1FvwmPerl(1) Fvwm Modules FvwmPerl(1)
2
6 FvwmPerl - the fvwm perl manipulator and preprocessor
7
9 FvwmPerl should be spawned by fvwm(1) for normal functionality.
10 To run this module, place this command somewhere in the configuration:
12 Module FvwmPerl [params]
14 or:
16 ModuleSynchronize FvwmPerl [params]
18 if you want to immediately start to send commands to FvwmPerl.
20
22 This module is intended to extend fvwm commands with the perl scripting
23 power. It enables to embed perl expressions in the fvwm config files
24 and construct fvwm commands.
25
27 If you want to invoke the unique and persistent instance of FvwmPerl,
28 it is suggested to do this from the StartFunction. Calling it from the
29 top is also possible, but involves some issues not discussed here.
30 AddToFunc StartFunction I Module FvwmPerl
32 There are several command line switches:
34 FvwmPerl [ --eval line ] [ --load file ] [ --preprocess [ --quote char
36 ] [ --winid wid ] [ --cmd ] [ --nosend ] [ --noremove ] [ line ⎪ file ]
37 ] [ --export [names] ] [ --stay ] [ --nolock ] [ alias ]
38 Long switches may be abbreviated to short one-letter switches.
40 -e⎪--eval line - evaluate the given perl code
42 -l⎪--load file - evaluate perl code in the given file
44 -p⎪--preprocess [ file ] - preprocess the given fvwm config file
46 The following 5 options are only valid together with --preprocess
48 option.
49 -c⎪--cmd line - an fvwm command to be preprocessed instead of file
51 -q⎪--quote char - change the default '%' quote
53 -w⎪--winid wid - set explicit window context (should begin with digit,
55 may be in oct or hex form; this window id overwrites implicit window
56 context if any)
57 --nosend - do not send the preprocessed file to fvwm for Reading, the
59 default is send. Useful for preprocessing non fvwm config files.
60 --noremove - do not remove the preprocessed file after sending it to
62 fvwm for Reading, the default is remove. Useful for debugging.
63 -x⎪--export [names] - define fvwm shortcut functions (by default, two
65 functions named "Eval" and "."). This option implies --stay.
66 -s⎪--stay - continues an execution after --eval, --load or --preprocess
68 are processed. By default, the module is not persistent in this case,
69 i.e. --nostay is assumed.
70 --nolock - when one of the 3 action options is given, this option
72 causes unlocking fvwm immediately. By default the requested action is
73 executed synchronously; this only makes difference when invoked like:
74 ModuleSynchronous FvwmPerl --preprocess someconfig.ppp
76 If --nolock is added here, ModuleSynchronous returns immediately. Note
78 that Module returns immediately regardless of this option.
79
81 Aliases allow to have several module invocations and work separately
82 with all invocations, here is an example:
83 ModuleSynchronous FvwmPerl FvwmPerl-JustTest
85 SendToModule FvwmPerl-JustTest eval $a = 2 + 2; $b = $a
86 SendToModule FvwmPerl-JustTest eval cmd("Echo 2 + 2 = $b")
87 KillModule FvwmPerl FvwmPerl-JustTest
88
90 One of the effective proprocessing solutions is to pass the whole fvwm
91 configuration with embeded perl code to "FvwmPerl --preprocess". An
92 alternative approach is to write a perl script that produces fvwm com‐
93 mands and sends them for execution, this script may be loaded using
94 "FvwmPerl --load". There are hovewer intermediate solutions that pre‐
95 process only separate configuration lines (or alternatively, execute
96 separate perl commands that produce fvwm commands).
97 The following code snippet adds ability of arithmetics and string
99 scripting to certain lines that need this. To use this, you want to
100 start FvwmPerl as your first command so that other commands may be
101 asked to be preprosessed.
