Annotation of freem/doc/freem.texi, revision 1.3
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3: @setfilename freem.info
4: @settitle The FreeM Manual
5:
6: @copying
1.3 ! snw 7: This manual is for FreeM, (version cvs-current), which is a free and open-source implementation of the M programming language.
1.1 snw 8:
9:
10: Copyright @copyright{} 2014-2024 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}
1.3 ! snw 21: @subtitle Version cvs-current
1.1 snw 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 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:
114: 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.
115:
116: 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.
117:
118: 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.
119:
120: @section Production Readiness
121:
122: FreeM is not yet production-ready. There are several show-stopping bugs that preclude a general release for public use:
123:
124: @itemize @bullet
125:
126: @item
127: @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.
128:
129: @item
130: Server sockets are not yet implemented.
131:
132: @item
133: There are some situations that can result in segmentation faults and/or lock-ups.
134:
135: @item
136: In spite of our best efforts, this manual is not yet complete.
137:
138: @end itemize
139:
140: @section Contributors
141: Current contributors denoted with a @emph{+} following their name and role.
142: @cindex contributors, ha-Ashkenaz, Shalom
143: @cindex contributors, Best, John
144: @cindex contributors, Diamond, Jon
145: @cindex contributors, Fox, Ronald L.
146: @cindex contributors, Gerum, Winfried
147: @cindex contributors, Kreis, Greg
148: @cindex contributors, Landis, Larry
149: @cindex contributors, Milligan, Lloyd
150: @cindex contributors, Morris, Steve
151: @cindex contributors, Murray, John
152: @cindex contributors, Pastoors, Wilhelm
153: @cindex contributors, Schell, Kate
154: @cindex contributors, Schofield, Lyle
155: @cindex contributors, Stefanik, Jim
156: @cindex contributors, Trocha, Axel
157: @cindex contributors, Walters, Dick
158: @cindex contributors, Whitten, David
159: @cindex contributors, Wicksell, David
160: @cindex contributors, Willis, Serena
161: @cindex contributors, Zeck, Steve
162:
163: @itemize @bullet
164:
165: @item
166: Shalom ha-Ashkenaz (Original Implementer)
167:
168: @item
169: John Best (IBM i and OS/400)
170:
171: @item
172: Jon Diamond (Library, Utilities, Conformance)
173:
174: @item
175: Ronald L. Fox (Initial port to Red Hat 5/libc-6)
176:
177: @item
178: Winfried Gerum (Code, Advice, MTA coordination)
179:
180: @item
181: Greg Kreis (Hardhats coordination, Dependencies)
182:
183: @item
184: Larry Landis (Coordination, Code, Documentation)
185:
186: @item
187: Rick Marshall (Testing, MDC Conformance) @emph{+}
188:
189: @item
190: Lloyd Milligan (Code, Testing, Documentation)
191:
192: @item
193: Steve Morris (Code, Microsoft)
194:
195: @item
196: John Murray (Code, Conformance)
197:
198: @item
199: Wilhelm Pastoors (Testing, Documentation)
200:
201: @item
202: Kate Schell (Coordination, Conformance, MTA, MDC, Advice)
203:
204: @item
205: Lyle Schofield (Advice, Prioritization, Tracking, Project Management)
206:
207: @item
208: Jim Stefanik (GNU/Linux on s390x, IBM AIX, IBM z/OS)
209:
210: @item
211: Axel Trocha (Code, Utilities)
212:
213: @item
214: Dick Walters (Project Lead, Chief Coordinator, MTA)
215:
216: @item
217: David Whitten (QA Test Suite, MDC, Advice) @emph{+}
218:
219: @item
220: David Wicksell (Debugging, Code, Testing) @emph{+}
221:
222: @item
223: Serena Willis (Current Maintainer and Project Lead) @emph{+}
224:
225: @item
226: Steve Zeck (Code)
227:
228: @end itemize
229: @node FreeM Invocation
230: @chapter FreeM Invocation
231: @cindex invocation, command-line
232: @cindex options, command-line
233:
234: @section Synopsis
235: @example
236: $ @command{./freem} [@emph{OPTIONS}...] [[-r <entryref>] | [--routine=<entryref>]]
237: @end example
238:
239: When FreeM loads, it searches the @code{SYSTEM} namespace for the @code{^%SYSINIT} routine, and begins executing it.
240:
241: When @code{-r} or @code{--routine} are passed on the command line, FreeM will load and run the specified routine instead of @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.
242:
243: @section Command-Line Options
244:
245: @table @asis
246:
247: @item @option{-d}, @option{--daemon}
248: Starts the FreeM daemon, exactly one of which must be running at all times in order for FreeM interpreter and fmadm processes to function.
249:
250: @item @option{-e}, @option{--environment}
251: Selects the environment to be used. If no environment is specified, @code{DEFAULT} is used.
252:
253: @item @option{-k}, @option{--nofork}
254: When used with @option{-d} or @option{--daemon}, causes the FreeM daemon to run instead in the foreground. Useful for debugging.
255:
256: @item @option{-p}, @option{--pidfile}
257: When used with @option{-d} or @option{--daemon}, sets the file in which the PID of the running daemon is stored.
258:
259: @item @option{-S}, @option{--shmsize}
260: 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.
261:
262: @item @option{-c}, @option{--config}
263: Specify a configuration file other than @code{$PREFIX/etc/freem.conf}.
264:
265: @item @option{-h}, @option{--help}
266: Display a help message showing valid FreeM options.
267:
268: @item @option{-i}, @option{--import}
269: Causes your UNIX environment variables to be imported into FreeM's local symbol table.
270:
271: @item @option{-f}, @option{--filter}
272: Allows your M routines to be used as UNIX filters.
273:
274: @item @option{-n @emph{<namespace-name>}}, @option{--namespace=@emph{<namespace-name>}}
275: Selects the FreeM namespace to be entered on startup. Must be defined in @file{/etc/freem.conf}.
276:
277: @item @option{-r @emph{<entryref>}}, @option{--routine=@emph{<entryref>}}
278: Causes @code{<entryref>} to be executed at load, instead of @code{^%SYSINIT}.
279:
280: @item @option{--standard=@emph{<standard>}}
281: Sets the default FreeM dialect to use for new routine buffers.
282:
283: Valid values for @code{@emph{<standard>}} are as follows:
284:
285: @table @code
286: @item @code{M77}
287: Restricts FreeM to use only features specified by the 1977 M standard.
288: @item @code{M84}
289: Restricts FreeM to use only features specified by the 1984 M standard.
290: @item @code{M90}
291: Restricts FreeM to use only features specified by the 1990 M standard.
292: @item @code{M95}
293: Restricts FreeM to use only features specified by the 1995 M standard.
294: @item @code{MDS}
295: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
296: @item @code{M5}
297: Restricts FreeM to use only features proposed by the upcoming M5 standard.
298: @item @code{FREEM}, @code{EXTENDED}
299: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{$DIALECT}.
300: @end table
301:
302: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{@emph{<standard>}}.
303:
304: @item @option{-v}, @option{--version}
305: Displays FreeM version information.
306:
307: @item @option{-x @emph{<mcode>}}, @option{--execute=@emph{<mcode>}}
308: Executes M code @code{<mcode>} at startup instead of the startup routine.
309:
310: @end table
311:
312: @section Using FreeM for Shell Scripting
313: @cindex routines, as shell scripts
314: @cindex shebang line
315: @cindex shell scripting
316:
317: 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.
318: The following example presumes that FreeM is installed at @file{/usr/local/bin/freem} and uses the @code{USER} namespace:
319:
320: @example
321: #!/usr/local/bin/freem
322: MYSCRIPT ;
323: SET ^$JOB($JOB,"NAMESPACE")="USER"
324: WRITE "This is output from an M routine used as a shell script.",!
325: Q
326: @end example
327:
328: 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.
329:
330: You will also need to set the script's permissions to @emph{executable} in order for this to work:
331:
332: @example
333: $ chmod +x @emph{myscript.m}
334: @end example
335:
336: @node The FreeM Daemon
337: @chapter The FreeM Daemon
338: @cindex daemon, freem
339:
340: The FreeM 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 daemon does @emph{not} function as a write daemon for global storage.
341:
342: One daemon process is required per FreeM environment, and can be started as follows:
343:
344: @example
345: $ freem --daemon [--nofork] [--environment=<environment-name>] [--user=<username>] \
346: [--group=<group-name>] [--pidfile=<pid-file>] [--shmsize=<bytes>]
347: @end example
348:
349: 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.
350:
351: 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.
352:
353: The @option{--user} and @option{--group} options are only valid when the FreeM daemon is started by the superuser, and will cause the daemon to reduce its runtime privileges to those of the specified user and group, and run as that user and/or group. We recommend creating a @code{freem} user and group and running the FreeM daemon with @code{--user=freem --group=freem}.
354:
355: The @option{--pidfile} option specifies the file in which the FreeM daemon will store its own PID. If running as the superuser, the FreeM daemon will store the PID file in @code{/var/run/freem.pid}. Otherwise, the PID file will be stored as @code{.freem.pid} in the home directory of the user account which owns the FreeM daemon process.
356:
357: 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.
358:
359: Attempting to start a FreeM interpreter process without a daemon running with the same environment name will result in an error.
360:
361: @node The FreeM Direct-Mode Environment
362: @chapter The FreeM Direct-Mode Environment
363: @cindex command line interface
364: @cindex direct mode
365: @cindex execution, interactive
366: @cindex modes, programmer
367:
368:
369: 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>}}:
370:
371: @example
1.3 ! snw 372: Coherent Logic Development FreeM version cvs-current (x86_64-pc-linux-gnu)
1.1 snw 373: Copyright (C) 2014, 2020, 2021 Coherent Logic Development LLC
374:
375:
376: USER>
377: @end example
378:
379: The prompt (@code{USER>}) indicates the currently-active namespace. If any uncommitted direct-mode transactions have been started, the prompt will change to reflect the current value of @code{@ref{$TLEVEL}}:
380:
381: @example
382: TL1:USER>
383: @end example
384:
385: In the above example, @code{TL1} indicates that @code{@ref{$TLEVEL}} is currently @emph{1}.
386:
387: @section Direct-Mode Commands
388:
389: When you are in direct mode, in addition to M commands, a number of internal commands are available to help developers be more productive:
390:
391: @table @asis
392:
393: @item @command{?}
394: Accesses FreeM online help. Requires GNU @command{info(1)} to be installed on your local system.
395:
396: @item @command{events}
397: Writes a list of @emph{event classes} and their @code{ABLOCK} counts:
398:
399: @example
400: USER> events
401:
402: Event Class Processing Mode ABLOCK Count
403: ----------- --------------- ------------
404: COMM Disabled 0
405: HALT Disabled 0
406: IPC Disabled 0
407: INTERRUPT Disabled 0
408: POWER Disabled 0
409: TIMER Disabled 0
410: USER Disabled 0
411: WAPI Disabled 0
412: TRIGGER Disabled 0
413: @end example
414:
415:
416: @anchor{trantab}
417: @item @command{trantab}
418: Displays information about any uncommitted transactions currently in-flight for this process.
419:
420: @anchor{jobtab}
421: @item @command{jobtab}
422: Displays a summary of the FreeM job table.
423:
424: @anchor{locktab}
425: @item @command{locktab}
426: Displays a list of @code{LOCK}s held in the current environment.
427:
428: @anchor{rbuf}
429: @item @command{rbuf}
430: Lists the status of all FreeM routine buffers.
431:
432: @anchor{dbstats}
433: @item @command{dbstats}
434: Shows statistics for the BerkeleyDB global handler.
435:
436: @anchor{wh}
437: @item @command{wh}
438: Forces an immediate flush of this process's @code{readline} history buffer to disk.
439:
440: @anchor{shmstat}
441: @item @command{shmstat}
442: Displays the configuration of FreeM shared memory. Intended only for advanced debugging of the FreeM environment.
443:
444: @anchor{shmpages}
445: @item @command{shmpages}
446: Lists the status of each FreeM shared memory page. Intended only for advanced debugging of the FreeM environment.
447:
448: @anchor{history}
449: @item @command{history}
450: Prints a list of all the direct-mode commands you have entered across all sessions.
451:
452: @anchor{rcl}
453: @item @command{rcl @emph{<history-index>}}
454: 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.
455:
456: @item @command{!!}
457: Launches a subshell within the FreeM direct mode, allowing the user to run operating system commands.
458:
459: @example
460: USER> !!
461:
462: Type Ctrl-D to exit from the shell
463: $ uname -a
464: Linux hesperos 4.19.0-17-amd64 #1 SMP Debian 4.19.194-3 (2021-07-18) x86_64 GNU/Linux
465: $ exit
466:
467: USER>
468: @end example
469:
470: @item @command{!@emph{<external-command>}}
471: 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}.
472:
473: 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>}.
474:
475: 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")}.
476:
477: 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}.
478:
479: @end table
480:
481: @cindex HALT, in direct-mode
482: 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:
483:
484: @example
485: USER> TSTART
486:
487:
488: TL1:USER> SET ^MYGLOBAL=1
489:
490:
491: TL1:USER> HALT
492:
493: UNCOMMITTED TRANSACTIONS EXIST:
494:
495: $TLEVEL 1*
496: Operations for Transaction ID: k8xj1de
497: 1: action = 0 key = ^MYGLOBAL data = 1
498:
499: Would you like to c)ommit or r)ollback the above transactions and their operations? ($TLEVEL = 1) r
500:
501:
502: Transactions have been rolled back.
503: @end example
504:
505: In the above example, the user selected @code{r} to rollback the single pending transaction.
506:
507: @section REPL Functionality
508: @cindex REPL, direct-mode
509:
510: FreeM direct mode allows you to enter M expressions directly from the direct-mode prompt, as long as they begin with a number:
511:
512: @example
513: USER> S DENOM=10
514:
515:
516: USER> 100/DENOM
517:
518: 10
519: USER>
520: @end example
521:
522: Such expressions will be immediately evaluated, and the result printed on @code{@ref{$IO}}.
523:
524: @node Directives
525: @chapter Directives
526: @cindex directives
527:
528: In FreeM, a directive is an instruction embedded in an M comment, and passed to the interpreter to affect a change that is specific to the current routine only.
529:
530: The format of a directive is @code{;%@emph{<directive-name>}}, where @code{@emph{<directive-name>}} is one of the directives listed below.
531:
532: @menu
533: * %DIALECT:: Sets the M dialect in effect.
534: @end menu
535:
536: @anchor{%DIALECT}
537: @section %DIALECT
538: @cindex %DIALECT
539: @cindex directives, %DIALECT
540:
541: Sets the M dialect in effect for the current routine buffer; also sets the @code{$DIALECT} special variable to match. See also @ref{$DIALECT}.
542:
543: @emph{Syntax}
544:
545: @example
546: ;%DIALECT @emph{<dialect>}
547: @end example
548:
549: Valid values for @code{@emph{<dialect>}} are as follows:
550:
551: @table @code
552: @item @code{M77}
553: Restricts FreeM to use only features specified by the 1977 M standard.
554: @item @code{M84}
555: Restricts FreeM to use only features specified by the 1984 M standard.
556: @item @code{M90}
557: Restricts FreeM to use only features specified by the 1990 M standard.
558: @item @code{M95}
559: Restricts FreeM to use only features specified by the 1995 M standard.
560: @item @code{MDS}
561: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
562: @item @code{M5}
563: Restricts FreeM to use only features proposed by the upcoming M5 standard.
564: @item @code{FREEM}, @code{EXTENDED}
565: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{%DIALECT}.
566: @end table
567:
568: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{%DIALECT}.
569:
570:
571: @node Intrinsic Special Variables
572: @chapter Intrinsic Special Variables
573: @cindex variables, intrinsic special
574:
575: @menu
576: * $DEVICE:: $IO device status.
577: * $DIALECT:: Current M dialect.
578: * $ECODE:: Latest M error code.
579: * $ESTACK:: Error stack info.
580: * $ETRAP:: Standard error handler code.
581: * $HOROLOG:: Current date and time.
582: * $IO:: Current I/O device.
583: * $JOB:: PID of current process.
584: * $KEY:: Characters terminating last @code{READ} command.
585: * $PDISPLAY:: Current primary MWAPI display.
586: * $PRINCIPAL:: I/O channel of terminal.
587: * $REFERENCE:: Most recent global reference.
588: * $QUIT:: Whether a @code{QUIT} command requires an argument in the current execution context.
589: * $STACK:: Current program execution stack level.
590: * $STORAGE:: Number of bytes available in the heap.
591: * $SYSTEM:: MDC system ID of FreeM.
592: * $TEST:: Truth value of last conditional expression or result of certain @code{LOCK} operations.
593: * $TLEVEL:: Current level of transaction nesting.
594: * $WITH:: Current variable prefix set by @code{WITH} command.
595: * $X:: Current horizontal screen position.
596: * $Y:: Current vertical screen position.
597: * $ZA:: Current position of file on @code{$IO}.
598: * $ZB:: Most recent keystroke.
599: * $ZCONTROLC:: Control-C handling flag.
600: * $ZDATE:: Current date in locale-specific representation.
601: * $ZERROR:: Last error message.
602: * $ZHOROLOG:: Date and time, including milliseconds.
603: * $ZINRPT:: State of the interrupt enable/disable flag.
604: * $ZJOB:: PID of parent process, if applicable.
605: * $ZLOCAL:: Last local variable reference.
606: * $ZNAME:: Name of current M routine.
607: * $ZPRECISION:: Digits of arithmetical precision.
608: * $ZREFERENCE:: Last gvn referenced.
609: * $ZSYSTEM:: Return value of last external command.
610: * $ZTIME:: Current time in locale-specific representation.
611: * $ZTRAP:: Entryref to be executed on error condition.
612: * $ZUT:: Microseconds since the UNIX epoch.
613: * $ZVERSION:: Version of FreeM and GNU host triplet.
614: @end menu
615:
616: @node $DEVICE
617: @section $DEVICE
618: @cindex $DEVICE
619: @cindex intrinsic special variables, $DEVICE
620:
621: Returns the status of the device currently in use.
622:
623: If @code{$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.
624:
625: @node $DIALECT
626: @section $DIALECT
627: @cindex $DIALECT
628: @cindex intrinsic special variables, $DIALECT
629:
630: Returns or sets the language dialect of the current routine.
631:
632: Valid values for @code{$DIALECT} are as follows:
633:
634: @table @code
635: @item @code{M77}
636: Restricts FreeM to use only features specified by the 1977 M standard.
637: @item @code{M84}
638: Restricts FreeM to use only features specified by the 1984 M standard.
639: @item @code{M90}
640: Restricts FreeM to use only features specified by the 1990 M standard.
641: @item @code{M95}
642: Restricts FreeM to use only features specified by the 1995 M standard.
643: @item @code{MDS}
644: Restricts FreeM to use only features proposed by the Millennium Draft Standard.
645: @item @code{M5}
646: Restricts FreeM to use only features proposed by the upcoming M5 standard.
647: @item @code{FREEM}, @code{EXTENDED}
648: Removes all standards-based restrictions and allows full access to all FreeM features. This is the default value of @code{$DIALECT}.
649: @end table
650:
651: Please note that FreeM is not entirely standards-compliant, regardless of the value of @code{$DIALECT}.
652:
653: @node $ECODE
654: @section $ECODE
655: @cindex $ECODE
656: @cindex intrinsic special variables, $ECODE
657:
658: Returns a comma-delimited list of error conditions currently present, and is writable. An empty @code{$ECODE} indicates no errors.
659:
660: @node $ESTACK
661: @section $ESTACK
662: @cindex $ESTACK
663: @cindex intrinsic special variables, $ESTACK
664:
665: Returns the depth of the program execution stack since the last time @code{$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.
666:
667: @node $ETRAP
668: @section $ETRAP
669: @cindex $ETRAP
670: @cindex intrinsic special variables, $ETRAP
671:
672: Sets or retrieves the M code that is run when an error is encountered or @code{@ref{$ECODE}} is set to a non-blank value. @code{$ETRAP} code executes when @code{$ECODE} becomes non-blank.
673:
674:
675: @node $HOROLOG
676: @section $HOROLOG
677: @cindex $HOROLOG
678: @cindex intrinsic special variables, $HOROLOG
679:
680: Returns a string containing the current date and time as @code{<days>,<seconds>}, where @code{<days>} represents the number of days since the M epoch (midnight on 31 December 1840),
681: and @code{<seconds>} represents the number of seconds since the most recent midnight.
682:
683: @cartouche
684: @quotation
685: @emph{FreeM Extension}
686:
687: In FreeM, @code{$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.
688: @end quotation
689: @end cartouche
690:
691: @node $IO
692: @section $IO
693: @cindex $IO
694: @cindex intrinsic special variables, $IO
695:
696: Represents the current input/output device. Read-only.
697:
698: @node $JOB
699: @section $JOB
700: @cindex $JOB
701: @cindex intrinsic special variables, $JOB
702:
703: Represents the process ID of the FreeM instance currently in use.
704:
705: @node $KEY
706: @section $KEY
707: @cindex $KEY
708: @cindex intrinsic special variables, $KEY
709:
710: Represents the sequence of control characters that terminated the last @code{@ref{READ}} command on @code{@ref{$IO}}.
711:
712: @node $PDISPLAY
713: @section $PDISPLAY
714: @cindex $PDISPLAY
715: @cindex intrinsic special variables, $PDISPLAY
716:
717: Represents the current principal display for M Windowing API operations. Commonly used as an index into the @code{@ref{^$DISPLAY}} structured system variable.
718:
719: @node $PRINCIPAL
720: @section $PRINCIPAL
721: @cindex $PRINCIPAL
722: @cindex intrinsic special variables, $PRINCIPAL
723:
724: Represents the primary input/output device. Usually a terminal or virtual terminal.
725:
726: @node $REFERENCE
727: @section $REFERENCE
728: @cindex $REFERENCE
729: @cindex intrinsic special variables, $REFERENCE
730:
731: Returns the last @emph{glvn} referenced. Can be @code{@ref{SET}}, and also stacked with @code{@ref{NEW}}.
732:
733: @node $QUIT
734: @section $QUIT
735: @cindex $QUIT
736: @cindex intrinsic special variables, $QUIT
737:
738: If the current execution context was invoked as an extrinsic function, @code{$QUIT} returns @emph{1}. Otherwise, returns @emph{0}.
739:
740: When @code{$QUIT} returns @emph{1}, a subsequent @code{@ref{QUIT}} command must have an argument.
741:
742: @node $STACK
743: @section $STACK
744: @cindex $STACK
745: @cindex intrinsic special variables, $STACK
746:
747: Represents the current stack level.
748:
749: @node $STORAGE
750: @section $STORAGE
751: @cindex $STORAGE
752: @cindex intrinsic special variables, $STORAGE
753:
754: Represents the number of bytes of free space available in FreeM's heap.
755:
756: @node $SYSTEM
757: @section $SYSTEM
758: @cindex $SYSTEM
759: @cindex intrinsic special variables, $SYSTEM
760:
761: Returns the MDC system ID of FreeM, as well as the environment ID of the current environment.
762:
763: @node $TEST
764: @section $TEST
765: @cindex $TEST
766: @cindex intrinsic special variables, $TEST
767:
768: @code{$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}.
769:
770: @code{$TEST} is implicitly @code{NEW}ed when entering a new stack frame for extrinsic functions and argumentless @code{@ref{DO}}. @code{$TEST}
771: is @emph{not} implicitly @code{NEW}ed when a new stack frame is entered with an argumented @code{DO}.
772:
773: 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.
774:
775: @node $TLEVEL
776: @section $TLEVEL
777: @cindex $TLEVEL
778: @cindex intrinsic special variables, $TLEVEL
779:
780: Returns a numeric value indicating the current level of transaction nesting in the process. When @code{$TLEVEL} is greater than @emph{0},
781: uncommitted transactions exist.
782:
783: @node $WITH
784: @section $WITH
785: @cindex $WITH
786: @cindex intrinsic special variables, $WITH
787:
788: Returns the variable prefix set by the @code{@ref{WITH}} command.
789:
790: @node $X
791: @section $X
792: @cindex $X
793: @cindex intrinsic special variables, $X
794:
795: Represents the current column position of the FreeM cursor.
796:
797: @cartouche
798: @quotation
799: In FreeM, setting @code{$X} will move the FreeM cursor.
800: @end quotation
801: @end cartouche
802:
803:
804: @node $Y
805: @section $Y
806: @cindex $Y
807: @cindex intrinsic special variables, $Y
808:
809: Represents the current row position of the FreeM cursor.
810:
811: @cartouche
812: @quotation
813: In FreeM, setting @code{$Y} will move the FreeM cursor.
814: @end quotation
815: @end cartouche
816:
817:
818: @node $ZA
819: @section $ZA
820: @cindex $ZA
821: @cindex intrinsic special variables, $ZA
822: @cindex intrinsic special variables, implementation-specific
823:
824: On the @code{HOME} device, always @code{0}. On other devices, returns the current position of the file opened on I/O channel @code{@ref{$IO}}.
825:
826: @node $ZB
827: @section $ZB
828: @cindex $ZB
829: @cindex intrinsic special variables, $ZB
830: @cindex intrinsic special variables, implementation-specific
831:
832: Represents the last keystroke.
833:
834: @node $ZCONTROLC
835: @section $ZCONTROLC
836: @cindex $ZCONTROLC
837: @cindex intrinsic special variables, $ZCONTROLC
838: @cindex intrinsic special variables, implementation-specific
839:
840: Returns the status of the Ctrl-C flag and resets it to @emph{false}.
841:
842: @node $ZDATE
843: @section $ZDATE
844: @cindex $ZDATE
845: @cindex intrinsic special variables, $ZDATE
846: @cindex intrinsic special variables, implementation-specific
847:
848: Returns the current date, in the preferred representation for the current system locale.
849:
850: @node $ZERROR
851: @section $ZERROR
852: @cindex $ZERROR
853: @cindex intrinsic special variables, $ZERROR
854: @cindex intrinsic special variables, implementation-specific
855:
856: Returns the last error message.
857:
858: @node $ZHOROLOG
859: @section $ZHOROLOG
860: @cindex $ZHOROLOG
861: @cindex intrinsic special variables, $ZHOROLOG
862: @cindex intrinsic special variables, implementation-specific
863:
864: Output @code{@ref{$HOROLOG}}-style time, with the addition of milliseconds.
