ZNAME
1606: @cindex intrinsic functions, $ZNAME
1607: @cindex intrinsic functions, implementation-specific
1608:
1609: Purpose unknown.
1610:
1611: @node $ZNEXT()
1612: @section $ZNEXT
1613: @cindex $ZNEXT
1614: @cindex intrinsic functions, $ZNEXT
1615: @cindex intrinsic functions, implementation-specific
1616:
1617: Purpose unknown.
1618:
1619: @node $ZORDER()
1620: @section $ZORDER
1621: @cindex $ZORDER
1622: @cindex intrinsic functions, $ZORDER
1623: @cindex intrinsic functions, implementation-specific
1624:
1625: Purpose unknown.
1626:
1627: @node $ZPIECE()
1628: @section $ZPIECE
1629: @cindex $ZPIECE
1630: @cindex intrinsic functions, $ZPIECE
1631: @cindex intrinsic functions, implementation-specific
1632:
1633: Purpose unknown.
1634:
1635: @node $ZPREVIOUS()
1636: @section $ZPREVIOUS
1637: @cindex $ZPREVIOUS
1638: @cindex intrinsic functions, $ZPREVIOUS
1639: @cindex intrinsic functions, implementation-specific
1640:
1641: Purpose unknown.
1642:
1643: @node $ZREPLACE()
1644: @section $ZREPLACE
1645: @cindex $ZREPLACE
1646: @cindex intrinsic functions, $ZREPLACE
1647: @cindex intrinsic functions, implementation-specific
1648:
1649: Replaces all instances of @code{arg2} with @code{arg3} in string @code{arg1}.
1650:
1651: @emph{Syntax}
1652: @code{$ZREPLACE(@emph{arg1},@emph{arg2},@emph{arg3})}
1653:
1654: @emph{Example}
1655:
1656: @code{SET VAR=$ZREPLACE("CAT","C","B") ; => BAT}
1657:
1658: @node $ZSYNTAX()
1659: @section $ZSYNTAX
1660: @cindex $ZSYNTAX
1661: @cindex intrinsic functions, $ZSYNTAX
1662: @cindex intrinsic functions, implementation-specific
1663:
1664: @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.
1665:
1666: @emph{Syntax}
1667: @example
1668: $ZSYNTAX(@emph{expr V mcode})
1669: @end example
1670:
1671: If no syntax error is found, returns the empty string.
1672:
1673: 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.
1674:
1675: @node $ZTIME()
1676: @section $ZTIME
1677: @cindex $ZTIME
1678: @cindex intrinsic functions, $ZTIME
1679: @cindex intrinsic functions, implementation-specific
1680:
1681: Converts a @code{@ref{$HOROLOG}} string into a human-readable time.
1682:
1683: @emph{Syntax}
1684:
1685: @example
1686: SET VAR=$ZTIME($H[,@emph{<format-string>}])
1687: @end example
1688:
1689: 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}).
1690:
1691: @node OBJECT Methods
1692: @chapter OBJECT Methods
1693:
1694: These methods are part of the @code{^%OBJECT} class, from which all FreeM objects ultimately inherit.
1695:
1696: 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.
1697:
1698: @menu
1699: * $$TONUMBER:: Returns the canonical numeric representation of the object.
1700: * $$TYPE:: Returns the fully-qualified class name of the object.
1701: * $$VALUE:: Returns the value of the object.
1702: @end menu
1703:
1704: @node $$TONUMBER
1705: @section $$TONUMBER
1706:
1707: Returns (when applicable) a canonical numeric representation of the referenced object.
1708:
1709: @emph{Syntax}
1710:
1711: @example
1712: W $$MYOBJECT.TONUMBER(),!
1713: @end example
1714:
1715: If no canonical numeric representation of the object is possible, will return the empty string.
1716:
1717: @node $$TYPE
1718: @section $$TYPE
1719:
1720: Returns the fully-qualified class of the referenced object.
1721:
1722: @emph{Syntax}
1723:
1724: @example
1725: W $$MYOBJECT.TYPE()
1726: @end example
1727:
1728: Note that M variables that are created by non-object-oriented means will be objects of the @code{^%STRING} class.
1729:
1730: @node $$VALUE
1731: @section $$VALUE
1732:
1733: Returns the value of the referenced object.
1734:
1735: @emph{Syntax}
1736:
1737: @example
1738: W $$MYOBJECT.VALUE()
1739: @end example
1740:
1741: @node STRING Methods
1742: @chapter STRING Methods
1743:
1744: These are methods inherent to the @code{^%STRING} class, which is the default class for M variables created without specifying a class.
1745:
1746: @menu
1747: * $$ASCII:: Return the ASCII code of a character within the string.
1748: * $$DATA:: Return tree characteristics of the string.
1749: * $$DISTANCE:: Determine Levenstein distance between this string and another.
1750: * $$EXTRACT:: Return a substring of the string.
1751: * $$FIND:: Find the position of a substring within the string.
1752: * $$FNUMBER:: Format numbers.
1753: * $$JUSTIFY:: Pad the string to specific positions.
1754: * $$LENGTH:: Return the length of the string.
1755: * $$PIECECOUNT:: Return the count of pieces existing between instances of a delimiter.
1756: * $$PIECE:: Return a delimited subset of the string.
1757: * $$REPLACE:: Replace instances of a substring within the string.
1758: * $$REVERSE:: Reverse the order of characters in the string.
1759: * $$TOLOWER:: Return a lowercase version of the string.
1760: * $$TOUPPER:: Return an uppercase version of the string.
1761: * $$TRANSLATE:: Replace individual characters within the string.
1762: @end menu
1763:
1764: @node $$ASCII
1765: @section $$ASCII
1766:
1767: Returns the ASCII code of a character within the string. See @ref{$ASCII()}.
1768:
1769: @emph{Syntax}
1770:
1771: @example
1772: W $$MYOBJECT.ASCII(3)
1773: @end example
1774:
1775: The above example returns the ASCII code in position 3 of string object @code{MYOBJECT}.
1776:
1777: @node $$DATA
1778: @section $$DATA
1779:
1780: Returns the value of the @code{$DATA} intrinsic function as performed on the value of the object. See @ref{$DATA()}.
1781:
1782: @emph{Syntax}
1783:
1784: @example
1785: W $$MYOBJECT.DATA()
1786: @end example
1787:
1788: @node $$DISTANCE
1789: @section $$DISTANCE
1790:
1791: Returns the Levenstein distance between the string and another string. See @ref{$ZLSD()}.
1792:
1793: @emph{Syntax}
1794:
1795: @example
1796: W $$MYOBJECT.DISTANCE("someString")
1797: @end example
1798:
1799: @node $$EXTRACT
1800: @section $$EXTRACT
1801:
1802: Returns a substring of the string. See @ref{$EXTRACT()}.
1803:
1804: @emph{Syntax}
1805:
1806: @example
1807: $$<objectName>.EXTRACT(<start>,<end>)
1808: @end example
1809:
1810:
1811: @node $$FIND
1812: @section $$FIND
1813:
1814: Finds the character immediately following the first occurence of a substring within a string.
1815:
1816: The first argument is the substring to be located.
1817:
1818: The second argument is the position within the string at which to begin searching.
1819:
1820: See @ref{$FIND()}.
1821:
1822: @node $$FNUMBER
1823: @section $$FNUMBER
1824:
1825: Formats a number according to a set of formatting codes.
1826:
1827: The argument is a series of formatting codes. See @ref{$FNUMBER()} for details.
1828:
1829: @node $$JUSTIFY
1830: @section $$JUSTIFY
1831:
1832: Right-justifies a string based on a specified fixed length.
1833:
1834: The first argument is the character length of the output.
1835:
1836: 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.
1837:
1838: See @ref{$JUSTIFY()} for details.
1839:
1840: @node $$LENGTH
1841: @section $$LENGTH
1842:
1843: Returns the length of the string.
1844:
1845: @node $$PIECECOUNT
1846: @section $$PIECECOUNT
1847:
1848: Returns the number of items in a list delimited by the character specified in the argument.
1849:
1850: @node $$PIECE
1851: @section $$PIECE
1852:
1853: @emph{Syntax}
1854:
1855: @code{$PIECE(@emph{d}[,@emph{n}[,@emph{end}]])}
1856:
1857: Accesses the @code{n}th through @code{end} @code{d}-delimited pieces of the string.
1858:
1859: The first argument is the delimiter to be used.
1860:
1861: The optional second argument is the first @code{d}-delimited piece to access, and defaults to @code{1}.
1862:
1863: The optional third argument is the final @code{d}-delimited piece to access, and defaults to the value of the third argument (@code{n}).
1864:
1865:
1866: @node $$REPLACE
1867: @section $$REPLACE
1868:
1869: @emph{Syntax}
1870: @code{myString.$$REPLACE(@emph{arg1},@emph{arg2})}
1871:
1872: Replaces all instances of @code{arg2} with @code{arg3} in @code{myString}.
1873:
1874: @node $$REVERSE
1875: @section $$REVERSE
1876:
1877: Returns the reverse of the string.
1878:
1879: @node $$TOLOWER
1880: @section $$TOLOWER
1881:
1882: Returns an all-lowercase version of the string.
1883:
1884: @node $$TOUPPER
1885: @section $$TOUPPER
1886:
1887: Returns an all-uppercase version of the string.
1888:
1889: @node $$TRANSLATE
1890: @section $$TRANSLATE
1891:
1892: Identical to @ref{$TRANSLATE()}, except that the arguments are shifted left by one, and the input string is implicit (the object).
1893:
1894: @node Commands
1895: @chapter Commands
1896: @cindex commands
1897:
1898: @menu
1899: * @@:: Execute the following expression as M code.
1900: * !:: Run an external program or command.
1901: * !!:: Launch a subshell from FreeM direct mode.
1902: * ABLOCK:: Increment the block counter for one or more event classes.
1903: * ASSERT:: Raise error when a conditional expression evaluates @emph{false}.
1904: * ASTART:: Enable asynchronous event handling for one or more event classes.
1905: * ASTOP:: Disable asynchronous event handling for one or more event classes.
1906: * AUNBLOCK:: Decrement the block counter for one or more event classes.
1907: * BREAK:: Interrupt a running routine to allow interactive debugging.
1908: * CLOSE:: Close an input/output device.
1909: * CONST:: Define a constant that cannot be altered after initial definition.
1910: * DO:: Transfer program control to one or more subroutines or introduces a new execution level.
1911: * ELSE:: Execute the remainder of a line if @code{@ref{$TEST}} evaluates @emph{false}.
1912: * FOR:: Repeat execution of a line or block of code.
1913: * GOTO:: Unconditionally transfer program execution to a supplied @emph{entryref}.
1914: * HALT:: Terminate the current FreeM interpreter instance.
1915: * HANG:: Temporarily suspend the running program.
1916: * IF:: Execute the remainder of a line if a conditional expression evaluates @emph{true}.
1917: * JOB:: Execute an @emph{entryref} in a child process.
1918: * KILL:: Remove data from a local, global, or structured system variable.
1919: * KSUBSCRIPTS:: Kill only the descendant subscripts of a local, global, global, or structured system variable.
1920: * KVALUE:: Kill only the value of a local, global, or structured system variable.
1921: * LOCK:: Control advisory locking for concurrency control.
1922: * MAP:: Map a global name to a non-default namespace.
1923: * MERGE:: Merge contents of one local, global, or structured system variable into another.
1924: * NEW:: Introduce a new scope for a specified local variable or intrinsic special variable or instantiate an object.
1925: * OPEN:: Open a sequential or socket input/output device.
1926: * QUIT:: End execution of the current process level, optionally with return value.
1927: * READ:: Read input from an input/output device.
1928: * SET:: Set the value of a local variable, global, intrinsic special variable, or structured system variable.
1929: * TCOMMIT:: Commit a transaction.
1930: * THEN:: Preserve @code{@ref{$TEST}} until the end of the current line.
1931: * THROW:: Programmatically raise an error condition.
1932: * TROLLBACK:: Roll back all pending transactions.
1933: * TSTART:: Introduce a new transaction processing level.
1934: * UNMAP:: Remove a mapping of a global to a non-default namespace.
1935: * USE:: Set the currently-active input/output device.
1936: * VIEW:: Modify FreeM internal parameters.
1937: * WATCH:: Enable or disable watchpoints, or set or clear watchpoints on specified globals, locals, or structured system variables.
1938: * WITH:: Set prefix for future variable references.
1939: * WRITE:: Write output to current input/output device.
1940: * XECUTE:: Interpret string as M code.
1941: * ZALLOCATE:: Alternative to @code{LOCK}.
1942: * ZBREAK:: Unknown.
1943: * ZDEALLOCATE:: Alternative to @code{LOCK}.
1944: * ZGO:: Unknown.
1945: * ZHALT:: Unknown.
1946: * ZINSERT:: Insert code into routine buffer.
1947: * ZJOB:: Unknown.
1948: * ZLOAD:: Load routine into routine buffer.
1949: * ZNEW:: Unknown.
1950: * ZPRINT:: Print contents of routine buffer.
1951: * ZQUIT:: Unknown.
1952: * ZREMOVE:: Remove code from routine buffer.
1953: * ZSAVE:: Save routine buffer to disk.
1954: * ZTRAP:: Unknown.
1955: * ZWRITE:: Write local variable, global, or structured system variable to @code{@ref{$IO}}.
1956: @end menu
1957:
1958: @node @@
1959: @section @@
1960: @cindex @@
1961: @cindex commands, @@
1962: @cindex commands, implementation-specific
1963: @cindex commands, non-standard
1964:
1965: Executes FreeM code @emph{expr V mcode}.
1966:
1967: @emph{Syntax}
1968:
1969: @example
1970: @@@emph{expr V mcode}
1971: @end example
1972:
1973: @emph{Example (Using Variable)}
1974:
1975: @example
1976: DEFAULT.USER> SET FOO="WRITE ""HELLO WORLD"",!"
1977: DEFAULT.USER> @@FOO
1978:
1979: HELLO WORLD
1980:
1981: DEFAULT.USER>
1982: @end example
1983:
1984: @emph{Example (Using String Literal)}
1985:
1986: @example
1987: DEFAULT.USER> @@"WRITE ""HELLO WORLD"",!"
1988:
1989: HELLO WORLD
1990:
1991: DEFAULT.USER>
1992: @end example
1993:
1994: @emph{Example (Using Indirection)}
1995:
1996: @example
1997: DEFAULT.USER> SET FOO="BAR"
1998:
1999: DEFAULT.USER> SET BAR="WRITE ""HELLO WORLD"",!"
2000:
2001: DEFAULT.USER> @@@@FOO
2002:
2003: HELLO WORLD
2004:
2005: DEFAULT.USER>
2006: @end example
2007:
2008:
2009: @node !
2010: @section !
2011: @cindex !
2012: @cindex commands, !
2013: @cindex commands, external
2014: @cindex commands, non-standard
2015: @emph{FreeM Extension}
2016:
2017: 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}.
2018:
2019: 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.
2020:
2021: 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{%}.
2022:
2023: @code{%} contains the number of lines in the input or output. @code{%(1)..%(@emph{n})} contains the data for lines 1-@emph{n}.
2024:
2025: @node !!
2026: @section !!
2027: @cindex !!
2028: @cindex commands, !!
2029: @cindex commands, external
2030: @cindex commands, non-standard
2031: @emph{FreeM Extension}
2032:
2033: Launches a subshell within the FreeM direct mode, allowing the user to run operating system commands.
2034:
2035: @example
2036: DEFAULT.USER> !!
2037:
2038: Type Ctrl-D to exit from the shell
2039: $ uname -a
2040: Linux hesperos 4.19.0-17-amd64 #1 SMP Debian 4.19.194-3 (2021-07-18) x86_64 GNU/Linux
2041: $ exit
2042:
2043: DEFAULT.USER>
2044: @end example
2045:
2046:
2047: @node ABLOCK
2048: @section ABLOCK
2049: @cindex ABLOCK
2050: @cindex commands, ABLOCK
2051:
2052: 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).
2053:
2054: 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.
2055:
2056: @emph{Syntax}
2057:
2058: @example
2059: ABLOCK@emph{:postcondition}
2060: @end example
2061:
2062: 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.
2063:
2064: @example
2065: ABLOCK@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2066: @end example
2067:
2068: 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.
2069:
2070: @example
2071: ABLOCK@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN}
2072: @end example
2073:
2074: 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.
2075:
2076: @node ASSERT
2077: @section ASSERT
2078: @cindex ASSERT
2079: @cindex commands, ASSERT
2080: @cindex commands, debugging
2081: @cindex commands, implementation-specific
2082: @cindex commands, non-standard
2083: @emph{FreeM Extension}
2084:
2085: Triggers error @code{ASSERT} 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.
2086:
2087: The @code{ASSERT} error is catchable whether using standard-style, FreeM-style, or DSM 2.0-style error processing.
2088:
2089: @emph{Syntax}
2090:
2091: @example
2092: ASSERT@emph{:postcondition} @emph{<tvexpr>}
2093: @end example
2094:
2095: @emph{Example}
2096:
2097: @example
2098: DEFAULT.USER> SET DEBUG=1
2099:
2100:
2101: DEFAULT.USER> ASSERT:DEBUG 1=1
2102:
2103:
2104: DEFAULT.USER> ASSERT:DEBUG 1=0
2105:
2106:
2107: >> Error ZASSERT: programmer assertion failed in SYSTEM::^%SYSINIT [$STACK = 0]
2108: >> ASSERT:DEBUG 1=0
2109: ^
2110: @end example
2111:
2112: @node ASTART
2113: @section ASTART
2114: @cindex ASTART
2115: @cindex commands, ASTART
2116:
2117: Enables asynchronous event handling for one or more event classes.
2118:
2119: @emph{Syntax}
2120:
2121: @example
2122: ASTART@emph{:postcondition}
2123: @end example
2124:
2125: 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.
2126:
2127: @example
2128: ASTART@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2129: @end example
2130:
2131: 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.
2132:
2133: @example
2134: ASTART@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN})
2135: @end example
2136:
2137: 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.
2138:
2139: @node ASTOP
2140: @section ASTOP
2141: @cindex ASTOP
2142: @cindex commands, ASTOP
2143:
2144: Disables asynchronous event handling for one or more event classes.
2145:
2146: @emph{Syntax}
2147:
2148: @example
2149: ASTOP@emph{:postcondition}
2150: @end example
2151:
2152: 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.
2153:
2154: @example
2155: ASTOP@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2156: @end example
2157:
2158: 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.
2159:
2160: @example
2161: ASTOP@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN})
2162: @end example
2163:
2164: 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.
2165:
2166: @node AUNBLOCK
2167: @section AUNBLOCK
2168: @cindex AUNBLOCK
2169: @cindex commands, AUNBLOCK
2170:
2171: Decrements the event block counter for one or more event classes.
2172:
2173: @emph{Syntax}
2174:
2175: @example
2176: AUNBLOCK@emph{:postcondition}
2177: @end example
2178:
2179: 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.
2180:
2181: @example
2182: AUNBLOCK@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2183: @end example
2184:
2185: 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.
2186:
2187: @example
2188: AUNBLOCK@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN}
2189: @end example
2190:
2191: 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.
2192:
2193:
2194: @node BREAK
2195: @section BREAK
2196: @cindex BREAK
2197: @cindex commands, BREAK
2198:
2199: Interrupts running routine to allow interactive debugging.
2200:
2201: @emph{Syntax}
2202:
2203: @example
2204: @code{BREAK@emph{:postcondition}}
2205: @end example
2206:
2207: In its argumentless form, @code{BREAK} suspends execution of running code, provided the optional @emph{postcondition} is @emph{true} or omitted.