102 ModuleSynchronize FvwmPerl
104 AddToFunc .
106 + I SendToModule FvwmPerl preprocess -c -- $*
107 . Exec exec xterm -name xterm-%{++$i}% # use unique name
109 . GotoDesk 0 %{ $[desk.n] + 1 }% # go to next desk
111 . Exec exec %{ -x "/usr/bin/X11/aterm" ? "aterm" : "xterm" }% -sb
113 # center a window
115 Next (MyWindow) . Move \
116 %{($WIDTH - $[w.width]) / 2}%p %{($HEIGHT - $[w.height]) / 2}%p
117 . Exec exec xmessage %{2 + 2}% # simple calculator
119 . %{main::showMessage(2 + 2, "Yet another Calculator"); ""}%
121
123 There are several actions that FvwmPerl may perform:
124 eval perl-code
126 Evaluate a line of perl code.
127 A special function cmd("command") may be used in perl code to send
129 commands back to fvwm.
130 If perl code contains an error, it is printed to the standard error
132 stream with the [FvwmPerl][eval]: header prepended.
133 load file-name
135 Load a file of perl code. If the file is not fully qualified, it
136 is searched in the user directory $FVWM_USERDIR (usually ~/.fvwm)
137 and the system wide data directory $FVWM_DATADIR.
138 A special function cmd("command") may be used in perl code to send
140 commands back to fvwm.
141 If perl code contains an error, it is printed to the standard error
143 stream with the [FvwmPerl][load]: header prepended.
144 preprocess [-q⎪--quote char] [-c⎪--cmd] [line ⎪ file]
146 Preprocess fvwm config file or (if --cmd is given) line. This file
147 contains lines that are not touched (usually fvwm commands) and
148 specially preformatted perl code that is processed and replaced.
149 Text enclosed in %{ ... }% delimiters, that may start anywhere on
150 the line and end anywhere on the same or an other line, is perl
151 code.
152 The quote parameter changes perl code delimiters. If a single char
154 is given, like '@', the delimiters are @{ ... }@. If the given
155 quote is 2 chars, like <>, the quotes are <{ ... }>
156 The perl code is substituted for the result of its evaluation.
158 I.e. %{$a = "c"; ++$a}% is replaced with "d".
159 The evaluation is unlike eval and load is done under the package
161 PreprocessNamespace and without use strict, so you are free to use
162 any variable names without fear of conflicts. Just don't use unini‐
163 tialized variables to mean undef or empty list (they may be in fact
164 initialized by the previous preprocess action), and do a clean-up
165 if needed. The variables and function in the main package are
166 still available, like ::cmd() or ::skip(), but it is just not a
167 good idea to access them while preprocessing.
168 There is a special function include(file) that loads a file, pre‐
170 processes it and returns the preprocessed result. Avoid recursion.
171 If any embedded perl code contains an error, it is printed to the
173 standard error stream and prepended with the [FvwmPerl][prepro‐
174 cess]: header. The result of substitution is empty in this case.
175 The following variables may be used in the perl code:
177 $USER, $DISPLAY, $WIDTH, $HEIGHT, $FVWM_VERSION, $FVWM_MODULEDIR,
179 $FVWM_DATADIR, $FVWM_USERDIR
180 The following line based directives are recognized when preprocess‐
182 ing. They are processed after the perl code (if any) is substi‐
183 tuted.
184 %Repeat count
186 Causes the following lines to be repeated count times.
187 %ModuleConfig module-name [ destroy ]
189 Causes the following lines to be interpreted as the given mod‐
190 ule configuration. If "destroy" is specified the previous mod‐
191 ule configuration is destroyed first.
192 %Prefix prefix
194 Prefixes the following lines with the quoted prefix.
195 %End any-optional-comment
197 Ends any of the directives described above, may be nested.
198 Examples:
200 %Prefix "AddToFunc SwitchToWindow I"
202 Iconify off
203 WindowShade off
204 Raise
205 WrapToWindow 50 50
206 %End
207 %ModuleConfig FvwmPager destroy
209 Colorset 0
210 Font lucidasans-10
211 DeskTopScale 28
212 MiniIcons
213 %End ModuleConfig FvwmPager
214 %Prefix "All (MyWindowToAnimate) ResizeMove "
216 100 100 %{($WIDTH - 100) / 2}% %{($HEIGHT - 100) / 2}%
217 %Repeat %{$count}%
218 br w+2c w+2c w-1c w-1c
219 %End
220 %Repeat %{$count}%
221 br w-2c w-2c w+1c w+1c
222 %End
223 %End Prefix
224 Additional preprocess parameters --nosend and --noremove may be
226 given too. See their description at the top.