865:
866: @node $ZINRPT
867: @section $ZINRPT
868: @cindex $ZINRPT
869: @cindex intrinsic special variables, $ZINRPT
870: @cindex intrinsic special variables, implementation-specific
871:
872: Gets or sets the interrupt enable/disable flag.
873:
874: @node $ZJOB
875: @section $ZJOB
876: @cindex $ZJOB
877: @cindex intrinsic special variables, $ZJOB
878: @cindex intrinsic special variables, implementation-specific
879:
880: Returns the @code{@ref{$JOB}} value of the parent process if the current process was started by a @code{@ref{JOB}} command. Otherwise, returns an empty string.
881:
882: @node $ZLOCAL
883: @section $ZLOCAL
884: @cindex $ZLOCAL
885: @cindex intrinsic special variables, $ZLOCAL
886: @cindex intrinsic special variables, implementation-specific
887:
888: Returns the last local variable referenced.
889:
890: @node $ZNAME
891: @section $ZNAME
892: @cindex $ZNAME
893: @cindex intrinsic special variables, $ZNAME
894: @cindex intrinsic special variables, implementation-specific
895:
896: Returns the name of the current routine.
897:
898: @node $ZPRECISION
899: @section $ZPRECISION
900: @cindex $ZPRECISION
901: @cindex intrinsic special variables, $ZPRECISION
902: @cindex intrinsic special variables, implementation-specific
903:
904: Gets or sets the number of digits of numeric precision used for fixed-point decimal arithmetic. If @code{^$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{$ZPRECISION} defaults to 100 digits, with a maximum of 20,000 digits.
905:
906: @xref{^$JOB}.
907:
908: @node $ZREFERENCE
909: @section $ZREFERENCE
910: @cindex $ZREFERENCE
911: @cindex intrinsic special variables, $ZREFERENCE
912: @cindex intrinsic special variables, implementation-specific
913:
914: Returns the last @emph{gvn} referenced.
915:
916: @node $ZSYSTEM
917: @section $ZSYSTEM
918: @cindex $ZSYSTEM
919: @cindex intrinsic special variables, $ZSYSTEM
920: @cindex intrinsic special variables, implementation-specific
921:
922: Represents the return value of the last external command run with @code{!}.
923:
924: @node $ZTIME
925: @section $ZTIME
926: @cindex $ZTIME
927: @cindex intrinsic special variables, $ZTIME
928: @cindex intrinsic special variables, implementation-specific
929:
930: Returns the system time in the preferred representation for the current system locale.
931:
932: @node $ZTRAP
933: @section $ZTRAP
934: @cindex $ZTRAP
935: @cindex intrinsic special variables, $ZTRAP
936: @cindex intrinsic special variables, implementation-specific
937:
938: Sets or retrieves the entryref to be executed when an M program execution error occurs under FreeM-style or DSM 2.0-style error processing.
939:
940: In FreeM-style error processing, @code{$ZTRAP} is specific to each program execution stack level.
941:
942: In DSM 2.0-style error processing, @code{$ZTRAP} is the same for all program execution stack levels.
943:
944: When FreeM encounters an error, if @code{$ZTRAP} is nonempty and @code{$ETRAP} is empty, FreeM will perform an implicit @code{@ref{GOTO}} to the entryref indicated in @code{$ZTRAP}.
945:
946: 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.
947:
948: @node $ZUT
949: @section $ZUT
950: @cindex $ZUT
951: @cindex intrinsic special variables, $ZUT
952: @cindex intrinsic special variables, implementation-specific
953:
954: Returns the number of microseconds elapsed since the UNIX epoch (Jan 1, 1970 0:00:00).
955:
956: @node $ZVERSION
957: @section $ZVERSION
958: @cindex $ZVERSION
959: @cindex intrinsic special variables, $ZVERSION
960: @cindex intrinsic special variables, implementation-specific
961:
962: Returns the version of FreeM in use, as well as the GNU host triplet for the current FreeM build.
963:
964: See @emph{https://wiki.osdev.org/Target_Triplet}.
965:
966: @node Intrinsic Functions
967: @chapter Intrinsic Functions
968:
969: @menu
970: * $ASCII():: Return ASCII code for character in string.
971: * $CHAR():: Return character for one or more ASCII codes.
972: * $DATA():: Retrieve definition and characteristics of array node.
973: * $EXTRACT():: Return a substring of a string.
974: * $FIND():: Find position of substring within string.
975: * $FNUMBER():: Format a number according to formatting codes.
976: * $GET():: Return value of glvn or a default if undefined.
977: * $INSTANCEOF():: Determine if lvn is an instance of a class.
978: * $JUSTIFY():: Right-justify a string based on specified length.
979: * $LENGTH():: Return length or delimiter-based piece count of string.
980: * $NAME():: Return canonical name from string representation of glvn.
981: * $NEXT():: Return next numeric subscript following given glvn.
982: * $ORDER():: Return next subscript at same level of specified glvn.
983: * $PIECE():: Return one or more delimited pieces of a string.
984: * $QLENGTH():: Return subscript count of glvn.
985: * $QSUBSCRIPT():: Return a specified subscript from glvn.
986: * $QUERY():: Return next subscript of specified glvn.
987: * $RANDOM():: Return pseudorandom integer up to a maximum value.
988: * $REVERSE():: Reverse a string.
989: * $SELECT():: Return value from first true condition in list of expressions.
990: * $STACK():: Return information about the program stack.
991: * $TEXT():: Return line of code from a routine.
992: * $TRANSLATE():: Substitute specified characters in a string.
993: * $TYPE():: Return class of the specified lvn.
994: * $VIEW():: Retrieve implementation-specific information.
995: * $ZBOOLEAN():: Perform boolean operations on numeric arguments.
996: * $ZCALL():: Unknown.
997: * $ZCRC():: Generate checksum of a string argument.
998: * $ZDATA():: Unknown.
999: * $ZDATE():: Convert @code{@ref{$HOROLOG}} string into human-readable date.
1000: * $ZEDIT():: Unknown.
1001: * $ZHOROLOG():: Convert date/time values to @code{@ref{$HOROLOG}} format.
1002: * $ZKEY():: Unknown.
1003: * $ZLENGTH():: Unknown.
1004: * $ZLSD():: Compute Levenshtein distance between two arguments.
1005: * $ZM():: Unknown.
1006: * $ZNAME():: Unknown.
1007: * $ZNEXT():: Unknown.
1008: * $ZORDER():: Unknown.
1009: * $ZPIECE():: Unknown.
1010: * $ZPREVIOUS():: Unknown.
1011: * $ZREPLACE():: Replace all instances of a substring within a string.
1012: * $ZSYNTAX():: Perform syntax check on string argument.
1013: * $ZTIME():: Convert a @code{@ref{$HOROLOG}} string into human-readable time.
1014: @end menu
1015:
1016: @node $ASCII()
1017: @section $ASCII
1018: @cindex $ASCII
1019: @cindex intrinsic functions, $ASCII
1020:
1021: Returns the ASCII code (in decimal) for one character in a string.
1022:
1023: @example
1024: SET RESULT=$ASCII(@emph{<string>}[,@emph{<index>}])
1025: @end example
1026:
1027:
1028: 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>}.
1029:
1030: @node $CHAR()
1031: @section $CHAR
1032: @cindex $CHAR
1033: @cindex intrinsic functions, $CHAR
1034:
1035: Returns a string of characters corresponding to a list of ASCII codes.
1036:
1037: @example
1038: SET RESULT=$CHAR(@emph{<ascii-code>}[,@emph{<ascii-code>},...])
1039: @end example
1040:
1041: @node $DATA()
1042: @section $DATA
1043: @cindex $DATA
1044: @cindex intrinsic functions, $DATA
1045:
1046: Returns a numeric value 0, 1, 10, or 11, depending on whether a referenced node is defined, has data, or has children:
1047:
1048: @example
1049: SET RESULT=$DATA(@emph{<node>})
1050: @end example
1051:
1052: The return values are as follows:
1053:
1054: @example
1055: 0: @emph{<node>} is undefined
1056: 1: @emph{<node>} has data but no children
1057: 10: @emph{<node>} has children but no data
1058: 11: @emph{<node>} has children and data
1059: @end example
1060:
1061: @node $EXTRACT()
1062: @section $EXTRACT
1063: @cindex $EXTRACT
1064: @cindex intrinsic functions, $EXTRACT
1065:
1066: Extracts a substring of a string.
1067:
1068: The first argument is the source string.
1069:
1070: The optional second argument specifies the starting position of the substring to extract, and defaults to @code{1}.
1071:
1072: The optional third argument specifies the ending position of the substring to extract, and defaults to the value of the second argument, or @code{1}.
1073:
1074: This example will extract the string @emph{FreeM} into the local variable @code{M}.
1075:
1076: @example
1077: SET NAME="FreeM is the best!"
1078: SET M=$EXTRACT(NAME,1,5)
1079: @end example
1080:
1081: It is also possible to use @code{$EXTRACT} on the left-hand side of a @code{SET} assignment in order to modify a substring:
1082:
1083: @example
1084: USER> SET FOO="ABCDEFG"
1085:
1086:
1087: USER> SET $EXTRACT(FOO,1,3)="XYZ"
1088:
1089:
1090: USER> WRITE FOO
1091:
1092: XYZDEFG
1093: @end example
1094:
1095: @node $FIND()
1096: @section $FIND
1097: @cindex $FIND
1098: @cindex intrinsic functions, $FIND
1099:
1100: Finds the character immediately following the first occurence of a substring within a string.
1101:
1102: The first argument is the source string.
1103:
1104: The second argument is the substring to be located.
1105:
1106: The optional third argument indicates the position within the source string at which to begin searching.
1107:
1108: @node $FNUMBER()
1109: @section $FNUMBER
1110: @cindex $FNUMBER
1111: @cindex intrinsic functions, $FNUMBER
1112:
1113: Formats a number according to a particular set of formatting codes.
1114:
1115: The first argument is the number to format.
1116:
1117: The second argument is the series of formatting codes.
1118:
1119: @node $GET()
1120: @section $GET
1121: @cindex $GET
1122: @cindex intrinsic functions, $GET
1123:
1124: Returns the value of a local, global, or SSVN if the specified item is defined, or a default value otherwise.
1125:
1126: The first argument is the local, global, or SSVN to be examined.
1127:
1128: The optional second argument is the default value to be returned if the referenced item is undefined, and defaults to the empty string.
1129:
1130: @node $INSTANCEOF()
1131: @section $INSTANCEOF
1132: @cindex $INSTANCEOF
1133: @cindex intrinsic functions, $INSTANCEOF
1134: @cindex object functions, $INSTANCEOF
1135:
1136: Returns @code{1} if the specified @emph{lvn} is an instance of class @emph{class}, or @code{0} otherwise.
1137:
1138: The first argument is a string representing a valid FreeM local variable.
1139:
1140: The second argument is a string representing a valid FreeM class.
1141:
1.2 snw 1142:
1.1 snw 1143:
1144: @example
1145: USER> N STR=$$^%STRING
1146:
1147: USER> W $INSTANCEOF("STR","^%STRING")
1148: 1
1149: @end example
1150:
1151: @node $JUSTIFY()
1152: @section $JUSTIFY
1153: @cindex $JUSTIFY
1154: @cindex intrinsic functions, $JUSTIFY
1155:
1156: Right-justifies a string based on a specified fixed length.
1157:
1158: The first argument is the source string.
1159:
1160: The second argument is the character length of the output.
1161:
1162: 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.
1163:
1164: @node $LENGTH()
1165: @section $LENGTH
1166: @cindex $LENGTH
1167: @cindex intrinsic functions, $LENGTH
1168:
1169: 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()}}).
1170:
1171: The first argument is the source string.
1172:
1173: 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.
1174:
1175: @node $NAME()
1176: @section $NAME
1177: @cindex $NAME
1178: @cindex intrinsic functions, $NAME
1179:
1180: Returns the canonical name reference along with some or all of its subscripts.
1181:
1182: The first argument is the source name.
1183:
1184: The optional second argument indicates the maximum subscript count to be returned, and defaults to the subscript count of the source name.
1185:
1186: @node $NEXT()
1187: @section $NEXT
1188: @cindex $NEXT
1189: @cindex intrinsic functions, $NEXT
1190:
1191: @node $ORDER()
1192: @section $ORDER
1193: @cindex $ORDER
1194: @cindex intrinsic functions, $ORDER
1195:
1196: @node $PIECE()
1197: @section $PIECE
1198: @cindex $PIECE
1199: @cindex intrinsic functions, $PIECE
1200:
1201: @emph{Syntax}
1202:
1203: @code{$PIECE(@emph{s},@emph{d}[,@emph{n}[,@emph{end}]])}
1204:
1205: Accesses the @code{n}th through @code{end} @code{d}-delimited pieces of string @code{s}.
1206:
1207: The first argument is the string to be evaluated.
1208:
1209: The second argument is the delimiter to be used.
1210:
1211: The optional third argument is the first @code{d}-delimited piece to access, and defaults to @code{1}.
1212:
1213: The optional fourth argument is the final @code{d}-delimited piece to access, and defaults to the value of the third argument (@code{n}).
1214:
1215: 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:
1216:
1217: @example
1218: ; ^jpw="this^is^a^piece"
1219: SET $PIECE(^jpw,"^",2)="isn't" ; => "this^isn't^a^piece"
1220: @end example
1221:
1222: @node $QLENGTH()
1223: @section $QLENGTH
1224: @cindex $QLENGTH
1225: @cindex intrinsic functions, $QLENGTH
1226:
1227: @emph{Syntax}
1228:
1229: @example
1230: @code{$QLENGTH(@emph{expr V glvn})}
1231: @end example
1232:
1233: Returns the number of subscripts in @emph{glvn}.
1234:
1235: @emph{Example}
1236: @example
1237: @code{SET SUBCT=$QLENGTH("^GBL(1,2,3)") ; => 3}
1238: @end example
1239:
1240: @node $QSUBSCRIPT()
1241: @section $QSUBSCRIPT
1242: @cindex $QSUBSCRIPT
1243: @cindex intrinsic functions, $QSUBSCRIPT
1244:
1245: @emph{Syntax}
1246:
1247: @example
1248: @code{$QSUBSCRIPT(@emph{expr V glvn},@emph{expr V n})}
1249: @end example
1250:
1251: Returns the @emph{n}th subscript of @emph{glvn}.
1252:
1253: @emph{Example}
1254:
1255: @example
1256: @code{SET SUB=$QSUBSCRIPT("^GBL(1,2,3)",2) ; => 2}
1257: @end example
1258:
1259: @node $QUERY()
1260: @section $QUERY
1261: @cindex $QUERY
1262: @cindex intrinsic functions, $QUERY
1263:
1264: Returns the next subscripted reference in a global.
1265:
1266: @emph{Syntax}
1267:
1268: @example
1269: @code{$QUERY(@emph{glvn})}
1270: @end example
1271:
1272: @emph{Example}
1273:
1274: We will assume the following data structure exists:
1275: @example
1276: ^jpw(1)=1
1277: ^jpw(1,2)="foo"
1278: ^jpw(2)=3
1279: ^jpw(3)=""
1280: @end example
1281:
1282: The following code will retrieve the next subscripted name after @code{^jpw(1)}:
1283:
1284: @example
1285: @code{SET NEXTNAM=$QUERY(^jpw(1)) ; => ^jpw(1,2)}
1286: @end example
1287:
1288: @node $RANDOM()
1289: @section $RANDOM
1290: @cindex $RANDOM
1291: @cindex intrinsic functions, $RANDOM
1292:
1293: @emph{Syntax}
1294:
1295: @example
1296: $RANDOM(@emph{max})
1297: @end example
1298:
1299: Returns a pseudo-random integer in the range of @code{0..@emph{max} - 1}
1300:
1301: @node $REVERSE()
1302: @section $REVERSE
1303: @cindex $REVERSE
1304: @cindex intrinsic functions, $REVERSE
1305:
1306: @emph{Syntax}
1307:
1308: @example
1309: $REVERSE(@emph{s})
1310: @end example
1311:
1312: Returns the reverse of string @emph{s}.
1313:
1314: @emph{Example}
1315:
1316: @example
1317: SET FOO=$REVERSE("ABC") ; => CBA
1318: @end example
1319:
1320: @node $SELECT()
1321: @section $SELECT
1322: @cindex $SELECT
1323: @cindex intrinsic functions, $SELECT
1324:
1325: 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.
1326:
1327: @emph{Example}
1328:
1329: @example
1330: SET FOO=$SELECT(1=2:"math is broken",1=1:"the world makes sense") ; => "the world makes sense"
1331: @end example
1332:
1333: @node $STACK()
1334: @section $STACK
1335: @cindex $STACK
1336: @cindex intrinsic functions, $STACK
1337:
1338: Returns information about the program execution stack. The @code{$STACK} intrinsic function has both a one-argument form and a two-argument form.
1339:
1340: @emph{Syntax (One-Argument)}
1341:
1342: @example
1343: $STACK(@emph{<num>})
1344: @end example
1345:
1346: If @emph{num} is @code{0}, returns the command with which this FreeM instance was invoked.
1347:
1348: If @emph{num} is @code{-1}, returns the current program execution stack level.
1349:
1350: 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:
1351:
1352: @table @asis
1353:
1354: @item @code{$$}
1355: If @code{$STACK(@emph{<num>})="$$"}, program execution stack level @code{num} was created as the result of an extrinsic function call
1356:
1357: @item @emph{<m-command>}
1358: 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.
1359:
1360: @end table
1361:
1362: @emph{Syntax (Two-Argument})
1363:
1364: @example
1365: $STACK(@emph{<num>},"[ECODE|MCODE|PLACE]")
1366: @end example
1367:
1368: Returns the error codes, M program code, or entryref applicable to the action that created program execution stack level @emph{num}.
1369:
1370: @node $TEXT()
1371: @section $TEXT
1372: @cindex $TEXT
1373: @cindex intrinsic functions, $TEXT
1374:
1375: Returns a line of code from a routine.
1376:
1377: @node $TRANSLATE()
1378: @section $TRANSLATE
1379: @cindex $TRANSLATE
1380: @cindex intrinsic functions, $TRANSLATE
1381:
1382: @node $TYPE()
1383: @section $TYPE
1384: @cindex $TYPE
1385: @cindex intrinsic functions, $TYPE
1386: @cindex object functions, $TYPE
1387:
1388: Returns a string giving the class of the object specified in the parameter.
1389:
1390: @xref{Object-Oriented Programming}
1391:
1392: @node $VIEW()
1393: @section $VIEW
1394: @cindex $VIEW
1395: @cindex intrinsic functions, $VIEW
1396:
1397: @node $ZBOOLEAN()
1398: @section $ZBOOLEAN
1399: @cindex $ZBOOLEAN
1400: @cindex intrinsic functions, $ZBOOLEAN
1401: @cindex intrinsic functions, implementation-specific
1402:
1403:
1404: Performs @emph{boolean-operation} on numeric arguments @emph{A} and @emph{B}.
1405:
1406: @emph{Syntax}
1407:
1408: @example
1409: SET RESULT=$ZBOOLEAN(@emph{A},@emph{B},@emph{boolean-operation})
1410: @end example
1411:
1412: @code{$ZBOOLEAN} Operations (@emph{boolean-operation} values)
1413:
1414: @table @code
1415: @item 0
1416: Always @emph{false}
1417: @item 1
1418: @code{A AND B}
1419: @item 2
1420: @code{A AND NOT B}
1421: @item 3
1422: @code{A}
1423: @item 4
1424: @code{NOT A AND B}
1425: @item 5
1426: @code{B}
1427: @item 6
1428: @code{A XOR B}
1429: @item 7
1430: @code{A OR B}
1431: @item 8
1432: @code{A NOR B}
1433: @item 9
1434: @code{A EQUALS B}
1435: @item 10
1436: @code{NOT B}
1437: @item 11
1438: @code{A OR NOT B}
1439: @item 12
1440: @code{NOT A}
1441: @item 13
1442: @code{NOT A OR B}
1443: @item 14
1444: @code{A NAND B}
1445: @item 15
1446: Always @emph{true}
1447: @end table
1448:
1449: @node $ZCALL()
1450: @section $ZCALL
1451: @cindex $ZCALL
1452: @cindex intrinsic functions, $ZCALL
1453: @cindex intrinsic functions, implementation-specific
1454:
1455: @node $ZCRC()
1456: @section $ZCRC
1457: @cindex $ZCRC
1458: @cindex intrinsic functions, $ZCRC
1459: @cindex intrinsic functions, implementation-specific
1460:
1461: Returns a checksum of @code{arg1}.
1462:
1463: @emph{Syntax}
1464:
1465: @code{$ZCRC(@emph{arg1})}
1466:
1467: @code{SET VAR=$ZCRC("MUMPS") ; => 86}
1468:
1469: @node $ZDATA()
1470: @section $ZDATA
1471: @cindex $ZDATA
1472: @cindex intrinsic functions, $ZDATA
1473: @cindex intrinsic functions, implementation-specific
1474:
1475: @node $ZDATE()
1476: @section $ZDATE
1477: @cindex $ZDATE
1478: @cindex intrinsic functions, $ZDATE
1479: @cindex intrinsic functions, implementation-specific
1480:
1481: Converts a @code{@ref{$HOROLOG}} string into a human-readable date.
1482:
1483: @emph{Syntax}
1484:
1485: @example
1486: SET VAR=$ZDATE($H[,@emph{<format-string>}])
1487: @end example
1488:
1489: 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}).
1490:
1491: @xref{^$SYSTEM}
1492:
1493: @node $ZEDIT()
1494: @section $ZEDIT
1495: @cindex $ZEDIT
1496: @cindex intrinsic functions, $ZEDIT
1497: @cindex intrinsic functions, implementation-specific
1498:
1499: @node $ZHOROLOG()
1500: @section $ZHOROLOG
1501: @cindex $ZHOROLOG
1502: @cindex intrinsic functions, $ZHOROLOG
1503: @cindex intrinsic functions, implementation-specific
1504:
1505: Converts date and/or time values producible by @code{@ref{$ZDATE()}} or @code{@ref{$ZTIME()}} to @code{@ref{$HOROLOG}} format.
1506:
1507: @emph{Syntax}
1508:
1509: @example
1510: $ZHOROLOG(@emph{<date-value>},@emph{<format-string>})
1511: @end example
1512:
1513: @emph{<date-value>} is a date or time string compatible with the formats from @code{@ref{$ZDATE()}} or @code{@ref{$ZTIME}}.
1514:
1515: @emph{<format-string>} is a format string of the same format as used by the @code{strptime(3)} UNIX function.
1516:
1517: @node $ZKEY()
1518: @section $ZKEY
1519: @cindex $ZKEY
1520: @cindex intrinsic functions, $ZKEY
1521: @cindex intrinsic functions, implementation-specific
1522:
1523: @node $ZLENGTH()
1524: @section $ZLENGTH
1525: @cindex $ZLENGTH
1526: @cindex intrinsic functions, $ZLENGTH
1527: @cindex intrinsic functions, implementation-specific
1528:
1529: @node $ZLSD()
1530: @section $ZLSD
1531: @cindex $ZLSD
1532: @cindex intrinsic functions, $ZLSD
1533: @cindex intrinsic functions, implementation-specific
1534:
1535: 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.
1536:
1537: @emph{Syntax}
1538:
1539: @code{SET VAR=$ZLSD(@emph{arg1},@emph{arg2})}
1540:
1541: @emph{Example}
1542:
1543: @code{SET VAR=$ZLSD("KITTENS","MITTENS") ; => 1}
1544:
1545: @node $ZM()
1546: @section $ZM
1547: @cindex $ZM
1548: @cindex intrinsic functions, $ZM
1549: @cindex intrinsic functions, implementation-specific
1550:
1551: @node $ZNAME()
1552: @section $ZNAME
1553: @cindex $ZNAME
1554: @cindex intrinsic functions, $ZNAME
1555: @cindex intrinsic functions, implementation-specific
1556:
1557: @node $ZNEXT()
1558: @section $ZNEXT
1559: @cindex $ZNEXT
1560: @cindex intrinsic functions, $ZNEXT
1561: @cindex intrinsic functions, implementation-specific
1562:
1563: @node $ZORDER()
1564: @section $ZORDER
1565: @cindex $ZORDER
1566: @cindex intrinsic functions, $ZORDER
1567: @cindex intrinsic functions, implementation-specific
1568:
1569: @node $ZPIECE()
1570: @section $ZPIECE
1571: @cindex $ZPIECE
1572: @cindex intrinsic functions, $ZPIECE
1573: @cindex intrinsic functions, implementation-specific
1574:
1575: @node $ZPREVIOUS()
1576: @section $ZPREVIOUS
1577: @cindex $ZPREVIOUS
1578: @cindex intrinsic functions, $ZPREVIOUS
1579: @cindex intrinsic functions, implementation-specific
1580:
1581: @node $ZREPLACE()
1582: @section $ZREPLACE
1583: @cindex $ZREPLACE
1584: @cindex intrinsic functions, $ZREPLACE
1585: @cindex intrinsic functions, implementation-specific
1586:
1587: Replaces all instances of @code{arg2} with @code{arg3} in string @code{arg1}.
1588:
1589: @emph{Syntax}
1590: @code{$ZREPLACE(@emph{arg1},@emph{arg2},@emph{arg3})}
1591:
1592: @emph{Example}
1593:
1594: @code{SET VAR=$ZREPLACE("CAT","C","B") ; => BAT}
1595:
1596: @node $ZSYNTAX()
1597: @section $ZSYNTAX
1598: @cindex $ZSYNTAX
1599: @cindex intrinsic functions, $ZSYNTAX
1600: @cindex intrinsic functions, implementation-specific
1601:
1602: @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.
1603:
1604: @emph{Syntax}
1605: @example
1606: $ZSYNTAX(@emph{expr V mcode})
1607: @end example
1608:
1609: If no syntax error is found, returns the empty string.
1610:
1611: 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.
1612:
1613: @node $ZTIME()
1614: @section $ZTIME
1615: @cindex $ZTIME
1616: @cindex intrinsic functions, $ZTIME
1617: @cindex intrinsic functions, implementation-specific
1618:
1619: Converts a @code{@ref{$HOROLOG}} string into a human-readable time.