2208:
2209: @example
2210: @code{BREAK@emph{:postcondition} @emph{breakflag}}
2211: @end example
2212:
2213: @emph{FreeM Extension}
2214:
2215: In its single-argument form, @code{BREAK} sets @emph{Ctrl-C} handling and error handling characteristics, provided the optional @emph{postcondition} is @emph{true} or omitted.
2216: The following table enumerates the possible values of @emph{breakflag}
2217:
2218: @table @code
2219: @item 0
2220: Disables @emph{Ctrl-C} handling
2221: @item -2
2222: Enables normal FreeM error handling
2223: @item 2
2224: Enables @emph{Digital Standard MUMPS} v2 error handling
2225: @item @emph{any integer value other than 0, 2, or -2}
2226: Enables @emph{Ctrl-C} handling
2227: @end table
2228:
2229: @node CLOSE
2230: @section CLOSE
2231: @cindex CLOSE
2232: @cindex commands, CLOSE
2233:
2234: Closes an input/output device.
2235:
2236: @emph{Syntax}
2237:
2238: @example
2239: @code{CLOSE@emph{:postcondition}}
2240: @end example
2241:
2242: 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.
2243:
2244: @example
2245: @code{CLOSE@emph{:postcondition} @emph{channel}}
2246: @end example
2247:
2248: 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.
2249:
2250: @node CONST
2251: @section CONST
2252: @cindex CONST
2253: @cindex commands, CONST
2254: @cindex commands, non-standard
2255: @emph{FreeM Extension}
2256:
2257: 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.
2258:
2259: Constants must only be locals, and globals are not supported.
2260:
2261: @emph{Syntax}
2262:
2263: @example
2264: @code{CONST@emph{:postcondition} @emph{mref1}=@emph{initial-value1},...,@emph{mrefN}=@emph{initial-valueN}}
2265: @end example
2266:
2267: @node DO
2268: @section DO
2269: @cindex DO
2270: @cindex commands, DO
2271:
2272: 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.
2273:
2274: @emph{Syntax}
2275:
2276: @example
2277: DO[@emph{:postcondition}] @emph{entryref}[@emph{:postcondition}[,...]]
2278: @end example
2279:
2280: 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.
2281:
2282: @emph{Syntax}
2283:
2284: @example
2285: DO[@emph{:postcondition}]
2286: @end example
2287:
2288: @node ELSE
2289: @section ELSE
2290: @cindex ELSE
2291: @cindex commands, ELSE
2292:
2293: 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.
2294:
2295: @emph{Syntax}
2296:
2297: @example
2298: ELSE[@emph{:postcondition}]
2299: @end example
2300:
2301: @cartouche
2302: @quotation
2303: @emph{Non-Standard Behavior}
2304:
2305: FreeM allows a @emph{postcondition} on @code{ELSE}. While explicitly forbidden in the @emph{standard}--and for good reason--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.
2306:
2307: 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, Daily WTF rants, or meltdown of global financial markets.
2308: @end quotation
2309: @end cartouche
2310:
2311: @node FOR
2312: @section FOR
2313: @cindex FOR
2314: @cindex commands, FOR
2315:
2316: 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.
2317:
2318: @emph{Syntax}
2319:
2320: @example
2321: FOR[@emph{:postcondition}]
2322: @end example
2323:
2324: @cartouche
2325: @quotation
2326: @emph{Non-Standard Behavior}
2327:
2328: 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.
2329:
2330: 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.
2331: @end quotation
2332: @end cartouche
2333:
2334: 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.
2335:
2336: 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}.
2337:
2338: @emph{Syntax}
2339:
2340: @example
2341: FOR[@emph{:postcondition}] @emph{glvn}=@emph{initializer-expression}:@emph{increment-expression}:@emph{max-expression}
2342: @end example
2343:
2344: @emph{Example}
2345:
2346: @example
2347: DEFAULT.USER> FOR I=1:1:10 WRITE I,!
2348:
2349: 1
2350: 2
2351: 3
2352: 4
2353: 5
2354: 6
2355: 7
2356: 8
2357: 9
2358: 10
2359:
2360: DEFAULT.USER> FOR I=2:2:10 WRITE I,!
2361:
2362: 2
2363: 4
2364: 6
2365: 8
2366: 10
2367: @end example
2368:
2369: 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.
2370:
2371: @emph{Syntax}
2372:
2373: @example
2374: FOR[@emph{:postcondition}] @emph{glvn}=@emph{expr1}[,..@emph{exprN}]
2375: @end example
2376:
2377: @emph{Example}
2378:
2379: @example
2380: DEFAULT.USER> FOR I=60,"FOO",-3,"George",1450,$HOROLOG WRITE I,!
2381:
2382: 60
2383: FOO
2384: -3
2385: George
2386: 1450
2387: 66106,52388
2388: @end example
2389:
2390: @node GOTO
2391: @section GOTO
2392: @cindex GOTO
2393: @cindex commands, GOTO
2394:
2395: 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}.
2396:
2397: @emph{Syntax}
2398:
2399: @example
2400: GOTO[@emph{:postcondition}] @emph{entryref}
2401: @end example
2402:
2403: @node HALT
2404: @section HALT
2405: @cindex HALT
2406: @cindex commands, HALT
2407:
2408: Halts program execution and frees resources allocated during execution, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2409:
2410: @emph{Syntax}
2411:
2412: @example
2413: HALT[@emph{:postcondition}]
2414: @end example
2415:
2416: @node HANG
2417: @section HANG
2418: @cindex HANG
2419: @cindex commands, HANG
2420:
2421: 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.
2422:
2423: @emph{Syntax}
2424:
2425: @example
2426: HANG[@emph{:postcondition}] @emph{expr}
2427: @end example
2428:
2429: @cartouche
2430: @quotation
2431: @emph{Non-Standard Behavior}
2432:
2433: FreeM supports sub-second values for @emph{expr}.
2434: @end quotation
2435: @end cartouche
2436:
2437: @node IF
2438: @section IF
2439: @cindex IF
2440: @cindex commands, IF
2441:
2442: 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.
2443:
2444: @emph{Syntax}
2445: @example
2446: IF[@emph{:postcondition}] @emph{tvexpr}[,...@emph{tvexpr}]
2447: @end example
2448:
2449: 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.
2450:
2451: @emph{Syntax}
2452: @example
2453: IF[@emph{:postcondition}]
2454: @end example
2455:
2456: @node JOB
2457: @section JOB
2458: @cindex JOB
2459: @cindex commands, JOB
2460:
2461: Executes @emph{entryref} in a separate process, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2462:
2463: @emph{Syntax}
2464: @example
2465: JOB[@emph{:postcondition}] @emph{entryref}[:@emph{job-parameters}[:@emph{timeout}]]
2466: @end example
2467:
2468: If @emph{timeout} is supplied, FreeM will set @code{$TEST} to @emph{1} if the child process completes within @emph{timeout} seconds.
2469:
2470: @node KILL
2471: @section KILL
2472: @cindex KILL
2473: @cindex commands, KILL
2474:
2475: 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.
2476:
2477: @emph{Syntax}
2478: @example
2479: KILL[@emph{:postcondition}] @emph{glvn}[,...@emph{glvn}]
2480: @end example
2481:
2482: 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.
2483:
2484: @emph{Syntax}
2485: @example
2486: KILL[@emph{:postcondition}] (@emph{lvn}[,...@emph{lvn}])
2487: @end example
2488:
2489: In its argumentless form, @code{KILL} deletes all local variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2490:
2491: @emph{Syntax}
2492: @example
2493: KILL[@emph{:postcondition}]
2494: @end example
2495:
2496: @node KSUBSCRIPTS
2497: @section KSUBSCRIPTS
2498: @cindex KSUBSCRIPTS
2499: @cindex commands, KSUBSCRIPTS
2500:
2501: Kills only the descendant subscripts (but not the data value) of a referenced global, local, or SSVN (where allowed).
2502:
2503: @emph{Syntax}
2504:
2505: @example
2506: KSUBSCRIPTS@emph{:postcondition} @emph{var1},...
2507: @end example
2508:
2509: 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.
2510:
2511: @cartouche
2512: @quotation
2513: @emph{Note}
2514: The below @emph{argumentless} and @emph{exclusive} forms of @code{KSUBSCRIPTS} are not implemented in FreeM, as of version 0.64.0-rc0, but are planned for a future release.
2515: @end quotation
2516: @end cartouche
2517:
2518: @example
2519: KSUBSCRIPTS@emph{:postcondition}
2520: @end example
2521:
2522: 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.
2523:
2524: @example
2525: KSUBSCRIPTS@emph{:postcondition} (@emph{var1},...)
2526: @end example
2527:
2528: 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.
2529:
2530:
2531: @node KVALUE
2532: @section KVALUE
2533: @cindex KVALUE
2534: @cindex commands, KVALUE
2535:
2536: Kills only the data value (but not descendant subscripts) of a referenced global, local, or SSVN (where allowed).
2537:
2538: @emph{Syntax}
2539:
2540: @example
2541: KVALUE@emph{:postcondition} @emph{var1},...
2542: @end example
2543:
2544: 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.
2545:
2546: @cartouche
2547: @quotation
2548: @emph{Note}
2549: The below @emph{argumentless} and @emph{exclusive} forms of @code{KVALUE} are not implemented in FreeM, as of version 0.64.0-rc0, but are planned for a future release.
2550: @end quotation
2551: @end cartouche
2552:
2553: @example
2554: KVALUE@emph{:postcondition}
2555: @end example
2556:
2557: 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.
2558:
2559: @example
2560: KVALUE@emph{:postcondition} (@emph{var1},...)
2561: @end example
2562:
2563: 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.
2564:
2565: @node LOCK
2566: @section LOCK
2567: @cindex LOCK
2568: @cindex commands, LOCK
2569:
2570: Acquires or releases ownership of names.
2571:
2572: 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.
2573:
2574: @emph{Syntax}
2575: @example
2576: LOCK[@emph{:postcondition}]
2577: @end example
2578:
2579: 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}.
2580:
2581: If @code{LOCK} succeeds within @emph{timeout}, @code{$TEST} is set to @emph{1}. Otherwise, @code{$TEST} is set to @emph{0}.
2582:
2583: @emph{Syntax}
2584: @example
2585: LOCK[@emph{:postcondition}] [+|-]@emph{name}[:@emph{timeout}][,...[+|-]@emph{name}[:@emph{timeout}]]
2586: @end example
2587:
2588: @emph{Example}
2589:
2590: This example will increment the lock counter for @code{^SNW} and decrement the lock counter for @code{^MJR}.
2591:
2592: @example
2593: LOCK +^SNW,-^MJR
2594: @end example
2595:
2596: 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.
2597:
2598: If @code{LOCK} succeeds within @emph{timeout}, @code{$TEST} is set to @emph{1}. Otherwise, @code{$TEST} is set to @emph{0}.
2599:
2600: @emph{Syntax}
2601: @example
2602: LOCK[@emph{:postcondition}] @emph{name}[:@emph{timeout}][,...@emph{name}[:@emph{timeout}]]
2603: @end example
2604:
2605: @node MAP
2606: @section MAP
2607: @cindex MAP
2608: @cindex commands, MAP
2609: @cindex commands, implementation-specific
2610: @cindex commands, non-standard
2611:
2612: 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.
2613:
2614: @emph{Syntax}
2615:
2616: @example
2617: MAP[@emph{:postcondition}] GLOBAL @emph{gvn}=@emph{expr V namespace}
2618: @end example
2619:
2620: @node MERGE
2621: @section MERGE
2622: @cindex MERGE
2623: @cindex commands, MERGE
2624:
2625: Merges the contents of one global, local, or SSVN subtree to another global, local, or SSVN.
2626:
2627: @emph{Syntax}
2628:
2629: @example
2630: @code{MERGE A=^$JOB}
2631: @end example
2632:
2633: 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.
2634:
2635: @node NEW
2636: @section NEW
2637: @cindex NEW
2638: @cindex commands, NEW
2639:
2640: In all forms of @code{NEW}, @emph{name} must be a local variable name or @code{NEW}-able structured or intrinsic system variable.
2641:
2642: 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.
2643:
2644: @emph{Syntax}
2645:
2646: @example
2647: NEW[@emph{:postcondition}] @emph{name}[,...@emph{name}]
2648: @end example
2649:
2650: 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.
2651:
2652: @emph{Syntax}
2653: @example
2654: NEW[@emph{:postcondition}] (@emph{name}[,...@emph{name}])
2655: @end example
2656:
2657: 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.
2658:
2659: @emph{Syntax}
2660: @example
2661: NEW@emph{:postcondition} @emph{name}=@emph{expr}
2662: @end example
2663:
2664: 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.
2665:
2666: @emph{Syntax}
2667: @example
2668: NEW@emph{:postcondition} @emph{name}=$%@emph{^CLASS}(@emph{initializer-list})
2669: @end example
2670:
2671: 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).
2672:
2673: @node OPEN
2674: @section OPEN
2675: @cindex OPEN
2676: @cindex commands, OPEN
2677:
2678: Opens sequential or socket I/O devices and files and associates them with a numeric FreeM input/output channel.
2679:
2680: @emph{Syntax (Sequential Files)}
2681:
2682: @example
2683: @code{OPEN@emph{:postcondition} @emph{channel}:"@emph{filename}/@emph{access-mode}"}
2684: @end example
2685:
2686: 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.
2687: The below table lists the valid options for @emph{access-mode}:
2688:
2689: @table @code
2690: @item r
2691: Read-only access
2692: @item w
2693: Create a new file for write access
2694: @item a
2695: Write access; append to existing file
2696: @item r+
2697: Read/write access
2698: @end table
2699:
2700: @cartouche
2701: @quotation
2702: @emph{I/O Path}
2703:
2704: 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
2705: access files in other directories, you must first set the @emph{I/O Path} in @code{^$JOB($JOB,"IOPATH")}.
2706:
2707: The following example will set the I/O path to @code{/etc}:
2708:
2709: @example
2710: @code{SET ^$JOB($JOB,"IOPATH")="/etc"}
2711: @end example
2712:
2713: @end quotation
2714: @end cartouche
2715:
2716: 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}.
2717:
2718: @emph{Syntax (Network Sockets)}
2719:
2720: 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.
2721:
2722: @example
2723: OPEN@emph{:postcondition} @emph{socket-channel}:"@emph{hostname-or-address}:@emph{port}:@emph{address-family}:@emph{connection-type}"
2724: @end example
2725:
2726: @emph{Socket Parameters}
2727:
2728: @table @emph
2729:
2730: @item socket-channel
2731: The socket I/O channel to use. This must be in the range of 100-255.
2732:
2733: @item hostname-or-address
2734: 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.
2735:
2736: @item port
2737: The TCP or UDP port to which the socket will connect on the remote host.
2738:
2739: @item address-family
2740: The address family to use. Either @emph{IPV4} or @emph{IPV6}.
2741:
2742: @item connection-type
2743: Which connection type to use. Either @emph{TCP} or @emph{UDP}.
2744:
2745: @end table
2746:
2747: If you do not specify the address family and connection type, they will default to @emph{IPV4} and @emph{TCP}, respectively.
2748:
2749: @node QUIT
2750: @section QUIT
2751: @cindex QUIT
2752: @cindex commands, QUIT
2753:
2754: @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.
2755:
2756: @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}.
2757:
2758: Argumentless @code{QUIT} may also be used to exit a @code{FOR} loop occurring on the same line.
2759:
2760: @emph{Syntax}
2761: @example
2762: QUIT[@emph{:postcondition}] [@emph{expr}]
2763: @end example
2764:
2765: @node READ
2766: @section READ
2767: @cindex READ
2768: @cindex commands, READ
2769:
2770: 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.
2771:
2772: @emph{Syntax}
2773: @example
2774: READ[@emph{:postcondition}] @emph{read-argument}[,...@emph{read-argument}]
2775: @end example
2776:
2777: Each @emph{read-argument} may be one of the following:
2778:
2779: @table @asis
2780:
2781: @item String Literal
2782: String literal @emph{read-argument}s will be output to @code{$IO} unmodified.
2783:
2784: @item Format Specifier
2785: One or more of the following:
2786:
2787: @table @asis
2788: @item @code{!} (newline)
2789: Advances the cursor down by one line and returns it to the first column.
2790:
2791: @item @code{#} (form-feed)
2792: Advances the screen down by @code{$ZROWS} and moves the cursor to the upper-left corner of the screen.
2793:
2794: @item @code{?@emph{n}} (position)
2795: Advances the cursor and @code{$X} forward to position @emph{n}.
2796:
2797: @end table
2798:
2799: @item Single-Character Read (@code{*@emph{variable-name}[@emph{:timeout}]})
2800: 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}.
2801:
2802: @item Variable-Length Character Read (@code{@emph{variable-name}[@emph{:timeout}]})
2803: 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}.
2804:
2805: @item Fixed-Length Character Read (@code{@emph{variable-name}#@emph{count}[@emph{:timeout}]})
2806: 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}.
2807:
2808: @item Control Mnemonic (@code{/@emph{control-mnemonic}[@emph{(arg1[,...argN])}]})
2809: Outputs X3.64 control mnemonic @emph{control-mnemonic} to @code{$IO}. Please see the appendix on X3.64 Control Mnemonics for more information.
2810:
2811: @end table
2812:
2813: @node SET
2814: @section SET
2815: @cindex SET
2816: @cindex commands, SET
2817:
2818: The @code{SET} command places values into one or more variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2819:
2820: @emph{Syntax}
2821: @example
2822: SET[@emph{:postcondition}] @emph{set-argument}[=@emph{expression} | @emph{postfix-operator}][@emph{,...set-argument}[=@emph{expression} | @emph{postfix-operator}]]
2823: @end example
2824:
2825: Each @emph{set-argument} can be:
2826:
2827: @table @asis
2828: @item @emph{variable-name}
2829: A local variable, global variable, writable intrinsic special variable, or writable structured system variable.
2830:
2831: @item @emph{lhs-function}
2832: @code{$EXTRACT} or @code{$PIECE}.
2833: @end table
2834:
2835: 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}.
2836:
2837: 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.
2838:
2839: @emph{Example (postfix-operator)}
2840:
2841: @example
2842: SET A++,B-- ; increments A, decrements B
2843: @end example
2844:
2845: @node TCOMMIT
2846: @section TCOMMIT
2847: @cindex TCOMMIT
2848: @cindex commands, TCOMMIT
2849:
2850: Commits all pending transactions to the data files, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2851:
2852: @emph{Syntax}
2853: @example
2854: TCOMMIT[@emph{:postcondition}]
2855: @end example
2856:
2857: @node THEN
2858: @section THEN
2859: @cindex THEN
2860: @cindex commands, THEN
2861:
2862: 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}.
2863:
2864: @emph{Example}
2865: @example
2866: IF 1 THEN WRITE "HELLO!",!
2867: @end example
2868:
2869: @node THROW
2870: @section THROW
2871: @cindex THROW
2872: @cindex commands, THROW
2873: @cindex commands, non-standard
2874: @emph{FreeM Extension}
2875:
2876: Raises an error condition as long as the optional @emph{postcondition} is @emph{true} or omitted.
2877:
2878: @emph{Syntax}
2879:
2880: @example
2881: @code{THROW@emph{:postcondition} @emph{expr V error-code}}
2882: @end example
2883:
2884: @emph{Example}
2885:
2886: @example
2887: @code{THROW "M102"}
2888: @end example
2889:
2890: @node TROLLBACK
2891: @section TROLLBACK
2892: @cindex TROLLBACK
2893: @cindex commands, TROLLBACK
2894:
2895: Rolls back all pending transactions for the current process, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2896:
2897: @emph{Syntax}
2898:
2899: @example
2900: TROLLBACK[@emph{:postcondition}]
2901: @end example
2902:
2903: @node TSTART
2904: @section TSTART
2905: @cindex TSTART
2906: @cindex commands, TSTART
2907:
2908: 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.