227 export [func-names]
229 Send to fvwm the definition of shortcut functions that help to
230 activate different actions of the module (i.e. eval, load and pre‐
231 process).
232 Function names (func-names) may be separated by commas or/and
234 whitespace. By default, two functions "Eval" and "." are assumed.
235 The actual action defined in a function is guessed from the func‐
237 tion name if possible, where function name "." is reserved for pre‐
238 process action.
239 For example, any of these two fvwm commands
241 SendToModule MyPerl export PerlEval,PP
243 FvwmPerl --export PerlEval,PP MyPerl
244 define the following two shortcut functions:
246 DestroyFunc PerlEval
248 AddToFunc I SendToModule MyPerl eval $*
249 DestroyFunc PP
250 AddToFunc I SendToModule MyPerl preprocess -c -- $*
251 These 4 actions may be requested in one of 3 ways: 1) in the command
253 line when FvwmPerl is invoked (in this case FvwmPerl is short-lived
254 unless --stay or --export is also given), 2) by sending the correspond‐
255 ing message in fvwm config using SendToModule, 3) by calling the corre‐
256 sponding perl function in perl code.
257
259 There are several functions that perl code may call:
260 cmd($fvwmCommand)
262 In case of eval or load - send back to fvwm a string $fvwmCommand.
263 In case of preprocess - append a string $fvwmCommand to the output
264 of the embedded perl code.
265 doEval($perlCode)
267 This function is equivalent to the eval functionality on the string
268 $perlCode, described above.
269 load($fileName)
271 This function is equivalent to the load functionality on the file
272 $fileName, described above.
273 preprocess(@params, ["-c $command"] [$fileName])
275 This function is equivalent to the preprocess functionality with
276 the given parameters and the file $fileName described above.
277 export($funcNames, [$doUnexport])
279 This function is equivalent to the export functionality with the
280 given $funcNames, described above. May also unexport the function
281 names if the second parameter is true.
282 Function names should be separated by commas or/and whitespace. If
284 $funcNames is empty then functions "Eval" and "." are assumed.
285 stop()
287 Terminates the module.
288 skip()
290 Skips the rest of the event callback code, i.e. the module returns
291 to listen to new module events.
292 unlock()
294 Unsynchronizes the event callback from fvwm. This may be useful to
295 prevent deadlocks, i.e. usually fvwm kills the non-responding mod‐
296 ule if the event callback is not finished in ModuleTimeout seconds.
297 This prevents it.
298 This example causes FvwmPerl to suspend its execution for one
300 minute:
301 SendModule FvwmPerl eval unlock(); sleep(60);
303 However, verify that there is no way a new message is sent by fvwm
305 while the module is busy, and fvwm stays locked on this new message
306 for too long. See also the detach solution if you need long last‐
307 ing operations.
308 detach()
310 Forks and detaches the rest of the event callback code from the
311 main process. This may be useful to prevent killing the module if
312 its event callback should take a long time to complete and it may
313 be done in the detached child. The detached child may still send
314 commands to fvwm (don't rely on this), but not receive the events
315 of course, it exits immediately after the callback execution is
316 finished.
317 If you use detach(), better only send commands to fvwm in one
319 process (the main one or the detached one), doing otherwise may
320 often cause conflicts.
321 showMessage($msg, $title[, $useStderrToo=1])
323 Shows a dialog window with the given message, using whichever tool
324 is find in the system.
325 See FVWM::Module::Toolkit::showMessage for more information.
327
329 There are several global variables in the main namespace that may be
330 used in the perl code:
331 $a, $b, ... $h
333 @a, @b, ... @h
334 %a, %b, ... %h
335 They all are initialized to the empty value and may be used to store a
337 state between different calls to FvwmPerl actions (eval and load).
338 If you need more readable variable names, either write "no strict
340 'vars';" at the start of every perl code or use a hash for this, like:
341 $h{id} = $h{firstName} . " " . $h{secondName}
343 or use a package name, like:
345 @MyMenu::terminals = qw( xterm rxvt );
347 $MyMenu::itemNum = @MyMenu::terminals;
348 There may be a configuration option to turn strictness on and off.
350
352 FvwmPerl may receive messages using the fvwm command SendToModule. The
353 names, meanings and parameters of the messages are the same as the cor‐
354 responding actions, described above.