1620:
1621: @emph{Syntax}
1622:
1623: @example
1624: SET VAR=$ZTIME($H[,@emph{<format-string>}])
1625: @end example
1626:
1627: 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}).
1628:
1629: @node OBJECT Methods
1630: @chapter OBJECT Methods
1631:
1632: These methods are part of the @code{^%OBJECT} class, from which all FreeM objects ultimately inherit.
1633:
1634: 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.
1635:
1636: @menu
1637: * $$TONUMBER:: Returns the canonical numeric representation of the object.
1638: * $$TYPE:: Returns the fully-qualified class name of the object.
1639: * $$VALUE:: Returns the value of the object.
1640: @end menu
1641:
1642: @node $$TONUMBER
1643: @section $$TONUMBER
1644:
1645: Returns (when applicable) a canonical numeric representation of the referenced object.
1646:
1647: @emph{Syntax}
1648:
1649: @example
1650: W $$MYOBJECT.TONUMBER(),!
1651: @end example
1652:
1653: If no canonical numeric representation of the object is possible, will return the empty string.
1654:
1655: @node $$TYPE
1656: @section $$TYPE
1657:
1658: Returns the fully-qualified class of the referenced object.
1659:
1660: @emph{Syntax}
1661:
1662: @example
1663: W $$MYOBJECT.TYPE()
1664: @end example
1665:
1666: Note that M variables that are created by non-object-oriented means will be objects of the @code{^%STRING} class.
1667:
1668: @node $$VALUE
1669: @section $$VALUE
1670:
1671: Returns the value of the referenced object.
1672:
1673: @emph{Syntax}
1674:
1675: @example
1676: W $$MYOBJECT.VALUE()
1677: @end example
1678:
1679: @node STRING Methods
1680: @chapter STRING Methods
1681:
1682: These are methods inherent to the @code{^%STRING} class, which is the default class for M variables created without specifying a class.
1683:
1684: @menu
1685: * $$ASCII:: Return the ASCII code of a character within the string.
1686: * $$DATA:: Return tree characteristics of the string.
1687: * $$DISTANCE:: Determine Levenstein distance between this string and another.
1688: * $$EXTRACT:: Return a substring of the string.
1689: * $$FIND:: Find the position of a substring within the string.
1690: * $$FNUMBER:: Format numbers.
1691: * $$JUSTIFY:: Pad the string to specific positions.
1692: * $$LENGTH:: Return the length of the string.
1693: * $$PIECECOUNT:: Return the count of pieces existing between instances of a delimiter.
1694: * $$PIECE:: Return a delimited subset of the string.
1695: * $$REPLACE:: Replace instances of a substring within the string.
1696: * $$REVERSE:: Reverse the order of characters in the string.
1697: * $$TOLOWER:: Return a lowercase version of the string.
1698: * $$TOUPPER:: Return an uppercase version of the string.
1699: * $$TRANSLATE:: Replace individual characters within the string.
1700: @end menu
1701:
1702: @node $$ASCII
1703: @section $$ASCII
1704:
1705: Returns the ASCII code of a character within the string. See @ref{$ASCII()}.
1706:
1707: @emph{Syntax}
1708:
1709: @example
1710: W $$MYOBJECT.ASCII(3)
1711: @end example
1712:
1713: The above example returns the ASCII code in position 3 of string object @code{MYOBJECT}.
1714:
1715: @node $$DATA
1716: @section $$DATA
1717:
1718: Returns the value of the @code{$DATA} intrinsic function as performed on the value of the object. See @ref{$DATA()}.
1719:
1720: @emph{Syntax}
1721:
1722: @example
1723: W $$MYOBJECT.DATA()
1724: @end example
1725:
1726: @node $$DISTANCE
1727: @section $$DISTANCE
1728:
1729: Returns the Levenstein distance between the string and another string. See @ref{$ZLSD()}.
1730:
1731: @emph{Syntax}
1732:
1733: @example
1734: W $$MYOBJECT.DISTANCE("someString")
1735: @end example
1736:
1737: @node $$EXTRACT
1738: @section $$EXTRACT
1739:
1740: Returns a substring of the string. See @ref{$EXTRACT()}.
1741:
1742: @emph{Syntax}
1743:
1744: @example
1745: $$<objectName>.EXTRACT(<start>,<end>)
1746: @end example
1747:
1748:
1749: @node $$FIND
1750: @section $$FIND
1751:
1752: @node $$FNUMBER
1753: @section $$FNUMBER
1754:
1755: @node $$JUSTIFY
1756: @section $$JUSTIFY
1757:
1758: @node $$LENGTH
1759: @section $$LENGTH
1760:
1761: @node $$PIECECOUNT
1762: @section $$PIECECOUNT
1763:
1764: @node $$PIECE
1765: @section $$PIECE
1766:
1767: @node $$REPLACE
1768: @section $$REPLACE
1769:
1770: @node $$REVERSE
1771: @section $$REVERSE
1772:
1773: @node $$TOLOWER
1774: @section $$TOLOWER
1775:
1776: @node $$TOUPPER
1777: @section $$TOUPPER
1778:
1779: @node $$TRANSLATE
1780: @section $$TRANSLATE
1781:
1782: @node Commands
1783: @chapter Commands
1784: @cindex commands
1785:
1786: @menu
1787: * @@:: Execute the following expression as M code.
1788: * !:: Run an external program or command.
1789: * !!:: Launch a subshell from FreeM direct mode.
1790: * ABLOCK:: Increment the block counter for one or more event classes.
1791: * ASSERT:: Raise error when a conditional expression evaluates @emph{false}.
1792: * ASTART:: Enable asynchronous event handling for one or more event classes.
1793: * ASTOP:: Disable asynchronous event handling for one or more event classes.
1794: * AUNBLOCK:: Decrement the block counter for one or more event classes.
1795: * BREAK:: Interrupt a running routine to allow interactive debugging.
1796: * CLOSE:: Close an input/output device.
1797: * CONST:: Define a constant that cannot be altered after initial definition.
1798: * DO:: Transfer program control to one or more subroutines or introduces a new execution level.
1799: * ELSE:: Execute the remainder of a line if @code{@ref{$TEST}} evaluates @emph{false}.
1800: * FOR:: Repeat execution of a line or block of code.
1801: * GOTO:: Unconditionally transfer program execution to a supplied @emph{entryref}.
1802: * HALT:: Terminate the current FreeM interpreter instance.
1803: * HANG:: Temporarily suspend the running program.
1804: * IF:: Execute the remainder of a line if a conditional expression evaluates @emph{true}.
1805: * JOB:: Execute an @emph{entryref} in a child process.
1806: * KILL:: Remove data from a local, global, or structured system variable.
1807: * KSUBSCRIPTS:: Kill only the descendant subscripts of a local, global, global, or structured system variable.
1808: * KVALUE:: Kill only the value of a local, global, or structured system variable.
1809: * LOCK:: Control advisory locking for concurrency control.
1810: * MAP:: Map a global name to a non-default namespace.
1811: * MERGE:: Merge contents of one local, global, or structured system variable into another.
1812: * NEW:: Introduce a new scope for a specified local variable or intrinsic special variable or instantiate an object.
1813: * OPEN:: Open a sequential or socket input/output device.
1814: * QUIT:: End execution of the current process level, optionally with return value.
1815: * READ:: Read input from an input/output device.
1816: * SET:: Set the value of a local variable, global, intrinsic special variable, or structured system variable.
1817: * TCOMMIT:: Commit a transaction.
1818: * THEN:: Preserve @code{@ref{$TEST}} until the end of the current line.
1819: * THROW:: Programmatically raise an error condition.
1820: * TROLLBACK:: Roll back all pending transactions.
1821: * TSTART:: Introduce a new transaction processing level.
1822: * UNMAP:: Remove a mapping of a global to a non-default namespace.
1823: * USE:: Set the currently-active input/output device.
1824: * VIEW:: Modify FreeM internal parameters.
1825: * WATCH:: Enable or disable watchpoints, or set or clear watchpoints on specified globals, locals, or structured system variables.
1826: * WITH:: Set prefix for future variable references.
1827: * WRITE:: Write output to current input/output device.
1828: * XECUTE:: Interpret string as M code.
1829: * ZALLOCATE:: Alternative to @code{LOCK}.
1830: * ZBREAK:: Unknown.
1831: * ZDEALLOCATE:: Alternative to @code{LOCK}.
1832: * ZGO:: Unknown.
1833: * ZHALT:: Unknown.
1834: * ZINSERT:: Insert code into routine buffer.
1835: * ZJOB:: Unknown.
1836: * ZLOAD:: Load routine into routine buffer.
1837: * ZNEW:: Unknown.
1838: * ZPRINT:: Print contents of routine buffer.
1839: * ZQUIT:: Unknown.
1840: * ZREMOVE:: Remove code from routine buffer.
1841: * ZSAVE:: Save routine buffer to disk.
1842: * ZTRAP:: Unknown.
1843: * ZWRITE:: Write local variable, global, or structured system variable to @code{@ref{$IO}}.
1844: @end menu
1845:
1846: @node @@
1847: @section @@
1848: @cindex @@
1849: @cindex commands, @@
1850: @cindex commands, implementation-specific
1851: @cindex commands, non-standard
1852:
1853: Executes FreeM code @emph{expr V mcode}.
1854:
1855: @emph{Syntax}
1856:
1857: @example
1858: @@@emph{expr V mcode}
1859: @end example
1860:
1861: @emph{Example (Using Variable)}
1862:
1863: @example
1864: USER> SET FOO="WRITE ""HELLO WORLD"",!"
1865: USER> @@FOO
1866:
1867: HELLO WORLD
1868:
1869: USER>
1870: @end example
1871:
1872: @emph{Example (Using String Literal)}
1873:
1874: @example
1875: USER> @@"WRITE ""HELLO WORLD"",!"
1876:
1877: HELLO WORLD
1878:
1879: USER>
1880: @end example
1881:
1882: @emph{Example (Using Indirection)}
1883:
1884: @example
1885: USER> SET FOO="BAR"
1886:
1887: USER> SET BAR="WRITE ""HELLO WORLD"",!"
1888:
1889: USER> @@@@FOO
1890:
1891: HELLO WORLD
1892:
1893: USER>
1894: @end example
1895:
1896:
1897: @node !
1898: @section !
1899: @cindex !
1900: @cindex commands, !
1901: @cindex commands, external
1902: @cindex commands, non-standard
1903: @emph{FreeM Extension}
1904:
1905: 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}.
1906:
1907: 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.
1908:
1909: 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{%}.
1910:
1911: @code{%} contains the number of lines in the input or output. @code{%(1)..%(@emph{n})} contains the data for lines 1-@emph{n}.
1912:
1913: @node !!
1914: @section !!
1915: @cindex !!
1916: @cindex commands, !!
1917: @cindex commands, external
1918: @cindex commands, non-standard
1919: @emph{FreeM Extension}
1920:
1921: Launches a subshell within the FreeM direct mode, allowing the user to run operating system commands.
1922:
1923: @example
1924: USER> !!
1925:
1926: Type Ctrl-D to exit from the shell
1927: $ uname -a
1928: Linux hesperos 4.19.0-17-amd64 #1 SMP Debian 4.19.194-3 (2021-07-18) x86_64 GNU/Linux
1929: $ exit
1930:
1931: USER>
1932: @end example
1933:
1934:
1935: @node ABLOCK
1936: @section ABLOCK
1937: @cindex ABLOCK
1938: @cindex commands, ABLOCK
1939:
1940: 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).
1941:
1942: 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.
1943:
1944: @emph{Syntax}
1945:
1946: @example
1947: ABLOCK@emph{:postcondition}
1948: @end example
1949:
1950: 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.
1951:
1952: @example
1953: ABLOCK@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
1954: @end example
1955:
1956: 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.
1957:
1958: @example
1959: ABLOCK@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN}
1960: @end example
1961:
1962: 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.
1963:
1964: @node ASSERT
1965: @section ASSERT
1966: @cindex ASSERT
1967: @cindex commands, ASSERT
1968: @cindex commands, debugging
1969: @cindex commands, implementation-specific
1970: @cindex commands, non-standard
1971: @emph{FreeM Extension}
1972:
1973: 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.
1974:
1975: The @code{ASSERT} error is catchable whether using standard-style, FreeM-style, or DSM 2.0-style error processing.
1976:
1977: @emph{Syntax}
1978:
1979: @example
1980: ASSERT@emph{:postcondition} @emph{<tvexpr>}
1981: @end example
1982:
1983: @emph{Example}
1984:
1985: @example
1986: USER> SET DEBUG=1
1987:
1988:
1989: USER> ASSERT:DEBUG 1=1
1990:
1991:
1992: USER> ASSERT:DEBUG 1=0
1993:
1994:
1995: >> Error ZASSERT: programmer assertion failed in SYSTEM::^%SYSINIT [$STACK = 0]
1996: >> ASSERT:DEBUG 1=0
1997: ^
1998: @end example
1999:
2000: @node ASTART
2001: @section ASTART
2002: @cindex ASTART
2003: @cindex commands, ASTART
2004:
2005: Enables asynchronous event handling for one or more event classes.
2006:
2007: @emph{Syntax}
2008:
2009: @example
2010: ASTART@emph{:postcondition}
2011: @end example
2012:
2013: 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.
2014:
2015: @example
2016: ASTART@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2017: @end example
2018:
2019: 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.
2020:
2021: @example
2022: ASTART@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN})
2023: @end example
2024:
2025: 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.
2026:
2027: @node ASTOP
2028: @section ASTOP
2029: @cindex ASTOP
2030: @cindex commands, ASTOP
2031:
2032: Disables asynchronous event handling for one or more event classes.
2033:
2034: @emph{Syntax}
2035:
2036: @example
2037: ASTOP@emph{:postcondition}
2038: @end example
2039:
2040: 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.
2041:
2042: @example
2043: ASTOP@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2044: @end example
2045:
2046: 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.
2047:
2048: @example
2049: ASTOP@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN})
2050: @end example
2051:
2052: 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.
2053:
2054: @node AUNBLOCK
2055: @section AUNBLOCK
2056: @cindex AUNBLOCK
2057: @cindex commands, AUNBLOCK
2058:
2059: Decrements the event block counter for one or more event classes.
2060:
2061: @emph{Syntax}
2062:
2063: @example
2064: AUNBLOCK@emph{:postcondition}
2065: @end example
2066:
2067: 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.
2068:
2069: @example
2070: AUNBLOCK@emph{:postcondition} @emph{evclass1}...,@emph{evclassN}
2071: @end example
2072:
2073: 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.
2074:
2075: @example
2076: AUNBLOCK@emph{:postcondition} (@emph{evclass1}...,@emph{evclassN}
2077: @end example
2078:
2079: 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.
2080:
2081:
2082: @node BREAK
2083: @section BREAK
2084: @cindex BREAK
2085: @cindex commands, BREAK
2086:
2087: Interrupts running routine to allow interactive debugging.
2088:
2089: @emph{Syntax}
2090:
2091: @example
2092: @code{BREAK@emph{:postcondition}}
2093: @end example
2094:
2095: In its argumentless form, @code{BREAK} suspends execution of running code, provided the optional @emph{postcondition} is @emph{true} or omitted.
2096:
2097: @example
2098: @code{BREAK@emph{:postcondition} @emph{breakflag}}
2099: @end example
2100:
2101: @emph{FreeM Extension}
2102:
2103: 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.
2104: The following table enumerates the possible values of @emph{breakflag}
2105:
2106: @table @code
2107: @item 0
2108: Disables @emph{Ctrl-C} handling
2109: @item -2
2110: Enables normal FreeM error handling
2111: @item 2
2112: Enables @emph{Digital Standard MUMPS} v2 error handling
2113: @item @emph{any integer value other than 0, 2, or -2}
2114: Enables @emph{Ctrl-C} handling
2115: @end table
2116:
2117: @node CLOSE
2118: @section CLOSE
2119: @cindex CLOSE
2120: @cindex commands, CLOSE
2121:
2122: Closes an input/output device.
2123:
2124: @emph{Syntax}
2125:
2126: @example
2127: @code{CLOSE@emph{:postcondition}}
2128: @end example
2129:
2130: 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.
2131:
2132: @example
2133: @code{CLOSE@emph{:postcondition} @emph{channel}}
2134: @end example
2135:
2136: 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.
2137:
2138: @node CONST
2139: @section CONST
2140: @cindex CONST
2141: @cindex commands, CONST
2142: @cindex commands, non-standard
2143: @emph{FreeM Extension}
2144:
2145: 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.
2146:
2147: Constants must only be locals, and globals are not supported.
2148:
2149: @emph{Syntax}
2150:
2151: @example
2152: @code{CONST@emph{:postcondition} @emph{mref1}=@emph{initial-value1},...,@emph{mrefN}=@emph{initial-valueN}}
2153: @end example
2154:
2155: @node DO
2156: @section DO
2157: @cindex DO
2158: @cindex commands, DO
2159:
2160: 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.
2161:
2162: @emph{Syntax}
2163:
2164: @example
2165: DO[@emph{:postcondition}] @emph{entryref}[@emph{:postcondition}[,...]]
2166: @end example
2167:
2168: 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.
2169:
2170: @emph{Syntax}
2171:
2172: @example
2173: DO[@emph{:postcondition}]
2174: @end example
2175:
2176: @node ELSE
2177: @section ELSE
2178: @cindex ELSE
2179: @cindex commands, ELSE
2180:
2181: 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.
2182:
2183: @emph{Syntax}
2184:
2185: @example
2186: ELSE[@emph{:postcondition}]
2187: @end example
2188:
2189: @cartouche
2190: @quotation
2191: @emph{Non-Standard Behavior}
2192:
2193: 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.
2194:
2195: 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.
2196: @end quotation
2197: @end cartouche
2198:
2199: @node FOR
2200: @section FOR
2201: @cindex FOR
2202: @cindex commands, FOR
2203:
2204: 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.
2205:
2206: @emph{Syntax}
2207:
2208: @example
2209: FOR[@emph{:postcondition}]
2210: @end example
2211:
2212: @cartouche
2213: @quotation
2214: @emph{Non-Standard Behavior}
2215:
2216: 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.
2217:
2218: 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.
2219: @end quotation
2220: @end cartouche
2221:
2222: 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.
2223:
2224: 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}.
2225:
2226: @emph{Syntax}
2227:
2228: @example
2229: FOR[@emph{:postcondition}] @emph{glvn}=@emph{initializer-expression}:@emph{increment-expression}:@emph{max-expression}
2230: @end example
2231:
2232: @emph{Example}
2233:
2234: @example
2235: USER> FOR I=1:1:10 WRITE I,!
2236:
2237: 1
2238: 2
2239: 3
2240: 4
2241: 5
2242: 6
2243: 7
2244: 8
2245: 9
2246: 10
2247:
2248: USER> FOR I=2:2:10 WRITE I,!
2249:
2250: 2
2251: 4
2252: 6
2253: 8
2254: 10
2255: @end example
2256:
2257: 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.
2258:
2259: @emph{Syntax}
2260:
2261: @example
2262: FOR[@emph{:postcondition}] @emph{glvn}=@emph{expr1}[,..@emph{exprN}]
2263: @end example
2264:
2265: @emph{Example}
2266:
2267: @example
2268: USER> FOR I=60,"FOO",-3,"George",1450,$HOROLOG WRITE I,!
2269:
2270: 60
2271: FOO
2272: -3
2273: George
2274: 1450
2275: 66106,52388
2276: @end example
2277:
2278: @node GOTO
2279: @section GOTO
2280: @cindex GOTO
2281: @cindex commands, GOTO
2282:
2283: 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}.
2284:
2285: @emph{Syntax}
2286:
2287: @example
2288: GOTO[@emph{:postcondition}] @emph{entryref}
2289: @end example
2290:
2291: @node HALT
2292: @section HALT
2293: @cindex HALT
2294: @cindex commands, HALT
2295:
2296: Halts program execution and frees resources allocated during execution, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2297:
2298: @emph{Syntax}
2299:
2300: @example
2301: HALT[@emph{:postcondition}]
2302: @end example
2303:
2304: @node HANG
2305: @section HANG
2306: @cindex HANG
2307: @cindex commands, HANG
2308:
2309: 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.
2310:
2311: @emph{Syntax}
2312:
2313: @example
2314: HANG[@emph{:postcondition}] @emph{expr}
2315: @end example
2316:
2317: @cartouche
2318: @quotation
2319: @emph{Non-Standard Behavior}
2320:
2321: FreeM supports sub-second values for @emph{expr}.
2322: @end quotation
2323: @end cartouche
2324:
2325: @node IF
2326: @section IF
2327: @cindex IF
2328: @cindex commands, IF
2329:
2330: 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.
2331:
2332: @emph{Syntax}
2333: @example
2334: IF[@emph{:postcondition}] @emph{tvexpr}[,...@emph{tvexpr}]
2335: @end example
2336:
2337: In its argumentless form, allows the remainder of the line of code following @code{IF} to execute only if @code{$TEST} evaluates to @emph{1}, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2338:
2339: @emph{Syntax}
2340: @example
2341: IF[@emph{:postcondition}]
2342: @end example
2343:
2344: @node JOB
2345: @section JOB
2346: @cindex JOB
2347: @cindex commands, JOB
2348:
2349: Executes @emph{entryref} in a separate process, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2350:
2351: @emph{Syntax}
2352: @example
2353: JOB[@emph{:postcondition}] @emph{entryref}[:@emph{job-parameters}[:@emph{timeout}]]
2354: @end example
2355:
2356: If @emph{timeout} is supplied, FreeM will set @code{$TEST} to @emph{1} if the child process completes within @emph{timeout} seconds.
2357:
2358: @node KILL
2359: @section KILL
2360: @cindex KILL
2361: @cindex commands, KILL
2362:
2363: 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.
2364:
2365: @emph{Syntax}
2366: @example
2367: KILL[@emph{:postcondition}] @emph{glvn}[,...@emph{glvn}]
2368: @end example
2369:
2370: 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.
2371:
2372: @emph{Syntax}
2373: @example
2374: KILL[@emph{:postcondition}] (@emph{lvn}[,...@emph{lvn}])
2375: @end example
2376:
2377: In its argumentless form, @code{KILL} deletes all local variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2378:
2379: @emph{Syntax}
2380: @example
2381: KILL[@emph{:postcondition}]
2382: @end example
2383:
2384: @node KSUBSCRIPTS
2385: @section KSUBSCRIPTS
2386: @cindex KSUBSCRIPTS
2387: @cindex commands, KSUBSCRIPTS
2388:
2389: Kills only the descendant subscripts (but not the data value) of a referenced global, local, or SSVN (where allowed).
2390:
2391: @emph{Syntax}
2392:
2393: @example
2394: KSUBSCRIPTS@emph{:postcondition} @emph{var1},...
2395: @end example
2396:
2397: 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.
2398:
2399: @cartouche
2400: @quotation
2401: @emph{Note}
2402: The below @emph{argumentless} and @emph{exclusive} forms of @code{KSUBSCRIPTS} are not implemented in FreeM, as of version 0.3.3, but are planned for a future release.
2403: @end quotation
2404: @end cartouche
2405:
2406: @example
2407: KSUBSCRIPTS@emph{:postcondition}
2408: @end example
2409:
2410: 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.
2411:
2412: @example
2413: KSUBSCRIPTS@emph{:postcondition} (@emph{var1},...)
2414: @end example
2415:
2416: 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.
2417:
2418:
2419: @node KVALUE
2420: @section KVALUE
2421: @cindex KVALUE
2422: @cindex commands, KVALUE
2423:
2424: Kills only the data value (but not descendant subscripts) of a referenced global, local, or SSVN (where allowed).
2425:
2426: @emph{Syntax}
2427:
2428: @example
2429: KVALUE@emph{:postcondition} @emph{var1},...
2430: @end example
2431:
2432: 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.
2433:
2434: @cartouche
2435: @quotation
2436: @emph{Note}
1.3 ! snw 2437: The below @emph{argumentless} and @emph{exclusive} forms of @code{KVALUE} are not implemented in FreeM, as of version cvs-current, but are planned for a future release.
1.1 snw 2438: @end quotation
2439: @end cartouche
2440:
2441: @example
2442: KVALUE@emph{:postcondition}
2443: @end example
2444:
2445: 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.
2446:
2447: @example
2448: KVALUE@emph{:postcondition} (@emph{var1},...)
2449: @end example
2450:
2451: 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.
2452:
2453: @node LOCK
2454: @section LOCK
2455: @cindex LOCK
2456: @cindex commands, LOCK
2457:
2458: Acquires or releases ownership of names.
2459:
2460: 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.
2461:
2462: @emph{Syntax}
2463: @example
2464: LOCK[@emph{:postcondition}]
2465: @end example
2466:
2467: 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}.
2468:
2469: If @code{LOCK} succeeds within @emph{timeout}, @code{$TEST} is set to @emph{1}. Otherwise, @code{$TEST} is set to @emph{0}.
2470:
2471: @emph{Syntax}
2472: @example
2473: LOCK[@emph{:postcondition}] [+|-]@emph{name}[:@emph{timeout}][,...[+|-]@emph{name}[:@emph{timeout}]]
2474: @end example
2475:
2476: @emph{Example}
2477:
2478: This example will increment the lock counter for @code{^JPW} and decrement the lock counter for @code{^MJR}.
2479:
2480: @example
2481: LOCK +^JPW,-^MJR
2482: @end example
2483:
2484: 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.
2485:
2486: If @code{LOCK} succeeds within @emph{timeout}, @code{$TEST} is set to @emph{1}. Otherwise, @code{$TEST} is set to @emph{0}.
2487:
2488: @emph{Syntax}
2489: @example
2490: LOCK[@emph{:postcondition}] @emph{name}[:@emph{timeout}][,...@emph{name}[:@emph{timeout}]]
2491: @end example
2492:
2493: @node MAP
2494: @section MAP
2495: @cindex MAP
2496: @cindex commands, MAP
2497: @cindex commands, implementation-specific
2498: @cindex commands, non-standard
2499:
2500: 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.
2501:
2502: @emph{Syntax}
2503:
2504: @example
2505: MAP[@emph{:postcondition}] GLOBAL @emph{gvn}=@emph{expr V namespace}
2506: @end example
2507:
2508: @node MERGE
2509: @section MERGE
2510: @cindex MERGE
2511: @cindex commands, MERGE
2512:
2513: Merges the contents of one global, local, or SSVN subtree to another global, local, or SSVN.