2909:
2910: If a transaction is restartable, variables in the @emph{variables-list} will be restored to their original values on a restart of the transaction.
2911:
2912: @emph{Syntax}
2913:
2914: @example
2915: TSTART[@emph{:postcondition}] @emph{<variables-list>}:@emph{<transaction-parameters>}
2916: @end example
2917:
2918: @emph{<variables-list>} can be:
2919:
2920: @table @asis
2921:
2922: @item @code{()}
2923: Do not save off any local variables. Makes the transaction non-restartable.
2924:
2925: @item @code{*}
2926: Save off all local variables. Makes the transaction restartable.
2927:
2928: @item @code{@emph{variableName}}
2929: Saves off only one local variable, @emph{variableName}. Makes the transaction restartable.
2930:
2931: @item @code{(@emph{variableName1},...,@emph{variableNameN})}
2932: Saves off all local variables listed. Makes the transaction restartable.
2933:
2934: @end table
2935:
2936: @emph{<transaction-parameters>} can be:
2937:
2938: @table @asis
2939:
2940: @item @code{S[ERIAL]}
2941: 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.
2942:
2943: @item @code{T[RANSACTIONID]=@emph{transaction-id}}
2944: Sets the ID of the transaction to @emph{transaction-id}
2945:
2946: @end table
2947:
2948: If you are using more than one transaction parameter, surround all of them in parentheses and separate them with commas, e.g.:
2949:
2950: @example
2951: TSTART (FOO,BAR):(SERIAL,TRANSACTIONID="FOO")
2952: @end example
2953:
2954: @node UNMAP
2955: @section UNMAP
2956: @cindex UNMAP
2957: @cindex commands, UNMAP
2958: @cindex commands, implementation-specific
2959: @cindex commands, non-standard
2960:
2961: Removes any mapping connecting @emph{gvn} to a non-default namespace, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2962:
2963: @emph{Syntax}
2964:
2965: @example
2966: UNMAP GLOBAL @emph{gvn}
2967: @end example
2968:
2969: @node USE
2970: @section USE
2971: @cindex USE
2972: @cindex commands, USE
2973:
2974: 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.
2975:
2976: @emph{Syntax (Terminal)}
2977:
2978: @example
2979: 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})]
2980: @end example
2981:
2982: For terminals, @emph{io-channel} must be 0.
2983:
2984: Semantic and functional description of each device parameter TBA.
2985:
2986: @emph{Syntax (Sequential Files)}
2987:
2988: @example
2989: USE@emph{:postcondition} @emph{io-channel}[:@emph{seek-position}:@emph{terminator}:@emph{nodelay})]
2990: @end example
2991:
2992: For sequential files, @emph{io-channel} must be in the range 1-99.
2993:
2994: Semantic and functional description of each device parameter TBA.
2995:
2996: @emph{Syntax (Network Sockets)}
2997:
2998: @example
2999: USE@emph{:postcondition} @emph{io-channel}
3000: @end example
3001:
3002: 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.
3003:
3004: @example
3005: USE@emph{:postcondition} @emph{io-channel}:/CONNECT
3006: @end example
3007:
3008: 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).
3009:
3010: For network sockets, @emph{io-channel} must be in the range 100-255.
3011:
3012: @node VIEW
3013: @section VIEW
3014: @cindex VIEW
3015: @cindex commands, VIEW
3016:
3017: Provides write access to various FreeM internal parameters, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
3018:
3019: @emph{Syntax}
3020: @example
3021: VIEW[@emph{:postcondition}] @emph{view-number}[:@emph{view-argument}[:@emph{view-argument}...]]
3022: @end example
3023:
3024: The @emph{view-number} argument can be one of the following:
3025:
3026: @table @asis
3027:
3028: @item @code{21} - Close All Globals
3029: Closes all global data files open in the current process. Takes no arguments.
3030:
3031: @emph{Syntax}
3032: @example
3033: VIEW 21
3034: @end example
3035:
3036: @item @code{52} - Set G0 Input Translation Table for @code{$IO}
3037:
3038: @emph{Syntax}
3039: @example
3040: VIEW 52:@emph{expr V trantab}
3041: @end example
3042:
3043: @item @code{53} - Set G0 Output Translation Table for @code{$IO}
3044:
3045: @emph{Syntax}
3046: @example
3047: VIEW 53:@emph{expr V trantab}
3048: @end example
3049:
3050: @item @code{54} - Set G1 Input Translation Table for @code{$IO}
3051:
3052: @emph{Syntax}
3053: @example
3054: VIEW 54:@emph{expr V trantab}
3055: @end example
3056:
3057: @item @code{55} - Set G1 Output Translation Table for @code{$IO}
3058:
3059: @emph{Syntax}
3060: @example
3061: VIEW 55:@emph{expr V trantab}
3062: @end example
3063:
3064: @item @code{62} - Set @code{$RANDOM} Seed Number
3065: Sets the seed number used by @code{$RANDOM} to @emph{numexpr}.
3066:
3067: @emph{Syntax}
3068: @example
3069: VIEW 62:@emph{numexpr}
3070: @end example
3071:
3072: @item @code{63} - Set @code{$RANDOM} Parameter A
3073: Sets the number used for @code{$RANDOM} Parameter A to @emph{numexpr}.
3074:
3075: @emph{Syntax}
3076: @example
3077: VIEW 63:@emph{numexpr}
3078: @end example
3079:
3080: @item @code{64} - Set @code{$RANDOM} Parameter B
3081: Sets the number used for @code{$RANDOM} Parameter B to @emph{numexpr}.
3082:
3083: @emph{Syntax}
3084: @example
3085: VIEW 64:@emph{numexpr}
3086: @end example
3087:
3088: @item @code{65} - Set @code{$RANDOM} Parameter C
3089: Sets the number used for @code{$RANDOM} Parameter C to @emph{numexpr}.
3090:
3091: @emph{Syntax}
3092: @example
3093: VIEW 65:@emph{numexpr}
3094: @end example
3095:
3096: @item @code{66} - Set or Clear @code{SIGTERM} Handling Flag
3097: 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.
3098:
3099: @emph{Syntax}
3100: @example
3101: VIEW 66:@emph{tvexpr}
3102: @end example
3103:
3104: @item @code{67} - Set or Clear @code{SIGHUP} Handling Flag
3105: 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.
3106:
3107: @emph{Syntax}
3108: @example
3109: VIEW 67:@emph{tvexpr}
3110: @end example
3111:
3112: @item @code{70} - Set @code{$ZSORT}/@code{$ZSYNTAX} Flag
3113: Selects whether @code{$ZS} resolves to @code{$ZSORT} or @code{$ZSYNTAX}.
3114:
3115: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZSYNTAX}. Otherwise, selects @code{$ZSORT}.
3116:
3117: @emph{Syntax}
3118: @example
3119: VIEW 70:@emph{tvexpr}
3120: @end example
3121:
3122: @item @code{71} - Set @code{$ZNEXT}/@code{$ZNAME} Flag
3123: Selects whether @code{$ZN} resolves to @code{$ZNEXT} or @code{$ZNAME}.
3124:
3125: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZNAME}. Otherwise, selects @code{$ZNEXT}.
3126:
3127: @emph{Syntax}
3128: @example
3129: VIEW 71:@emph{tvexpr}
3130: @end example
3131:
3132: @item @code{72} - Set @code{$ZPREVIOUS}/@code{$ZPIECE} Flag
3133: Selects whether @code{$ZP} resolves to @code{$ZPREVIOUS} or @code{$ZPIECE}.
3134:
3135: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZPIECE}. Otherwise, selects @code{$ZPREVIOUS}.
3136:
3137: @emph{Syntax}
3138: @example
3139: VIEW 72:@emph{tvexpr}
3140: @end example
3141:
3142: @item @code{73} - Set @code{$ZDATA}/@code{$ZDATE} Flag
3143: Selects whether @code{$ZD} resolves to @code{$ZDATA} or @code{$ZDATE}.
3144:
3145: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZDATE}. Otherwise, selects @code{$ZDATA}.
3146:
3147: @emph{Syntax}
3148: @example
3149: VIEW 73:@emph{tvexpr}
3150: @end example
3151:
3152: @item @code{79} - Set Old @code{ZJOB} vs. New @code{ZJOB} Flag
3153: If @emph{tvexpr} evaluates to @emph{true}, sets the @code{ZJOB} mode to new, otherwise, sets it to old.
3154:
3155: @emph{Syntax}
3156: @example
3157: VIEW 79:@emph{tvexpr}
3158: @end example
3159:
3160: @item @code{80} - Set or Clear 8-Bit Flag
3161: If @emph{tvexpr} evaluates to @emph{true}, sets FreeM to 8-bit mode. Otherwise, sets FreeM to 7-bit mode.
3162:
3163: @emph{Syntax}
3164: @example
3165: VIEW 80:@emph{tvexpr}
3166: @end example
3167:
3168: @item @code{81} - Set or Clear PF1 Flag
3169: If @emph{tvexpr} evaluates to @emph{true}, sets the @code{PF1} flag. We do not yet know what this does.
3170:
3171: @emph{Syntax}
3172: @example
3173: VIEW 81:@emph{tvexpr}
3174: @end example
3175:
3176: @item @code{83} - Set or Clear Text in @code{$ZERROR} Flag
3177: 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}.
3178:
3179: @emph{Syntax}
3180: @example
3181: VIEW 83:@emph{tvexpr}
3182: @end example
3183:
3184: @item @code{92} - Set Type Mismatch Error Flag on @code{EUR2DEM}
3185: 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.
3186:
3187: @emph{Syntax}
3188: @example
3189: VIEW 92:@emph{tvexpr}
3190: @end example
3191:
3192: @item @code{93} - Define @code{ZKEY} Production Rule
3193: We do not know what this does.
3194:
3195: @item @code{96} - Set Global Prefix
3196: Forces global data filenames to be prefixed with the result of @emph{expr}.
3197:
3198: @emph{Syntax}
3199: @example
3200: VIEW 96:@emph{expr V string}
3201: @end example
3202:
3203: @item @code{97} - Set Global Postfix
3204: Forces global data filenames to be postfixed with the result of @emph{expr}.
3205:
3206: @emph{Syntax}
3207: @example
3208: VIEW 97:@emph{expr V string}
3209: @end example
3210:
3211: @item @code{98} - Set Routine Extension
3212: Sets the default extension for M routine filenames to the result of @emph{expr}.
3213:
3214: @emph{Syntax}
3215: @example
3216: VIEW 98:@emph{expr V string}
3217: @end example
3218:
3219: @item @code{101} - Set @code{ierr}
3220: Sets the FreeM internal @code{ierr} value to @emph{intexpr}. Used by some FreeM polyfills (commands or functions implemented in M code).
3221:
3222: @emph{Syntax}
3223: @example
3224: VIEW 101:@emph{intexpr}
3225: @end example
3226:
3227: @item @code{102} - Set @code{ierr} (Deferred)
3228: 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.
3229:
3230: @emph{Syntax}
3231: @example
3232: VIEW 102:@emph{intexpr}
3233: @end example
3234:
3235: @item @code{103} - Signal @code{MERGE} to @code{^$WINDOW} Complete
3236: Signals FreeM's MWAPI implementation that a @code{MERGE} to @code{^$WINDOW} or descendant subscripts thereof has completed.
3237:
3238: @emph{Syntax}
3239: @example
3240: VIEW 103[@emph{:subscript}]
3241: @end example
3242:
3243: @item @code{110} - Set Local @code{$ORDER}/@code{$QUERY} Data Value
3244: Sets the local variable @code{$ORDER}/@code{$QUERY} data value to the result of @emph{expr}. We're not entirely sure what this is.
3245:
3246: @emph{Syntax}
3247: @example
3248: VIEW 110:@emph{expr}
3249: @end example
3250:
3251: @item @code{111} - Set Global @code{$ORDER}/@code{$QUERY} Data Value
3252: Sets the global variable @code{$ORDER}/@code{$QUERY} data value to the result of @emph{expr}. We're not entirely sure what this is.
3253:
3254: @emph{Syntax}
3255: @example
3256: VIEW 111:@emph{expr}
3257: @end example
3258:
3259: @item @code{113} - Set @code{termio} Information
3260: We don't know what this does.
3261:
3262: @item @code{133} - Remember @code{ZLOAD} Directory on @code{ZSAVE}
3263: We don't know what this does, but it takes a @emph{tvexpr}.
3264:
3265: @emph{Syntax}
3266: @example
3267: VIEW 133:@emph{tvexpr}
3268: @end example
3269:
3270: @end table
3271:
3272: @node WATCH
3273: @section WATCH
3274: @cindex WATCH
3275: @cindex commands, WATCH
3276: @cindex commands, debugging
3277: @cindex commands, implementation-specific
3278: @cindex commands, non-standard
3279: @emph{FreeM Extension}
3280:
3281: Sets a watchpoint on a global, local, or SSVN node.
3282:
3283: @emph{Syntax}
3284:
3285:
3286: In its @emph{argumentless} form, @code{WATCH} toggles watchpoints on and off, provided the optional @emph{postcondition} is @emph{true} or omitted.
3287:
3288: @example
3289: WATCH[@emph{:postcondition}]
3290: @end example
3291:
3292: In its @emph{inclusive} form, @code{WATCH} adds, removes, or examines watchpoints, provided the optional @emph{postcondition} is @emph{true} or omitted.
3293:
3294: A @code{+} adds a new watchpoint to the following variable.
3295:
3296: A @code{-} removes an existing watchpoint for the following variable.
3297:
3298: A @code{?} examines the status of a watchpoint for the following variable.
3299:
3300: @example
3301: WATCH[@emph{:postcondition}] [+|-|?]@emph{var1}...,[+|-|?]@emph{varN}
3302: @end example
3303:
3304:
3305: The following example demonstrates turning watchpoint processing on and adding a watchpoint for global variable @code{^jpw(1)}. It then changes the value of @code{^jpw(1)}.
3306:
3307: @example
3308: DEFAULT.USER> WATCH
3309:
3310: Watchpoints enabled.
3311:
3312: DEFAULT.USER> WATCH +^JPW(1)
3313:
3314: Added '^JPW("1")' to the watchlist.
3315:
3316: DEFAULT.USER> SET ^JPW(1)="new value"
3317:
3318: >> WATCHPOINT: ^JPW("1") => 'new value' (changed 1 times)
3319:
3320: @end example
3321:
3322: The following example will remove that watchpoint:
3323:
3324: @example
3325: DEFAULT.USER> WATCH -^JPW(1)
3326:
3327: Removed '^JPW("1")' from the watchlist.
3328:
3329: DEFAULT.USER> WATCH ?^JPW(1)
3330:
3331: '^JPW("1")' is not being watched.
3332: @end example
3333:
3334: @node WITH
3335: @section WITH
3336: @cindex WITH
3337: @cindex commands, WITH
3338: @cindex commands, non-standard
3339: @emph{FreeM Extension}
3340:
3341: NOTE: This command may be deprecated and removed in future FreeM releases.
3342:
3343: Sets a prefix to be applied to all subsequent local variable or constant references.
3344:
3345: @emph{Syntax}
3346:
3347: @example
3348: @code{WITH@emph{:postcondition} @emph{var-prefix}}
3349: @end example
3350:
3351: 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.
3352:
3353: The @emph{var-prefix} argument may be a string literal or any valid FreeM expression.
3354:
3355: @example
3356: @code{WITH@emph{:postcondition}}
3357: @end example
3358:
3359: In the above argumentless form, clears the @code{$WITH} prefix, provided the optional @emph{postcondition} is either @emph{true} or omitted. Equivalent to @code{WITH ""}.
3360:
3361:
3362: @node WRITE
3363: @section WRITE
3364: @cindex WRITE
3365: @cindex commands, WRITE
3366:
3367: @node XECUTE
3368: @section XECUTE
3369: @cindex XECUTE
3370: @cindex commands, XECUTE
3371:
3372: @node ZBREAK
3373: @section ZBREAK
3374: @cindex ZBREAK
3375: @cindex commands, ZBREAK
3376: @cindex commands, debugging
3377: @cindex commands, implementation-specific
3378: @cindex commands, non-standard
3379: @emph{FreeM Extension}
3380:
3381: @node ZGO
3382: @section ZGO
3383: @cindex ZGO
3384: @cindex commands, ZGO
3385: @cindex commands, implementation-specific
3386: @cindex commands, non-standard
3387: @emph{FreeM Extension}
3388:
3389: @node ZHALT
3390: @section ZHALT
3391: @cindex ZHALT
3392: @cindex commands, ZHALT
3393: @cindex commands, implementation-specific
3394: @cindex commands, non-standard
3395: @emph{FreeM Extension}
3396:
3397: @node ZINSERT
3398: @section ZINSERT
3399: @cindex ZINSERT
3400: @cindex commands, ZINSERT
3401: @cindex commands, implementation-specific
3402: @cindex commands, non-standard
3403: @emph{FreeM Extension}
3404:
3405: @node ZJOB
3406: @section ZJOB
3407: @cindex ZJOB
3408: @cindex commands, ZJOB
3409: @cindex commands, implementation-specific
3410: @cindex commands, non-standard
3411: @emph{FreeM Extension}
3412:
3413: 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.
3414:
3415: For more information, see @code{JOB}.
3416:
3417: @node ZLOAD
3418: @section ZLOAD
3419: @cindex ZLOAD
3420: @cindex commands, ZLOAD
3421: @cindex commands, implementation-specific
3422: @cindex commands, non-standard
3423: @emph{FreeM Extension}
3424:
3425: Loads routine @emph{<routine-name>} into FreeM's routine buffer, provided the optional @emph{postcondition} is @emph{true} or omitted.
3426:
3427: @emph{Syntax}
3428:
3429: @example
3430: ZLOAD@emph{:postcondition} @emph{<routine-name>}
3431: @end example
3432:
3433: @node ZNEW
3434: @section ZNEW
3435: @cindex ZNEW
3436: @cindex commands, ZNEW
3437: @cindex commands, implementation-specific
3438: @cindex commands, non-standard
3439: @emph{FreeM Extension}
3440:
3441: @node ZPRINT
3442: @section ZPRINT
3443: @cindex ZPRINT
3444: @cindex commands, ZPRINT
3445: @cindex commands, implementation-specific
3446: @cindex commands, non-standard
3447: @emph{FreeM Extension}
3448:
3449: Prints the contents of the current routine buffer, provided the optional @emph{postcondition} is @emph{true} or omitted.
3450:
3451: @emph{Syntax}
3452:
3453: @example
3454: ZPRINT@emph{:postcondition}
3455: @end example
3456:
3457: @node ZQUIT
3458: @section ZQUIT
3459: @cindex ZQUIT
3460: @cindex commands, ZQUIT
3461: @cindex commands, implementation-specific
3462: @cindex commands, non-standard
3463: @emph{FreeM Extension}
3464:
3465: In its single-argument form, quits from @emph{levels} levels of the stack, provided the optional @emph{postcondition} is @emph{true} or omitted.
3466:
3467: In its argumentless form, quits from @code{$STACK} levels of the stack, provided the optional @emph{postcondition} is @emph{true} or omitted.