355 Additionally, a message stop causes a module to quit.
357 A message unexport [func-names] undoes the effect of export, described
359 in the ACTIONS section.
360 A message dump dumps the contents of the changed variables (not yet).
362
364 A simple test:
365 SendToModule FvwmPerl eval $h{dir} = $ENV{HOME}
367 SendToModule FvwmPerl eval load($h{dir} . "/test.fpl")
368 SendToModule FvwmPerl load $[HOME]/test.fpl
369 SendToModule FvwmPerl preprocess config.ppp
370 SendToModule FvwmPerl export Eval,PerlEval,PerlLoad,PerlPP
371 SendToModule FvwmPerl unexport PerlEval,PerlLoad,PerlPP
372 SendToModule FvwmPerl stop
373 The following example handles root backgrounds in fvwmrc. All these
375 commands may be added to StartFunction.
376 Module FvwmPerl --export PerlEval
378 # find all background pixmaps for a later use
380 PerlEval $a = $ENV{HOME} . "/bg"; \
381 opendir DIR, $a; @b = grep { /xpm$/ } readdir(DIR); closedir DIR
382 # build a menu of background pixmaps
384 AddToMenu MyBackgrounds "My Backgrounds" Title
385 PerlEval foreach $b (@b) \
386 { cmd("AddToMenu MyBackgrounds '$b' Exec fvwm-root $a/$b") }
387 # choose a random background to load on start-up
389 PerlEval cmd("AddToFunc \
390 InitFunction + I Exec exec fvwm-root $a/" . $b[int(random(@b))])
391
393 SendToModule just like any other fvwm commands expands several dollar
394 prefixed variables. This may clash with the dollars perl uses. You
395 may avoid this by prefixing SendToModule with a leading dash. The fol‐
396 lowing 2 lines in each pair are equivalent:
397 SendToModule FvwmPerl eval $$d = "$[DISPLAY]"
399 -SendToModule FvwmPerl eval $d = "$ENV{DISPLAY}"
400 SendToModule FvwmPerl eval \
402 cmd("Echo desk=$d, display=$$d")
403 SendToModule FvwmPerl preprocess -c \
404 Echo desk=%("$d")%, display=%{$$d}%
405 Another solution to avoid escaping of special symbols like dollars and
407 backslashes is to create a perl file in ~/.fvwm and then load it:
408 SendToModule FvwmPerl load build-menus.fpl
410 If you need to preprocess one command starting with a dash, you should
412 precede it using "--".
413 # this prints the current desk, i.e. "0"
415 SendToModule FvwmPerl preprocess -c Echo "$%{$a = "c"; ++$a}%"
416 # this prints "$d"
417 SendToModule FvwmPerl preprocess -c -- -Echo "$%{"d"}%"
418 # this prints "$d" (SendToModule expands $$ to $)
419 SendToModule FvwmPerl preprocess -c -- -Echo "$$%{"d"}%"
420 # this prints "$$d"
421 -SendToModule FvwmPerl preprocess -c -- -Echo "$$%{"d"}%"
422 Again, it is suggested to put your command(s) into file and preprocess
424 the file instead.
425
427 FvwmPerl being written in perl and dealing with perl, follows the
428 famous perl motto: "There's more than one way to do it", so the choice
429 is yours.
430 Here are more pairs of equivalent lines:
432 Module FvwmPerl --load "my.fpl" --stay
434 Module FvwmPerl -e 'load("my.fpl")' -s
435 SendToModule FvwmPerl preprocess --quote '@' my.ppp
437 SendToModule FvwmPerl eval preprocess({quote => '@'}, "my.ppp");
438 Warning, you may affect the way FvwmPerl works by evaluating appropri‐
440 ate perl code, this is considered a feature not a bug. But please
441 don't do this, write your own fvwm module in perl instead.
442
444 The fvwm(1) man page describes all available commands.
445 Basically, in your perl code you may use any function or class method
447 from the perl library installed with fvwm, see the man pages of perl
448 packages General::FileSystem, General::Parse and FVWM::Module.
449
451 Mikhael Goikhman <migo@homemail.com>.
452perl v5.8.6 2005-08-11 FvwmPerl(1)