2514:
2515: @emph{Syntax}
2516:
2517: @example
2518: @code{MERGE A=^$JOB}
2519: @end example
2520:
2521: The above example will merge the @code{^$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.
2522:
2523: @node NEW
2524: @section NEW
2525: @cindex NEW
2526: @cindex commands, NEW
2527:
2528: In all forms of @code{NEW}, @emph{name} must be a local variable name or @code{NEW}-able structured or intrinsic system variable.
2529:
2530: 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.
2531:
2532: @emph{Syntax}
2533:
2534: @example
2535: NEW[@emph{:postcondition}] @emph{name}[,...@emph{name}]
2536: @end example
2537:
2538: 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.
2539:
2540: @emph{Syntax}
2541: @example
2542: NEW[@emph{:postcondition}] (@emph{name}[,...@emph{name}])
2543: @end example
2544:
2545: 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.
2546:
2547: @emph{Syntax}
2548: @example
2549: NEW@emph{:postcondition} @emph{name}=@emph{expr}
2550: @end example
2551:
2552: 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.
2553:
2554: @node OPEN
2555: @section OPEN
2556: @cindex OPEN
2557: @cindex commands, OPEN
2558:
2559: Opens sequential or socket I/O devices and files and associates them with a numeric FreeM input/output channel.
2560:
2561: @emph{Syntax (Sequential Files)}
2562:
2563: @example
2564: @code{OPEN@emph{:postcondition} @emph{channel}:"@emph{filename}/@emph{access-mode}"}
2565: @end example
2566:
2567: 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.
2568: The below table lists the valid options for @emph{access-mode}:
2569:
2570: @table @code
2571: @item r
2572: Read-only access
2573: @item w
2574: Create a new file for write access
2575: @item a
2576: Write access; append to existing file
2577: @item r+
2578: Read/write access
2579: @end table
2580:
2581: @cartouche
2582: @quotation
2583: @emph{I/O Path}
2584:
2585: 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
2586: access files in other directories, you must first set the @emph{I/O Path} in @code{^$JOB($JOB,"IOPATH")}.
2587:
2588: The following example will set the I/O path to @code{/etc}:
2589:
2590: @example
2591: @code{SET ^$JOB($JOB,"IOPATH")="/etc"}
2592: @end example
2593:
2594: @end quotation
2595: @end cartouche
2596:
2597: 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}.
2598:
2599: @emph{Syntax (Network Sockets)}
2600:
2601: 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.
2602:
2603: @example
2604: OPEN@emph{:postcondition} @emph{socket-channel}:"@emph{hostname-or-address}:@emph{port}:@emph{address-family}:@emph{connection-type}"
2605: @end example
2606:
2607: @emph{Socket Parameters}
2608:
2609: @table @emph
2610:
2611: @item socket-channel
2612: The socket I/O channel to use. This must be in the range of 100-255.
2613:
2614: @item hostname-or-address
2615: 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.
2616:
2617: @item port
2618: The TCP or UDP port to which the socket will connect on the remote host.
2619:
2620: @item address-family
2621: The address family to use. Either @emph{IPV4} or @emph{IPV6}.
2622:
2623: @item connection-type
2624: Which connection type to use. Either @emph{TCP} or @emph{UDP}.
2625:
2626: @end table
2627:
2628: If you do not specify the address family and connection type, they will default to @emph{IPV4} and @emph{TCP}, respectively.
2629:
2630: @node QUIT
2631: @section QUIT
2632: @cindex QUIT
2633: @cindex commands, QUIT
2634:
2635: @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.
2636:
2637: @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}.
2638:
2639: Argumentless @code{QUIT} may also be used to exit a @code{FOR} loop occurring on the same line.
2640:
2641: @emph{Syntax}
2642: @example
2643: QUIT[@emph{:postcondition}] [@emph{expr}]
2644: @end example
2645:
2646: @node READ
2647: @section READ
2648: @cindex READ
2649: @cindex commands, READ
2650:
2651: The @code{READ} command takes input from I/O channel @code{$IO} and stores it into specified variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2652:
2653: @emph{Syntax}
2654: @example
2655: READ[@emph{:postcondition}] @emph{read-argument}[,...@emph{read-argument}]
2656: @end example
2657:
2658: Each @emph{read-argument} may be one of the following:
2659:
2660: @table @asis
2661:
2662: @item String Literal
2663: String literal @emph{read-argument}s will be output to @code{$IO} unmodified.
2664:
2665: @item Format Specifier
2666: One or more of the following:
2667:
2668: @table @asis
2669: @item @code{!} (newline)
2670: Advances the cursor down by one line and returns it to the first column.
2671:
2672: @item @code{#} (form-feed)
2673: Advances the screen down by @code{$ZROWS} and moves the cursor to the upper-left corner of the screen.
2674:
2675: @item @code{?@emph{n}} (position)
2676: Advances the cursor and @code{$X} forward to position @emph{n}.
2677:
2678: @end table
2679:
2680: @item Single-Character Read (@code{*@emph{variable-name}[@emph{:timeout}]})
2681: 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}.
2682:
2683: @item Variable-Length Character Read (@code{@emph{variable-name}[@emph{:timeout}]})
2684: 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{$TEST} will be set to @emph{0}.
2685:
2686: @item Fixed-Length Character Read (@code{@emph{variable-name}#@emph{count}[@emph{:timeout}]})
2687: Reads @emph{count} characters into @emph{variable-name}. If the optional @emph{timeout} is specified, will wait @emph{timeout} seconds to retrieve characters. If characters are read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{1}. If no character is read within @emph{timeout} seconds, @code{$TEST} will be set to @emph{0}.
2688:
2689: @item Control Mnemonic (@code{/@emph{control-mnemonic}[@emph{(arg1[,...argN])}]})
2690: Outputs X3.64 control mnemonic @emph{control-mnemonic} to @code{$IO}. Please see the appendix on X3.64 Control Mnemonics for more information.
2691:
2692: @end table
2693:
2694: @node SET
2695: @section SET
2696: @cindex SET
2697: @cindex commands, SET
2698:
2699: The @code{SET} command places values into one or more variables, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2700:
2701: @emph{Syntax}
2702: @example
2703: SET[@emph{:postcondition}] @emph{set-argument}[=@emph{expression} | @emph{postfix-operator}][@emph{,...set-argument}[=@emph{expression} | @emph{postfix-operator}]]
2704: @end example
2705:
2706: Each @emph{set-argument} can be:
2707:
2708: @table @asis
2709: @item @emph{variable-name}
2710: A local variable, global variable, writable intrinsic special variable, or writable structured system variable.
2711:
2712: @item @emph{lhs-function}
2713: @code{$EXTRACT} or @code{$PIECE}.
2714: @end table
2715:
2716: 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}.
2717:
2718: 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.
2719:
2720: @emph{Example (postfix-operator)}
2721:
2722: @example
2723: SET A++,B-- ; increments A, decrements B
2724: @end example
2725:
2726: @node TCOMMIT
2727: @section TCOMMIT
2728: @cindex TCOMMIT
2729: @cindex commands, TCOMMIT
2730:
2731: Commits all pending transactions to the data files, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2732:
2733: @emph{Syntax}
2734: @example
2735: TCOMMIT[@emph{:postcondition}]
2736: @end example
2737:
2738: @node THEN
2739: @section THEN
2740: @cindex THEN
2741: @cindex commands, THEN
2742:
2743: Saves the value of @code{$TEST} until the end of the current line, restoring it at the end of the current line or when a @code{QUIT} is encountered. @code{THEN} should be used in all new code in conjunction with @code{IF}.
2744:
2745: @emph{Example}
2746: @example
2747: IF 1 THEN WRITE "HELLO!",!
2748: @end example
2749:
2750: @node THROW
2751: @section THROW
2752: @cindex THROW
2753: @cindex commands, THROW
2754: @cindex commands, non-standard
2755: @emph{FreeM Extension}
2756:
2757: Raises an error condition as long as the optional @emph{postcondition} is @emph{true} or omitted.
2758:
2759: @emph{Syntax}
2760:
2761: @example
2762: @code{THROW@emph{:postcondition} @emph{expr V error-code}}
2763: @end example
2764:
2765: @emph{Example}
2766:
2767: @example
2768: @code{THROW "M102"}
2769: @end example
2770:
2771: @node TROLLBACK
2772: @section TROLLBACK
2773: @cindex TROLLBACK
2774: @cindex commands, TROLLBACK
2775:
2776: Rolls back all pending transactions for the current process, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2777:
2778: @emph{Syntax}
2779:
2780: @example
2781: TROLLBACK[@emph{:postcondition}]
2782: @end example
2783:
2784: @node TSTART
2785: @section TSTART
2786: @cindex TSTART
2787: @cindex commands, TSTART
2788:
2789: Introduces a new transaction level, incrementing @code{$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.
2790:
2791: If a transaction is restartable, variables in the @emph{variables-list} will be restored to their original values on a restart of the transaction.
2792:
2793: @emph{Syntax}
2794:
2795: @example
2796: TSTART[@emph{:postcondition}] @emph{<variables-list>}:@emph{<transaction-parameters>}
2797: @end example
2798:
2799: @emph{<variables-list>} can be:
2800:
2801: @table @asis
2802:
2803: @item @code{()}
2804: Do not save off any local variables. Makes the transaction non-restartable.
2805:
2806: @item @code{*}
2807: Save off all local variables. Makes the transaction restartable.
2808:
2809: @item @code{@emph{variableName}}
2810: Saves off only one local variable, @emph{variableName}. Makes the transaction restartable.
2811:
2812: @item @code{(@emph{variableName1},...,@emph{variableNameN})}
2813: Saves off all local variables listed. Makes the transaction restartable.
2814:
2815: @end table
2816:
2817: @emph{<transaction-parameters>} can be:
2818:
2819: @table @asis
2820:
2821: @item @code{S[ERIAL]}
2822: 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.
2823:
2824: @item @code{T[RANSACTIONID]=@emph{transaction-id}}
2825: Sets the ID of the transaction to @emph{transaction-id}
2826:
2827: @end table
2828:
2829: If you are using more than one transaction parameter, surround all of them in parentheses and separate them with commas, e.g.:
2830:
2831: @example
2832: TSTART (FOO,BAR):(SERIAL,TRANSACTIONID="FOO")
2833: @end example
2834:
2835: @node UNMAP
2836: @section UNMAP
2837: @cindex UNMAP
2838: @cindex commands, UNMAP
2839: @cindex commands, implementation-specific
2840: @cindex commands, non-standard
2841:
2842: Removes any mapping connecting @emph{gvn} to a non-default namespace, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2843:
2844: @emph{Syntax}
2845:
2846: @example
2847: UNMAP GLOBAL @emph{gvn}
2848: @end example
2849:
2850: @node USE
2851: @section USE
2852: @cindex USE
2853: @cindex commands, USE
2854:
2855: 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.
2856:
2857: @emph{Syntax (Terminal)}
2858:
2859: @example
2860: 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})]
2861: @end example
2862:
2863: For terminals, @emph{io-channel} must be 0.
2864:
2865: Semantic and functional description of each device parameter TBA.
2866:
2867: @emph{Syntax (Sequential Files)}
2868:
2869: @example
2870: USE@emph{:postcondition} @emph{io-channel}[:@emph{seek-position}:@emph{terminator}:@emph{nodelay})]
2871: @end example
2872:
2873: For sequential files, @emph{io-channel} must be in the range 1-99.
2874:
2875: Semantic and functional description of each device parameter TBA.
2876:
2877: @emph{Syntax (Network Sockets)}
2878:
2879: @example
2880: USE@emph{:postcondition} @emph{io-channel}
2881: @end example
2882:
2883: The above syntax will set @code{$IO} to @emph{io-channel}, directing successive @code{READ}s and @code{WRITE}s to @emph{io-channel}, provided the optional @emph{postcondition} is @emph{true} or omitted.
2884:
2885: @example
2886: USE@emph{:postcondition} @emph{io-channel}:/CONNECT
2887: @end example
2888:
2889: The above syntax will set @code{$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).
2890:
2891: For network sockets, @emph{io-channel} must be in the range 100-255.
2892:
2893: @node VIEW
2894: @section VIEW
2895: @cindex VIEW
2896: @cindex commands, VIEW
2897:
2898: Provides write access to various FreeM internal parameters, provided the optional @emph{postcondition} evaluates to @emph{true} or is omitted.
2899:
2900: @emph{Syntax}
2901: @example
2902: VIEW[@emph{:postcondition}] @emph{view-number}[:@emph{view-argument}[:@emph{view-argument}...]]
2903: @end example
2904:
2905: The @emph{view-number} argument can be one of the following:
2906:
2907: @table @asis
2908:
2909: @item @code{21} - Close All Globals
2910: Closes all global data files open in the current process. Takes no arguments.
2911:
2912: @emph{Syntax}
2913: @example
2914: VIEW 21
2915: @end example
2916:
2917: @item @code{29} - Symbol Table Copy
2918: Copies the primary symbol table's contents to the alternate symbol table. Takes no arguments.
2919:
2920: @emph{Syntax}
2921: @example
2922: VIEW 29
2923: @end example
2924:
2925: @item @code{52} - Set G0 Input Translation Table for @code{$IO}
2926:
2927: @emph{Syntax}
2928: @example
2929: VIEW 52:@emph{expr V trantab}
2930: @end example
2931:
2932: @item @code{53} - Set G0 Output Translation Table for @code{$IO}
2933:
2934: @emph{Syntax}
2935: @example
2936: VIEW 53:@emph{expr V trantab}
2937: @end example
2938:
2939: @item @code{54} - Set G1 Input Translation Table for @code{$IO}
2940:
2941: @emph{Syntax}
2942: @example
2943: VIEW 54:@emph{expr V trantab}
2944: @end example
2945:
2946: @item @code{55} - Set G1 Output Translation Table for @code{$IO}
2947:
2948: @emph{Syntax}
2949: @example
2950: VIEW 55:@emph{expr V trantab}
2951: @end example
2952:
2953: @item @code{62} - Set @code{$RANDOM} Seed Number
2954: Sets the seed number used by @code{$RANDOM} to @emph{numexpr}.
2955:
2956: @emph{Syntax}
2957: @example
2958: VIEW 62:@emph{numexpr}
2959: @end example
2960:
2961: @item @code{63} - Set @code{$RANDOM} Parameter A
2962: Sets the number used for @code{$RANDOM} Parameter A to @emph{numexpr}.
2963:
2964: @emph{Syntax}
2965: @example
2966: VIEW 63:@emph{numexpr}
2967: @end example
2968:
2969: @item @code{64} - Set @code{$RANDOM} Parameter B
2970: Sets the number used for @code{$RANDOM} Parameter B to @emph{numexpr}.
2971:
2972: @emph{Syntax}
2973: @example
2974: VIEW 64:@emph{numexpr}
2975: @end example
2976:
2977: @item @code{65} - Set @code{$RANDOM} Parameter C
2978: Sets the number used for @code{$RANDOM} Parameter C to @emph{numexpr}.
2979:
2980: @emph{Syntax}
2981: @example
2982: VIEW 65:@emph{numexpr}
2983: @end example
2984:
2985: @item @code{66} - Set or Clear @code{SIGTERM} Handling Flag
2986: 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.
2987:
2988: @emph{Syntax}
2989: @example
2990: VIEW 66:@emph{tvexpr}
2991: @end example
2992:
2993: @item @code{67} - Set or Clear @code{SIGHUP} Handling Flag
2994: 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.
2995:
2996: @emph{Syntax}
2997: @example
2998: VIEW 67:@emph{tvexpr}
2999: @end example
3000:
3001: @item @code{70} - Set @code{$ZSORT}/@code{$ZSYNTAX} Flag
3002: Selects whether @code{$ZS} resolves to @code{$ZSORT} or @code{$ZSYNTAX}.
3003:
3004: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZSYNTAX}. Otherwise, selects @code{$ZSORT}.
3005:
3006: @emph{Syntax}
3007: @example
3008: VIEW 70:@emph{tvexpr}
3009: @end example
3010:
3011: @item @code{71} - Set @code{$ZNEXT}/@code{$ZNAME} Flag
3012: Selects whether @code{$ZN} resolves to @code{$ZNEXT} or @code{$ZNAME}.
3013:
3014: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZNAME}. Otherwise, selects @code{$ZNEXT}.
3015:
3016: @emph{Syntax}
3017: @example
3018: VIEW 71:@emph{tvexpr}
3019: @end example
3020:
3021: @item @code{72} - Set @code{$ZPREVIOUS}/@code{$ZPIECE} Flag
3022: Selects whether @code{$ZP} resolves to @code{$ZPREVIOUS} or @code{$ZPIECE}.
3023:
3024: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZPIECE}. Otherwise, selects @code{$ZPREVIOUS}.
3025:
3026: @emph{Syntax}
3027: @example
3028: VIEW 72:@emph{tvexpr}
3029: @end example
3030:
3031: @item @code{73} - Set @code{$ZDATA}/@code{$ZDATE} Flag
3032: Selects whether @code{$ZD} resolves to @code{$ZDATA} or @code{$ZDATE}.
3033:
3034: If @emph{tvexpr} evaluates to @emph{true}, selects @code{$ZDATE}. Otherwise, selects @code{$ZDATA}.
3035:
3036: @emph{Syntax}
3037: @example
3038: VIEW 73:@emph{tvexpr}
3039: @end example
3040:
3041: @item @code{79} - Set Old @code{ZJOB} vs. New @code{ZJOB} Flag
3042: If @emph{tvexpr} evaluates to @emph{true}, sets the @code{ZJOB} mode to new, otherwise, sets it to old.
3043:
3044: @emph{Syntax}
3045: @example
3046: VIEW 79:@emph{tvexpr}
3047: @end example
3048:
3049: @item @code{80} - Set or Clear 8-Bit Flag
3050: If @emph{tvexpr} evaluates to @emph{true}, sets FreeM to 8-bit mode. Otherwise, sets FreeM to 7-bit mode.
3051:
3052: @emph{Syntax}
3053: @example
3054: VIEW 80:@emph{tvexpr}
3055: @end example
3056:
3057: @item @code{81} - Set or Clear PF1 Flag
3058: If @emph{tvexpr} evaluates to @emph{true}, sets the @code{PF1} flag. We do not yet know what this does.
3059:
3060: @emph{Syntax}
3061: @example
3062: VIEW 81:@emph{tvexpr}
3063: @end example
3064:
3065: @item @code{83} - Set or Clear Text in @code{$ZERROR} Flag
3066: If @emph{tvexpr} evaluates to @emph{true}, descriptive error messages will be included in @code{$ZERROR}. Otherwise, only the short error code (i.e. @emph{ZILLFUN}) will be included in @code{$ZERROR}.
3067:
3068: @emph{Syntax}
3069: @example
3070: VIEW 83:@emph{tvexpr}
3071: @end example
3072:
3073: @item @code{87} - Date Type Definition
3074: We believe this defines date formats for @code{$ZDATE}, but we have not yet figured out how it works.
3075:
3076: @emph{Syntax}
3077: @example
3078: ; Syntax unknown
3079: @end example
3080:
3081: @item @code{88} - Time Type Definition
3082: We believe this defines time formats for @code{$ZTIME}, but we have not yet figured out how it works.
3083:
3084: @emph{Syntax}
3085: @example
3086: ; Syntax unknown
3087: @end example
3088:
3089: @item @code{91} - Set Default Expression for Missing @code{QUIT} Expression
3090: Sets the default expression to be printed when a @code{QUIT} is encountered where a @code{QUIT} argument would be expected, but was not provided. We're not entirely sure what this does.
3091:
3092: @emph{Syntax}
3093: @example
3094: ; Syntax unknown
3095: @end example
3096:
3097: @item @code{92} - Set Type Mismatch Error Flag on @code{EUR2DEM}
3098: 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.
3099:
3100: @emph{Syntax}
3101: @example
3102: VIEW 92:@emph{tvexpr}
3103: @end example
3104:
3105: @item @code{93} - Define @code{ZKEY} Production Rule
3106: We do not know what this does.
3107:
3108: @item @code{96} - Set Global Prefix
3109: Forces global data filenames to be prefixed with the result of @emph{expr}.
3110:
3111: @emph{Syntax}
3112: @example
3113: VIEW 96:@emph{expr V string}
3114: @end example
3115:
3116: @item @code{97} - Set Global Postfix
3117: Forces global data filenames to be postfixed with the result of @emph{expr}.
3118:
3119: @emph{Syntax}
3120: @example
3121: VIEW 97:@emph{expr V string}
3122: @end example
3123:
3124: @item @code{98} - Set Routine Extension
3125: Sets the default extension for M routine filenames to the result of @emph{expr}.
3126:
3127: @emph{Syntax}
3128: @example
3129: VIEW 98:@emph{expr V string}
3130: @end example
3131:
3132: @item @code{101} - Set @code{ierr}
3133: Sets the FreeM internal @code{ierr} value to @emph{intexpr}. Used by some FreeM polyfills (commands or functions implemented in M code).
3134:
3135: @emph{Syntax}
3136: @example
3137: VIEW 101:@emph{intexpr}
3138: @end example
3139:
3140: @item @code{102} - Set @code{ierr} (Deferred)
3141: 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.
3142:
3143: @emph{Syntax}
3144: @example
3145: VIEW 102:@emph{intexpr}
3146: @end example
3147:
3148: @item @code{103} - Signal @code{MERGE} to @code{^$WINDOW} Complete
3149: Signals FreeM's MWAPI implementation that a @code{MERGE} to @code{^$WINDOW} or descendant subscripts thereof has completed.
3150:
3151: @emph{Syntax}
3152: @example
3153: VIEW 103[@emph{:subscript}]
3154: @end example
3155:
3156: @item @code{110} - Set Local @code{$ORDER}/@code{$QUERY} Data Value
3157: Sets the local variable @code{$ORDER}/@code{$QUERY} data value to the result of @emph{expr}. We're not entirely sure what this is.
3158:
3159: @emph{Syntax}
3160: @example
3161: VIEW 110:@emph{expr}
3162: @end example
3163:
3164: @item @code{111} - Set Global @code{$ORDER}/@code{$QUERY} Data Value
3165: Sets the global variable @code{$ORDER}/@code{$QUERY} data value to the result of @emph{expr}. We're not entirely sure what this is.
3166:
3167: @emph{Syntax}
3168: @example
3169: VIEW 111:@emph{expr}
3170: @end example
3171:
3172: @item @code{113} - Set @code{termio} Information
3173: We don't know what this does.
3174:
3175: @item @code{133} - Remember @code{ZLOAD} Directory on @code{ZSAVE}
3176: We don't know what this does, but it takes a @emph{tvexpr}.
3177:
3178: @emph{Syntax}
3179: @example
3180: VIEW 133:@emph{tvexpr}
3181: @end example
3182:
3183: @end table
3184:
3185: @node WATCH
3186: @section WATCH
3187: @cindex WATCH
3188: @cindex commands, WATCH
3189: @cindex commands, debugging
3190: @cindex commands, implementation-specific
3191: @cindex commands, non-standard
3192: @emph{FreeM Extension}
3193:
3194: Sets a watchpoint on a global, local, or SSVN node.
3195:
3196: @emph{Syntax}
3197:
3198:
3199: In its @emph{argumentless} form, @code{WATCH} toggles watchpoints on and off, provided the optional @emph{postcondition} is @emph{true} or omitted.
3200:
3201: @example
3202: WATCH[@emph{:postcondition}]
3203: @end example
3204:
3205: In its @emph{inclusive} form, @code{WATCH} adds, removes, or examines watchpoints, provided the optional @emph{postcondition} is @emph{true} or omitted.
3206:
3207: A @code{+} adds a new watchpoint to the following variable.
3208:
3209: A @code{-} removes an existing watchpoint for the following variable.
3210:
3211: A @code{?} examines the status of a watchpoint for the following variable.
3212:
3213: @example
3214: WATCH[@emph{:postcondition}] [+|-|?]@emph{var1}...,[+|-|?]@emph{varN}
3215: @end example
3216:
3217:
3218: 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)}.
3219:
3220: @example
3221: USER> WATCH
3222:
3223: Watchpoints enabled.
3224:
3225: USER> WATCH +^JPW(1)
3226:
3227: Added '^JPW("1")' to the watchlist.
3228:
3229: USER> SET ^JPW(1)="new value"
3230:
3231: >> WATCHPOINT: ^JPW("1") => 'new value' (changed 1 times)
3232:
3233: @end example
3234:
3235: The following example will remove that watchpoint:
3236:
3237: @example
3238: USER> WATCH -^JPW(1)
3239:
3240: Removed '^JPW("1")' from the watchlist.
3241:
3242: USER> WATCH ?^JPW(1)
3243:
3244: '^JPW("1")' is not being watched.
3245: @end example
3246:
3247: @node WITH
3248: @section WITH
3249: @cindex WITH
3250: @cindex commands, WITH
3251: @cindex commands, non-standard
3252: @emph{FreeM Extension}
3253:
3254: Sets a prefix to be applied to all subsequent local variable or constant references.
3255:
3256: @emph{Syntax}
3257:
3258: @example
3259: @code{WITH@emph{:postcondition} @emph{var-prefix}}
3260: @end example
3261:
3262: 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.
3263:
3264: The @emph{var-prefix} argument may be a string literal or any valid FreeM expression.
3265:
3266: @example
3267: @code{WITH@emph{:postcondition}}
3268: @end example
3269:
3270: 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 ""}.