3468:
3469: @emph{Syntax}
3470:
3471: @example
3472: @code{ZQUIT@emph{:postcondition} [@emph{levels}]}
3473: @end example
3474:
3475: @node ZREMOVE
3476: @section ZREMOVE
3477: @cindex ZREMOVE
3478: @cindex commands, ZREMOVE
3479: @cindex commands, implementation-specific
3480: @cindex commands, non-standard
3481: @emph{FreeM Extension}
3482:
3483: @node ZSAVE
3484: @section ZSAVE
3485: @cindex ZSAVE
3486: @cindex commands, ZSAVE
3487: @cindex commands, implementation-specific
3488: @cindex commands, non-standard
3489: @emph{FreeM Extension}
3490:
3491: @node ZTRAP
3492: @section ZTRAP
3493: @cindex ZTRAP
3494: @cindex commands, ZTRAP
3495: @cindex commands, debugging
3496: @cindex commands, implementation-specific
3497: @cindex commands, non-standard
3498: @emph{FreeM Extension}
3499:
3500: @node ZWRITE
3501: @section ZWRITE
3502: @cindex ZWRITE
3503: @cindex commands, ZWRITE
3504: @cindex commands, implementation-specific
3505: @cindex commands, non-standard
3506: @emph{FreeM Extension}
3507:
3508: Writes the names and values of M variables to @code{$IO}.
3509:
3510: @emph{Syntax}
3511:
3512: @example
3513: ZWRITE@emph{:postcondition}
3514: @end example
3515:
3516: 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.
3517:
3518: @example
3519: ZWRITE@emph{:postcondition} @emph{ArrayName},@dots{}
3520: @end example
3521:
3522: 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.
3523:
3524: @example
3525: ZWRITE@emph{:postcondition} (@emph{ArrayName},@dots{})
3526: @end example
3527:
3528: 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.
3529:
3530:
3531: @node Structured System Variables
3532: @chapter Structured System Variables
3533: @cindex variables, structured system
3534: @cindex structured system variables
3535: @cindex SSVNs
3536:
3537: @menu
3538: * ^$CHARACTER:: Character set information.
3539: * ^$DEVICE:: Device information.
3540: * ^$DISPLAY:: Information about graphic display.
3541: * ^$EVENT:: Information supplied about a synchronous or asynchronous event.
3542: * ^$GLOBAL:: Information about M globals.
3543: * ^$JOB:: Information about and control of FreeM jobs.
3544: * ^$LOCK:: Information about the FreeM lock table.
3545: * ^$OBJECT:: Information about FreeM objects.
3546: * ^$ROUTINE:: Information about FreeM routines.
3547: * ^$SYSTEM:: Information about the running system.
3548: * ^$WINDOW:: Configuration of MWAPI windows.
3549: * ^$ZPROCESS:: Information about and control of system processes.
3550: * ^$ZRPI:: Information about and control of Raspberry Pi GPIO pins.
3551: @end menu
3552:
3553: SSVN subscripts are each described in the following format:
3554:
3555: @table @asis
3556: @item @code{@emph{<ssvn-subscript-name>}} +/-R +/-U +/-D
3557: @end table
3558:
3559: 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.
3560:
3561: @node ^$CHARACTER
3562: @section ^$CHARACTER
3563: @cindex ^$CHARACTER
3564: @cindex structured system variables, ^$CHARACTER
3565:
3566: 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"}.
3567:
3568: The following values for the second subscript are supported:
3569:
3570: @table @asis
3571:
3572: @item @code{IDENT} +R -U -D
3573: Returns the empty string.
3574:
3575: @item @code{COLLATE} +R -U -D
3576: Returns the empty string.
3577:
3578: @item @code{INPUT} +R -U -D
3579: Returns the empty string if the third subscript is @code{M}, otherwise, raises error @code{M38}.
3580:
3581: @item @code{OUTPUT} +R -U -D
3582: Returns the empty string if the third subscript is @code{M}, otherwise, raises error @code{M38}.
3583:
3584: @end table
3585:
3586: @node ^$DEVICE
3587: @section ^$DEVICE
3588: @cindex ^$DEVICE
3589: @cindex structured system variables, ^$DEVICE
3590:
3591: FreeM implements several important pieces of functionality in the @code{^$DEVICE} SSVN.
3592:
3593: The first subscript of @code{^$DEVICE} represents the I/O channel of an @code{OPEN}ed device.
3594:
3595: The following values for the second subscript are supported:
3596:
3597: @table @asis
3598:
3599: @item @code{$DEVICE}
3600: Returns the value of @code{$DEVICE} for the specified I/O channel.
3601:
3602: @item @code{$X} +R -U -D
3603: Returns the horizontal cursor position of a terminal device. Only valid if the I/O channel is @code{0}.
3604:
3605: @item @code{$Y} +R -U -D
3606: Returns the vertical cursor position of a terminal device. Only valid if the I/O channel is @code{0}.
3607:
3608: @item @code{ROWS} +R -U -D
3609: Returns the number of character rows on the terminal device. Only valid if the I/O channel is @code{0}.
3610:
3611: @item @code{COLUMNS} +R -U -D
3612: Returns the number of character columns on the terminal device. Only valid if the I/O channel is @code{0}.
3613:
3614: @item @code{CHARACTER} +R -U -D
3615: Returns the character set of the specified I/O channel; always @code{M} in the current implementation.
3616:
3617: @item @code{INPUT_BUFFER} +R +U -D
3618: 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.
3619:
3620: @item @code{NAME} +R -U -D
3621: Returns the operating system's name for the file, device, or socket attached to the specified I/O channel.
3622:
3623: @item @code{FD} +R -U -D
3624: Returns the UNIX file descriptor of the specified I/O channel.
3625:
3626: @item @code{MODE} +R -U -D
3627: 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.
3628:
3629: @item @code{EOF} +R -U -D
3630: 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.
3631:
3632: @item @code{LENGTH} +R -U -D
3633: 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.
3634:
3635: @item @code{NAMESPACE} +R -U -D
3636: Returns the current @emph{mnemonic-space} in use for the referenced I/O channel. Always @code{X364} for terminals and blank for sequential files.
3637:
3638: @item @code{TYPE} +R -U -D
3639: Returns either @code{1,FILE}, @code{2,SOCKET}, or @code{4,TERMINAL}, depending on the device type associated with the specified I/O channel.
3640:
3641: @item @code{OPTIONS} -R -U -D
3642: 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:
3643:
3644: @table @asis
3645:
3646: @item @code{DSW} +R +U -D
3647: Sets or returns the current @emph{Device Status Word} controlling terminal characteristics. Only valid for I/O channel 0.
3648:
3649: @item @code{TERMINATOR} +R +U -D
3650: 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).
3651:
3652: @item @code{TERMID} +R -U -D
3653: Returns the type of terminal connected to channel 0. Only valid for I/O channel 0.
3654:
3655: @item @code{ECHO} +R +U -D
3656: 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.
3657:
3658: @item @code{DELMODE} +R +U -D
3659: 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.
3660:
3661: @item @code{ESCAPE} +R +U -D
3662: 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.
3663:
3664: @item @code{CONVUPPER} +R +U -D
3665: 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.
3666:
3667: @item @code{DELEMPTY} +R +U -D
3668: 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.
3669:
3670: @item @code{NOCTRLS} +R +U -D
3671: TBD. Only valid for I/O channel 0. Corresponds to bit 20 of the Device Status Word.
3672:
3673: @item @code{CTRLOPROC} +R +U -D
3674: 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.
3675:
3676: @item @code{NOTYPEAHEAD} +R +U -D
3677: 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.
3678: @end table
3679: @end table
3680:
3681: @emph{Example}
3682:
3683: 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.
3684:
3685: @example
3686: SET ^$JOB($JOB,"IOPATH")="/etc" ; set I/O path to /etc
3687: OPEN 1:"freem.conf/r" ; open freem.conf for reading
3688: ;
3689: ; read until we run out of lines
3690: ;
3691: FOR USE 1 READ LINE USE 0 QUIT:^$DEVICE(1,"EOF") D
3692: . WRITE LINE,!
3693: ;
3694: CLOSE 1
3695: QUIT
3696: @end example
3697:
3698: @node ^$DISPLAY
3699: @section ^$DISPLAY
3700: @cindex ^$DISPLAY
3701: @cindex structured system variables, ^$DISPLAY
3702:
3703: 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.
3704:
3705: The following second-level subscripts and specified descendant subscripts are supported:
3706:
3707: @table @asis
3708:
3709: @item @code{CLIPBOARD} +R +U +D
3710: Retrieves, sets, or erases the contents of the system clipboard.
3711:
3712: @item @code{PLATFORM} +R -U -D
3713: Retrieves the name and version of the underlying window system platform.
3714:
3715: @item @code{SIZE} +R -U -D
3716: Retrieves the display resolution of the specified graphical display. For instance, a 1080p display would have a @code{SIZE} value of @code{1920,1080}.
3717:
3718: @item @code{SPECTRUM} +R -U -D
3719: Retrieves the color depth (number of colors supported) of the specified graphical display.
3720:
3721: @item @code{COLORTYPE} +R -U -D
3722: Always returns @code{COLOR}, as monochrome and grayscale displays are not yet supported in FreeM.
3723:
3724: @item @code{UNITS} +R -U -D
3725: Returns the measurement unit of the specified display, i.e., @code{PIXEL}.
3726:
3727: @item @code{TYPEFACE} +R -U -D
3728: 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.
3729:
3730: @end table
3731:
3732: @node ^$EVENT
3733: @section ^$EVENT
3734: @cindex ^$EVENT
3735: @cindex structured system variables, ^$EVENT
3736:
3737: The @code{^$EVENT} SSVN is not yet implemented.
3738:
3739: @node ^$GLOBAL
3740: @section ^$GLOBAL
3741: @cindex ^$GLOBAL
3742: @cindex structured system variables, ^$GLOBAL
3743:
3744: The @code{^$GLOBAL} structured system variable provides information about M globals. The first-level subscript is a global name, sans the leading caret symbol.
3745:
3746: The following second-level subscripts are supported:
3747:
3748: @table @asis
3749:
3750: @item @code{BYTES} +R -U -D
3751: Returns the number of bytes this global occupies in fixed storage.
3752:
3753: @item @code{BLOCKS} +R -U -D
3754: Returns the number of blocks contained in this global.
3755:
3756: @item @code{BLOCKSIZE} +R -U -D
3757: Returns the size of data blocks for this global. Currently, FreeM only supports 1024-byte blocks.
3758:
3759: @item @code{FILE} +R -U -D
3760: Returns the full filesystem path to the data file where this global resides in fixed storage.
3761:
3762: @item @code{NAMESPACE} +R +U +D
3763: 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.
3764:
3765: @end table
3766:
3767: @node ^$JOB
3768: @section ^$JOB
3769: @cindex ^$JOB
3770: @cindex structured system variables, ^$JOB
3771:
3772: FreeM fully implements @code{^$JOB} per ANSI X11.1-1995, as well as several extensions proposed in the M Millennium Draft Standard.
3773:
3774: The first subscript of @code{^$JOB} represents the @code{$JOB} of the process.
3775:
3776: 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.
3777:
3778: The following subscripts are supported:
3779:
3780: @table @asis
3781:
3782: @item @code{GVNDEFAULT} +R +U +D
3783: Contains a default expression to be evaluated if a global variable access attempt results in an @code{M7} error.
3784:
3785: Equivalent to wrapping all global accesses in @code{$GET(@emph{global-name},@emph{string-expr})}.
3786:
3787: @item @code{LVNDEFAULT} +R +U +D
3788: Contains a default expression to be evaluated if a local variable access attempt results in an @code{M6} error.
3789:
3790: Equivalent to wrapping all local accesses in @code{$GET(@emph{global-name},@emph{string-expr})}.
3791:
3792: @item @code{LVNQOVAL} +R +U +D
3793: Contains the data value (if any) at the subscripted local variable reference from the most recent @code{$ORDER} or @code{$QUERY} operation.
3794:
3795: 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.
3796:
3797: @item @code{GVNQOVAL} +R +U +D
3798: Contains the data value (if any) at the subscripted global variable reference from the most recent @code{$ORDER} or @code{$QUERY} operation.
3799:
3800: 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.
3801:
3802: @item @code{ZCOMMANDS} +R +U -D
3803: 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.
3804:
3805: 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.
3806:
3807: If you remove a command from this list, you may provide your own private M implementation of the command in the manner described above.
3808:
3809: 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{%}.
3810:
3811: @item @code{PIPE_GLVN} +R +U -D
3812: 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{!>}.
3813:
3814: @item @code{ZCOMMAND_ARGUMENT_NAME} +R +U -D
3815: Returns or sets the variable name in which arguments to user-defined @code{Z}-commands are passed. Defaults to @code{%}.
3816:
3817: @item @code{ZFUNCTIONS} +R +U -D
3818: 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.
3819:
3820: 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.
3821:
3822: If you remove a function from this list, you may provide your own private M implementation of the function in the manner described above.
3823:
3824: @item @code{ZSVS} +R +U -D
3825: 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.
3826:
3827: 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.
3828:
3829: 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.
3830:
3831: @item @code{BREAK_HANDLER} +R +U -D
3832: Contains M code to be executed when the @code{BREAK} command is run.
3833:
3834: @item @code{ROUTINE_BUFFER_SIZE} +R +U -D
3835: 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.
3836:
3837: @item @code{ROUTINE_BUFFER_COUNT} +R +U -D
3838: 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.
3839:
3840: @item @code{ROUTINE_BUFFER_AUTO_ADJUST} +R +U -D
3841: 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.
3842:
3843: @item @code{SYMBOL_TABLE_SIZE} +R +U -D
3844: 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.
3845:
3846: @item @code{SYMBOL_TABLE_AUTO_ADJUST} +R +U -D
3847: 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.
3848:
3849:
3850: @item @code{USER_DEFINED_ISV_TABLE_SIZE} +R +U -D
3851: 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.
3852:
3853: @item @code{USER_DEFINED_ISV_TABLE_AUTO_ADJUST} +R +U -D
3854: 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.
3855:
3856: @item @code{GVN_UNIQUE_CHARS} +R +U -D
3857: Returns or sets the number of characters of a global name that make it unique, from 1 to 255.
3858:
3859: @item @code{GVN_CASE_SENSITIVE} +R +U -D
3860: 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.
3861:
3862: @item @code{GVN_NAME_SUB_LENGTH} +R +U -D
3863: Returns or sets the maximum number of characters of a global name plus all of its subscripts, from 1-255.
3864:
3865: @item @code{GVN_SUB_LENGTH} +R +U -D
3866: Returns or sets the maximum number of characters of a single global subscript, from 1-255.
3867:
3868: @item @code{SINGLE_USER} +R +U -D
3869: If set to @code{1}, FreeM will skip all file locking operations on globals, as well as the @code{LOCK} and @code{ZALLOCATE} tables. If set to @code{0}, FreeM will enforce file locking on both.
3870:
3871: 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 and @code{LOCK}/@code{ZALLOCATE} table corruption!
3872:
3873: @item @code{CHARACTER} +R -U -D
3874: Returns the character set of the job.
3875:
3876: @item @code{CWD} +R +U -D
3877: Returns or sets the current working directory of the job.
3878:
3879: @item @code{OPEN} +R -U -D
3880: The @code{^$JOB($JOB,"OPEN",<channel>} subscripts list the open I/O channels in the specified job.
3881:
3882: @item @code{BERKELEYDB,FLUSH_THRESHOLD} +R +U -D
3883: 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.
3884:
3885: @item @code{EVENT} +R +U +D
3886: 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.
3887:
3888: @item @code{GLOBAL} +R -U -D
3889: Returns the global environment of the job.
3890:
3891: @item @code{IOPATH} +R +U -D
3892: Returns or sets the @emph{I/O path} to be used by the @code{OPEN} command.
3893:
3894: @item @code{PRIORITY} +R +U -D
3895: Returns or sets the @emph{nice} value of the FreeM job.
3896:
3897: @item @code{REVSTR} +R +U -D
3898: When set to 1, allows @code{$EXTRACT} to accept negative values.
3899:
3900: @item @code{ROUTINE} +R -U -D
3901: Returns the name of the routine currently being executed by the job.
3902:
3903: @item @code{SYMTAB} +R +U -D
3904: Returns or sets the current local variable symbol table in use.
3905:
3906: FreeM supports two unique and independent symbol tables, allowing FreeM programs to maintain two independent sets of identically- or differently-named local variables per process.
3907:
3908: The default symbol table is @code{0}, and the alternate symbol table is @code{1}, corresponding to the valid values for @code{^$JOB($JOB,"SYMTAB")}.
3909:
3910: Setting this subscript to values other than @code{0} or @code{1} will result in a @code{ZINVEXPR} error.
3911:
3912: @item @code{$PDISPLAY} +R -U -D
3913: Returns the value of @code{$PDISPLAY} for the job.
3914:
3915: @item @code{$PRINCIPAL} +R -U -D
3916: Returns the value of @code{$PRINCIPAL} for the job.
3917:
3918: @item @code{$TLEVEL} +R -U -D
3919: Returns the current transaction level (value of @code{$TLEVEL} for the job.
3920:
3921: @item @code{$IO} +R -U -D
3922: Returns the current value of @code{$IO} for the job.
3923:
3924: @item @code{USER} +R -U -D
3925: Returns the UID of the user owning the job.
3926:
3927: @item @code{GROUP} +R -U -D
3928: Returns the GID of the group owning the job.
3929:
3930: @item @code{NAMESPACE} +R +U -D
3931: Returns or sets the name of the job's currently-active namespace.
3932:
3933: @item @code{MATH} +R +U -D
3934: Returns or sets the mode in which decimal comparisons and arithmetic calculations are conducted. Valid values are @code{FIXED}, for fixed-point decimals having up to 20,000 digits of precision, as determined by the @code{$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.
3935:
3936: @code{IEEE754} mode will make mathematical calculations significantly faster, especially when accelerated by a floating-point processor, at the expense of precision and accuracy.
3937:
3938: @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.
3939:
3940: Attempting to @code{SET} this node to values other than @code{FIXED} or @code{IEEE754} will set @code{$ECODE} to @code{M29}.
3941:
3942: @end table
3943:
3944: @node ^$LOCK
3945: @section ^$LOCK
3946: @cindex ^$LOCK
3947: @cindex structured system variables, ^$LOCK
3948:
3949: The first-level subscript of @code{^$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.
3950:
3951: Attempting to @code{SET} or @code{KILL} any node in @code{^$LOCK} will raise error @code{M29}.
3952:
3953: @node ^$OBJECT
3954: @section ^$OBJECT
3955: @cindex ^$OBJECT
3956: @cindex structured system variables, ^$OBJECT
3957:
3958: @node ^$ROUTINE
3959: @section ^$ROUTINE
3960: @cindex ^$ROUTINE
3961: @cindex structured system variables, ^$ROUTINE
3962:
3963: The @code{^$ROUTINE} SSVN exposes a list of routines available in the current FreeM namespace, as well as additional attributes further describing each routine.
3964:
3965: The first-level subscript is the name of a FreeM routine minus the leading caret symbol.
3966:
3967: The following second-level subscripts are supported:
3968:
3969: @table @asis
3970:
3971: @item @code{CHARACTER} +R -U -D
3972: Returns the character set of the routine.
3973:
3974: @item @code{NAMESPACE} +R -U -D
3975: Returns the name of the FreeM namespace in which the routine resides.
3976:
3977: @item @code{PATH} +R -U -D
3978: Returns the full filesystem path to the routine in fixed storage.
3979:
3980: @end table
3981:
3982: @node ^$SYSTEM
3983: @section ^$SYSTEM
3984: @cindex ^$SYSTEM
3985: @cindex structured system variables, ^$SYSTEM
3986:
3987: The @code{^$SYSTEM} SSVN exposes system-level implementation details.
3988:
3989: The following first-level subscripts are supported:
3990:
3991: @table @asis
3992:
3993: @item @code{DEFPSIZE} +R -U -D
3994: Returns the default size in bytes of the symbol table and routine buffer memory partition.