3271:
3272:
3273: @node WRITE
3274: @section WRITE
3275: @cindex WRITE
3276: @cindex commands, WRITE
3277:
3278: @node XECUTE
3279: @section XECUTE
3280: @cindex XECUTE
3281: @cindex commands, XECUTE
3282:
3283: @node ZALLOCATE
3284: @section ZALLOCATE
3285: @cindex ZALLOCATE
3286: @cindex commands, ZALLOCATE
3287: @cindex commands, implementation-specific
3288: @cindex commands, non-standard
3289: @emph{FreeM Extension}
3290:
3291: @node ZBREAK
3292: @section ZBREAK
3293: @cindex ZBREAK
3294: @cindex commands, ZBREAK
3295: @cindex commands, debugging
3296: @cindex commands, implementation-specific
3297: @cindex commands, non-standard
3298: @emph{FreeM Extension}
3299:
3300: @node ZDEALLOCATE
3301: @section ZDEALLOCATE
3302: @cindex ZDEALLOCATE
3303: @cindex commands, ZDEALLOCATE
3304: @cindex commands, implementation-specific
3305: @cindex commands, non-standard
3306: @emph{FreeM Extension}
3307:
3308: @node ZGO
3309: @section ZGO
3310: @cindex ZGO
3311: @cindex commands, ZGO
3312: @cindex commands, implementation-specific
3313: @cindex commands, non-standard
3314: @emph{FreeM Extension}
3315:
3316: @node ZHALT
3317: @section ZHALT
3318: @cindex ZHALT
3319: @cindex commands, ZHALT
3320: @cindex commands, implementation-specific
3321: @cindex commands, non-standard
3322: @emph{FreeM Extension}
3323:
3324: @node ZINSERT
3325: @section ZINSERT
3326: @cindex ZINSERT
3327: @cindex commands, ZINSERT
3328: @cindex commands, implementation-specific
3329: @cindex commands, non-standard
3330: @emph{FreeM Extension}
3331:
3332: @node ZJOB
3333: @section ZJOB
3334: @cindex ZJOB
3335: @cindex commands, ZJOB
3336: @cindex commands, implementation-specific
3337: @cindex commands, non-standard
3338: @emph{FreeM Extension}
3339:
3340: 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.
3341:
3342: For more information, see @code{JOB}.
3343:
3344: @node ZLOAD
3345: @section ZLOAD
3346: @cindex ZLOAD
3347: @cindex commands, ZLOAD
3348: @cindex commands, implementation-specific
3349: @cindex commands, non-standard
3350: @emph{FreeM Extension}
3351:
3352: Loads routine @emph{<routine-name>} into FreeM's routine buffer, provided the optional @emph{postcondition} is @emph{true} or omitted.
3353:
3354: @emph{Syntax}
3355:
3356: @example
3357: ZLOAD@emph{:postcondition} @emph{<routine-name>}
3358: @end example
3359:
3360: @node ZNEW
3361: @section ZNEW
3362: @cindex ZNEW
3363: @cindex commands, ZNEW
3364: @cindex commands, implementation-specific
3365: @cindex commands, non-standard
3366: @emph{FreeM Extension}
3367:
3368: @node ZPRINT
3369: @section ZPRINT
3370: @cindex ZPRINT
3371: @cindex commands, ZPRINT
3372: @cindex commands, implementation-specific
3373: @cindex commands, non-standard
3374: @emph{FreeM Extension}
3375:
3376: Prints the contents of the current routine buffer, provided the optional @emph{postcondition} is @emph{true} or omitted.
3377:
3378: @emph{Syntax}
3379:
3380: @example
3381: ZPRINT@emph{:postcondition}
3382: @end example
3383:
3384: @node ZQUIT
3385: @section ZQUIT
3386: @cindex ZQUIT
3387: @cindex commands, ZQUIT
3388: @cindex commands, implementation-specific
3389: @cindex commands, non-standard
3390: @emph{FreeM Extension}
3391:
3392: In its single-argument form, quits from @emph{levels} levels of the stack, provided the optional @emph{postcondition} is @emph{true} or omitted.
3393:
3394: In its argumentless form, quits from @code{$STACK} levels of the stack, provided the optional @emph{postcondition} is @emph{true} or omitted.
3395:
3396: @emph{Syntax}
3397:
3398: @example
3399: @code{ZQUIT@emph{:postcondition} [@emph{levels}]}
3400: @end example
3401:
3402: @node ZREMOVE
3403: @section ZREMOVE
3404: @cindex ZREMOVE
3405: @cindex commands, ZREMOVE
3406: @cindex commands, implementation-specific
3407: @cindex commands, non-standard
3408: @emph{FreeM Extension}
3409:
3410: @node ZSAVE
3411: @section ZSAVE
3412: @cindex ZSAVE
3413: @cindex commands, ZSAVE
3414: @cindex commands, implementation-specific
3415: @cindex commands, non-standard
3416: @emph{FreeM Extension}
3417:
3418: @node ZTRAP
3419: @section ZTRAP
3420: @cindex ZTRAP
3421: @cindex commands, ZTRAP
3422: @cindex commands, debugging
3423: @cindex commands, implementation-specific
3424: @cindex commands, non-standard
3425: @emph{FreeM Extension}
3426:
3427: @node ZWRITE
3428: @section ZWRITE
3429: @cindex ZWRITE
3430: @cindex commands, ZWRITE
3431: @cindex commands, implementation-specific
3432: @cindex commands, non-standard
3433: @emph{FreeM Extension}
3434:
3435: Writes the names and values of M variables to @code{$IO}.
3436:
3437: @emph{Syntax}
3438:
3439: @example
3440: ZWRITE@emph{:postcondition}
3441: @end example
3442:
3443: In the argumentless form, writes the names and values of all local variables to @code{$IO} if the optional @emph{postcondition} is @emph{true} or omitted.
3444:
3445: @example
3446: ZWRITE@emph{:postcondition} @emph{ArrayName},@dots{}
3447: @end example
3448:
3449: 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{$IO} if the optional @emph{postcondition} is @emph{true} or omitted.
3450:
3451: @example
3452: ZWRITE@emph{:postcondition} (@emph{ArrayName},@dots{})
3453: @end example
3454:
3455: In the exclusive form, writes all local variables @emph{except} those specified in the list of @emph{ArrayName}s to @code{$IO} if the optional @emph{postcondition} is @emph{true} or omitted.
3456:
3457:
3458: @node Structured System Variables
3459: @chapter Structured System Variables
3460: @cindex variables, structured system
3461: @cindex structured system variables
3462: @cindex SSVNs
3463:
3464: @menu
3465: * ^$CHARACTER:: Character set information.
3466: * ^$DEVICE:: Device information.
3467: * ^$DISPLAY:: Information about graphic display.
3468: * ^$EVENT:: Information supplied about a synchronous or asynchronous event.
3469: * ^$GLOBAL:: Information about M globals.
3470: * ^$JOB:: Information about and control of FreeM jobs.
3471: * ^$LOCK:: Information about the FreeM lock table.
3472: * ^$OBJECT:: Information about FreeM objects.
3473: * ^$ROUTINE:: Information about FreeM routines.
3474: * ^$SYSTEM:: Information about the running system.
3475: * ^$WINDOW:: Configuration of MWAPI windows.
3476: * ^$ZPROCESS:: Information about and control of system processes.
3477: * ^$ZRPI:: Information about and control of Raspberry Pi GPIO pins.
3478: @end menu
3479:
3480: SSVN subscripts are each described in the following format:
3481:
3482: @table @asis
3483: @item @code{@emph{<ssvn-subscript-name>}} +/-R +/-U +/-D
3484: @end table
3485:
3486: The R, U, and D flags represent Read, Update, and Delete. A minus sign indicates that the given operation is @emph{not} allowed, and a plus sign indicates that the given operation @emph{is} allowed.
3487:
3488: @node ^$CHARACTER
3489: @section ^$CHARACTER
3490: @cindex ^$CHARACTER
3491: @cindex structured system variables, ^$CHARACTER
3492:
3493: Exposes character set information. As FreeM currently only supports the @code{M} character set, the first subscript of @code{^$CHARACTER} must always be @code{"M"}.
3494:
3495: The following values for the second subscript are supported:
3496:
3497: @table @asis
3498:
3499: @item @code{IDENT} +R -U -D
3500: Returns the empty string.
3501:
3502: @item @code{COLLATE} +R -U -D
3503: Returns the empty string.
3504:
3505: @item @code{INPUT} +R -U -D
3506: Returns the empty string if the third subscript is @code{M}, otherwise, raises error @code{M38}.
3507:
3508: @item @code{OUTPUT} +R -U -D
3509: Returns the empty string if the third subscript is @code{M}, otherwise, raises error @code{M38}.
3510:
3511: @end table
3512:
3513: @node ^$DEVICE
3514: @section ^$DEVICE
3515: @cindex ^$DEVICE
3516: @cindex structured system variables, ^$DEVICE
3517:
3518: FreeM implements several important pieces of functionality in the @code{^$DEVICE} SSVN.
3519:
3520: The first subscript of @code{^$DEVICE} represents the I/O channel of an @code{OPEN}ed device.
3521:
3522: The following values for the second subscript are supported:
3523:
3524: @table @asis
3525:
3526: @item @code{$DEVICE}
3527: Returns the value of @code{$DEVICE} for the specified I/O channel.
3528:
3529: @item @code{$X} +R -U -D
3530: Returns the horizontal cursor position of a terminal device. Only valid if the I/O channel is @code{0}.
3531:
3532: @item @code{$Y} +R -U -D
3533: Returns the vertical cursor position of a terminal device. Only valid if the I/O channel is @code{0}.
3534:
3535: @item @code{ROWS} +R -U -D
3536: Returns the number of character rows on the terminal device. Only valid if the I/O channel is @code{0}.
3537:
3538: @item @code{COLUMNS} +R -U -D
3539: Returns the number of character columns on the terminal device. Only valid if the I/O channel is @code{0}.
3540:
3541: @item @code{CHARACTER} +R -U -D
3542: Returns the character set of the specified I/O channel; always @code{M} in the current implementation.
3543:
3544: @item @code{INPUT_BUFFER} +R +U -D
3545: 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.
3546:
3547: @item @code{NAME} +R -U -D
3548: Returns the operating system's name for the file, device, or socket attached to the specified I/O channel.
3549:
3550: @item @code{FD} +R -U -D
3551: Returns the UNIX file descriptor of the specified I/O channel.
3552:
3553: @item @code{MODE} +R -U -D
3554: 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.
3555:
3556: @item @code{EOF} +R -U -D
3557: 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.
3558:
3559: @item @code{LENGTH} +R -U -D
3560: 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.
3561:
3562: @item @code{NAMESPACE} +R -U -D
3563: Returns the current @emph{mnemonic-space} in use for the referenced I/O channel. Always @code{X364} for terminals and blank for sequential files.
3564:
3565: @item @code{TYPE} +R -U -D
3566: Returns either @code{1,FILE}, @code{2,SOCKET}, or @code{4,TERMINAL}, depending on the device type associated with the specified I/O channel.
3567:
3568: @item @code{OPTIONS} -R -U -D
3569: The following subscripts reside beneath @code{^$DEVICE(<io-channel>,"OPTIONS")}, and this subscript may not be accessed without one of the following third-level subscripts being specified:
3570:
3571: @table @asis
3572:
3573: @item @code{DSW} +R +U -D
3574: Sets or returns the current @emph{Device Status Word} controlling terminal characteristics. Only valid for I/O channel 0.
3575:
3576: @item @code{TERMINATOR} +R +U -D
3577: Sets or returns the @code{READ} terminator for the specified I/O channel. Must be either @code{$C(13,10)} or @code{$C(10)}. Currently only supported for socket devices (those having an I/O channel of 100-255).
3578:
3579: @item @code{TERMID} +R -U -D
3580: Returns the type of terminal connected to channel 0. Only valid for I/O channel 0.
3581:
3582: @item @code{ECHO} +R +U -D
3583: 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.
3584:
3585: @item @code{DELMODE} +R +U -D
3586: 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.
3587:
3588: @item @code{ESCAPE} +R +U -D
3589: 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.
3590:
3591: @item @code{CONVUPPER} +R +U -D
3592: 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.
3593:
3594: @item @code{DELEMPTY} +R +U -D
3595: 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.
3596:
3597: @item @code{NOCTRLS} +R +U -D
3598: TBD. Only valid for I/O channel 0. Corresponds to bit 20 of the Device Status Word.
3599:
3600: @item @code{CTRLOPROC} +R +U -D
3601: 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.
3602:
3603: @item @code{NOTYPEAHEAD} +R +U -D
3604: 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.
3605: @end table
3606: @end table
3607:
3608: @emph{Example}
3609:
3610: 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.
3611:
3612: @example
3613: SET ^$JOB($JOB,"IOPATH")="/etc" ; set I/O path to /etc
3614: OPEN 1:"freem.conf/r" ; open freem.conf for reading
3615: ;
3616: ; read until we run out of lines
3617: ;
3618: FOR USE 1 READ LINE USE 0 QUIT:^$DEVICE(1,"EOF") D
3619: . WRITE LINE,!
3620: ;
3621: CLOSE 1
3622: QUIT
3623: @end example
3624:
3625: @node ^$DISPLAY
3626: @section ^$DISPLAY
3627: @cindex ^$DISPLAY
3628: @cindex structured system variables, ^$DISPLAY
3629:
3630: 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{$PDISPLAY} ISV.
3631:
3632: The following second-level subscripts and specified descendant subscripts are supported:
3633:
3634: @table @asis
3635:
3636: @item @code{CLIPBOARD} +R +U +D
3637: Retrieves, sets, or erases the contents of the system clipboard.
3638:
3639: @item @code{PLATFORM} +R -U -D
3640: Retrieves the name and version of the underlying window system platform.
3641:
3642: @item @code{SIZE} +R -U -D
3643: Retrieves the display resolution of the specified graphical display. For instance, a 1080p display would have a @code{SIZE} value of @code{1920,1080}.
3644:
3645: @item @code{SPECTRUM} +R -U -D
3646: Retrieves the color depth (number of colors supported) of the specified graphical display.
3647:
3648: @item @code{COLORTYPE} +R -U -D
3649: Always returns @code{COLOR}, as monochrome and grayscale displays are not yet supported in FreeM.
3650:
3651: @item @code{UNITS} +R -U -D
3652: Returns the measurement unit of the specified display, i.e., @code{PIXEL}.
3653:
3654: @item @code{TYPEFACE} +R -U -D
3655: The third-level subscripts beneath this subscript represent a list of font families available on this display. The fourth level subscript is a list of sizes supported for the specified typeface, or @code{0} for vector typefaces, such as TrueType, OpenType, and Adobe Type 1 fonts.
3656:
3657: @end table
3658:
3659: @node ^$EVENT
3660: @section ^$EVENT
3661: @cindex ^$EVENT
3662: @cindex structured system variables, ^$EVENT
3663:
3664: The @code{^$EVENT} SSVN is not yet implemented.
3665:
3666: @node ^$GLOBAL
3667: @section ^$GLOBAL
3668: @cindex ^$GLOBAL
3669: @cindex structured system variables, ^$GLOBAL
3670:
3671: The @code{^$GLOBAL} structured system variable provides information about M globals. The first-level subscript is a global name, sans the leading caret symbol.
3672:
3673: The following second-level subscripts are supported:
3674:
3675: @table @asis
3676:
3677: @item @code{BYTES} +R -U -D
3678: Returns the number of bytes this global occupies in fixed storage.
3679:
3680: @item @code{BLOCKS} +R -U -D
3681: Returns the number of blocks contained in this global.
3682:
3683: @item @code{BLOCKSIZE} +R -U -D
3684: Returns the size of data blocks for this global. Currently, FreeM only supports 1024-byte blocks.
3685:
3686: @item @code{FILE} +R -U -D
3687: Returns the full filesystem path to the data file where this global resides in fixed storage.
3688:
3689: @item @code{NAMESPACE} +R +U +D
3690: Returns or sets the name of the FreeM namespace to which this global belongs. @code{SET}ting this node creates a mapping for the specified global name to a non-default namespace. @code{KILL}ing this node restores the mapping configuration for the specified global to the default.
3691:
3692: @end table
3693:
3694: @node ^$JOB
3695: @section ^$JOB
3696: @cindex ^$JOB
3697: @cindex structured system variables, ^$JOB
3698:
3699: FreeM fully implements @code{^$JOB} per ANSI X11.1-1995, as well as several extensions proposed in the M Millennium Draft Standard.
3700:
3701: The first subscript of @code{^$JOB} represents the @code{$JOB} of the process.
3702:
3703: If you @code{KILL} a first-level subscript of @code{^$JOB}, the @code{SIGTERM} signal will be sent to the corresponding UNIX process, causing pending transactions to be rolled back and the process to be terminated. If the targeted process is in direct mode, the user will be prompted with options of either rolling back or committing any pending transactions.
3704:
3705: The following subscripts are supported:
3706:
3707: @table @asis
3708:
3709: @item @code{GVNDEFAULT} +R +U +D
3710: Contains a default expression to be evaluated if a global variable access attempt results in an @code{M7} error.
3711:
3712: Equivalent to wrapping all global accesses in @code{$GET(@emph{global-name},@emph{string-expr})}.
3713:
3714: @item @code{LVNDEFAULT} +R +U +D
3715: Contains a default expression to be evaluated if a local variable access attempt results in an @code{M6} error.
3716:
3717: Equivalent to wrapping all local accesses in @code{$GET(@emph{global-name},@emph{string-expr})}.
3718:
3719: @item @code{LVNQOVAL} +R +U +D
3720: Contains the data value (if any) at the subscripted local variable reference from the most recent @code{$ORDER} or @code{$QUERY} operation.
3721:
3722: This node is useful for code that uses @code{$ORDER} or @code{$QUERY} heavily in loops that retrieve successive data values, as it will prevent an additional symbol table scan that would result from retrieving the data value in the usual way, thus improving application performance. However, this optimization comes at the cost of compatibility with other M implementations.
3723:
3724: @item @code{GVNQOVAL} +R +U +D
3725: Contains the data value (if any) at the subscripted global variable reference from the most recent @code{$ORDER} or @code{$QUERY} operation.
3726:
3727: This node is useful for code that uses @code{$ORDER} or @code{$QUERY} heavily in loops that retrieve successive data values, as it will prevent an additional data file scan that would result from retrieving the data value in the usual way, thus improving application performance. However, this optimization comes at the cost of compatibility with other M implementations.
3728:
3729: @item @code{ZCOMMANDS} +R +U -D
3730: Contains a space-delimited list of @code{Z}-commands to be treated as intrinsic. Any @code{Z}-command not appearing in this list will be treated as a user-defined command.
3731:
3732: For instance, if command @code{ZFOO} does @emph{not} appear in this list, FreeM will attempt to run @code{^%ZFOO} as a subroutine when the @code{ZFOO} command is encountered in program code.
3733:
3734: If you remove a command from this list, you may provide your own private M implementation of the command in the manner described above.
3735:
3736: If an argument is passed to a @code{Z}-command you implement in M, it is made available to your M code in a variable whose name is specified in @code{^$JOB($JOB,"ZCOMMAND_ARGUMENT_NAME")}, which defaults to @code{%}.
3737:
3738: @item @code{PIPE_GLVN} +R +U -D
3739: Contains an M local or global variable to be used as standard input or standard output for the external shell commands run by @code{!<} and @code{!>}.
3740:
3741: @item @code{ZCOMMAND_ARGUMENT_NAME} +R +U -D
3742: Returns or sets the variable name in which arguments to user-defined @code{Z}-commands are passed. Defaults to @code{%}.
3743:
3744: @item @code{ZFUNCTIONS} +R +U -D
3745: Contains a space-delimited list of @code{Z} functions to be treated as intrinsic. Any @code{Z} function not appearing in this list will be treated as a user-defined extrinsic function.
3746:
3747: For instance, if function @code{$ZFOO} does @emph{not} appear in this list, FreeM will attempt to return the value of @code{$$^%ZFOO} called as an extrinsic function.
3748:
3749: If you remove a function from this list, you may provide your own private M implementation of the function in the manner described above.
3750:
3751: @item @code{ZSVS} +R +U -D
3752: Contains a space-delimited list of @code{Z} special variables to be treated as intrinsic. Any @code{Z} special variable not appearing in this list will be treated as a user-defined extrinsic function taking no arguments.
3753:
3754: For instance, if the special variable @code{$ZFOO} does @emph{not} appear in this list, FreeM will attempt to return the value of @code{$$^%ZFOO} called as an extrinsic function.
3755:
3756: 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.
3757:
3758: @item @code{BREAK_HANDLER} +R +U -D
3759: Contains M code to be executed when the @code{BREAK} command is run.
3760:
3761: @item @code{ROUTINE_BUFFER_SIZE} +R +U -D
3762: 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.
3763:
3764: @item @code{ROUTINE_BUFFER_COUNT} +R +U -D
3765: 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.
3766:
3767: @item @code{ROUTINE_BUFFER_AUTO_ADJUST} +R +U -D
3768: 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.
3769:
3770: @item @code{SYMBOL_TABLE_SIZE} +R +U -D
3771: 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.
3772:
3773: @item @code{SYMBOL_TABLE_AUTO_ADJUST} +R +U -D
3774: 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.
3775:
3776:
3777: @item @code{USER_DEFINED_ISV_TABLE_SIZE} +R +U -D
3778: 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.
3779:
3780: @item @code{USER_DEFINED_ISV_TABLE_AUTO_ADJUST} +R +U -D
3781: 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.
3782:
3783: @item @code{GVN_UNIQUE_CHARS} +R +U -D
3784: Returns or sets the number of characters of a global name that make it unique, from 1 to 255.
3785:
3786: @item @code{GVN_CASE_SENSITIVE} +R +U -D
3787: 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.
3788:
3789: @item @code{GVN_NAME_SUB_LENGTH} +R +U -D
3790: Returns or sets the maximum number of characters of a global name plus all of its subscripts, from 1-255.
3791:
3792: @item @code{GVN_SUB_LENGTH} +R +U -D
3793: Returns or sets the maximum number of characters of a single global subscript, from 1-255.
3794:
3795: @item @code{SINGLE_USER} +R +U -D
3796: 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.
3797:
3798: 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!
3799:
3800: @item @code{CHARACTER} +R -U -D
3801: Returns the character set of the job.
3802:
3803: @item @code{CWD} +R +U -D
3804: Returns or sets the current working directory of the job.
3805:
3806: @item @code{OPEN} +R -U -D
3807: The @code{^$JOB($JOB,"OPEN",<channel>} subscripts list the open I/O channels in the specified job.
3808:
3809: @item @code{ENGINES} +R -U -D
3810: Returns or sets the storage engines for various FreeM subsystems.
3811:
3812: The following table lists the types of storage engines that can be defined.
3813:
3814: @table @asis
3815:
3816: @item @code{GLOBAL} +R +U -D
3817: Returns or sets the global handler for a particular FreeM namespace:
3818:
3819: The following code would set the global handler for the @code{SYSTEM} namespace to @code{BERKELEYDB}:
3820:
3821: @code{SET ^$JOB($JOB,"ENGINES","GLOBAL","SYSTEM")="BERKELEYDB"}
3822:
3823: @item @code{LOCAL} +R -U -D
3824: Returns the local handler for a particular FreeM namespace. Always @code{BUILTIN} in the current FreeM release.
3825:
3826: @end table
3827:
3828: @item @code{BERKELEYDB,FLUSH_THRESHOLD} +R +U -D
3829: 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.
3830:
3831: @item @code{EVENT} +R +U +D
3832: 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.
3833:
3834: @item @code{GLOBAL} +R -U -D
3835: Returns the global environment of the job.
3836:
3837: @item @code{IOPATH} +R +U -D
3838: Returns or sets the @emph{I/O path} to be used by the @code{OPEN} command.
3839:
3840: @item @code{PRIORITY} +R +U -D
3841: Returns or sets the @emph{nice} value of the FreeM job.
3842:
3843: @item @code{REVSTR} +R +U -D
3844: When set to 1, allows @code{$EXTRACT} to accept negative values.
3845:
3846: @item @code{ROUTINE} +R -U -D
3847: Returns the name of the routine currently being executed by the job.
3848:
3849: @item @code{SYMTAB} +R +U -D
3850: Returns or sets the current local variable symbol table in use.
3851:
3852: FreeM supports two unique and independent symbol tables, allowing FreeM programs to maintain two independent sets of identically- or differently-named local variables per process.
3853:
3854: The default symbol table is @code{0}, and the alternate symbol table is @code{1}, corresponding to the valid values for @code{^$JOB($JOB,"SYMTAB")}.
3855:
3856: Setting this subscript to values other than @code{0} or @code{1} will result in a @code{ZINVEXPR} error.
3857:
3858: @item @code{$PDISPLAY} +R -U -D
3859: Returns the value of @code{$PDISPLAY} for the job.
3860:
3861: @item @code{$PRINCIPAL} +R -U -D
3862: Returns the value of @code{$PRINCIPAL} for the job.
3863:
3864: @item @code{$TLEVEL} +R -U -D
3865: Returns the current transaction level (value of @code{$TLEVEL} for the job.
3866:
3867: @item @code{$IO} +R -U -D
3868: Returns the current value of @code{$IO} for the job.
3869:
3870: @item @code{USER} +R -U -D
3871: Returns the UID of the user owning the job.
3872:
3873: @item @code{GROUP} +R -U -D
3874: Returns the GID of the group owning the job.
3875:
3876: @item @code{NAMESPACE} +R +U -D
3877: Returns or sets the name of the job's currently-active namespace.
3878:
3879: @item @code{MATH} +R +U -D
3880: Returns or sets the mode in which decimal comparisons and arithmetic calculations are conducted. Valid values are @code{FIXED}, for fixed-point decimals having up to 20,000 digits of precision, as determined by the @code{$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.
3881:
3882: @code{IEEE754} mode will make mathematical calculations significantly faster, especially when accelerated by a floating-point processor, at the expense of precision and accuracy.
3883:
3884: @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.
3885:
3886: Attempting to @code{SET} this node to values other than @code{FIXED} or @code{IEEE754} will set @code{$ECODE} to @code{M29}.
3887:
3888: @end table
3889:
3890: @node ^$LOCK
3891: @section ^$LOCK
3892: @cindex ^$LOCK
3893: @cindex structured system variables, ^$LOCK
3894:
3895: The first-level subscript of @code{^$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.
3896:
3897: Attempting to @code{SET} or @code{KILL} any node in @code{^$LOCK} will raise error @code{M29}.
3898:
3899: @node ^$OBJECT
3900: @section ^$OBJECT
3901: @cindex ^$OBJECT
3902: @cindex structured system variables, ^$OBJECT
3903:
3904: @node ^$ROUTINE
3905: @section ^$ROUTINE
3906: @cindex ^$ROUTINE
3907: @cindex structured system variables, ^$ROUTINE
3908:
3909: The @code{^$ROUTINE} SSVN exposes a list of routines available in the current FreeM namespace, as well as additional attributes further describing each routine.
3910:
3911: The first-level subscript is the name of a FreeM routine minus the leading caret symbol.