3995:
3996: @item @code{DEFUDFSVSIZ} +R -U -D
3997: Returns the default size in bytes of the user-defined intrinsic special variable table.
3998:
3999: @item @code{DEFNSIZE} +R -U -D
4000: Returns the default size of the @code{NEW} stack, in number of entries.
4001:
4002: @item @code{MAXNO_OF_RBUF} +R -U -D
4003: Returns the maximum number of routine buffers.
4004:
4005: @item @code{DEFNO_OF_RBUF} +R -U -D
4006: Returns the default number of routine buffers.
4007:
4008: @item @code{DEFPSIZE0} +R -U -D
4009: Returns the default size in bytes of each routine buffer.
4010:
4011: @item @code{NO_GLOBLS} +R -U -D
4012: Returns the maximum number of globals that can be concurrently opened.
4013:
4014: @item @code{NO_OF_GBUF} +R -U -D
4015: Returns the number of global buffers.
4016:
4017: @item @code{NESTLEVLS} +R -U -D
4018: Returns the depth of the @code{DO}, @code{FOR}, @code{XECUTE} stack.
4019:
4020: @item @code{PARDEPTH} +R -U -D
4021: Returns the maximum depth of the parser's parameter stack.
4022:
4023: @item @code{PATDEPTH} +R -U -D
4024: Returns the maximum number of @emph{patatom}s in each pattern.
4025:
4026: @item @code{TRLIM} +R -U -D
4027: Returns the trace limit of the @code{BUILTIN} global handler.
4028:
4029: @item @code{ARGS_IN_ESC} +R -U -D
4030: Returns the maximum number of arguments in a terminal escape sequence.
4031:
4032: @item @code{ZTLEN} +R -U -D
4033: Returns the maximum length of @code{$ZTRAP}.
4034:
4035: @item @code{FUNLEN} +R -U -D
4036: Returns the maximum length of the @code{$ZF} (function key) variable.
4037:
4038: @item @code{NAME_LENGTH} +R -U -D
4039: Returns the maximum length of variable names in the current FreeM build. Compatible with the same SSVN node in @emph{Reference Standard M}
4040:
4041: @item @code{STRING_MAX} +R -U -D
4042: Returns the maximum length of character strings in the current FreeM build. Compatible with the same SSVN node in @emph{Reference Standard M}
4043:
4044: @item @code{$NEXTOK} +R -U -D
4045: 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}.
4046:
4047: @item @code{EOK} +R -U -D
4048: 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}.
4049:
4050: @item @code{OFFOK} +R -U -D
4051: 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}.
4052:
4053: @item @code{BIG_ENDIAN} +R -U -D
4054: 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}.
4055:
4056: @item @code{NAMESPACE} +R -U -D
4057: The descendant subscripts of this node list each namespace in the current FreeM environment.
4058:
4059: @item @code{MAPPINGS,GLOBAL} +R -U -D
4060: Descendant subscripts of this node represent global name mappings set in @code{^$GLOBAL(@emph{gvn},"NAMESPACE")}
4061:
4062: @end table
4063:
4064: @node ^$WINDOW
4065: @section ^$WINDOW
4066: @cindex ^$WINDOW
4067: @cindex structured system variables, ^$WINDOW
4068:
4069: The @code{^$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.
4070:
4071: @node ^$ZPROCESS
4072: @section ^$ZPROCESS
4073: @cindex ^$ZPROCESS
4074: @cindex structured system variables, ^$ZPROCESS
4075:
4076: 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.
4077:
4078: The first subscript always represents the @emph{process ID} of the external process being acted upon.
4079:
4080: The following values for the second subscript are supported:
4081:
4082:
4083: @table @asis
4084:
4085: @item @code{EXISTS} +R -U -D
4086: Returns 1 if the referenced process exists; 0 otherwise.
4087:
4088: @item @code{ATTRIBUTE} +R -U -D
4089: Exposes the @code{/proc} files as descendant subscripts, i.e., @code{WRITE ^$ZPROCESS(2900,"ATTRIBUTE","cmdline"),!} would print the initial command line used to invoke process ID 2900. Note that the third subscript (the immediate descendant of the @code{ATTRIBUTE} subscript) is case sensitive.
4090:
4091: @item @code{SIGNAL} -R +U -D
4092: Allows signals to be sent to the referenced process. The following subscript is an integer value corresponding to the desired signal number. You may obtain a list of signal numbers on most UNIX systems with the command @code{kill -l}.
4093:
4094: The constants @code{%SYS.SIGNAL.HUP}, @code{%SYS.SIGNAL.INT}, @code{%SYS.SIGNAL.KILL}, and @code{%SYS.SIGNAL.TERM} are provided for convenient use of this SSVN subscript.
4095:
4096: @end table
4097:
4098: @node ^$ZRPI
4099: @section ^$ZRPI
4100: @cindex ^$ZRPI
4101: @cindex structured system variables, ^$ZRPI
4102:
4103: The @code{^$ZRPI} structured system variable provides easy access to general-purpose input/output (GPIO) pins on Raspberry Pi single-board computers.
4104:
4105: To initialize the GPIO subsystem, @code{SET ^$ZRPI("INITIALIZE")=1}.
4106:
4107: Individual pins are accessed through @code{^$ZRPI("GPIO",<pin>,...)}, where @code{<pin>} represents the desired pin number. Descendant subscripts of @code{^$ZRPI("GPIO",<pin>)} are as follows:
4108:
4109: @table @asis
4110:
4111: @item @code{MODE} +R +U -D
4112: Represents the operating mode of the selected pin. One of @code{INPUT}, @code{OUTPUT}, @code{PWM_OUTPUT}, or @code{GPIO_CLOCK}.
4113:
4114: @item @code{DIGITAL} +R +U -D
4115: Reads or writes the selected pin digitally. The value is limited to @code{1} or @code{0}.
4116:
4117: @item @code{ANALOG} +R +U -D
4118: Reads or writes the selected pin in an analog fashion. The value represents analog voltage.
4119:
4120: @end table
4121:
4122: @node Operators
4123: @chapter Operators
4124:
4125: @menu
4126: * Unary +:: Force a value to positive.
4127: * Unary -:: Force a value to negative.
4128: * +:: Add.
4129: * +=:: Add and assign.
4130: * ++:: Postfix increment.
4131: * -:: Subtract.
4132: * -=:: Subtract and assign.
4133: * --:: Postfix decrement.
4134: * *:: Multiply.
4135: * *=:: Multiply and assign.
4136: * /:: Divide.
4137: * /=:: Divide and assign.
4138: * \:: Integer divide.
4139: * \=:: Integer divide and assign.
4140: * #:: Modulo.
4141: * #=:: Modulo and assign.
4142: * **:: Exponentiate.
4143: * **=:: Exponentiate and assign.
4144: * <:: Less than.
4145: * <=:: Less than or equal to.
4146: * >:: Greater than.
4147: * >=:: Greater than or equal to.
4148: * _:: Concatenate.
4149: * _=:: Concatenate and assign.
4150: * =:: Equals.
4151: * [:: Contains.
4152: * ]:: Follows.
4153: * ]]:: Sorts after.
4154: * ?:: Pattern match.
4155: * &:: Logical AND.
4156: * ! (Operator):: Logical OR.
4157: * ':: Logical NOT.
4158: * @@ (Operator):: Indirect
4159: @end menu
4160:
4161: @node Unary +
4162: @section Unary +
4163: @cindex operators, unary +
4164:
4165: Forces a number to positive, whether positive or negative. Also forces numeric coercion of strings.
4166:
4167: @node Unary -
4168: @section Unary -
4169: @cindex operators, unary -
4170:
4171: @node +
4172: @section + (Add)
4173: @cindex operators, +
4174:
4175: @node +=
4176: @section += (Add/Assign)
4177: @cindex operators, +=
4178:
4179: @node ++
4180: @section ++ (Postfix Increment)
4181: @cindex operators, ++
4182:
4183: @node -
4184: @section - (Subtract)
4185: @cindex operators, -
4186:
4187: @node -=
4188: @section -= (Subtract/Assign)
4189: @cindex operators, -=
4190:
4191: @node --
4192: @section -- (Postfix Decrement)
4193: @cindex operators, --
4194:
4195: @node *
4196: @section * (Multiply)
4197: @cindex operators, *
4198:
4199: @node *=
4200: @section *= (Multiply/Assign)
4201: @cindex operators, *=
4202:
4203: @node /
4204: @section / (Divide)
4205: @cindex operators, /
4206:
4207: @node /=
4208: @section /= (Divide/Assign)
4209: @cindex operators, /=
4210:
4211: @node \
4212: @section \ (Integer Divide)
4213: @cindex operators, \
4214:
4215: @node \=
4216: @section \= (Integer Divide/Assign)
4217: @cindex operators, \=
4218:
4219: @node #
4220: @section # (Modulo)
4221: @cindex operators, #
4222:
4223: @node #=
4224: @section #= (Modulo/Assign)
4225: @cindex operators, #=
4226:
4227: @node **
4228: @section ** (Exponentiate)
4229: @cindex operators, **
4230:
4231: @node **=
4232: @section **= (Exponentiate/Assign)
4233: @cindex operators, **=
4234:
4235: @node <
4236: @section < (Less Than)
4237: @cindex operators, <
4238:
4239: @node <=
4240: @section <= (Less Than or Equal To)
4241: @cindex operators, <=
4242:
4243: @node >
4244: @section > (Greater Than)
4245: @cindex operators, >
4246:
4247: @node >=
4248: @section >= (Greater Than or Equal To)
4249: @cindex operators, >=
4250:
4251: @node _
4252: @section _ (Concatenate)
4253: @cindex operators, _
4254:
4255: @node _=
4256: @section _= (Concatenate/Assign)
4257: @cindex operators, _=
4258:
4259: @node =
4260: @section = (Equals)
4261: @cindex operators, =
4262:
4263: @node [
4264: @section [ (Contains)
4265: @cindex operators, [
4266:
4267: @node ]
4268: @section ] (Follows)
4269: @cindex operators, ]
4270:
4271: @node ]]
4272: @section ]] (Sorts After)
4273: @cindex operators, ]]
4274:
4275: @node ?
4276: @section ? (Pattern Match)
4277: @cindex operators, ?
4278:
4279: @node &
4280: @section & (Logical AND)
4281: @cindex operators, &
4282:
4283: @node ! (Operator)
4284: @section ! (Logical OR)
4285: @cindex operators, !
4286:
4287: @node '
4288: @section ' (Logical NOT)
4289: @cindex operators, '
4290:
4291: @node @@ (Operator)
4292: @section @@ (Indirect)
4293: @cindex operators, @@
4294:
4295: @node Routines
4296: @chapter Routines
4297: @cindex routines
4298:
4299: A @emph{routine} is a file containing M source code to be processed by FreeM.
4300:
4301: 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}).
4302:
4303: @menu
4304: * Routine Naming:: Requirements and conventions for routine names.
4305: @end menu
4306:
4307:
4308: @node Routine Naming
4309: @section Routine Naming
4310: 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.
4311:
4312: Routine naming rules are as follows:
4313:
4314: @itemize @bullet
4315: @item Routine names must begin with an upper- or lower-case letter, or a @code{%} sign
4316: @item Within the routine name, you may have upper-case or lower-case letters or digits
4317: @item The entire routine name must not be longer than 255 characters
4318: @end itemize
4319:
4320: Routines whose names begin with @code{%} must be located in the @code{SYSTEM} namespace. Other routines may be located in any namespace.
4321:
4322: @node Types
4323: @chapter Types
4324: @cindex types
4325: @cindex data types
4326:
4327: 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.
4328:
4329: @menu
4330: * BOOLEAN:: Truth values.
4331: * COMPLEX:: Numbers with real and imaginary parts.
4332: * INTEGER:: Numbers with no decimal part.
4333: * REAL:: Numbers with a decimal part.
4334: * STRING:: Arbitrary strings of characters.
4335: * Custom Types (Classes):: User-defined, object-oriented types.
4336: @end menu
4337:
4338: @node BOOLEAN
4339: @section BOOLEAN
4340: @cindex data types, BOOLEAN
4341: @cindex types, BOOLEAN
4342:
4343: The @code{BOOLEAN} type represents any M value that can be interpreted as a truth-value.
4344:
4345: @node COMPLEX
4346: @section COMPLEX
4347: @cindex data types, COMPLEX
4348: @cindex types, COMPLEX
4349:
4350: 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.
4351:
4352: 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}.
4353:
4354: @node INTEGER
4355: @section INTEGER
4356: @cindex data types, INTEGER
4357: @cindex types, INTEGER
4358:
4359: An @code{INTEGER} is an interpretation of numeric data with any fractional part removed.
4360:
4361: @node REAL
4362: @section REAL
4363: @cindex data types, REAL
4364: @cindex types, REAL
4365:
4366: @node STRING
4367: @section STRING
4368: @cindex data types, STRING
4369: @cindex types, STRING
4370:
4371: @node Custom Types (Classes)
4372: @section Custom Types (Classes)
4373: @cindex data types, custom
4374: @cindex types, custom
4375: @cindex classes
4376:
4377: See @ref{Classes}.
4378:
4379: @node Globals
4380: @chapter Globals
4381: @cindex globals
4382: @cindex variables, global
4383: @cindex data
4384:
4385: @node Concurrency Control
4386: @chapter Concurrency Control
4387: @cindex concurrency control
4388: @cindex locking
4389: @cindex transaction processing
4390:
4391: @node Local Variables
4392: @chapter Local Variables
4393: @cindex variables, local
4394: @cindex local variables
4395:
4396: @node Scoping
4397: @chapter Scoping
4398: @cindex scoping
4399:
4400: @node Decision Constructs
4401: @chapter Decision Constructs
4402: @cindex decision constructs
4403: @cindex IF
4404: @cindex ELSE
4405: @cindex THEN
4406: @cindex postconditionals
4407:
4408: @node Branch Constructs
4409: @chapter Branch Constructs
4410: @cindex branch constructs
4411: @cindex DO
4412: @cindex GOTO
4413: @cindex JOB
4414:
4415: @node Loop Constructs
4416: @chapter Loop Constructs
4417: @cindex loop constructs
4418: @cindex FOR
4419:
4420: @node Modular Programming
4421: @chapter Modular Programming
4422: @cindex modular programming
4423: @cindex functions, extrinsic
4424: @cindex subroutines
4425:
4426: @menu
4427: * Subroutines:: Making sections of code reusable.
4428: * Extrinsic Functions:: Reusable code that returns a value.
4429: @end menu
4430:
4431: @node Subroutines
4432: @section Subroutines
4433:
4434: @node Extrinsic Functions
4435: @section Extrinsic Functions
4436:
4437: @node Object-Oriented Programming
4438: @chapter Object-Oriented Programming
4439: @cindex object-oriented programming
4440: @cindex programming, object-oriented
4441:
4442: @menu
4443: * Classes:: The basis of object-oriented programming.
4444: @end menu
4445:
4446: @node Classes
4447: @section Classes
4448:
4449: @menu
4450: * Inheritance:: Basing one class upon another.
4451: * Methods:: Attaching code to a class.
4452: * Public Variables:: Variables visible outside of a class.
4453: * Private Variables:: Variables only visible within a class.
4454: @end menu
4455:
4456: @node Inheritance
4457: @subsection Inheritance
4458:
4459: @node Methods
4460: @subsection Methods
4461:
4462: @node Public Variables
4463: @subsection Public Variables
4464:
4465: @node Private Variables
4466: @subsection Private Variables
4467:
4468: @node Libraries
4469: @chapter Libraries
4470: @cindex libraries
4471:
4472: @node Sequential I/O
4473: @chapter Sequential I/O
4474:
4475: @node Network I/O
4476: @chapter Network I/O
4477: @cindex networks, input and output
4478:
4479: 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.
4480:
4481: @section Opening and Connecting a Client Socket
4482: @cindex networks, opening and connecting client sockets
4483:
4484: To open a client socket and connect to it, you will need to call the @code{OPEN} command and the @code{USE} command:
4485:
4486: @example
4487: ;
4488: ; Set socket read terminator to LF
4489: ;
4490: SET ^$DEVICE(100,"OPTIONS","TERMINATOR")=$C(10)
4491: ;
4492: ; Open an IPv4 TCP socket to mail.mydomain.com on port 25 (SMTP)
4493: ; and connect to it
4494: ;
4495: OPEN 100:"mail.mydomain.com:25:IPV4:TCP"
4496: USE 100:/CONNECT
4497: ;
4498: ; Read a line of input from the remote host and write it to the terminal
4499: ;
4500: NEW LINE
4501: READ LINE
4502: USE 0
4503: WRITE LINE,!
4504: ;
4505: ; CLOSE the socket and disconnect
4506: ;
4507: CLOSE 100
4508: QUIT
4509: @end example
4510:
4511: @node Extended Global References
4512: @chapter Extended Global References
4513: @cindex global references, extended
4514: @cindex extended global references
4515:
4516: @section Standard Extended Global References
4517: @cindex extended global references, standard
4518:
4519: FreeM supports extended global references, allowing the user to access globals in namespaces other than the current default namespace and the @code{SYSTEM} namespace, without switching to the other namespace.
4520:
4521: For example, if you are in the @code{USER} namespace, the following code will print the value of @code{^VA(200,0)} in the @code{VISTA} namespace:
4522:
4523: @example
4524: WRITE ^|"VISTA"|VA(200,0),!
4525: @end example
4526:
4527: You may also use an expression that resolves to a string containing a valid namespace name:
4528:
4529: @example
4530: SET NS="VISTA"
4531: WRITE ^|NS|VA(200,0),!
4532: @end example
4533:
4534: @node Global Aliasing
4535: @chapter Global Aliasing
4536: @cindex aliasing, global
4537: @cindex globals, aliasing
4538:
4539: FreeM provides the ability to set alternative names for M global variables.
4540:
4541: To create an alias of @code{^FOO} named @code{^BAR}, use the following command:
4542:
4543: @example
4544: SET ^$JOB($JOB,"ALIASES","^BAR")="^FOO"
4545: @end example
4546:
4547: If such an alias is set, any reference to global variable @code{^BAR} will affect @code{^FOO} instead of @code{^BAR} until @code{^$JOB($JOB,"ALIASES","^BAR")} is @code{KILL}ed. If @code{^BAR} existed prior to the definition of this alias, its data will be unavailable to and unaffected by application code.
4548:
4549: @node Global Mappings
4550: @chapter Global Mappings
4551: @cindex mappings, global
4552: @cindex globals, mapping
4553:
4554: FreeM supports creating persistent mappings through which arbitrary global names may be mapped to specific namespaces. This allows non-@code{%} globals to be stored in the @code{SYSTEM} namespace, or @code{%} globals to be stored in non-@code{SYSTEM} namespaces.
4555:
4556: To map the @code{^FOO} global to the @code{SYSTEM} namespace, any of the following will work:
4557:
4558: @example
4559: MAP GLOBAL ^FOO="SYSTEM"
4560: SET ^$GLOBAL("FOO","NAMESPACE")="SYSTEM"
4561: SET ^$SYSTEM("MAPPINGS","GLOBAL","^FOO")="SYSTEM"
4562: @end example
4563:
4564: There is no functional difference in any of the three approaches; the method you choose is a matter of personal preference.
4565:
4566: To remove the above mapping, any of the following examples will also work:
4567:
4568: @example
4569: UNMAP GLOBAL ^FOO
4570: KILL ^$GLOBAL("FOO","NAMESPACE")
4571: KILL ^$SYSTEM("MAPPINGS","GLOBAL","^FOO")
4572: @end example
4573:
4574: @node Transaction Processing
4575: @chapter Transaction Processing
4576: @cindex transaction processing
4577:
4578: 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 concurrency is not disturbed), or in serial mode (where writes are guaranteed to be atomic, consistent, isolated, and durable).
4579:
4580: @section Theory of Operation
4581:
4582: 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.
4583:
4584: 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.
4585:
4586: 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.
4587:
4588: Checkpoints can have one of two modes:
4589:
4590: @table @asis
4591:
4592: @item @code{CP_REMOVE}
4593: 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.
4594:
4595: @item @code{CP_RESTORE}
4596: 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.
4597:
4598: @end table
4599:
4600: The below example shows a few global operations and checkpoints for a transaction in-flight using the @code{trantab} direct-mode command:
4601:
4602: @verbatim
4603: TL1:DEFAULT.USER> trantab
4604: $TLEVEL 1*
4605: Operations for Transaction ID: 6ea14aad-b8f1-47f9-9f52-4f513f892bc0 [RESTARTABLE SERIAL]
4606:
4607: OP. NO. ACTION KEY/DATA
4608: ------- ------ --------
4609: 1 SET ^FOO=3
4610: 2 KILL ^FOO
4611: 3 SET ^jpw=10
4612: 4 SET ^BRANDNEW=6
4613:
4614: Global checkpoints:
4615:
4616: GLOBAL MODE FILES
4617: ------ ---- -----
4618: ^BRANDNEW CP_REMOVE IN: /usr/local/var/freem/USER/globals/^BRANDNEW
4619: ^jpw CP_RESTORE IN: /usr/local/var/freem/USER/globals/^jpw
4620: OUT: /usr/local/var/freem/USER/globals/^jpw.23390.1.chk
4621: ^FOO CP_RESTORE IN: /usr/local/var/freem/USER/globals/^FOO
4622: OUT: /usr/local/var/freem/USER/globals/^FOO.23390.1.chk
4623: @end verbatim
4624:
4625: In the above example, @code{IN} files are the live data file that will be overwritten or removed, and @code{OUT} files are the checkpoints themselves. Note that @code{OUT} files are only used for @code{CP_RESTORE} checkpoints.
4626:
4627:
4628: @node Asynchronous Event Handling
4629: @chapter Asynchronous Event Handling
4630: @cindex event handling, asynchronous
4631:
4632: Asynchronous event handling in FreeM follows the specifications of the unpublished MDC @emph{Millennium Draft Standard}.
4633:
4634: @section Setting Up Async Event Handlers
4635:
4636: Asynchronous event handlers are configured through the @code{^$JOB} structured system variable for job-specific events, and the @code{^$SYSTEM} structured system variable for system-wide events. In order to become proficient in writing asynchronous event handling code, you need to be aware of several important concepts:
4637:
4638: @table @emph
4639:
4640: @item Event Classes
4641: @emph{Event classes} denote particular categories of events. These include @code{COMM}, @code{HALT}, @code{IPC}, @code{INTERRUPT}, @code{POWER}, @code{TIMER}, @code{TRIGGER}, and @code{USER} event classes. At present, only @code{INTERRUPT} and @code{TRIGGER} event classes are supported.
4642:
4643: @item Event Identifiers
4644: @emph{Event identifiers} denote the precise nature of the event that has occurred. For instance, resizing the terminal window in which a FreeM job is running will send an event of class @code{INTERRUPT} with an event identifier of @code{SIGWINCH} (short for @emph{SIGnal WINdow CHange}).
4645:
4646: @item Event Handlers
4647: @emph{Event handlers} are M routines or subroutines that can be registered to run when an event of a certain event class occurs.
4648:
4649: @item Event Registration
4650: @emph{Event registration} is the process of modifying the @code{^$JOB} or @code{^$SYSTEM} SSVN to associate a particular event class and event identifier with an event handler routine or subroutine.
4651:
4652: @item Event Blocking and Unblocking
4653: @emph{Event blocking} is the means by which asynchronous event handling can be temporarily suspended. For example, asynchronous events are temporarily and implicitly blocked for the duration of event handler execution, unless explicitly un-blocked within the event handler. Event handling can also be blocked and unblocked programatically from M code using the @code{ABLOCK} and @code{AUNBLOCK} commands.
4654:
4655: @end table
4656:
4657: The following sections of this chapter will take you step-by-step through setting up an event handler for @code{SIGWINCH} signal handling.
4658:
4659: @section Registering an Asynchronous Event Handler
4660: @cindex event handlers, registration
4661:
4662: To register a job-specific event handler that will only execute in the current FreeM process, use the following syntax:
4663:
4664: @example
4665: SET ^$JOB($JOB,"EVENT",@emph{event-class},@emph{event-identifier})=@emph{entryref}
4666: @end example
4667:
4668: To register a system-wide event handler that will execute in every FreeM process, use the following syntax:
4669:
4670: @example
4671: SET ^$SYSTEM("EVENT",@emph{event-class},@emph{event-identifier})=@emph{entryref}
4672: @end example
4673:
4674: For example, use the following to register @code{^RESIZE} as an asynchronous event handler for @code{SIGWINCH} events:
4675:
4676: @example
4677: SET ^$JOB($JOB,"EVENT","INTERRUPT","SIGWINCH")="^RESIZE"
4678: @end example
4679:
4680: 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}.
4681:
4682: @section Enabling Asynchronous Event Handling
4683: @cindex event handlers, enabling
4684:
4685: 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:
4686:
4687: @example
4688: ASTART "INTERRUPT"
4689: @end example
4690:
4691: 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.
4692:
4693: Once this is done, any event handlers registered for the @code{INTERRUPT} event class in @code{^$JOB} will be executed asynchronously as appropriate.
4694:
4695: Please note that @code{ASTART "TRIGGER"} is run implicitly at FreeM startup, to ensure consistency in applications depending on business logic contained in system-wide global triggers. To disable this behavior, add @code{ASTOP "TRIGGER"} to the @code{LOCAL.STARTUP} routine in the @code{USER} namespace. If @code{LOCAL.STARTUP} does not yet exist in your environment, you may create it by typing @code{fmadm edit routine USER LOCAL.STARTUP} from your UNIX command-line shell.
4696:
4697: @section Disabling Asynchronous Event Handling
4698: @cindex event handlers, disabling
4699:
4700: To disable asynchronous event handling, the @code{ASTOP} command is used. In the following example, we will disable asynchronous event handling for the @code{INTERRUPT} event class:
4701:
4702: @example
4703: ASTOP "INTERRUPT"
4704: @end example
4705:
4706: Omitting the @code{"INTERRUPT"} argument will disable asynchronous event handling for @emph{all} event classes. See @code{ASTOP} in the commands section for more details.
4707:
4708: You may also disable asynchronous event handling for a specific event identifier by @code{KILL}ing the appropriate node in the @code{^$JOB} SSVN, which unregisters the event handler altogether. The following example will unregister the event handler for the @code{SIGWINCH} event identifier:
4709:
4710: @example
4711: KILL ^$JOB($JOB,"EVENT","INTERRUPT","SIGWINCH")
4712: @end example
4713:
4714: @section Temporarily Blocking Asynchronous Event Handling
4715: @cindex event handlers, blocking
4716:
4717: 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.
4718:
4719: The following example blocks asynchronous event handling for the @code{INTERRUPT} event class:
4720:
4721: @example
4722: ABLOCK "INTERRUPT"
4723: @end example
4724:
4725: 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.
4726:
4727: 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.
4728:
4729: @node Global Triggers
4730: @chapter Global Triggers
4731: @cindex global triggers
4732: @cindex triggers
4733:
4734: 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.
4735:
4736: 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:
4737:
4738: @table @asis
4739:
4740: @item @code{DATA}
4741: Trigger will fire when the @code{$DATA} intrinsic function is called on @emph{<gvn>}.
4742:
4743: @item @code{GET}
4744: Trigger will fire when @emph{<gvn>} is read from.
4745:
4746: @item @code{INCREMENT}
4747: Trigger will fire when intrinsic function @code{$INCREMENT} is called on @emph{<gvn>}.
4748:
4749: @item @code{KILL}
4750: Trigger will fire when @emph{<gvn>} is @code{KILL}ed.
4751:
4752: @item @code{NEXT}
4753: Trigger will fire when intrinsic function @code{$NEXT} is called on @emph{<gvn>}.
4754:
4755: @item @code{ORDER}
4756: Trigger will fire when intrinsic function @code{$ORDER} is called on @emph{<gvn>}.
4757:
4758: @item @code{QUERY}
4759: Trigger will fire when intrinsic function @code{$QUERY} is called on @emph{<gvn>}.
4760:
4761: @item @code{SET}
4762: Trigger will fire when @code{SET @emph{<gvn>}=@emph{value}} occurs.
4763:
4764: @item @code{ZDATA}
4765: Trigger will fire when intrinsic function @code{ZDATA} is called on @emph{<gvn>}.
4766:
4767: @end table
4768:
4769: When a @code{TRIGGER} event occurs, the @code{"GLOBAL"} node of the @code{^$EVENT} structured system variable will be populated with the global reference that invoked the trigger event.
4770:
4771: 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.
4772:
4773: The following example shows a trigger implemented for @code{SET} operations on the @code{^DD} global.
4774:
4775: @example
4776: TRIGGER ;
4777: ;
4778: ; Set up a SET trigger on ^DD
4779: ;
4780: SET ^$JOB($JOB,"EVENT","TRIGGER","SET:^DD")="ONSET^TRIGGER"
4781: ;
4782: ; Enable the TRIGGER event class
4783: ;
4784: ASTART "TRIGGER"
4785: ;
4786: ; Try setting a node in ^DD
4787: ;
4788: SET ^DD(1)="Test"
4789: ;
4790: ; Quit
4791: ;
4792: QUIT
4793: ;
4794: ;
4795: ONSET ;
4796: WRITE "The "_^$EVENT("GLOBAL")_" global node was SET.",!
4797: QUIT
4798: @end example
4799:
4800: You can also set up a trigger that applies to all FreeM processes by setting descendant subscripts of @code{^$SYSTEM("EVENT","TRIGGER",...)} instead of using @code{^$JOB($JOB,"EVENT","TRIGGER",...)}.
4801:
4802: @node Synchronous Event Handling
4803: @chapter Synchronous Event Handling
4804:
4805: @node GUI Programming with MWAPI
4806: @chapter GUI Programming with MWAPI
4807:
4808: @node User-Defined Z Commands
4809: @chapter User-Defined Z Commands
4810:
4811: @node User-Defined Z Functions
4812: @chapter User-Defined Z Functions
4813:
4814: @cindex z functions, user-defined
4815:
4816: @node User-Defined SSVNs
4817: @chapter User-Defined SSVNs
4818:
4819: @cindex structured system variables, user-defined
4820: @cindex structured system variables
4821:
4822: @node Language Dialects
4823: @chapter Language Dialects
4824:
4825: @cindex language dialects
4826: @cindex dialects, language
4827:
4828:
4829: @node System Library Routines
4830: @chapter System Library Routines
4831: @cindex system library routines
4832:
4833: @section ^%ZCOLUMNS
4834: @cindex ^%ZCOLUMNS
4835: @cindex system library routines, ^%ZCOLUMNS
4836:
4837: This routine is the implementation of the @code{$ZCOLUMNS} intrinsic special variable.
4838:
4839: @section ^%SYSINIT
4840: @cindex ^%SYSINIT
4841: @cindex system library routines, ^%SYSINIT
4842:
4843: This routine is the default startup routine for FreeM running in direct mode.
4844:
4845: Running @code{DO INFO} from direct mode will use this routine to display information about the current FreeM status and namespace configuration.
4846:
4847: @section ^%ZHELP
4848: @cindex ^%ZHELP
4849: @cindex system library routines, ^%ZHELP
4850:
4851: This routine implements the online help feature of FreeM, invoked by typing @code{?} in direct mode. It simply asks the underlying system to execute the command @command{info freem}.
4852:
4853: @section ^%ZROWS
4854: @cindex ^%ZROWS
4855: @cindex system library routines, ^%ZROWS
4856:
4857: This routine is the implementation of the @code{$ZROWS} intrinsic special variable.
4858:
4859: @node Interrupt Handling
4860: @chapter Interrupt Handling
4861: @cindex interrupt handling
4862:
4863: 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{$ZI} special variable:
4864:
4865: @table @asis
4866: @item @code{$ZI} evaluates @emph{true}
4867: 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.
4868:
4869: This is the default behavior of FreeM.
4870: @item @code{$ZI} evaluates @emph{false}
4871: In this case, no error is raised, but the @code{$ZCONTROLC} flag is set. In this mode of operation, it is up to program code to check for @code{$ZCONTROLC} and take appropriate action.
4872:
4873: Checking the value of @code{$ZCONTROLC} will reset it to @emph{false}.
4874: @end table
4875:
4876: 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.
4877:
4878: @node Error Processing
4879: @chapter Error Processing
4880: @cindex error processing
4881:
4882: FreeM exposes three means of processing M program execution errors:
4883:
4884: @table @emph
4885:
4886: @item FreeM-style error processing
4887: 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{$ZTRAP} error handler enabled.
4888:
4889: @item DSM 2.0-style error processing
4890: DSM 2.0-style error processing emulates the @code{$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{$ZTRAP} error handler is set across all program stack execution levels.
4891:
4892: @item Standard error processing
4893: Standard error processing uses the @code{NEW}-able @code{$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{$ESTACK} ISV.
4894:
4895: If @code{$ETRAP} is non-empty when an error condition occurs, @code{$ZTRAP} is ignored, regardless of whether FreeM-style or DSM 2.0-style error processing is enabled at the time of the error.
4896:
4897: @end table
4898:
4899: For further information on switching between FreeM-style and DSM 2.0-style @code{$ZTRAP} error handling, see the documentation for the @code{BREAK} command.
4900:
4901: @node FreeM Error Codes
4902: @chapter FreeM Error Codes
4903: @cindex Error Codes
4904:
4905: @table @asis
4906:
4907: @item @code{ZINRPT} - @emph{interrupt}
4908: Raised when an interrupt signal is received.
4909:
4910: @item @code{ZBKERR} - @emph{BREAK point}
4911: Raised when a @code{BREAK} point is reached.
4912:
4913: @item @code{ZNOSTAND} - @emph{non standard syntax}
4914: Raised when features incompatible with the current value of @code{$DIALECT} are used.
4915:
4916: @item @code{ZUNDEF} - @emph{variable not found}
4917: 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}.
4918:
4919: @item @code{ZLBLUNDEF} - @emph{label not found}
4920: Raised when a referenced label is not found.
4921:
4922: @item @code{ZMISSOPD} - @emph{missing operand}
4923: Raised when an operand is missing from an expression.
4924:
4925: @item @code{ZMISSOP} - @emph{missing operator}
4926: Raised when an operator is missing from an expression.
4927:
4928: @item @code{ZILLOP} - @emph{unrecognized operator}
4929: Raised when an unrecognized operator is encountered in an expression.
4930:
4931: @item @code{ZQUOTER} - @emph{unmatched quotes}
4932: Raised when unbalanced quotes are encountered.
4933:
4934: @item @code{ZCOMMAER} - @emph{comma expected}
4935: Raised when a comma is expected in program syntax but is not found.
4936:
4937: @item @code{ZASSIGNER} - @emph{equals '=' expected}
4938: Raised when an equals sign is expected in program syntax but is not found.
4939:
4940: @item @code{ZARGER} - @emph{argument not permitted}
4941: Raised when an argument is encountered in a syntactic position where arguments are not permitted.
4942:
4943: @item @code{ZSPACER} - @emph{blank ' ' expected}
4944: Raised when a space character is expected in program syntax but is not found.
4945:
4946: @item @code{ZBRAER} - @emph{unmatched parentheses}
4947: Raised when unbalanced parentheses are detected in program syntax.
4948:
4949: @item @code{ZLVLERR} - @emph{level error}
4950: Raised when a level error occurs.
4951:
4952: @item @code{ZDIVER} - @emph{divide by zero}
4953: Raised when program code attempts to divide by zero. Deprecated in favor of standard error code @code{M9}.
4954:
4955: @item @code{ZILLFUN} - @emph{function not found}
4956: Raised when program code attempts to call intrinsic or extrinsic functions that are not defined.
4957:
4958: @item @code{ZFUNARG} - @emph{wrong number of function arguments}
4959: Raised when an intrinsic or extrinsic function is called with the wrong number of arguments.
4960:
4961: @item @code{ZZTERR} - @emph{ZTRAP error}
4962: Raised when a @code{$ZTRAP} error occurs.
4963:
4964: @item @code{ZNEXTERR} - @emph{$NEXT/$ORDER error}
4965: Raised when an error occurs in @code{$NEXT} or @code{$ORDER}.
4966:
4967: @item @code{ZSELER} - @emph{$SELECT error}
4968: Raised when an error occurs in @code{$SELECT}
4969:
4970: @item @code{ZCMMND} - @emph{illegal command}
4971: Raised when program code attempts to execute an illegal command.
4972:
4973: @item @code{ZARGLIST} - @emph{argument list incorrect}
4974: Raised when the argument list supplied to an M language element does not match that language element's syntactic requirements.
4975:
4976: @item @code{ZINVEXPR} - @emph{invalid expression}
4977: Raised when an invalid expression is encountered.
4978:
4979: @item @code{ZINVREF} - @emph{invalid reference}
4980: Raised when an invalid variable reference is encountered.
4981:
4982: @item @code{ZMXSTR} - @emph{string too long}
4983: Raised when a string is encountered that exceeds @code{^$SYSTEM("STRING_MAX")}.
4984:
4985: @item @code{ZTOOPARA} - @emph{too many parameters}
4986: Raised when too many parameters are passed to a function or subroutine.
4987:
4988: @item @code{ZNOPEN} - @emph{unit not open}
4989: Raised when attempting to access an I/O channel that has not been opened.
4990:
4991: @item @code{ZNODEVICE} - @emph{unit does not exist}
4992: Raised when attempting to access a device that does not exist.
4993:
4994: @item @code{ZPROTECT} - @emph{file protection violation}
4995: Raised when attempting to access a file or device to which you do not have permission.
4996:
4997: @item @code{ZGLOBER} - @emph{global not permitted}
4998: Raised when attempting to use a global in a syntactic element where global variables are not permitted.
4999:
5000: @item @code{ZFILERR} - @emph{file not found}
5001: Raised when attempting to access a file that does not exist.
5002:
5003: @item @code{ZPGMOV} - @emph{program overflow}
5004: Raised when a program overflows the limits of a routine buffer.
5005:
5006: @item @code{ZSTKOV} - @emph{stack overflow}
5007: Raised when @code{DO}, @code{FOR}, or @code{XECUTE} nesting levels exceed the value in @code{^$SYSTEM("NESTLEVLS")}.
5008:
5009: @item @code{ZSTORE} - @emph{symbol table overflow}
5010: 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.
5011:
5012: @item @code{ZNOREAD} - @emph{file won't read}
5013: Raised when program code attempts to read from an unreadable file.
5014:
5015: @item @code{ZNOWRITE} - @emph{file won't write}
5016: Raised when program code attempts to write to an unwritable file.
5017:
5018: @item @code{ZNOPGM} - @emph{routine not found}
5019: Raised when an attempt is made to load or execute a routine that does not exist in the current namespace.
5020:
5021: @item @code{ZNAKED} - @emph{illegal naked reference}
5022: Raised when an attempt is made to use an illegal naked reference.
5023:
5024: @item @code{ZSBSCR} - @emph{illegal subscript}
5025: Raised when an illegal subscript access is attempted.
5026:
5027: @item @code{ZISYNTX} - @emph{insert syntax}
5028: Raised when illegal insert syntax is used.
5029:
5030: @item @code{ZDBDGD} - @emph{global data degradation}
5031: Raised when corruption is detected in global data files.