3912:
3913: The following second-level subscripts are supported:
3914:
3915: @table @asis
3916:
3917: @item @code{CHARACTER} +R -U -D
3918: Returns the character set of the routine.
3919:
3920: @item @code{NAMESPACE} +R -U -D
3921: Returns the name of the FreeM namespace in which the routine resides.
3922:
3923: @item @code{PATH} +R -U -D
3924: Returns the full filesystem path to the routine in fixed storage.
3925:
3926: @end table
3927:
3928: @node ^$SYSTEM
3929: @section ^$SYSTEM
3930: @cindex ^$SYSTEM
3931: @cindex structured system variables, ^$SYSTEM
3932:
3933: The @code{^$SYSTEM} SSVN exposes system-level implementation details.
3934:
3935: The following first-level subscripts are supported:
3936:
3937: @table @asis
3938:
3939: @item @code{DEFPSIZE} +R -U -D
3940: Returns the default size in bytes of the symbol table and routine buffer memory partition.
3941:
3942: @item @code{DEFUDFSVSIZ} +R -U -D
3943: Returns the default size in bytes of the user-defined intrinsic special variable table.
3944:
3945: @item @code{DEFNSIZE} +R -U -D
3946: Returns the default size of the @code{NEW} stack, in number of entries.
3947:
3948: @item @code{MAXNO_OF_RBUF} +R -U -D
3949: Returns the maximum number of routine buffers.
3950:
3951: @item @code{DEFNO_OF_RBUF} +R -U -D
3952: Returns the default number of routine buffers.
3953:
3954: @item @code{DEFPSIZE0} +R -U -D
3955: Returns the default size in bytes of each routine buffer.
3956:
3957: @item @code{NO_GLOBLS} +R -U -D
3958: Returns the maximum number of globals that can be concurrently opened.
3959:
3960: @item @code{NO_OF_GBUF} +R -U -D
3961: Returns the number of global buffers.
3962:
3963: @item @code{NESTLEVLS} +R -U -D
3964: Returns the depth of the @code{DO}, @code{FOR}, @code{XECUTE} stack.
3965:
3966: @item @code{PARDEPTH} +R -U -D
3967: Returns the maximum depth of the parser's parameter stack.
3968:
3969: @item @code{PATDEPTH} +R -U -D
3970: Returns the maximum number of @emph{patatom}s in each pattern.
3971:
3972: @item @code{TRLIM} +R -U -D
3973: Returns the trace limit of the @code{BUILTIN} global handler.
3974:
3975: @item @code{ARGS_IN_ESC} +R -U -D
3976: Returns the maximum number of arguments in a terminal escape sequence.
3977:
3978: @item @code{ZTLEN} +R -U -D
3979: Returns the maximum length of @code{$ZTRAP}.
3980:
3981: @item @code{FUNLEN} +R -U -D
3982: Returns the maximum length of the @code{$ZF} (function key) variable.
3983:
3984: @item @code{NAME_LENGTH} +R -U -D
3985: Returns the maximum length of variable names in the current FreeM build. Compatible with the same SSVN node in @emph{Reference Standard M}
3986:
3987: @item @code{STRING_MAX} +R -U -D
3988: Returns the maximum length of character strings in the current FreeM build. Compatible with the same SSVN node in @emph{Reference Standard M}
3989:
3990: @item @code{$NEXTOK} +R -U -D
3991: 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}.
3992:
3993: @item @code{EOK} +R -U -D
3994: 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}.
3995:
3996: @item @code{OFFOK} +R -U -D
3997: 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}.
3998:
3999: @item @code{BIG_ENDIAN} +R -U -D
4000: 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}.
4001:
4002: @item @code{NAMESPACE} +R -U -D
4003: The descendant subscripts of this node list each namespace in the current FreeM environment.
4004:
4005: @item @code{MAPPINGS,GLOBAL} +R -U -D
4006: Descendant subscripts of this node represent global name mappings set in @code{^$GLOBAL(@emph{gvn},"NAMESPACE")}
4007:
4008: @end table
4009:
4010: @node ^$WINDOW
4011: @section ^$WINDOW
4012: @cindex ^$WINDOW
4013: @cindex structured system variables, ^$WINDOW
4014:
4015: The @code{^$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.
4016:
4017: @node ^$ZPROCESS
4018: @section ^$ZPROCESS
4019: @cindex ^$ZPROCESS
4020: @cindex structured system variables, ^$ZPROCESS
4021:
4022: 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.
4023:
4024: The first subscript always represents the @emph{process ID} of the external process being acted upon.
4025:
4026: The following values for the second subscript are supported:
4027:
4028:
4029: @table @asis
4030:
4031: @item @code{EXISTS} +R -U -D
4032: Returns 1 if the referenced process exists; 0 otherwise.
4033:
4034: @item @code{ATTRIBUTE} +R -U -D
4035: Exposes the @code{/proc} files as descendant subscripts, i.e., @code{WRITE ^$ZPROCESS(2900,"ATTRIBUTE","cmdline"),!} would print the initial command line used to invoke process ID 2900. Note that the third subscript (the immediate descendant of the @code{ATTRIBUTE} subscript) is case sensitive.
4036:
4037: @item @code{SIGNAL} -R +U -D
4038: Allows signals to be sent to the referenced process. The following subscript is an integer value corresponding to the desired signal number. You may obtain a list of signal numbers on most UNIX systems with the command @code{kill -l}.
4039:
4040: The constants @code{%SYS.SIGNAL.HUP}, @code{%SYS.SIGNAL.INT}, @code{%SYS.SIGNAL.KILL}, and @code{%SYS.SIGNAL.TERM} are provided for convenient use of this SSVN subscript.
4041:
4042: @end table
4043:
4044: @node ^$ZRPI
4045: @section ^$ZRPI
4046: @cindex ^$ZRPI
4047: @cindex structured system variables, ^$ZRPI
4048:
4049: The @code{^$ZRPI} structured system variable provides easy access to general-purpose input/output (GPIO) pins on Raspberry Pi single-board computers.
4050:
4051: To initialize the GPIO subsystem, @code{SET ^$ZRPI("INITIALIZE")=1}.
4052:
4053: Individual pins are accessed through @code{^$ZRPI("GPIO",<pin>,...)}, where @code{<pin>} represents the desired pin number. Descendant subscripts of @code{^$ZRPI("GPIO",<pin>)} are as follows:
4054:
4055: @table @asis
4056:
4057: @item @code{MODE} +R +U -D
4058: Represents the operating mode of the selected pin. One of @code{INPUT}, @code{OUTPUT}, @code{PWM_OUTPUT}, or @code{GPIO_CLOCK}.
4059:
4060: @item @code{DIGITAL} +R +U -D
4061: Reads or writes the selected pin digitally. The value is limited to @code{1} or @code{0}.
4062:
4063: @item @code{ANALOG} +R +U -D
4064: Reads or writes the selected pin in an analog fashion. The value represents analog voltage.
4065:
4066: @end table
4067:
4068: @node Operators
4069: @chapter Operators
4070:
4071: @menu
4072: * Unary +:: Force a value to positive.
4073: * Unary -:: Force a value to negative.
4074: * +:: Add.
4075: * +=:: Add and assign.
4076: * ++:: Postfix increment.
4077: * -:: Subtract.
4078: * -=:: Subtract and assign.
4079: * --:: Postfix decrement.
4080: * *:: Multiply.
4081: * *=:: Multiply and assign.
4082: * /:: Divide.
4083: * /=:: Divide and assign.
4084: * \:: Integer divide.
4085: * \=:: Integer divide and assign.
4086: * #:: Modulo.
4087: * #=:: Modulo and assign.
4088: * **:: Exponentiate.
4089: * **=:: Exponentiate and assign.
4090: * <:: Less than.
4091: * <=:: Less than or equal to.
4092: * >:: Greater than.
4093: * >=:: Greater than or equal to.
4094: * _:: Concatenate.
4095: * _=:: Concatenate and assign.
4096: * =:: Equals.
4097: * [:: Contains.
4098: * ]:: Follows.
4099: * ]]:: Sorts after.
4100: * ?:: Pattern match.
4101: * &:: Logical AND.
4102: * ! (Operator):: Logical OR.
4103: * ':: Logical NOT.
4104: * @@ (Operator):: Indirect
4105: @end menu
4106:
4107: @node Unary +
4108: @section Unary +
4109: @cindex operators, unary +
4110:
4111: Forces a number to positive, whether positive or negative. Also forces numeric coercion of strings.
4112:
4113: @node Unary -
4114: @section Unary -
4115: @cindex operators, unary -
4116:
4117: @node +
4118: @section + (Add)
4119: @cindex operators, +
4120:
4121: @node +=
4122: @section += (Add/Assign)
4123: @cindex operators, +=
4124:
4125: @node ++
4126: @section ++ (Postfix Increment)
4127: @cindex operators, ++
4128:
4129: @node -
4130: @section - (Subtract)
4131: @cindex operators, -
4132:
4133: @node -=
4134: @section -= (Subtract/Assign)
4135: @cindex operators, -=
4136:
4137: @node --
4138: @section -- (Postfix Decrement)
4139: @cindex operators, --
4140:
4141: @node *
4142: @section * (Multiply)
4143: @cindex operators, *
4144:
4145: @node *=
4146: @section *= (Multiply/Assign)
4147: @cindex operators, *=
4148:
4149: @node /
4150: @section / (Divide)
4151: @cindex operators, /
4152:
4153: @node /=
4154: @section /= (Divide/Assign)
4155: @cindex operators, /=
4156:
4157: @node \
4158: @section \ (Integer Divide)
4159: @cindex operators, \
4160:
4161: @node \=
4162: @section \= (Integer Divide/Assign)
4163: @cindex operators, \=
4164:
4165: @node #
4166: @section # (Modulo)
4167: @cindex operators, #
4168:
4169: @node #=
4170: @section #= (Modulo/Assign)
4171: @cindex operators, #=
4172:
4173: @node **
4174: @section ** (Exponentiate)
4175: @cindex operators, **
4176:
4177: @node **=
4178: @section **= (Exponentiate/Assign)
4179: @cindex operators, **=
4180:
4181: @node <
4182: @section < (Less Than)
4183: @cindex operators, <
4184:
4185: @node <=
4186: @section <= (Less Than or Equal To)
4187: @cindex operators, <=
4188:
4189: @node >
4190: @section > (Greater Than)
4191: @cindex operators, >
4192:
4193: @node >=
4194: @section >= (Greater Than or Equal To)
4195: @cindex operators, >=
4196:
4197: @node _
4198: @section _ (Concatenate)
4199: @cindex operators, _
4200:
4201: @node _=
4202: @section _= (Concatenate/Assign)
4203: @cindex operators, _=
4204:
4205: @node =
4206: @section = (Equals)
4207: @cindex operators, =
4208:
4209: @node [
4210: @section [ (Contains)
4211: @cindex operators, [
4212:
4213: @node ]
4214: @section ] (Follows)
4215: @cindex operators, ]
4216:
4217: @node ]]
4218: @section ]] (Sorts After)
4219: @cindex operators, ]]
4220:
4221: @node ?
4222: @section ? (Pattern Match)
4223: @cindex operators, ?
4224:
4225: @node &
4226: @section & (Logical AND)
4227: @cindex operators, &
4228:
4229: @node ! (Operator)
4230: @section ! (Logical OR)
4231: @cindex operators, !
4232:
4233: @node '
4234: @section ' (Logical NOT)
4235: @cindex operators, '
4236:
4237: @node @@ (Operator)
4238: @section @@ (Indirect)
4239: @cindex operators, @@
4240:
4241: @node Routines
4242: @chapter Routines
4243: @cindex routines
4244:
4245: A @emph{routine} is a file containing M source code to be processed by FreeM.
4246:
4247: 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}).
4248:
4249: @menu
4250: * Routine Naming:: Requirements and conventions for routine names.
4251: @end menu
4252:
4253:
4254: @node Routine Naming
4255: @section Routine Naming
4256: 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.
4257:
4258: Routine naming rules are as follows:
4259:
4260: @itemize @bullet
4261: @item Routine names must begin with an upper- or lower-case letter, or a @code{%} sign
4262: @item Within the routine name, you may have upper-case or lower-case letters or digits
4263: @item The entire routine name must not be longer than 255 characters
4264: @end itemize
4265:
4266: Routines whose names begin with @code{%} must be located in the @code{SYSTEM} namespace. Other routines may be located in any namespace.
4267:
4268: @node Types
4269: @chapter Types
4270: @cindex types
4271: @cindex data types
4272:
4273: 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.
4274:
4275: @menu
4276: * BOOLEAN:: Truth values.
4277: * COMPLEX:: Numbers with real and imaginary parts.
4278: * INTEGER:: Numbers with no decimal part.
4279: * REAL:: Numbers with a decimal part.
4280: * STRING:: Arbitrary strings of characters.
4281: * Custom Types (Classes):: User-defined, object-oriented types.
4282: @end menu
4283:
4284: @node BOOLEAN
4285: @section BOOLEAN
4286: @cindex data types, BOOLEAN
4287: @cindex types, BOOLEAN
4288:
4289: The @code{BOOLEAN} type represents any M value that can be interpreted as a truth-value.
4290:
4291: @node COMPLEX
4292: @section COMPLEX
4293: @cindex data types, COMPLEX
4294: @cindex types, COMPLEX
4295:
4296: 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.
4297:
4298: 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}.
4299:
4300: @node INTEGER
4301: @section INTEGER
4302: @cindex data types, INTEGER
4303: @cindex types, INTEGER
4304:
4305: An @code{INTEGER} is an interpretation of numeric data with any fractional part removed.
4306:
4307: @node REAL
4308: @section REAL
4309: @cindex data types, REAL
4310: @cindex types, REAL
4311:
4312: @node STRING
4313: @section STRING
4314: @cindex data types, STRING
4315: @cindex types, STRING
4316:
4317: @node Custom Types (Classes)
4318: @section Custom Types (Classes)
4319: @cindex data types, custom
4320: @cindex types, custom
4321: @cindex classes
4322:
4323: See @ref{Classes}.
4324:
4325: @node Globals
4326: @chapter Globals
4327: @cindex globals
4328: @cindex variables, global
4329: @cindex data
4330:
4331: @node Concurrency Control
4332: @chapter Concurrency Control
4333: @cindex concurrency control
4334: @cindex locking
4335: @cindex transaction processing
4336:
4337: @node Local Variables
4338: @chapter Local Variables
4339: @cindex variables, local
4340: @cindex local variables
4341:
4342: @node Scoping
4343: @chapter Scoping
4344: @cindex scoping
4345:
4346: @node Decision Constructs
4347: @chapter Decision Constructs
4348: @cindex decision constructs
4349: @cindex IF
4350: @cindex ELSE
4351: @cindex THEN
4352: @cindex postconditionals
4353:
4354: @node Branch Constructs
4355: @chapter Branch Constructs
4356: @cindex branch constructs
4357: @cindex DO
4358: @cindex GOTO
4359: @cindex JOB
4360:
4361: @node Loop Constructs
4362: @chapter Loop Constructs
4363: @cindex loop constructs
4364: @cindex FOR
4365:
4366: @node Modular Programming
4367: @chapter Modular Programming
4368: @cindex modular programming
4369: @cindex functions, extrinsic
4370: @cindex subroutines
4371:
1.2 snw 4372: @menu
4373: * Subroutines:: Making sections of code reusable.
4374: * Extrinsic Functions:: Reusable code that returns a value.
4375: @end menu
4376:
1.1 snw 4377: @node Subroutines
4378: @section Subroutines
4379:
4380: @node Extrinsic Functions
4381: @section Extrinsic Functions
4382:
4383: @node Object-Oriented Programming
4384: @chapter Object-Oriented Programming
4385: @cindex object-oriented programming
4386: @cindex programming, object-oriented
4387:
1.2 snw 4388: @menu
4389: * Classes:: The basis of object-oriented programming.
4390: @end menu
4391:
1.1 snw 4392: @node Classes
4393: @section Classes
4394:
1.2 snw 4395: @menu
4396: * Inheritance:: Basing one class upon another.
4397: * Methods:: Attaching code to a class.
4398: * Public Variables:: Variables visible outside of a class.
4399: * Private Variables:: Variables only visible within a class.
4400: @end menu
4401:
1.1 snw 4402: @node Inheritance
4403: @subsection Inheritance
4404:
4405: @node Methods
4406: @subsection Methods
4407:
4408: @node Public Variables
4409: @subsection Public Variables
4410:
4411: @node Private Variables
4412: @subsection Private Variables
4413:
4414: @node Libraries
4415: @chapter Libraries
4416: @cindex libraries
4417:
4418: @node Sequential I/O
4419: @chapter Sequential I/O
4420:
4421: @node Network I/O
4422: @chapter Network I/O
4423: @cindex networks, input and output
4424:
4425: 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.
4426:
4427: @section Opening and Connecting a Client Socket
4428: @cindex networks, opening and connecting client sockets
4429:
4430: To open a client socket and connect to it, you will need to call the @code{OPEN} command and the @code{USE} command:
4431:
4432: @example
4433: ;
4434: ; Set socket read terminator to LF
4435: ;
4436: SET ^$DEVICE(100,"OPTIONS","TERMINATOR")=$C(10)
4437: ;
4438: ; Open an IPv4 TCP socket to mail.mydomain.com on port 25 (SMTP)
4439: ; and connect to it
4440: ;
4441: OPEN 100:"mail.mydomain.com:25:IPV4:TCP"
4442: USE 100:/CONNECT
4443: ;
4444: ; Read a line of input from the remote host and write it to the terminal
4445: ;
4446: NEW LINE
4447: READ LINE
4448: USE 0
4449: WRITE LINE,!
4450: ;
4451: ; CLOSE the socket and disconnect
4452: ;
4453: CLOSE 100
4454: QUIT
4455: @end example
4456:
4457: @node Extended Global References
4458: @chapter Extended Global References
4459: @cindex global references, extended
4460: @cindex extended global references
4461:
4462: @section Standard Extended Global References
4463: @cindex extended global references, standard
4464:
4465: 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.
4466:
4467: 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:
4468:
4469: @example
4470: WRITE ^|"VISTA"|VA(200,0),!
4471: @end example
4472:
4473: You may also use an expression that resolves to a string containing a valid namespace name:
4474:
4475: @example
4476: SET NS="VISTA"
4477: WRITE ^|NS|VA(200,0),!
4478: @end example
4479:
4480: @section File Path Extended Global References
4481: @cindex extended global references, file path
4482:
4483: If a namespace is configured to use the @code{BUILTIN} global handler, FreeM supports accessing a global data file by way of its filesystem path.
4484:
4485: The following file path extended global reference will write the value of @code{^VA(200,0)}, assuming the @code{^VA} data file exists at path @code{/home/jpw/^VA}:
4486:
4487: @example
4488: WRITE ^/home/jpw/VA(200,0),!
4489: @end example
4490:
4491:
4492: @node Global Aliasing
4493: @chapter Global Aliasing
4494: @cindex aliasing, global
4495: @cindex globals, aliasing
4496:
4497: FreeM provides the ability to set alternative names for M global variables.
4498:
4499: To create an alias of @code{^FOO} named @code{^BAR}, use the following command:
4500:
4501: @example
4502: SET ^$JOB($JOB,"ALIASES","^BAR")="^FOO"
4503: @end example
4504:
4505: If such an alias is set, any reference to global variable @code{^BAR} will affect @code{^FOO} instead of @code{^BAR} until @code{^$JOB($JOB,"ALIASES","^BAR")} is @code{KILL}ed. If @code{^BAR} existed prior to the definition of this alias, its data will be unavailable to and unaffected by application code.
4506:
4507: @node Global Mappings
4508: @chapter Global Mappings
4509: @cindex mappings, global
4510: @cindex globals, mapping
4511:
4512: FreeM supports creating persistent mappings through which arbitrary global names may be mapped to specific namespaces. This allows non-@code{%} globals to be stored in the @code{SYSTEM} namespace, or @code{%} globals to be stored in non-@code{SYSTEM} namespaces.
4513:
4514: To map the @code{^FOO} global to the @code{SYSTEM} namespace, any of the following will work:
4515:
4516: @example
4517: MAP GLOBAL ^FOO="SYSTEM"
4518: SET ^$GLOBAL("FOO","NAMESPACE")="SYSTEM"
4519: SET ^$SYSTEM("MAPPINGS","GLOBAL","^FOO")="SYSTEM"
4520: @end example
4521:
4522: There is no functional difference in any of the three approaches; the method you choose is a matter of personal preference.
4523:
4524: To remove the above mapping, any of the following examples will also work:
4525:
4526: @example
4527: UNMAP GLOBAL ^FOO
4528: KILL ^$GLOBAL("FOO","NAMESPACE")
4529: KILL ^$SYSTEM("MAPPINGS","GLOBAL","^FOO")
4530: @end example
4531:
4532: @node Transaction Processing
4533: @chapter Transaction Processing
4534: @cindex transaction processing
4535:
4536: 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).
4537:
4538: @section Theory of Operation
4539:
4540: 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.
4541:
4542: 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.
4543:
4544: 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.
4545:
4546: Checkpoints can have one of two modes:
4547:
4548: @table @asis
4549:
4550: @item @code{CP_REMOVE}
4551: 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.
4552:
4553: @item @code{CP_RESTORE}
4554: 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.
4555:
4556: @end table
4557:
4558: The below example shows a few global operations and checkpoints for a transaction in-flight using the @code{trantab} direct-mode command:
4559:
4560: @verbatim
4561: TL1:USER> trantab
4562: $TLEVEL 1*
4563: Operations for Transaction ID: 6ea14aad-b8f1-47f9-9f52-4f513f892bc0 [RESTARTABLE SERIAL]
4564:
4565: OP. NO. ACTION KEY/DATA
4566: ------- ------ --------
4567: 1 SET ^FOO=3
4568: 2 KILL ^FOO
4569: 3 SET ^jpw=10
4570: 4 SET ^BRANDNEW=6
4571:
4572: Global checkpoints:
4573:
4574: GLOBAL MODE FILES
4575: ------ ---- -----
4576: ^BRANDNEW CP_REMOVE IN: /usr/local/var/freem/USER/globals/^BRANDNEW
4577: ^jpw CP_RESTORE IN: /usr/local/var/freem/USER/globals/^jpw
4578: OUT: /usr/local/var/freem/USER/globals/^jpw.23390.1.chk
4579: ^FOO CP_RESTORE IN: /usr/local/var/freem/USER/globals/^FOO
4580: OUT: /usr/local/var/freem/USER/globals/^FOO.23390.1.chk
4581: @end verbatim
4582:
4583: In the above example, @code{IN} files are the live data file that will be overwritten or removed, and @code{OUT} files are the checkpoints themselves. Note that @code{OUT} files are only used for @code{CP_RESTORE} checkpoints.
4584:
4585:
4586: @node Asynchronous Event Handling
4587: @chapter Asynchronous Event Handling
4588: @cindex event handling, asynchronous
4589:
4590: Asynchronous event handling in FreeM follows the specifications of the unpublished MDC @emph{Millennium Draft Standard}.
4591:
4592: @section Setting Up Async Event Handlers
4593:
4594: Asynchronous event handlers are configured through the @code{^$JOB} structured system variable for job-specific events, and the @code{^$SYSTEM} structured system variable for system-wide events. In order to become proficient in writing asynchronous event handling code, you need to be aware of several important concepts:
4595:
4596: @table @emph
4597:
4598: @item Event Classes
4599: @emph{Event classes} denote particular categories of events. These include @code{COMM}, @code{HALT}, @code{IPC}, @code{INTERRUPT}, @code{POWER}, @code{TIMER}, @code{TRIGGER}, and @code{USER} event classes. At present, only @code{INTERRUPT} and @code{TRIGGER} event classes are supported.
4600:
4601: @item Event Identifiers
4602: @emph{Event identifiers} denote the precise nature of the event that has occurred. For instance, resizing the terminal window in which a FreeM job is running will send an event of class @code{INTERRUPT} with an event identifier of @code{SIGWINCH} (short for @emph{SIGnal WINdow CHange}).
4603:
4604: @item Event Handlers
4605: @emph{Event handlers} are M routines or subroutines that can be registered to run when an event of a certain event class occurs.
4606:
4607: @item Event Registration
4608: @emph{Event registration} is the process of modifying the @code{^$JOB} or @code{^$SYSTEM} SSVN to associate a particular event class and event identifier with an event handler routine or subroutine.
4609:
4610: @item Event Blocking and Unblocking
4611: @emph{Event blocking} is the means by which asynchronous event handling can be temporarily suspended. For example, asynchronous events are temporarily and implicitly blocked for the duration of event handler execution, unless explicitly un-blocked within the event handler. Event handling can also be blocked and unblocked programatically from M code using the @code{ABLOCK} and @code{AUNBLOCK} commands.
4612:
4613: @end table
4614:
4615: The following sections of this chapter will take you step-by-step through setting up an event handler for @code{SIGWINCH} signal handling.
4616:
4617: @section Registering an Asynchronous Event Handler
4618: @cindex event handlers, registration
4619:
4620: To register a job-specific event handler that will only execute in the current FreeM process, use the following syntax:
4621:
4622: @example
4623: SET ^$JOB($JOB,"EVENT",@emph{event-class},@emph{event-identifier})=@emph{entryref}
4624: @end example
4625:
4626: To register a system-wide event handler that will execute in every FreeM process, use the following syntax:
4627:
4628: @example
4629: SET ^$SYSTEM("EVENT",@emph{event-class},@emph{event-identifier})=@emph{entryref}
4630: @end example
4631:
4632: For example, use the following to register @code{^RESIZE} as an asynchronous event handler for @code{SIGWINCH} events:
4633:
4634: @example
4635: SET ^$JOB($JOB,"EVENT","INTERRUPT","SIGWINCH")="^RESIZE"
4636: @end example
4637:
4638: 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}.
4639:
4640: @section Enabling Asynchronous Event Handling
4641: @cindex event handlers, enabling
4642:
4643: 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:
4644:
4645: @example
4646: ASTART "INTERRUPT"
4647: @end example
4648:
4649: 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.
4650:
4651: Once this is done, any event handlers registered for the @code{INTERRUPT} event class in @code{^$JOB} will be executed asynchronously as appropriate.