5032:
5033: @item @code{ZKILLER} - @emph{job kill signal}
5034: Raised on a job kill signal.
5035:
5036: @item @code{ZHUPER} - @emph{hangup signal}
5037: Raised on a job hangup signal.
5038:
5039: @item @code{ZMXNUM} - @emph{numeric overflow}
5040: Raised when an assignment or expression result exceeds @code{$ZPRECISION}.
5041:
5042: @item @code{ZNOVAL} - @emph{function returns no value}
5043: Raised when a function does not return a value. Extrinsic functions must @code{QUIT} with a value.
5044:
5045: @item @code{ZTYPEMISMATCH} - @emph{type mismatch}
5046: Raised when a type mismatch occurs.
5047:
5048: @item @code{ZMEMOV} - @emph{out of memory}
5049: Raised when FreeM runs out of heap memory.
5050:
5051: @item @code{ZNAMERES} - @emph{error in name resolution}
5052: Raised when an attempted name resolution fails.
5053:
5054: @item @code{ZSCKCREAT} - @emph{error creating socket}
5055: Raised when an error occurs creating a socket for network I/O.
5056:
5057: @item @code{ZSCKIFAM} - @emph{invalid address family (must be IPV4 or IPV6)}
5058: Raised when the address family specified in an @code{OPEN} command for a socket I/O channel is not IPV4 or IPV6.
5059:
5060: @item @code{ZSCKITYP} - @emph{invalid connection type (must be TCP or UDP)}
5061: Raised when the connection type specified in an @code{OPEN} command for a socket I/O channel is not @code{TCP} or @code{UDP}.
5062:
5063: @item @code{ZSCKIPRT} - @emph{invalid port number}
5064: 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.
5065:
5066: @item @code{ZSCKCERR} - @emph{connection error}
5067: Raised when an error occurs on a @code{USE <channel>:/CONNECT} command.
5068:
5069: @item @code{ZSCKAERR} - @emph{USE action invalid for connection type (possibly CONNECT on UDP socket?)}
5070: Raised when an attempt is made to @code{USE <channel>:/CONNECT} on a UDP socket I/O channel. The UDP protocol is connectionless.
5071:
5072: @item @code{ZSCKACON} - @emph{attempted to CONNECT an already-connected socket}
5073: Raised when an attempt is made to @code{USE <channel>:/CONNECT} on a TCP socket I/O channel that is already connected.
5074:
5075: @item @code{ZSCKNCON} - @emph{attempted to READ from a disconnected TCP socket}
5076: Raised when an attempt is made to @code{READ} a TCP socket that has not yet been connected.
5077:
5078: @item @code{ZSCKEOPT} - @emph{error setting socket options}
5079: Raised when an error is encountered while setting socket options.
5080:
5081: @item @code{ZSCKERCV} - @emph{error in READ from socket}
5082: Raised when an error occurs in a socket I/O channel @code{READ}.
5083:
5084: @item @code{ZSCKESND} - @emph{error in WRITE to socket}
5085: Raised when an error occurs while attempting to @code{WRITE} to a socket I/O channel.
5086:
5087: @item @code{ZNORPI} - @emph{^$ZRPI only supported on Raspberry Pi hardware}
5088: 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.
5089:
5090: @item @code{ZCREDEF} - @emph{cannot redefine CONST}
5091: Raised when attempts are made to redefine a @code{CONST} after its initial definition.
5092:
5093: @item @code{ZCMODIFY} - @emph{cannot modify CONST}
5094: Raised when attempts are made to change the value of a @code{CONST}.
5095:
5096: @item @code{ZFILEXWR} - @emph{cannot open existing file for WRITE}
5097: Raised when an attempt is made to open an existing file in write (but not append) mode.
5098:
5099: @item @code{INEWMULT} - @emph{initializing NEW with multiple setarguments not supported}
5100: Raised when you attempt to use multiple setarguments with initializing @code{NEW}, e.g. @code{NEW X=2,Y=3}.
5101:
5102: @item @code{ZECODEINV} - @emph{invalid value for $ECODE}
5103: Raised when attempts are made to set @code{$ECODE} to an invalid error code value. Obsolete and replaced by standard error code @code{M101}.
5104:
5105: @item @code{ZASSERT} - @emph{programmer assertion failed}
5106: Raised when an @code{ASSERT} expression's result is not true.
5107:
5108: @item @code{ZUSERERR} - @emph{user-defined error}
5109: Raised when program code calls @code{THROW} with an error code argument for which the first character is @code{U}, or when @code{$ECODE} is set to an error code for which the first character is @code{U}.
5110:
5111: Custom error messages for @code{ZUSERERR} may be set in @code{^$JOB($JOB,"USER_ERRORS",<user_error_code>)}, where @code{<user_error_code>} represents the custom error code.
5112:
5113: For example:
5114:
5115: @example
5116: DEFAULT.USER> S ^$JOB($JOB,"USER_ERRORS","UBLACKHOLE")="black hole encountered"
5117:
5118:
5119: DEFAULT.USER> THROW UBLACKHOLE
5120:
5121:
5122: >> Error UBLACKHOLE: black hole encountered in SYSTEM::^%SYSINIT [$STACK = 0]
5123: >> THROW UBLACKHOLE
5124: ^
5125: @end example
5126:
5127: @item @code{ZSYNTERR} - @emph{syntax error}
5128: Raised when a syntax error without a more specific error code is encountered.
5129:
5130: @item @code{ZCTRLB} - @emph{break}
5131: Pseudo-error used by the FreeM debugger. Not visibly raised in normal program operation.
5132:
5133: @item @code{ZASYNC} - @emph{asynchronous interruption}
5134: Pseudo-error used by the FreeM asynchronous events subsystem. Not visibly raised in normal program operation.
5135:
5136: @item @code{M1} - @emph{naked indicator undefined}
5137: Raised when an attempt is made to use a naked reference before the naked indicator is set.
5138:
5139: @item @code{M2} - @emph{invalid combination with $FNUMBER code atom}
5140:
5141:
5142: @item @code{M3} - @emph{$RANDOM seed less than 1}
5143:
5144:
5145: @item @code{M4} - @emph{no true condition in $SELECT}
5146:
5147:
5148: @item @code{M5} - @emph{line reference less than zero}
5149:
5150:
5151: @item @code{M6} - @emph{undefined local variable}
5152:
5153:
5154: @item @code{M7} - @emph{undefined global variable}
5155:
5156:
5157: @item @code{M8} - @emph{undefined intrinsic special variable}
5158:
5159:
5160: @item @code{M9} - @emph{divide by zero}
5161:
5162:
5163: @item @code{M10} - @emph{invalid pattern match range}
5164:
5165:
5166: @item @code{M11} - @emph{no parameters passed}
5167:
5168:
5169: @item @code{M12} - @emph{invalid line reference (negative offset)}
5170:
5171:
5172: @item @code{M13} - @emph{invalid line reference (line not found)}
5173:
5174:
5175: @item @code{M14} - @emph{line level not 1}
5176:
5177:
5178: @item @code{M15} - @emph{undefined index variable}
5179:
5180:
5181: @item @code{M16} - @emph{argumented QUIT not allowed}
5182:
5183:
5184: @item @code{M17} - @emph{argumented QUIT required}
5185:
5186:
5187: @item @code{M18} - @emph{fixed length READ not greater than zero}
5188:
5189:
5190: @item @code{M19} - @emph{cannot copy a tree or subtree onto itself}
5191:
5192:
5193: @item @code{M20} - @emph{line must have a formal parameter list}
5194:
5195:
5196: @item @code{M21} - @emph{algorithm specification invalid}
5197:
5198:
5199: @item @code{M22} - @emph{SET or KILL to ^$GLOBAL when data in global}
5200:
5201:
5202: @item @code{M23} - @emph{SET or KILL to ^$JOB for non-existent job number}
5203:
5204:
5205: @item @code{M24} - @emph{change to collation algorithm while subscripted local variables defined}
5206:
5207:
5208: @item @code{M26} - @emph{non-existent environment}
5209:
5210:
5211: @item @code{M27} - @emph{attempt to rollback a transaction that is not restartable}
5212:
5213:
5214: @item @code{M28} - @emph{mathematical function, parameter out of range}
5215:
5216:
5217: @item @code{M29} - @emph{SET or KILL on structured system variable not allowed by implementation}
5218:
5219:
5220: @item @code{M30} - @emph{reference to global variable with different collating sequence within a collating algorithm}
5221:
5222:
5223: @item @code{M31} - @emph{control mnemonic used for device without a mnemonic space selected}
5224:
5225:
5226: @item @code{M32} - @emph{control mnemonic used in user-defined mnemonic space which has no associated line}
5227:
5228:
5229: @item @code{M33} - @emph{SET or KILL to ^$ROUTINE when routine exists}
5230:
5231:
5232: @item @code{M35} - @emph{device does not support mnemonic space}
5233:
5234:
5235: @item @code{M36} - @emph{incompatible mnemonic spaces}
5236:
5237:
5238: @item @code{M37} - @emph{READ from device identified by empty string}
5239:
5240:
5241: @item @code{M38} - @emph{invalid structured system variable subscript}
5242:
5243:
5244: @item @code{M39} - @emph{invalid $NAME argument}
5245:
5246:
5247: @item @code{M40} - @emph{call-by-reference in JOB actual parameter}
5248:
5249:
5250: @item @code{M41} - @emph{invalid LOCK argument within a transaction}
5251:
5252:
5253: @item @code{M42} - @emph{invalid QUIT within a transaction}
5254:
5255:
5256: @item @code{M43} - @emph{invalid range value ($X, $Y}
5257:
5258:
5259: @item @code{M44} - @emph{invalid command outside of a transaction}
5260:
5261:
5262: @item @code{M45} - @emph{invalid GOTO reference}
5263:
5264:
5265: @item @code{M56} - @emph{identifier exceeds maximum length}
5266:
5267:
5268: @item @code{M57} - @emph{more than one defining occurrence of label in routine}
5269:
5270:
5271: @item @code{M58} - @emph{too few formal parameters}
5272:
5273:
5274: @item @code{M60} - @emph{illegal attempt to use an undefined SSVN}
5275:
5276:
5277: @item @code{M101} - @emph{invalid value for $ECODE}
5278:
5279:
5280: @item @code{M102} - @emph{synchronous and asynchronous event processing cannot be simultaneously enabled for the same event class}
5281:
5282:
5283: @item @code{M103} - @emph{invalid event identifier}
5284:
5285:
5286: @item @code{M104} - @emph{ETRIGGER event identifier for IPC event class does not match job process identifier}
5287:
5288:
5289: @end table
5290:
5291: @node Debugging
5292: @chapter Debugging
5293: @cindex debugging
5294:
5295: @node System Configuration
5296: @chapter System Configuration
5297: @cindex configuration, system
5298:
5299: @section Installing FreeM
5300: @cindex installation
5301:
5302: @section Build Configuration
5303: @cindex build configuration
5304:
5305: 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:
5306:
5307: @table @asis
5308:
5309: @item @code{--enable-mwapigtk} (EXPERIMENTAL)
5310: Enables experimental support for the M Windowing API using the GTK3 libraries. Requires that you have GTK 3 libraries, their headers, and their dependencies installed on your system.
5311:
5312: Please consult your operating system's documentation for the correct commands to install the required libraries.
5313:
5314: @emph{Example}
5315:
5316: @example
5317: $ ./configure --enable-mwapigtk
5318: $ make
5319: $ sudo make install
5320: @end example
5321:
5322: @item @code{--enable-berkeleydb} (EXPERIMENTAL)
5323: Enables experimental support for using the BerkeleyDB database as a global handler for FreeM global namespaces. Requires that you have the @code{libdb} library, headers, and dependencies installed on your system.
5324:
5325: Please consult your operating system's documentation for the correct commands to install the required libraries.
5326:
5327: @emph{Example}
5328:
5329: @example
5330: $ ./configure --enable-berkeleydb
5331: $ make
5332: $ sudo make install
5333: @end example
5334:
5335:
5336: @item @code{--without-readline}
5337: Builds FreeM without GNU @code{readline} support, even if @code{readline} is installed on your system.
5338:
5339: Please note that building FreeM without GNU @code{readline} will also exclude REPL functionality and all direct-mode utility commands, i.e. @code{events}, @code{tdump}, @code{shmstat}, and @code{shmpages}.
5340:
5341: @emph{Example}
5342:
5343: @example
5344: $ ./configure --without-readline
5345: $ make
5346: $ sudo make install
5347: @end example
5348:
5349:
5350: @end table
5351:
5352: @node Accessing FreeM from C Programs
5353: @chapter Accessing FreeM from C Programs
5354:
5355: 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.
5356:
5357: 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.
5358:
5359: 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.
5360:
5361: 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}.
5362:
5363: @section freem_ref_t Data Structure
5364: @cindex libfreem, data structures: freem_ref_t
5365:
5366: 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.
5367:
5368: The data structure, defined in @file{freem.h}, looks like this:
5369:
5370: @verbatim
5371: typedef struct freem_ref_t {
5372:
5373: /*
5374: * The 'reftype' field can be one of:
5375: *
5376: * MREF_RT_LOCAL
5377: * MREF_RT_GLOBAL
5378: * MREF_RT_SSV
5379: */
5380: short reftype;
5381:
5382: /*
5383: * The 'name' field is the name of the local variable,
5384: * global variable, or SSVN (without ^ or ^$).
5385: */
5386: char name[256];
5387:
5388: /*
5389: * Returned data goes in a string, so you've got to figure out the
5390: * whole M canonical number thing yourself. Good luck. :-)
5391: */
5392: char value[STRLEN];
5393:
5394: short status;
5395:
5396: unsigned int subscript_count;
5397: char subscripts[255][256];
5398:
5399: } freem_ref_t;
5400: @end verbatim
5401:
5402: @emph{freem_ref_t Members}
5403:
5404: @table @asis
5405: @cindex libfreem, freem_ref_t.reftype
5406: @item @option{reftype}
5407: The @option{reftype} member determines whether we are operating on a local variable, a global variable, or a structured system variable. It may be set to any of following constants: @code{MREF_RT_LOCAL}, @code{MREF_RT_GLOBAL}, or @code{MREF_RT_SSV}.
5408:
5409: @cindex libfreem, freem_ref_t.name
5410: @item @option{name}
5411: The @option{name} member contains the name of the global, local, or SSVN to be accessed. You @emph{must not} include leading characters, such as @code{^} or @code{^$}.
5412:
5413: @cindex libfreem, freem_ref_t.value
5414: @item @option{value}
5415: This member contains the value read from or the value to be written to the global, local, or SSVN.
5416:
5417: @cindex libfreem, freem_ref_t.status
5418: @item @option{status}
5419: This member gives us various API status values after the API call returns. In general, this value is also returned by each API function.
5420:
5421: @cindex libfreem, freem_ref_t.subscript_count
5422: @item @option{subscript_count}
5423: 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.
5424:
5425: @cindex libfreem, freem_ref_t.subscripts
5426: @item @option{subscripts}
5427: A two-dimensional array containing the subscripts to which we are referring in this API call.
5428:
5429: @end table
5430:
5431: @section freem_ent_t Data Structure
5432: @cindex libfreem, data structures: freem_ent_t
5433:
5434: 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()}).
5435:
5436: The data structure, defined in @file{freem.h}, looks like this:
5437:
5438: @verbatim
5439: typedef struct freem_ent_t {
5440:
5441: /* name of function or procedure entry point */
5442: char name[256];
5443:
5444: /* return value */
5445: char value[STRLEN];
5446:
5447: /* value of ierr on return */
5448: short status;
5449:
5450: /* argument count and array */
5451: unsigned int argument_count;
5452: char arguments[255][256];
5453:
5454: } freem_ent_t;
5455: @end verbatim
5456:
5457: @emph{freem_ent_t Members}
5458:
5459: @table @asis
5460:
5461: @item @option{name}
5462: @cindex libfreem, freem_ent_t.name
5463: The @option{name} member contains the name of the extrinsic function or procedure to be called.
5464:
5465: @cindex libfreem, freem_ent_t.value
5466: @item @option{value}
5467: This member contains the value returned by the function called. Not used by @code{freem_procedure()}.
5468:
5469: @cindex libfreem, freem_ent_t.status
5470: @item @option{status}
5471: 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}.
5472:
5473: @cindex libfreem, freem_ent_t.argument_count
5474: @item @option{argument_count}
5475: 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.
5476:
5477: @cindex libfreem, freem_ent_t.arguments
5478: @item @option{arguments}
5479: A two-dimensional array containing the arguments to be passed into the extrinsic function or procedure being called.
5480:
5481: @end table
5482:
5483: @section freem_init()
5484: @cindex libfreem, freem_init()
5485:
5486: Initializes @code{libfreem} in preparation for calling other APIs.
5487:
5488: @emph{Synopsis}
5489:
5490: @code{pid_t freem_init(char *environment_name, char *namespace_name);}
5491:
5492: @emph{Parameters}
5493:
5494: @table @asis
5495: @item @code{environment_name}
5496: Specifies the environment to use.
5497: @item @code{namespace_name}
5498: Specifies the namespace to use.
5499: @end table
5500:
5501: @emph{Return Values}
5502:
5503: Returns the process ID of the @code{libfreem} process on success, or @code{-1} on failure.
5504:
5505: @emph{Example}
5506:
5507: This example prompts the user to enter a FreeM namespace and then attempts to initialize @code{libfreem} to use the selected namespace.
5508:
5509: @verbatim
5510: #include <stdio.h>
5511: #include <string.h>
5512: #include <freem.h>
5513:
5514: int main(int argc, char **argv, char **envp)
5515: {
5516: char namespace[256];
5517:
5518: /* get the namespace name to use */
5519: printf("Enter FreeM namespace to use: ");
5520: fgets(namespace, 255, stdin);
5521:
5522: /* remove the trailing newline */
5523: namespace[strcspn(buffer, "\n")] = '\0';
5524:
5525: /* initialize libfreem using the provided namespace */
5526: if(freem_init("DEFAULT", namespace) == TRUE) {
5527: printf("\nSuccess\n");
5528: }
5529: else {
5530: printf("\nFailure\n");
5531: }
5532:
5533: return 0;
5534: }
5535: @end verbatim
5536:
5537: @section freem_version()
5538: @cindex libfreem, freem_version()
5539:
5540: Returns the version of FreeM in use.
5541:
5542: @emph{Synopsis}
5543:
5544: @code{short freem_version(char *result);}
5545:
5546: @emph{Parameters}
5547:
5548: @table @asis
5549: @item @code{result}
5550: 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.
5551: @end table
5552:
5553: @emph{Return Value}
5554:
5555: Returns @code{0}.
5556:
5557: @emph{Example}
5558:
5559: This example will display the FreeM version on standard output.
5560:
5561: @verbatim
5562: #include <stdio.h>
5563: #include <string.h>
5564: #include <freem.h>
5565:
5566: int main(int argc, char **argv, char **envp)
5567: {
5568: char version[20] = {0};
5569:
5570: freem_init(``USER'');
5571: freem_version(version);
5572:
5573: printf(``FreeM version: %s\n'', version);
5574:
5575: }
5576: @end verbatim
5577:
5578: @section freem_set()
5579: @cindex libfreem, freem_set()
5580:
5581: Sets a FreeM local node, global node, or writable SSVN node.
5582:
5583: @emph{Synopsis}
5584:
5585: @code{short freem_set(freem_ref_t *ref);}
5586:
5587: @emph{Parameters}
5588:
5589: @table @asis
5590: @item @code{freem_ref_t}
5591: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
5592: @end table
5593:
5594: @emph{Return Value}
5595:
5596: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
5597:
5598: @emph{Example}
5599:
5600: This example sets the value @code{blue} into global node @code{^car("color")}.
5601:
5602: @verbatim
5603: #include <stdio.h>
5604: #include <string.h>
5605: #include <freem.h>
5606:
5607: int main(int argc, char **argv, char **envp)
5608: {
5609: freem_ref_t ref;
5610:
5611: /* we're setting a global */
5612: ref.reftype = MREF_RT_GLOBAL;
5613:
5614: /* access global "car" */
5615: strcpy(ref.name, "car");
5616:
5617: /* set up the subscripts */
5618: ref.subscript_count = 1;
5619: strcpy(ref.subscripts[0], "color");
5620:
5621:
5622: /* use the USER namespace */
5623: freem_init("USER");
5624:
5625: /* write the data out */
5626: freem_set(&ref);
5627:
5628: }
5629: @end verbatim
5630:
5631: @section freem_get()
5632: @cindex libfreem, freem_get()
5633:
5634: Retrieves a FreeM local node, global node, or writable SSVN node.
5635:
5636: @emph{Synopsis}
5637:
5638: @code{short freem_get(freem_ref_t *ref);}
5639:
5640: @emph{Parameters}
5641:
5642: @table @asis
5643: @item @code{freem_ref_t}
5644: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
5645: @end table
5646:
5647: @emph{Return Value}
5648:
5649: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
5650:
5651: @emph{Example}
5652:
5653: This example retrieves the character set of the current process.
5654:
5655: @verbatim
5656: #include <stdio.h>
5657: #include <sys/types.h>
5658: #include <unistd.h>
5659: #include <string.h>
5660: #include <freem.h>
5661:
5662: int main(int argc, char **argv, char)
5663: {
5664: pid_t pid;
5665: freem_ref_t ref;
5666:
5667: /* get the PID of this process */
5668: pid = getpid();
5669:
5670: /* we want to access an SSVN */
5671: ref.reftype = MREF_RT_SSV;
5672:
5673: /* set up the name and subscripts */
5674: strcpy(ref.name, "JOB");
5675:
5676: ref.subscript_count = 2;
5677: sprintf(ref.subscripts[0], "%d", pid);
5678: strcpy(ref.subscripts[1], "CHARACTER");
5679:
5680: /* initialize libfreem, using the USER namespace */
5681: freem_init("USER");
5682:
5683: /* call libfreem API */
5684: freem_get(&ref);
5685:
5686: /* output the character set info */
5687: printf("PID %d character set is '%s'\n", pid, ref.value);
5688: }
5689: @end verbatim
5690:
5691: @section freem_kill()
5692: @cindex libfreem, freem_kill()
5693:
5694: Deletes a FreeM local node, global node, or killable SSVN node, as well as all of its children.
5695:
5696: @emph{short freem_kill(freem_ref_t *ref);}
5697:
5698: @emph{Parameters}
5699:
5700: @table @asis
5701: @item @code{freem_ref_t}
5702: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
5703: @end table
5704:
5705: @emph{Return Value}
5706:
5707: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
5708:
5709: @emph{Example}
5710:
5711: @verbatim
5712: #include <stdio.h>
5713: #include <string.h>
5714: #include <freem.h>
5715:
5716: int main(int argc, char **argv, char **envp)
5717: {
5718: freem_ref_t ref;
5719:
5720: /* we're killing a global node */
5721: ref.reftype = MREF_RT_GLOBAL;
5722:
5723: /* access global "car" */
5724: strcpy(ref.name, "car");
5725:
5726: /* set up the subscripts */
5727: ref.subscript_count = 0;
5728:
5729: /* use the USER namespace */
5730: freem_init("USER");
5731:
5732: /* kill the global and all its descendant subscripts */
5733: freem_kill(&ref);
5734: }
5735: @end verbatim
5736:
5737: @section freem_data()
5738: @cindex libfreem, freem_data()
5739:
5740: @section freem_order()
5741: @cindex libfreem, freem_order()
5742:
5743: @section freem_query()
5744: @cindex libfreem, freem_query()
5745:
5746: @section freem_lock()
5747: @cindex libfreem, freem_lock()
5748:
5749: @section freem_unlock()
5750: @cindex libfreem, freem_unlock()
5751:
5752: @section freem_tstart()
5753: @cindex libfreem, freem_tstart()
5754:
5755: @section freem_trestart()
5756: @cindex libfreem, freem_trestart()
5757:
5758: @section freem_trollback()
5759: @cindex libfreem, freem_trollback()
5760:
5761: @section freem_tlevel()
5762: @cindex libfreem, freem_tlevel()
5763:
5764: @section freem_tcommit()
5765: @cindex libfreem, freem_tcommit()
5766:
5767: @section freem_function()
5768: @cindex libfreem, freem_function()
5769:
5770: @section freem_procedure()
5771: @cindex libfreem, freem_procedure()
5772:
5773: @node FreeM Administrator
5774: @appendix FreeM Administrator
5775: @cindex utilities, system management
5776: @cindex utilities, fmadm
5777: @cindex fmadm
5778:
5779: The @code{fmadm} utility is the preferred method of managing a FreeM installation, and will eventually replace all of the existing utilities.
5780: Unlike the existing, legacy utilities, @code{fmadm} presents a consistent, simple interface for all FreeM management tasks, and is namespace-aware.
5781: This appendix will document each @code{fmadm} facility as it is implemented, until all of the legacy utilities have been replaced.
5782:
5783: The @code{fmadm} utility's functions all follow the below, consistent syntax:
5784:
5785: @example
5786: usage: fmadm <action> <object> <namespace> [OPTIONS]
5787: @end example
5788:
5789: The @emph{action} keyword can be one of the following:
5790:
5791: @table @emph
5792:
5793: @item list
5794: Lists instances of @emph{object}
5795:
5796: @item examine
5797: Examines a single instance of @emph{object}
5798:
5799: @item verify
5800: Verifies the integrity of @emph{object}
5801:
5802: @item compact
5803: Compacts @emph{object}
5804:
5805: @item repair
5806: Repairs integrity problems in @emph{object}
5807:
5808: @item create
5809: Creates an instance of @emph{object}
5810:
5811: @item remove
5812: Removes an instance of @emph{object}
5813:
5814: @item import
5815: Imports an @emph{object}
5816:
5817: @item export
5818: Exports an @emph{object}
5819:
5820: @item backup
5821: Creates a backup of @emph{object}
5822:
5823: @item restore
5824: Restores a backup of @emph{object}
5825:
5826: @item migrate
5827: Migrates an instance of @emph{object} from an older FreeM version to the current version
5828:
5829: @item edit
5830: Edits an instance of @emph{object}
5831:
5832: @end table
5833:
5834: The @emph{object} keyword can be one of the following:
5835:
5836: @table @emph
5837:
5838: @item lock
5839: The FreeM @code{LOCK} table.
5840:
5841: Supported actions are @code{list} and @code{remove}.
5842:
5843: @item zallocate
5844: The FreeM @code{ZALLOCATE} table.
5845:
5846: No actions yet implemented.
5847:
5848: @item journal
5849: FreeM after-image journaling.
5850:
5851: Supported actions are @code{examine} and @code{restore}.
5852:
5853: The @code{examine} action will dump the after-image journal entries for the selected namespace in human-readable format.
5854:
5855: The @code{restore} action will play after-image journals forward for the selected namespace.
5856:
5857: @item namespace
5858: FreeM namespaces (collections of M routines and globals).
5859:
5860: No actions yet implemented.
5861:
5862: @item global
5863: The data files representing each FreeM @emph{global}.
5864:
5865: Supported actions are @code{list}, @code{examine}, @code{remove}, and @code{verify}.
5866:
5867: @item routine
5868: An M routine, stored as a @code{.m} file.
5869:
5870: Supported actions are @code{list}, @code{examine}, @code{remove}, @code{import}, @code{export}, @code{backup}, and @code{edit}.
5871:
5872: @item job
5873: A UNIX process representing an instance of the FreeM runtime.
5874:
5875: Supported actions are @code{list} and @code{examine}.
5876:
5877: @end table
5878:
5879:
5880: @node FreeM Legacy Utilities
5881: @appendix FreeM Legacy Utilities
5882: @cindex utilities, legacy
5883:
5884: @section Global Compactor (gcompact)
5885: @cindex utilities, legacy, gcompact
5886:
5887: Compacts the specified global in place.
5888:
5889: @emph{Syntax}
5890:
5891: @example
5892: gcompact @emph{/path/to/global/file}
5893: @end example
5894:
5895: @section Block Examiner (gfix)
5896: @cindex utilities, gfix
5897:
5898: The @emph{gfix} interactive utility program permits navigation of the B-tree structure of the specified global a block at a time.
5899:
5900: @emph{Syntax}
5901:
5902: @example
5903: gfix @emph{</path/to/global/file>}
5904: @end example
5905:
5906: @section Global Repair Tool (grestore)
5907: @cindex utilities, legacy, grestore
5908:
5909: This utility will fix problems with the specified global.
5910:
5911: @emph{Syntax}
5912:
5913: @example
5914: grestore @emph{</path/to/global/file>}
5915: @end example
5916:
5917: @node FreeM VIEW Commands and Functions
5918: @appendix FreeM VIEW Commands and Functions
5919:
5920: @section VIEW 16: Total Count of Error Messages/View Single Error Message
5921: @cindex VIEW commands/functions, 16, total count of error messages/view single error message
5922:
5923: Unknown semantics
5924:
5925: @section VIEW 17: Intrinsic Z-Commands
5926: @cindex VIEW commands/functions, 17, intrinsic Z-commands
5927:
5928: 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.
5929:
5930: @section VIEW 18: Intrinsic Z-Functions
5931: @cindex VIEW commands/functions, 18, intrinsic Z-functions
5932:
5933: 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.
5934:
5935: @section VIEW 19: Intrinsic Special Variables
5936: @cindex VIEW commands/functions, 19, intrinsic special variables
5937:
5938: Allows the user to retrieve or specify which special variables are implemented internally.
5939:
5940: @section VIEW 20: Break Service Code
5941: @cindex VIEW commands/functions, 20, break service code
5942:
5943: Allows the user to view or specify the code that will be run when a @code{BREAK} is encountered.
5944:
5945: @section VIEW 21: View Size of Last Global
5946: @cindex VIEW commands/functions, 21, view size of last global
5947:
5948: Allows the user to view the size of the last referenced global.
5949:
5950: @section VIEW 22: Count VIEW 22 Aliases
5951: @cindex VIEW commands/functions, 22, count VIEW 22 aliases
5952:
5953: Retrieves the number of VIEW 22 aliases in effect.
5954:
5955: @section VIEW 23: View Contents of Input Buffer
5956: @cindex VIEW commands/functions, 23, input buffer contents
5957:
5958: Retrieves the contents of the I/O input buffer.
5959:
5960: @section VIEW 24: Maximum Number of Screen Rows
5961: @cindex VIEW commands/functions, 24, maximum number of screen rows
5962:
5963: Retrieves the maximum number of screen rows supported in the current FreeM build.
5964:
5965: @section VIEW 25: Maximum Number of Screen Columns
5966: @cindex VIEW commands/functions, 25, maximum number of screen columns
5967:
5968: Retrieves the maximum number of screen columns supported in the current FreeM build.
5969:
5970: @section VIEW 26: DO/FOR/XECUTE Stack Pointer
5971: @cindex VIEW commands/functions, 26, DO/FOR/XECUTE stack pointer
5972:
5973: Retrieves the @code{DO}, @code{FOR}, and @code{XECUTE} stack pointer.
5974:
5975: @section VIEW 27: DO/FOR/XECUTE Stack Pointer (On Error)
5976: @cindex VIEW commands/functions, 27, DO/FOR/XECUTE stack pointer, on error
5977:
5978: Retrieves the @code{DO}, @code{FOR}, and @code{XECUTE} stack pointer (on error).
5979:
5980: @section VIEW 29: Copy Symbol Table
5981: @cindex VIEW commands/functions, 29, copy symbol table
5982:
5983: Copies the symbol table? We aren't currently aware of what this means.
5984:
5985: @section VIEW 30: Inspect Arguments
5986: @cindex VIEW commands/functions, 30, inspect arguments
5987:
5988: Retrieves the arguments passed to the @code{freem} executable.
5989:
5990: @section VIEW 31: Count Environment Variables
5991: @cindex VIEW commands/functions, 31, count environment variables
5992:
5993: Allows the user to inspect the number of variables in the process environment table.
5994:
5995: @emph{Syntax}
5996:
5997: @example
5998: WRITE $VIEW(31),!
5999: @end example
6000:
6001: @node Implementation Limits
6002: @appendix Implementation Limits
6003:
6004: @cindex limitations, memory
6005: @cindex maximum size, routine
6006: @cindex maximum size, global
6007: @cindex maximum size, string
6008:
6009: @node US-ASCII Character Set
6010: @appendix US-ASCII Character Set
6011:
6012: @multitable {Code} {Character}
6013: @item Code @tab Character
6014: @item 000 @tab @code{<NUL>}
6015: @item 001 @tab @code{<SOH>}
6016: @item 002 @tab @code{<STX>}
6017: @item 003 @tab @code{<ETX>}
6018: @item 004 @tab @code{<EOT>}
6019: @item 005 @tab @code{<ENQ>}
6020: @item 006 @tab @code{<ACK>}
6021: @item 007 @tab @code{<BEL>}
6022: @item 008 @tab @code{<BS>}
6023: @item 009 @tab @code{<HT>}
6024: @item 010 @tab @code{<LF>}
6025: @item 011 @tab @code{<VT>}
6026: @item 012 @tab @code{<FF>}
6027: @item 013 @tab @code{<CR>}
6028: @item 014 @tab @code{<SO>}
6029: @item 015 @tab @code{<SI>}
6030: @item 016 @tab @code{<DLE>}
6031: @item 017 @tab @code{<DC1>}
6032: @item 018 @tab @code{<DC2>}
6033: @item 019 @tab @code{<DC3>}
6034: @item 020 @tab @code{<DC4>}
6035: @item 021 @tab @code{<NAK>}
6036: @item 022 @tab @code{<SYN>}
6037: @item 023 @tab @code{<ETB>}
6038: @item 024 @tab @code{<CAN>}
6039: @item 025 @tab @code{<EM>}
6040: @item 026 @tab @code{<SUB>}
6041: @item 027 @tab @code{<ESC>}
6042: @item 028 @tab @code{<FS>}
6043: @item 029 @tab @code{<GS>}
6044: @item 030 @tab @code{<RS>}
6045: @item 031 @tab @code{<US>}
6046: @item 032 @tab @code{<space>}
6047: @item 033 @tab !
6048: @item 034 @tab ``
6049: @item 035 @tab #
6050:
6051:
6052: @end multitable
6053:
6054: @node FreeM Project Coding Standards
6055: @appendix FreeM Project Coding Standards
6056:
6057: @section Module Headers
6058: @cindex coding standards, module headers
6059:
6060: Module headers should adhere to the following format (where @code{Dollar} should be replaced with a dollar sign):
6061:
6062: @verbatim
6063: /*
6064: * DollarIdDollar
6065: * Function prototypes, structs, and macros for FreeM
6066: * binding library
6067: *
6068: *
6069: * Author: Serena Willis <jpw@coherent-logic.com>
6070: * Copyright (C) 1998 MUG Deutschland
6071: * Copyright (C) <Year> Coherent Logic Development LLC
6072: *
6073: * This file is part of FreeM.
6074: *
6075: * FreeM is free software: you can redistribute it and/or modify
6076: * it under the terms of the GNU Affero Public License as published by
6077: * the Free Software Foundation, either version 3 of the License, or
6078: * (at your option) any later version.
6079: *
6080: * FreeM is distributed in the hope that it will be useful,
6081: * but WITHOUT ANY WARRANTY; without even the implied warranty of
6082: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
6083: * GNU Affero Public License for more details.
6084: *
6085: * You should have received a copy of the GNU Affero Public License
6086: * along with FreeM. If not, see <https://www.gnu.org/licenses/>.
6087: *
6088: * DollarLogDollar
6089: *
6090: * SPDX-FileCopyrightText: (C) 2025 Coherent Logic Development LLC
6091: * SPDX-License-Identifier: AGPL-3.0-or-later
6092: **/
6093: @end verbatim
6094:
6095: @section Variable Naming
6096: @cindex coding standards, variable naming
6097:
6098: 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.
6099:
6100: Constants defined via the C preprocessor should be in all uppercase letters, with words within them likewise delimited by underscores, such as:
6101:
6102: @verbatim
6103: #define MY_USEFUL_CONSTANT 1
6104: @end verbatim
6105:
6106: @section Indentation and General Layout
6107: @cindex coding standards, indentation
6108: @cindex coding standards, layout
6109:
6110: 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.
6111:
6112: This project follows a modified version of what is known as the Stroustrup indentation style.
6113:
6114: @section Brace Placement (Functions)
6115: @cindex coding standards, brace placement, functions
6116:
6117: 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.
6118:
6119: Below is a correct example:
6120:
6121: @verbatim
6122: int main(int argc, char **argv, char **envp)
6123: {
6124:
6125: }
6126: @end verbatim
6127:
6128: @section Brace Placement (if-for-while-do)
6129: @cindex coding standards, brace placement, if-for-while-do
6130:
6131: 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}:
6132:
6133: @verbatim
6134: if (x) {
6135: ...
6136: }
6137: else {
6138: ...
6139: }
6140:
6141: while (1) {
6142: ...
6143: }
6144:
6145: for (i = 1; i < 10; i++) {
6146: ...
6147: }
6148:
6149: do {
6150: ...
6151: } while (x);
6152: @end verbatim
6153:
6154: Single-statement if blocks should be isolated to a single line:
6155:
6156: @verbatim
6157: if (x) stmt();
6158: @end verbatim
6159:
6160: not:
6161:
6162: @verbatim
6163: if (x)
6164: stmt ();
6165: @end verbatim
6166:
6167: 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.
6168:
6169: 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:
6170:
6171: @verbatim
6172: if (x) {
6173: foo();
6174: }
6175: else if (y) {
6176: bar();
6177: }
6178: else {
6179: bas();
6180: }
6181: @end verbatim
6182:
6183: @section Labels and goto
6184: @cindex coding standards, labels
6185: @cindex coding standards, goto
6186:
6187: Labels must begin in column 1, and have two lines of vertical space above and one beneath.
6188:
6189: @section Preprocessor Conditionals
6190: @section coding standards, preprocessor conditionals
6191:
6192: I have struggled with this, but have settled upon the standard practice of keeping them in column 1.
6193:
6194: @section Overall Program Spacing
6195: @cindex coding standards, spacing of programs
6196:
6197: @itemize @bullet
6198: @item
6199: Variable declarations fall immediately beneath the opening curly brace, and should initialize the variable right there whenever initialization is used.
6200:
6201: @item
6202: One line between the last variable declaration and the first line of real code.
6203:
6204: @item
6205: 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.
6206:
6207: @item
6208: 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.
6209: @end itemize
6210:
6211: @section The switch() Statement
6212: @cindex coding standards, switch()
6213:
6214: 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:
6215:
6216: @verbatim
6217: switch(foo) {
6218:
6219: case some_const:
6220: foo();
6221:
6222: break;
6223:
6224: case some_other_const:
6225: bar();
6226:
6227: break;
6228:
6229: default:
6230: exit(1);
6231:
6232: break;
6233: }
6234: @end verbatim
6235:
6236: @section Comments
6237: @cindex coding standards, comments
6238:
6239: We use C-style comments (@code{/* comment */}) exclusively, even on single-line comments. C++ comments (@code{// comment}) are not permitted.
6240:
6241: @node Index
6242: @unnumbered Index
6243:
6244: @printindex cp
6245:
6246: @bye
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