4652:
4653: Please note that @code{ASTART "TRIGGER"} is run implicitly at FreeM startup, to ensure consistency in applications depending on business logic contained in system-wide global triggers. To disable this behavior, add @code{ASTOP "TRIGGER"} to the @code{LOCAL.STARTUP} routine in the @code{USER} namespace. If @code{LOCAL.STARTUP} does not yet exist in your environment, you may create it by typing @code{fmadm edit routine USER LOCAL.STARTUP} from your UNIX command-line shell.
4654:
4655: @section Disabling Asynchronous Event Handling
4656: @cindex event handlers, disabling
4657:
4658: To disable asynchronous event handling, the @code{ASTOP} command is used. In the following example, we will disable asynchronous event handling for the @code{INTERRUPT} event class:
4659:
4660: @example
4661: ASTOP "INTERRUPT"
4662: @end example
4663:
4664: Omitting the @code{"INTERRUPT"} argument will disable asynchronous event handling for @emph{all} event classes. See @code{ASTOP} in the commands section for more details.
4665:
4666: You may also disable asynchronous event handling for a specific event identifier by @code{KILL}ing the appropriate node in the @code{^$JOB} SSVN, which unregisters the event handler altogether. The following example will unregister the event handler for the @code{SIGWINCH} event identifier:
4667:
4668: @example
4669: KILL ^$JOB($JOB,"EVENT","INTERRUPT","SIGWINCH")
4670: @end example
4671:
4672: @section Temporarily Blocking Asynchronous Event Handling
4673: @cindex event handlers, blocking
4674:
4675: 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.
4676:
4677: The following example blocks asynchronous event handling for the @code{INTERRUPT} event class:
4678:
4679: @example
4680: ABLOCK "INTERRUPT"
4681: @end example
4682:
4683: 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.
4684:
4685: 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.
4686:
4687: @node Global Triggers
4688: @chapter Global Triggers
4689: @cindex global triggers
4690: @cindex triggers
4691:
4692: 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.
4693:
4694: 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:
4695:
4696: @table @asis
4697:
4698: @item @code{DATA}
4699: Trigger will fire when the @code{$DATA} intrinsic function is called on @emph{<gvn>}.
4700:
4701: @item @code{GET}
4702: Trigger will fire when @emph{<gvn>} is read from.
4703:
4704: @item @code{INCREMENT}
4705: Trigger will fire when intrinsic function @code{$INCREMENT} is called on @emph{<gvn>}.
4706:
4707: @item @code{KILL}
4708: Trigger will fire when @emph{<gvn>} is @code{KILL}ed.
4709:
4710: @item @code{NEXT}
4711: Trigger will fire when intrinsic function @code{$NEXT} is called on @emph{<gvn>}.
4712:
4713: @item @code{ORDER}
4714: Trigger will fire when intrinsic function @code{$ORDER} is called on @emph{<gvn>}.
4715:
4716: @item @code{QUERY}
4717: Trigger will fire when intrinsic function @code{$QUERY} is called on @emph{<gvn>}.
4718:
4719: @item @code{SET}
4720: Trigger will fire when @code{SET @emph{<gvn>}=@emph{value}} occurs.
4721:
4722: @item @code{ZDATA}
4723: Trigger will fire when intrinsic function @code{ZDATA} is called on @emph{<gvn>}.
4724:
4725: @end table
4726:
4727: When a @code{TRIGGER} event occurs, the @code{"GLOBAL"} node of the @code{^$EVENT} structured system variable will be populated with the global reference that invoked the trigger event.
4728:
4729: 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.
4730:
4731: The following example shows a trigger implemented for @code{SET} operations on the @code{^DD} global.
4732:
4733: @example
4734: TRIGGER ;
4735: ;
4736: ; Set up a SET trigger on ^DD
4737: ;
4738: SET ^$JOB($JOB,"EVENT","TRIGGER","SET:^DD")="ONSET^TRIGGER"
4739: ;
4740: ; Enable the TRIGGER event class
4741: ;
4742: ASTART "TRIGGER"
4743: ;
4744: ; Try setting a node in ^DD
4745: ;
4746: SET ^DD(1)="Test"
4747: ;
4748: ; Quit
4749: ;
4750: QUIT
4751: ;
4752: ;
4753: ONSET ;
4754: WRITE "The "_^$EVENT("GLOBAL")_" global node was SET.",!
4755: QUIT
4756: @end example
4757:
4758: You can also set up a trigger that applies to all FreeM processes by setting descendant subscripts of @code{^$SYSTEM("EVENT","TRIGGER",...)} instead of using @code{^$JOB($JOB,"EVENT","TRIGGER",...)}.
4759:
4760: @node Synchronous Event Handling
4761: @chapter Synchronous Event Handling
4762:
4763: @node GUI Programming with MWAPI
4764: @chapter GUI Programming with MWAPI
4765:
4766: @node User-Defined Z Commands
4767: @chapter User-Defined Z Commands
4768:
4769: @node User-Defined Z Functions
4770: @chapter User-Defined Z Functions
4771:
4772: @cindex z functions, user-defined
4773:
4774: @node User-Defined SSVNs
4775: @chapter User-Defined SSVNs
4776:
4777: @cindex structured system variables, user-defined
4778: @cindex structured system variables
4779:
4780: @node Language Dialects
4781: @chapter Language Dialects
4782:
4783: @cindex language dialects
4784: @cindex dialects, language
4785:
4786:
4787: @node System Library Routines
4788: @chapter System Library Routines
4789: @cindex system library routines
4790:
4791: @section ^%ZCOLUMNS
4792: @cindex ^%ZCOLUMNS
4793: @cindex system library routines, ^%ZCOLUMNS
4794:
4795: This routine is the implementation of the @code{$ZCOLUMNS} intrinsic special variable.
4796:
4797: @section ^%SYSINIT
4798: @cindex ^%SYSINIT
4799: @cindex system library routines, ^%SYSINIT
4800:
4801: This routine is the default startup routine for FreeM running in direct mode.
4802:
4803: Running @code{DO INFO} from direct mode will use this routine to display information about the current FreeM status and namespace configuration.
4804:
4805: @section ^%ZHELP
4806: @cindex ^%ZHELP
4807: @cindex system library routines, ^%ZHELP
4808:
4809: This routine implements the online help feature of FreeM, invoked by typing @code{?} in direct mode. It simply asks the underlying system to execute the command @command{info freem}.
4810:
4811: @section ^%ZROWS
4812: @cindex ^%ZROWS
4813: @cindex system library routines, ^%ZROWS
4814:
4815: This routine is the implementation of the @code{$ZROWS} intrinsic special variable.
4816:
4817: @node Interrupt Handling
4818: @chapter Interrupt Handling
4819: @cindex interrupt handling
4820:
4821: 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 daemon, or another external process, one of two things can happen, depending on the state of the @code{$ZI} special variable:
4822:
4823: @table @asis
4824: @item @code{$ZI} evaluates @emph{true}
4825: 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.
4826:
4827: This is the default behavior of FreeM.
4828: @item @code{$ZI} evaluates @emph{false}
4829: In this case, no error is raised, but the @code{$ZCONTROLC} flag is set. In this mode of operation, it is up to program code to check for @code{$ZCONTROLC} and take appropriate action.
4830:
4831: Checking the value of @code{$ZCONTROLC} will reset it to @emph{false}.
4832: @end table
4833:
4834: 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.
4835:
4836: @node Error Processing
4837: @chapter Error Processing
4838: @cindex error processing
4839:
4840: FreeM exposes three means of processing M program execution errors:
4841:
4842: @table @emph
4843:
4844: @item FreeM-style error processing
4845: 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{$ZTRAP} error handler enabled.
4846:
4847: @item DSM 2.0-style error processing
4848: DSM 2.0-style error processing emulates the @code{$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{$ZTRAP} error handler is set across all program stack execution levels.
4849:
4850: @item Standard error processing
4851: Standard error processing uses the @code{NEW}-able @code{$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{$ESTACK} ISV.
4852:
4853: If @code{$ETRAP} is non-empty when an error condition occurs, @code{$ZTRAP} is ignored, regardless of whether FreeM-style or DSM 2.0-style error processing is enabled at the time of the error.
4854:
4855: @end table
4856:
4857: For further information on switching between FreeM-style and DSM 2.0-style @code{$ZTRAP} error handling, see the documentation for the @code{BREAK} command.
4858:
4859: @node FreeM Error Codes
4860: @chapter FreeM Error Codes
4861: @cindex Error Codes
4862:
4863: @table @asis
4864:
4865: @item @code{ZINRPT} - @emph{interrupt}
4866: Raised when an interrupt signal is received.
4867:
4868: @item @code{ZBKERR} - @emph{BREAK point}
4869: Raised when a @code{BREAK} point is reached.
4870:
4871: @item @code{ZNOSTAND} - @emph{non standard syntax}
4872: Raised when features incompatible with the current value of @code{$DIALECT} are used.
4873:
4874: @item @code{ZUNDEF} - @emph{variable not found}
4875: 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}.
4876:
4877: @item @code{ZLBLUNDEF} - @emph{label not found}
4878: Raised when a referenced label is not found.
4879:
4880: @item @code{ZMISSOPD} - @emph{missing operand}
4881: Raised when an operand is missing from an expression.
4882:
4883: @item @code{ZMISSOP} - @emph{missing operator}
4884: Raised when an operator is missing from an expression.
4885:
4886: @item @code{ZILLOP} - @emph{unrecognized operator}
4887: Raised when an unrecognized operator is encountered in an expression.
4888:
4889: @item @code{ZQUOTER} - @emph{unmatched quotes}
4890: Raised when unbalanced quotes are encountered.
4891:
4892: @item @code{ZCOMMAER} - @emph{comma expected}
4893: Raised when a comma is expected in program syntax but is not found.
4894:
4895: @item @code{ZASSIGNER} - @emph{equals '=' expected}
4896: Raised when an equals sign is expected in program syntax but is not found.
4897:
4898: @item @code{ZARGER} - @emph{argument not permitted}
4899: Raised when an argument is encountered in a syntactic position where arguments are not permitted.
4900:
4901: @item @code{ZSPACER} - @emph{blank ' ' expected}
4902: Raised when a space character is expected in program syntax but is not found.
4903:
4904: @item @code{ZBRAER} - @emph{unmatched parentheses}
4905: Raised when unbalanced parentheses are detected in program syntax.
4906:
4907: @item @code{ZLVLERR} - @emph{level error}
4908: Raised when a level error occurs.
4909:
4910: @item @code{ZDIVER} - @emph{divide by zero}
4911: Raised when program code attempts to divide by zero. Deprecated in favor of standard error code @code{M9}.
4912:
4913: @item @code{ZILLFUN} - @emph{function not found}
4914: Raised when program code attempts to call intrinsic or extrinsic functions that are not defined.
4915:
4916: @item @code{ZFUNARG} - @emph{wrong number of function arguments}
4917: Raised when an intrinsic or extrinsic function is called with the wrong number of arguments.
4918:
4919: @item @code{ZZTERR} - @emph{ZTRAP error}
4920: Raised when a @code{$ZTRAP} error occurs.
4921:
4922: @item @code{ZNEXTERR} - @emph{$NEXT/$ORDER error}
4923: Raised when an error occurs in @code{$NEXT} or @code{$ORDER}.
4924:
4925: @item @code{ZSELER} - @emph{$SELECT error}
4926: Raised when an error occurs in @code{$SELECT}
4927:
4928: @item @code{ZCMMND} - @emph{illegal command}
4929: Raised when program code attempts to execute an illegal command.
4930:
4931: @item @code{ZARGLIST} - @emph{argument list incorrect}
4932: Raised when the argument list supplied to an M language element does not match that language element's syntactic requirements.
4933:
4934: @item @code{ZINVEXPR} - @emph{invalid expression}
4935: Raised when an invalid expression is encountered.
4936:
4937: @item @code{ZINVREF} - @emph{invalid reference}
4938: Raised when an invalid variable reference is encountered.
4939:
4940: @item @code{ZMXSTR} - @emph{string too long}
4941: Raised when a string is encountered that exceeds @code{^$SYSTEM("STRING_MAX")}.
4942:
4943: @item @code{ZTOOPARA} - @emph{too many parameters}
4944: Raised when too many parameters are passed to a function or subroutine.
4945:
4946: @item @code{ZNOPEN} - @emph{unit not open}
4947: Raised when attempting to access an I/O channel that has not been opened.
4948:
4949: @item @code{ZNODEVICE} - @emph{unit does not exist}
4950: Raised when attempting to access a device that does not exist.
4951:
4952: @item @code{ZPROTECT} - @emph{file protection violation}
4953: Raised when attempting to access a file or device to which you do not have permission.
4954:
4955: @item @code{ZGLOBER} - @emph{global not permitted}
4956: Raised when attempting to use a global in a syntactic element where global variables are not permitted.
4957:
4958: @item @code{ZFILERR} - @emph{file not found}
4959: Raised when attempting to access a file that does not exist.
4960:
4961: @item @code{ZPGMOV} - @emph{program overflow}
4962: Raised when a program overflows the limits of a routine buffer.
4963:
4964: @item @code{ZSTKOV} - @emph{stack overflow}
4965: Raised when @code{DO}, @code{FOR}, or @code{XECUTE} nesting levels exceed the value in @code{^$SYSTEM("NESTLEVLS")}.
4966:
4967: @item @code{ZSTORE} - @emph{symbol table overflow}
4968: 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.
4969:
4970: @item @code{ZNOREAD} - @emph{file won't read}
4971: Raised when program code attempts to read from an unreadable file.
4972:
4973: @item @code{ZNOWRITE} - @emph{file won't write}
4974: Raised when program code attempts to write to an unwritable file.
4975:
4976: @item @code{ZNOPGM} - @emph{routine not found}
4977: Raised when an attempt is made to load or execute a routine that does not exist in the current namespace.
4978:
4979: @item @code{ZNAKED} - @emph{illegal naked reference}
4980: Raised when an attempt is made to use an illegal naked reference.
4981:
4982: @item @code{ZSBSCR} - @emph{illegal subscript}
4983: Raised when an illegal subscript access is attempted.
4984:
4985: @item @code{ZISYNTX} - @emph{insert syntax}
4986: Raised when illegal insert syntax is used.
4987:
4988: @item @code{ZDBDGD} - @emph{global data degradation}
4989: Raised when corruption is detected in global data files.
4990:
4991: @item @code{ZKILLER} - @emph{job kill signal}
4992: Raised on a job kill signal.
4993:
4994: @item @code{ZHUPER} - @emph{hangup signal}
4995: Raised on a job hangup signal.
4996:
4997: @item @code{ZMXNUM} - @emph{numeric overflow}
4998: Raised when an assignment or expression result exceeds @code{$ZPRECISION}.
4999:
5000: @item @code{ZNOVAL} - @emph{function returns no value}
5001: Raised when a function does not return a value. Extrinsic functions must @code{QUIT} with a value.
5002:
5003: @item @code{ZTYPEMISMATCH} - @emph{type mismatch}
5004: Raised when a type mismatch occurs.
5005:
5006: @item @code{ZMEMOV} - @emph{out of memory}
5007: Raised when FreeM runs out of heap memory.
5008:
5009: @item @code{ZNAMERES} - @emph{error in name resolution}
5010: Raised when an attempted name resolution fails.
5011:
5012: @item @code{ZSCKCREAT} - @emph{error creating socket}
5013: Raised when an error occurs creating a socket for network I/O.
5014:
5015: @item @code{ZSCKIFAM} - @emph{invalid address family (must be IPV4 or IPV6)}
5016: Raised when the address family specified in an @code{OPEN} command for a socket I/O channel is not IPV4 or IPV6.
5017:
5018: @item @code{ZSCKITYP} - @emph{invalid connection type (must be TCP or UDP)}
5019: Raised when the connection type specified in an @code{OPEN} command for a socket I/O channel is not @code{TCP} or @code{UDP}.
5020:
5021: @item @code{ZSCKIPRT} - @emph{invalid port number}
5022: 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.
5023:
5024: @item @code{ZSCKCERR} - @emph{connection error}
5025: Raised when an error occurs on a @code{USE <channel>:/CONNECT} command.
5026:
5027: @item @code{ZSCKAERR} - @emph{USE action invalid for connection type (possibly CONNECT on UDP socket?)}
5028: Raised when an attempt is made to @code{USE <channel>:/CONNECT} on a UDP socket I/O channel. The UDP protocol is connectionless.
5029:
5030: @item @code{ZSCKACON} - @emph{attempted to CONNECT an already-connected socket}
5031: Raised when an attempt is made to @code{USE <channel>:/CONNECT} on a TCP socket I/O channel that is already connected.
5032:
5033: @item @code{ZSCKNCON} - @emph{attempted to READ from a disconnected TCP socket}
5034: Raised when an attempt is made to @code{READ} a TCP socket that has not yet been connected.
5035:
5036: @item @code{ZSCKEOPT} - @emph{error setting socket options}
5037: Raised when an error is encountered while setting socket options.
5038:
5039: @item @code{ZSCKERCV} - @emph{error in READ from socket}
5040: Raised when an error occurs in a socket I/O channel @code{READ}.
5041:
5042: @item @code{ZSCKESND} - @emph{error in WRITE to socket}
5043: Raised when an error occurs while attempting to @code{WRITE} to a socket I/O channel.
5044:
5045: @item @code{ZNORPI} - @emph{^$ZRPI only supported on Raspberry Pi hardware}
5046: 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.
5047:
5048: @item @code{ZCREDEF} - @emph{cannot redefine CONST}
5049: Raised when attempts are made to redefine a @code{CONST} after its initial definition.
5050:
5051: @item @code{ZCMODIFY} - @emph{cannot modify CONST}
5052: Raised when attempts are made to change the value of a @code{CONST}.
5053:
5054: @item @code{ZFILEXWR} - @emph{cannot open existing file for WRITE}
5055: Raised when an attempt is made to open an existing file in write (but not append) mode.
5056:
5057: @item @code{INEWMULT} - @emph{initializing NEW with multiple setarguments not supported}
5058: Raised when you attempt to use multiple setarguments with initializing @code{NEW}, e.g. @code{NEW X=2,Y=3}.
5059:
5060: @item @code{ZECODEINV} - @emph{invalid value for $ECODE}
5061: Raised when attempts are made to set @code{$ECODE} to an invalid error code value. Obsolete and replaced by standard error code @code{M101}.
5062:
5063: @item @code{ZASSERT} - @emph{programmer assertion failed}
5064: Raised when an @code{ASSERT} expression's result is not true.
5065:
5066: @item @code{ZUSERERR} - @emph{user-defined error}
5067: Raised when program code calls @code{THROW} with an error code argument for which the first character is @code{U}, or when @code{$ECODE} is set to an error code for which the first character is @code{U}.
5068:
5069: Custom error messages for @code{ZUSERERR} may be set in @code{^$JOB($JOB,"USER_ERRORS",<user_error_code>)}, where @code{<user_error_code>} represents the custom error code.
5070:
5071: For example:
5072:
5073: @example
5074: USER> S ^$JOB($JOB,"USER_ERRORS","UBLACKHOLE")="black hole encountered"
5075:
5076:
5077: USER> THROW UBLACKHOLE
5078:
5079:
5080: >> Error UBLACKHOLE: black hole encountered in SYSTEM::^%SYSINIT [$STACK = 0]
5081: >> THROW UBLACKHOLE
5082: ^
5083: @end example
5084:
5085: @item @code{ZSYNTERR} - @emph{syntax error}
5086: Raised when a syntax error without a more specific error code is encountered.
5087:
5088: @item @code{ZCTRLB} - @emph{break}
5089: Pseudo-error used by the FreeM debugger. Not visibly raised in normal program operation.
5090:
5091: @item @code{ZASYNC} - @emph{asynchronous interruption}
5092: Pseudo-error used by the FreeM asynchronous events subsystem. Not visibly raised in normal program operation.
5093:
5094: @item @code{M1} - @emph{naked indicator undefined}
5095: Raised when an attempt is made to use a naked reference before the naked indicator is set.
5096:
5097: @item @code{M2} - @emph{invalid combination with $FNUMBER code atom}
5098:
5099:
5100: @item @code{M3} - @emph{$RANDOM seed less than 1}
5101:
5102:
5103: @item @code{M4} - @emph{no true condition in $SELECT}
5104:
5105:
5106: @item @code{M5} - @emph{line reference less than zero}
5107:
5108:
5109: @item @code{M6} - @emph{undefined local variable}
5110:
5111:
5112: @item @code{M7} - @emph{undefined global variable}
5113:
5114:
5115: @item @code{M8} - @emph{undefined intrinsic special variable}
5116:
5117:
5118: @item @code{M9} - @emph{divide by zero}
5119:
5120:
5121: @item @code{M10} - @emph{invalid pattern match range}
5122:
5123:
5124: @item @code{M11} - @emph{no parameters passed}
5125:
5126:
5127: @item @code{M12} - @emph{invalid line reference (negative offset)}
5128:
5129:
5130: @item @code{M13} - @emph{invalid line reference (line not found)}
5131:
5132:
5133: @item @code{M14} - @emph{line level not 1}
5134:
5135:
5136: @item @code{M15} - @emph{undefined index variable}
5137:
5138:
5139: @item @code{M16} - @emph{argumented QUIT not allowed}
5140:
5141:
5142: @item @code{M17} - @emph{argumented QUIT required}
5143:
5144:
5145: @item @code{M18} - @emph{fixed length READ not greater than zero}
5146:
5147:
5148: @item @code{M19} - @emph{cannot copy a tree or subtree onto itself}
5149:
5150:
5151: @item @code{M20} - @emph{line must have a formal parameter list}
5152:
5153:
5154: @item @code{M21} - @emph{algorithm specification invalid}
5155:
5156:
5157: @item @code{M22} - @emph{SET or KILL to ^$GLOBAL when data in global}
5158:
5159:
5160: @item @code{M23} - @emph{SET or KILL to ^$JOB for non-existent job number}
5161:
5162:
5163: @item @code{M24} - @emph{change to collation algorithm while subscripted local variables defined}
5164:
5165:
5166: @item @code{M26} - @emph{non-existent environment}
5167:
5168:
5169: @item @code{M27} - @emph{attempt to rollback a transaction that is not restartable}
5170:
5171:
5172: @item @code{M28} - @emph{mathematical function, parameter out of range}
5173:
5174:
5175: @item @code{M29} - @emph{SET or KILL on structured system variable not allowed by implementation}
5176:
5177:
5178: @item @code{M30} - @emph{reference to global variable with different collating sequence within a collating algorithm}
5179:
5180:
5181: @item @code{M31} - @emph{control mnemonic used for device without a mnemonic space selected}
5182:
5183:
5184: @item @code{M32} - @emph{control mnemonic used in user-defined mnemonic space which has no associated line}
5185:
5186:
5187: @item @code{M33} - @emph{SET or KILL to ^$ROUTINE when routine exists}
5188:
5189:
5190: @item @code{M35} - @emph{device does not support mnemonic space}
5191:
5192:
5193: @item @code{M36} - @emph{incompatible mnemonic spaces}
5194:
5195:
5196: @item @code{M37} - @emph{READ from device identified by empty string}
5197:
5198:
5199: @item @code{M38} - @emph{invalid structured system variable subscript}
5200:
5201:
5202: @item @code{M39} - @emph{invalid $NAME argument}
5203:
5204:
5205: @item @code{M40} - @emph{call-by-reference in JOB actual parameter}
5206:
5207:
5208: @item @code{M41} - @emph{invalid LOCK argument within a transaction}
5209:
5210:
5211: @item @code{M42} - @emph{invalid QUIT within a transaction}
5212:
5213:
5214: @item @code{M43} - @emph{invalid range value ($X, $Y}
5215:
5216:
5217: @item @code{M44} - @emph{invalid command outside of a transaction}
5218:
5219:
5220: @item @code{M45} - @emph{invalid GOTO reference}
5221:
5222:
5223: @item @code{M56} - @emph{identifier exceeds maximum length}
5224:
5225:
5226: @item @code{M57} - @emph{more than one defining occurrence of label in routine}
5227:
5228:
5229: @item @code{M58} - @emph{too few formal parameters}
5230:
5231:
5232: @item @code{M60} - @emph{illegal attempt to use an undefined SSVN}
5233:
5234:
5235: @item @code{M101} - @emph{invalid value for $ECODE}
5236:
5237:
5238: @item @code{M102} - @emph{synchronous and asynchronous event processing cannot be simultaneously enabled for the same event class}
5239:
5240:
5241: @item @code{M103} - @emph{invalid event identifier}
5242:
5243:
5244: @item @code{M104} - @emph{ETRIGGER event identifier for IPC event class does not match job process identifier}
5245:
5246:
5247: @end table
5248:
5249: @node Debugging
5250: @chapter Debugging
5251: @cindex debugging
5252:
5253: @node System Configuration
5254: @chapter System Configuration
5255: @cindex configuration, system
5256:
5257: @section Installing FreeM
5258: @cindex installation
5259:
5260: @section Build Configuration
5261: @cindex build configuration
5262:
5263: 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:
5264:
5265: @table @asis
5266:
5267: @item @code{--enable-mwapigtk} (EXPERIMENTAL)
5268: 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.
5269:
5270: Please consult your operating system's documentation for the correct commands to install the required libraries.
5271:
5272: @emph{Example}
5273:
5274: @example
5275: $ ./configure --enable-mwapigtk
5276: $ make
5277: $ sudo make install
5278: @end example
5279:
5280: @item @code{--enable-berkeleydb} (EXPERIMENTAL)
5281: 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.
5282:
5283: Please consult your operating system's documentation for the correct commands to install the required libraries.
5284:
5285: @emph{Example}
5286:
5287: @example
5288: $ ./configure --enable-berkeleydb
5289: $ make
5290: $ sudo make install
5291: @end example
5292:
5293:
5294: @item @code{--without-readline}
5295: Builds FreeM without GNU @code{readline} support, even if @code{readline} is installed on your system.
5296:
5297: 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}.
5298:
5299: @emph{Example}
5300:
5301: @example
5302: $ ./configure --without-readline
5303: $ make
5304: $ sudo make install
5305: @end example
5306:
5307:
5308: @end table
5309:
5310: @node Accessing FreeM from C Programs
5311: @chapter Accessing FreeM from C Programs
5312:
5313: 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.
5314:
5315: 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.
5316:
5317: 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.
5318:
5319: 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}.
5320:
5321: @section freem_ref_t Data Structure
5322: @cindex libfreem, data structures: freem_ref_t
5323:
5324: 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.
5325:
5326: The data structure, defined in @file{freem.h}, looks like this:
5327:
5328: @verbatim
5329: typedef struct freem_ref_t {
5330:
5331: /*
5332: * The 'reftype' field can be one of:
5333: *
5334: * MREF_RT_LOCAL
5335: * MREF_RT_GLOBAL
5336: * MREF_RT_SSV
5337: */
5338: short reftype;
5339:
5340: /*
5341: * The 'name' field is the name of the local variable,
5342: * global variable, or SSVN (without ^ or ^$).
5343: */
5344: char name[256];
5345:
5346: /*
5347: * Returned data goes in a string, so you've got to figure out the
5348: * whole M canonical number thing yourself. Good luck. :-)
5349: */
5350: char value[STRLEN];
5351:
5352: short status;
5353:
5354: unsigned int subscript_count;
5355: char subscripts[255][256];
5356:
5357: } freem_ref_t;
5358: @end verbatim
5359:
5360: @emph{freem_ref_t Members}
5361:
5362: @table @asis
5363: @cindex libfreem, freem_ref_t.reftype
5364: @item @option{reftype}
5365: The @option{reftype} member determines whether we are operating on a local variable, a global variable, or a structured system variable. It may be set to any of following constants: @code{MREF_RT_LOCAL}, @code{MREF_RT_GLOBAL}, or @code{MREF_RT_SSV}.
5366:
5367: @cindex libfreem, freem_ref_t.name
5368: @item @option{name}
5369: The @option{name} member contains the name of the global, local, or SSVN to be accessed. You @emph{must not} include leading characters, such as @code{^} or @code{^$}.
5370:
5371: @cindex libfreem, freem_ref_t.value
5372: @item @option{value}
5373: This member contains the value read from or the value to be written to the global, local, or SSVN.
5374:
5375: @cindex libfreem, freem_ref_t.status
5376: @item @option{status}
5377: This member gives us various API status values after the API call returns. In general, this value is also returned by each API function.
5378:
5379: @cindex libfreem, freem_ref_t.subscript_count
5380: @item @option{subscript_count}
5381: 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.
5382:
5383: @cindex libfreem, freem_ref_t.subscripts
5384: @item @option{subscripts}
5385: A two-dimensional array containing the subscripts to which we are referring in this API call.
5386:
5387: @end table
5388:
5389: @section freem_ent_t Data Structure
5390: @cindex libfreem, data structures: freem_ent_t
5391:
5392: 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()}).
5393:
5394: The data structure, defined in @file{freem.h}, looks like this:
5395:
5396: @verbatim
5397: typedef struct freem_ent_t {
5398:
5399: /* name of function or procedure entry point */
5400: char name[256];
5401:
5402: /* return value */
5403: char value[STRLEN];
5404:
5405: /* value of ierr on return */
5406: short status;
5407:
5408: /* argument count and array */
5409: unsigned int argument_count;
5410: char arguments[255][256];
5411:
5412: } freem_ent_t;
5413: @end verbatim
5414:
5415: @emph{freem_ent_t Members}
5416:
5417: @table @asis
5418:
5419: @item @option{name}
5420: @cindex libfreem, freem_ent_t.name
5421: The @option{name} member contains the name of the extrinsic function or procedure to be called.
5422:
5423: @cindex libfreem, freem_ent_t.value
5424: @item @option{value}
5425: This member contains the value returned by the function called. Not used by @code{freem_procedure()}.
5426:
5427: @cindex libfreem, freem_ent_t.status
5428: @item @option{status}
5429: 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}.
5430:
5431: @cindex libfreem, freem_ent_t.argument_count
5432: @item @option{argument_count}
5433: 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.
5434:
5435: @cindex libfreem, freem_ent_t.arguments
5436: @item @option{arguments}
5437: A two-dimensional array containing the arguments to be passed into the extrinsic function or procedure being called.
5438:
5439: @end table
5440:
5441: @section freem_init()
5442: @cindex libfreem, freem_init()
5443:
5444: Initializes @code{libfreem} in preparation for calling other APIs.
5445:
5446: @emph{Synopsis}
5447:
5448: @code{pid_t freem_init(char *environment_name, char *namespace_name);}
5449:
5450: @emph{Parameters}
5451:
5452: @table @asis
5453: @item @code{environment_name}
5454: Specifies the environment to use.
5455: @item @code{namespace_name}
5456: Specifies the namespace to use.
5457: @end table
5458:
5459: @emph{Return Values}
5460:
5461: Returns the process ID of the @code{libfreem} process on success, or @code{-1} on failure.
5462:
5463: @emph{Example}
5464:
5465: This example prompts the user to enter a FreeM namespace and then attempts to initialize @code{libfreem} to use the selected namespace.
5466:
5467: @verbatim
5468: #include <stdio.h>
5469: #include <string.h>
5470: #include <freem.h>
5471:
5472: int main(int argc, char **argv, char **envp)
5473: {
5474: char namespace[256];
5475:
5476: /* get the namespace name to use */
5477: printf("Enter FreeM namespace to use: ");
5478: fgets(namespace, 255, stdin);
5479:
5480: /* remove the trailing newline */
5481: namespace[strcspn(buffer, "\n")] = '\0';
5482:
5483: /* initialize libfreem using the provided namespace */
5484: if(freem_init("DEFAULT", namespace) == TRUE) {
5485: printf("\nSuccess\n");
5486: }
5487: else {
5488: printf("\nFailure\n");
5489: }
5490:
5491: return 0;
5492: }
5493: @end verbatim
5494:
5495: @section freem_version()
5496: @cindex libfreem, freem_version()
5497:
5498: Returns the version of FreeM in use.
5499:
5500: @emph{Synopsis}
5501:
5502: @code{short freem_version(char *result);}
5503:
5504: @emph{Parameters}
5505:
5506: @table @asis
5507: @item @code{result}
5508: 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.
5509: @end table
5510:
5511: @emph{Return Value}
5512:
5513: Returns @code{0}.
5514:
5515: @emph{Example}
5516:
5517: This example will display the FreeM version on standard output.
5518:
5519: @verbatim
5520: #include <stdio.h>
5521: #include <string.h>
5522: #include <freem.h>
5523:
5524: int main(int argc, char **argv, char **envp)
5525: {
5526: char version[20] = {0};
5527:
5528: freem_init(``USER'');
5529: freem_version(version);
5530:
5531: printf(``FreeM version: %s\n'', version);
5532:
5533: }
5534: @end verbatim
5535:
5536: @section freem_set()
5537: @cindex libfreem, freem_set()
5538:
5539: Sets a FreeM local node, global node, or writable SSVN node.
5540:
5541: @emph{Synopsis}
5542:
5543: @code{short freem_set(freem_ref_t *ref);}
5544:
5545: @emph{Parameters}
5546:
5547: @table @asis
5548: @item @code{freem_ref_t}
5549: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
5550: @end table
5551:
5552: @emph{Return Value}
5553:
5554: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
5555:
5556: @emph{Example}
5557:
5558: This example sets the value @code{blue} into global node @code{^car("color")}.
5559:
5560: @verbatim
5561: #include <stdio.h>
5562: #include <string.h>
5563: #include <freem.h>
5564:
5565: int main(int argc, char **argv, char **envp)
5566: {
5567: freem_ref_t ref;
5568:
5569: /* we're setting a global */
5570: ref.reftype = MREF_RT_GLOBAL;
5571:
5572: /* access global "car" */
5573: strcpy(ref.name, "car");
5574:
5575: /* set up the subscripts */
5576: ref.subscript_count = 1;
5577: strcpy(ref.subscripts[0], "color");
5578:
5579:
5580: /* use the USER namespace */
5581: freem_init("USER");
5582:
5583: /* write the data out */
5584: freem_set(&ref);
5585:
5586: }
5587: @end verbatim
5588:
5589: @section freem_get()
5590: @cindex libfreem, freem_get()
5591:
5592: Retrieves a FreeM local node, global node, or writable SSVN node.
5593:
5594: @emph{Synopsis}
5595:
5596: @code{short freem_get(freem_ref_t *ref);}
5597:
5598: @emph{Parameters}
5599:
5600: @table @asis
5601: @item @code{freem_ref_t}
5602: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
5603: @end table
5604:
5605: @emph{Return Value}
5606:
5607: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
5608:
5609: @emph{Example}
5610:
5611: This example retrieves the character set of the current process.
5612:
5613: @verbatim
5614: #include <stdio.h>
5615: #include <sys/types.h>
5616: #include <unistd.h>
5617: #include <string.h>
5618: #include <freem.h>
5619:
5620: int main(int argc, char **argv, char)
5621: {
5622: pid_t pid;
5623: freem_ref_t ref;
5624:
5625: /* get the PID of this process */
5626: pid = getpid();
5627:
5628: /* we want to access an SSVN */
5629: ref.reftype = MREF_RT_SSV;
5630:
5631: /* set up the name and subscripts */
5632: strcpy(ref.name, "JOB");
5633:
5634: ref.subscript_count = 2;
5635: sprintf(ref.subscripts[0], "%d", pid);
5636: strcpy(ref.subscripts[1], "CHARACTER");
5637:
5638: /* initialize libfreem, using the USER namespace */
5639: freem_init("USER");
5640:
5641: /* call libfreem API */
5642: freem_get(&ref);
5643:
5644: /* output the character set info */
5645: printf("PID %d character set is '%s'\n", pid, ref.value);
5646: }
5647: @end verbatim
5648:
5649: @section freem_kill()
5650: @cindex libfreem, freem_kill()
5651:
5652: Deletes a FreeM local node, global node, or killable SSVN node, as well as all of its children.
5653:
5654: @emph{short freem_kill(freem_ref_t *ref);}
5655:
5656: @emph{Parameters}
5657:
5658: @table @asis
5659: @item @code{freem_ref_t}
5660: This parameter is a pointer to a @code{freem_ref_t} struct. The caller must allocate the memory for this struct.
5661: @end table
5662:
5663: @emph{Return Value}
5664:
5665: Returns @code{OK} on success, or one of the other error values defined in @code{merr.h}.
5666:
5667: @emph{Example}
5668:
5669: @verbatim
5670: #include <stdio.h>
5671: #include <string.h>
5672: #include <freem.h>
5673:
5674: int main(int argc, char **argv, char **envp)
5675: {
5676: freem_ref_t ref;
5677:
5678: /* we're killing a global node */
5679: ref.reftype = MREF_RT_GLOBAL;
5680:
5681: /* access global "car" */
5682: strcpy(ref.name, "car");
5683:
5684: /* set up the subscripts */
5685: ref.subscript_count = 0;
5686:
5687: /* use the USER namespace */
5688: freem_init("USER");
5689:
5690: /* kill the global and all its descendant subscripts */
5691: freem_kill(&ref);
5692: }
5693: @end verbatim
5694:
5695: @section freem_data()
5696: @cindex libfreem, freem_data()
5697:
5698: @section freem_order()
5699: @cindex libfreem, freem_order()
5700:
5701: @section freem_query()
5702: @cindex libfreem, freem_query()
5703:
5704: @section freem_lock()
5705: @cindex libfreem, freem_lock()
5706:
5707: @section freem_unlock()
5708: @cindex libfreem, freem_unlock()
5709:
5710: @section freem_tstart()
5711: @cindex libfreem, freem_tstart()
5712:
5713: @section freem_trestart()
5714: @cindex libfreem, freem_trestart()
5715:
5716: @section freem_trollback()
5717: @cindex libfreem, freem_trollback()
5718:
5719: @section freem_tlevel()
5720: @cindex libfreem, freem_tlevel()
5721:
5722: @section freem_tcommit()
5723: @cindex libfreem, freem_tcommit()
5724:
5725: @section freem_function()
5726: @cindex libfreem, freem_function()
5727:
5728: @section freem_procedure()
5729: @cindex libfreem, freem_procedure()
5730:
5731: @node FreeM Administrator
5732: @appendix FreeM Administrator
5733: @cindex utilities, system management
5734: @cindex utilities, fmadm
5735: @cindex fmadm
5736:
5737: The @code{fmadm} utility is the preferred method of managing a FreeM installation, and will eventually replace all of the existing utilities.
5738: Unlike the existing, legacy utilities, @code{fmadm} presents a consistent, simple interface for all FreeM management tasks, and is namespace-aware.
5739: This appendix will document each @code{fmadm} facility as it is implemented, until all of the legacy utilities have been replaced.
5740:
5741: The @code{fmadm} utility's functions all follow the below, consistent syntax:
5742:
5743: @example
5744: usage: fmadm <action> <object> <namespace> [OPTIONS]
5745: @end example
5746:
5747: The @emph{action} keyword can be one of the following:
5748:
5749: @table @emph
5750:
5751: @item list
5752: Lists instances of @emph{object}
5753:
5754: @item examine
5755: Examines a single instance of @emph{object}
5756:
5757: @item verify
5758: Verifies the integrity of @emph{object}
5759:
5760: @item compact
5761: Compacts @emph{object}
5762:
5763: @item repair
5764: Repairs integrity problems in @emph{object}
5765:
5766: @item create
5767: Creates an instance of @emph{object}
5768:
5769: @item remove
5770: Removes an instance of @emph{object}
5771:
5772: @item import
5773: Imports an @emph{object}
5774:
5775: @item export
5776: Exports an @emph{object}
5777:
5778: @item backup
5779: Creates a backup of @emph{object}
5780:
5781: @item restore
5782: Restores a backup of @emph{object}
5783:
5784: @item migrate
5785: Migrates an instance of @emph{object} from an older FreeM version to the current version
5786:
5787: @item edit
5788: Edits an instance of @emph{object}
5789:
5790: @end table
5791:
5792: The @emph{object} keyword can be one of the following:
5793:
5794: @table @emph
5795:
5796: @item lock
5797: The FreeM @code{LOCK} table.
5798:
5799: Supported actions are @code{list} and @code{remove}.
5800:
5801: @item zallocate
5802: The FreeM @code{ZALLOCATE} table.
5803:
5804: No actions yet implemented.
5805:
5806: @item journal
5807: FreeM after-image journaling.
5808:
5809: Supported actions are @code{examine} and @code{restore}.
5810:
5811: The @code{examine} action will dump the after-image journal entries for the selected namespace in human-readable format.
5812:
5813: The @code{restore} action will play after-image journals forward for the selected namespace.
5814:
5815: @item namespace
5816: FreeM namespaces (collections of M routines and globals).
5817:
5818: No actions yet implemented.
5819:
5820: @item global
5821: The data files representing each FreeM @emph{global}.
5822:
5823: Supported actions are @code{list}, @code{examine}, @code{remove}, and @code{verify}.
5824:
5825: @item routine
5826: An M routine, stored as a @code{.m} file.
5827:
5828: Supported actions are @code{list}, @code{examine}, @code{remove}, @code{import}, @code{export}, @code{backup}, and @code{edit}.
5829:
5830: @item job
5831: A UNIX process representing an instance of the FreeM runtime.
5832:
5833: Supported actions are @code{list} and @code{examine}.
5834:
5835: @end table
5836:
5837:
5838: @node FreeM Legacy Utilities
5839: @appendix FreeM Legacy Utilities
5840: @cindex utilities, legacy
5841:
5842: @section Global Compactor (gcompact)
5843: @cindex utilities, legacy, gcompact
5844:
5845: Compacts the specified global in place.
5846:
5847: @emph{Syntax}
5848:
5849: @example
5850: gcompact @emph{/path/to/global/file}
5851: @end example
5852:
5853: @section Block Examiner (gfix)
5854: @cindex utilities, gfix
5855:
5856: The @emph{gfix} interactive utility program permits navigation of the B-tree structure of the specified global a block at a time.
5857:
5858: @emph{Syntax}
5859:
5860: @example
5861: gfix @emph{</path/to/global/file>}
5862: @end example
5863:
5864: @section Global Repair Tool (grestore)
5865: @cindex utilities, legacy, grestore
5866:
5867: This utility will fix problems with the specified global.
5868:
5869: @emph{Syntax}
5870:
5871: @example
5872: grestore @emph{</path/to/global/file>}
5873: @end example
5874:
5875: @node FreeM VIEW Commands and Functions
5876: @appendix FreeM VIEW Commands and Functions
5877:
5878: @section VIEW 16: Total Count of Error Messages/View Single Error Message
5879: @cindex VIEW commands/functions, 16, total count of error messages/view single error message
5880:
5881: Unknown semantics
5882:
5883: @section VIEW 17: Intrinsic Z-Commands
5884: @cindex VIEW commands/functions, 17, intrinsic Z-commands
5885:
5886: 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.
5887:
5888: @section VIEW 18: Intrinsic Z-Functions
5889: @cindex VIEW commands/functions, 18, intrinsic Z-functions
5890:
5891: 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.
5892:
5893: @section VIEW 19: Intrinsic Special Variables
5894: @cindex VIEW commands/functions, 19, intrinsic special variables
5895:
5896: Allows the user to retrieve or specify which special variables are implemented internally.
5897:
5898: @section VIEW 20: Break Service Code
5899: @cindex VIEW commands/functions, 20, break service code
5900:
5901: Allows the user to view or specify the code that will be run when a @code{BREAK} is encountered.
5902:
5903: @section VIEW 21: View Size of Last Global
5904: @cindex VIEW commands/functions, 21, view size of last global
5905:
5906: Allows the user to view the size of the last referenced global.
5907:
5908: @section VIEW 22: Count VIEW 22 Aliases
5909: @cindex VIEW commands/functions, 22, count VIEW 22 aliases
5910:
5911: Retrieves the number of VIEW 22 aliases in effect.
5912:
5913: @section VIEW 23: View Contents of Input Buffer
5914: @cindex VIEW commands/functions, 23, input buffer contents
5915:
5916: Retrieves the contents of the I/O input buffer.
5917:
5918: @section VIEW 24: Maximum Number of Screen Rows
5919: @cindex VIEW commands/functions, 24, maximum number of screen rows
5920:
5921: Retrieves the maximum number of screen rows supported in the current FreeM build.
5922:
5923: @section VIEW 25: Maximum Number of Screen Columns
5924: @cindex VIEW commands/functions, 25, maximum number of screen columns
5925:
5926: Retrieves the maximum number of screen columns supported in the current FreeM build.
5927:
5928: @section VIEW 26: DO/FOR/XECUTE Stack Pointer
5929: @cindex VIEW commands/functions, 26, DO/FOR/XECUTE stack pointer
5930:
5931: Retrieves the @code{DO}, @code{FOR}, and @code{XECUTE} stack pointer.
5932:
5933: @section VIEW 27: DO/FOR/XECUTE Stack Pointer (On Error)
5934: @cindex VIEW commands/functions, 27, DO/FOR/XECUTE stack pointer, on error
5935:
5936: Retrieves the @code{DO}, @code{FOR}, and @code{XECUTE} stack pointer (on error).
5937:
5938: @section VIEW 29: Copy Symbol Table
5939: @cindex VIEW commands/functions, 29, copy symbol table
5940:
5941: Copies the symbol table? We aren't currently aware of what this means.
5942:
5943: @section VIEW 30: Inspect Arguments
5944: @cindex VIEW commands/functions, 30, inspect arguments
5945:
5946: Retrieves the arguments passed to the @code{freem} executable.
5947:
5948: @section VIEW 31: Count Environment Variables
5949: @cindex VIEW commands/functions, 31, count environment variables
5950:
5951: Allows the user to inspect the number of variables in the process environment table.
5952:
5953: @emph{Syntax}
5954:
5955: @example
5956: WRITE $VIEW(31),!
5957: @end example
5958:
5959: @node Implementation Limits
5960: @appendix Implementation Limits
5961:
5962: @cindex limitations, memory
5963: @cindex maximum size, routine
5964: @cindex maximum size, global
5965: @cindex maximum size, string
5966:
5967: @node US-ASCII Character Set
5968: @appendix US-ASCII Character Set
5969:
5970: @multitable {Code} {Character}
5971: @item Code @tab Character
5972: @item 000 @tab @code{<NUL>}
5973: @item 001 @tab @code{<SOH>}
5974: @item 002 @tab @code{<STX>}
5975: @item 003 @tab @code{<ETX>}
5976: @item 004 @tab @code{<EOT>}
5977: @item 005 @tab @code{<ENQ>}
5978: @item 006 @tab @code{<ACK>}
5979: @item 007 @tab @code{<BEL>}
5980: @item 008 @tab @code{<BS>}
5981: @item 009 @tab @code{<HT>}
5982: @item 010 @tab @code{<LF>}
5983: @item 011 @tab @code{<VT>}
5984: @item 012 @tab @code{<FF>}
5985: @item 013 @tab @code{<CR>}
5986: @item 014 @tab @code{<SO>}
5987: @item 015 @tab @code{<SI>}
5988: @item 016 @tab @code{<DLE>}
5989: @item 017 @tab @code{<DC1>}
5990: @item 018 @tab @code{<DC2>}
5991: @item 019 @tab @code{<DC3>}
5992: @item 020 @tab @code{<DC4>}
5993: @item 021 @tab @code{<NAK>}
5994: @item 022 @tab @code{<SYN>}
5995: @item 023 @tab @code{<ETB>}
5996: @item 024 @tab @code{<CAN>}
5997: @item 025 @tab @code{<EM>}
5998: @item 026 @tab @code{<SUB>}
5999: @item 027 @tab @code{<ESC>}
6000: @item 028 @tab @code{<FS>}
6001: @item 029 @tab @code{<GS>}
6002: @item 030 @tab @code{<RS>}
6003: @item 031 @tab @code{<US>}
6004: @item 032 @tab @code{<space>}
6005: @item 033 @tab !
6006: @item 034 @tab ``
6007: @item 035 @tab #
6008:
6009:
6010: @end multitable
6011:
6012: @node FreeM Project Coding Standards
6013: @appendix FreeM Project Coding Standards
6014:
6015: @section Module Headers
6016: @cindex coding standards, module headers
6017:
6018: Module headers should adhere to the following format:
6019:
6020: @verbatim
6021: /*
6022: * *
6023: * * *
6024: * * *
6025: * ***************
6026: * * * * *
6027: * * MUMPS *
6028: * * * * *
6029: * ***************
6030: * * *
6031: * * *
6032: * *
6033: *
6034: * mlib.h
6035: * Function prototypes, structs, and macros for FreeM
6036: * binding library
6037: *
6038: *
6039: * Author: Serena Willis <jpw@coherent-logic.com>
6040: * Copyright (C) 1998 MUG Deutschland
6041: * Copyright (C) 2020 Coherent Logic Development LLC
6042: *
6043: * Last modified: 29 February 2020
6044: *
6045: **/
6046: @end verbatim
6047: @cindex ha-Ashkenaz, Shalom
6048: The Star of David in module headers is a convention started by Shalom ha-Ashkenaz, the unidentified original author of FreeMUMPS/FreeM. We will continue to employ it in honor of his most valuable contribution to the M community.
6049:
6050: @section Variable Naming
6051: @cindex coding standards, variable naming
6052:
6053: 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.
6054:
6055: Constants defined via the C preprocessor should be in all uppercase letters, with words within them likewise delimited by underscores, such as:
6056:
6057: @verbatim
6058: #define MY_USEFUL_CONSTANT 1
6059: @end verbatim
6060:
6061: @section Indentation and General Layout
6062: @cindex coding standards, indentation
6063: @cindex coding standards, layout
6064:
6065: 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.
6066:
6067: This project follows a modified version of what is known as the Stroustrup indentation style.
6068:
6069: @section Brace Placement (Functions)
6070: @cindex coding standards, brace placement, functions
6071:
6072: 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.
6073:
6074: Below is a correct example:
6075:
6076: @verbatim
6077: int main(int argc, char **argv, char **envp)
6078: {
6079:
6080: }
6081: @end verbatim
6082:
6083: @section Brace Placement (if-for-while-do)
6084: @cindex coding standards, brace placement, if-for-while-do
6085:
6086: 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}:
6087:
6088: @verbatim
6089: if (x) {
6090: ...
6091: }
6092: else {
6093: ...
6094: }
6095:
6096: while (1) {
6097: ...
6098: }
6099:
6100: for (i = 1; i < 10; i++) {
6101: ...
6102: }
6103:
6104: do {
6105: ...
6106: } while (x);
6107: @end verbatim
6108:
6109: Single-statement if blocks should be isolated to a single line:
6110:
6111: @verbatim
6112: if (x) stmt();
6113: @end verbatim
6114:
6115: not:
6116:
6117: @verbatim
6118: if (x)
6119: stmt ();
6120: @end verbatim
6121:
6122: 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.
6123:
6124: 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:
6125:
6126: @verbatim
6127: if (x) {
6128: foo();
6129: }
6130: else if (y) {
6131: bar();
6132: }
6133: else {
6134: bas();
6135: }
6136: @end verbatim
6137:
6138: @section Labels and goto
6139: @cindex coding standards, labels
6140: @cindex coding standards, goto
6141:
6142: Labels must begin in column 1, and have two lines of vertical space above and one beneath.
6143:
6144: @section Preprocessor Conditionals
6145: @section coding standards, preprocessor conditionals
6146:
6147: I have struggled with this, but have settled upon the standard practice of keeping them in column 1.
6148:
6149: @section Overall Program Spacing
6150: @cindex coding standards, spacing of programs
6151:
6152: @itemize @bullet
6153: @item
6154: Variable declarations fall immediately beneath the opening curly brace, and should initialize the variable right there whenever initialization is used.
6155:
6156: @item
6157: One line between the last variable declaration and the first line of real code.
6158:
6159: @item
6160: 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.
6161:
6162: @item
6163: 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.
6164: @end itemize
6165:
6166: @section The switch() Statement
6167: @cindex coding standards, switch()
6168:
6169: 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:
6170:
6171: @verbatim
6172: switch(foo) {
6173:
6174: case some_const:
6175: foo();
6176:
6177: break;
6178:
6179: case some_other_const:
6180: bar();
6181:
6182: break;
6183:
6184: default:
6185: exit(1);
6186:
6187: break;
6188: }
6189: @end verbatim
6190:
6191: @section Comments
6192: @cindex coding standards, comments
6193:
6194: We use C-style comments (@code{/* comment */}) exclusively, even on single-line comments. C++ comments (@code{// comment}) are not permitted.
6195:
6196: @node Index
6197: @unnumbered Index
6198:
6199: @printindex cp
6200:
6201: @bye
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