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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Guile Reference Manual. | |
ef4cbc08 | 3 | @c Copyright (C) 1996, 1997, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008 |
07d83abe MV |
4 | @c Free Software Foundation, Inc. |
5 | @c See the file guile.texi for copying conditions. | |
6 | ||
7 | @page | |
8 | @node Options and Config | |
9 | @section Configuration, Features and Runtime Options | |
10 | ||
11 | Why is my Guile different from your Guile? There are three kinds of | |
12 | possible variation: | |
13 | ||
14 | @itemize @bullet | |
15 | @item | |
16 | build differences --- different versions of the Guile source code, | |
17 | installation directories, configuration flags that control pieces of | |
18 | functionality being included or left out, etc. | |
19 | ||
20 | @item | |
21 | differences in dynamically loaded code --- behaviour and features | |
22 | provided by modules that can be dynamically loaded into a running Guile | |
23 | ||
24 | @item | |
25 | different runtime options --- some of the options that are provided for | |
26 | controlling Guile's behaviour may be set differently. | |
27 | @end itemize | |
28 | ||
29 | Guile provides ``introspective'' variables and procedures to query all | |
30 | of these possible variations at runtime. For runtime options, it also | |
31 | provides procedures to change the settings of options and to obtain | |
32 | documentation on what the options mean. | |
33 | ||
34 | @menu | |
35 | * Build Config:: Build and installation configuration. | |
36 | * Feature Tracking:: Available features in the Guile process. | |
37 | * Runtime Options:: Controlling Guile's runtime behaviour. | |
38 | @end menu | |
39 | ||
40 | ||
41 | @node Build Config | |
42 | @subsection Configuration, Build and Installation | |
43 | ||
44 | The following procedures and variables provide information about how | |
45 | Guile was configured, built and installed on your system. | |
46 | ||
47 | @deffn {Scheme Procedure} version | |
48 | @deffnx {Scheme Procedure} effective-version | |
49 | @deffnx {Scheme Procedure} major-version | |
50 | @deffnx {Scheme Procedure} minor-version | |
51 | @deffnx {Scheme Procedure} micro-version | |
52 | @deffnx {C Function} scm_version () | |
53 | @deffnx {C Function} scm_effective_version () | |
54 | @deffnx {C Function} scm_major_version () | |
55 | @deffnx {C Function} scm_minor_version () | |
56 | @deffnx {C Function} scm_micro_version () | |
57 | Return a string describing Guile's full version number, effective | |
58 | version number, major, minor or micro version number, respectively. | |
59 | The @code{effective-version} function returns the version name that | |
60 | should remain unchanged during a stable series. Currently that means | |
61 | that it omits the micro version. The effective version should be used | |
62 | for items like the versioned share directory name | |
63 | i.e. @file{/usr/share/guile/1.6/} | |
64 | ||
65 | @lisp | |
66 | (version) @result{} "1.6.0" | |
67 | (effective-version) @result{} "1.6" | |
68 | (major-version) @result{} "1" | |
69 | (minor-version) @result{} "6" | |
70 | (micro-version) @result{} "0" | |
71 | @end lisp | |
72 | @end deffn | |
73 | ||
74 | @deffn {Scheme Procedure} %package-data-dir | |
75 | @deffnx {C Function} scm_sys_package_data_dir () | |
76 | Return the name of the directory under which Guile Scheme files in | |
77 | general are stored. On Unix-like systems, this is usually | |
78 | @file{/usr/local/share/guile} or @file{/usr/share/guile}. | |
79 | @end deffn | |
80 | ||
81 | @deffn {Scheme Procedure} %library-dir | |
82 | @deffnx {C Function} scm_sys_library_dir () | |
83 | Return the name of the directory where the Guile Scheme files that | |
84 | belong to the core Guile installation (as opposed to files from a 3rd | |
85 | party package) are installed. On Unix-like systems, this is usually | |
86 | @file{/usr/local/share/guile/<GUILE_EFFECTIVE_VERSION>} or | |
87 | @file{/usr/share/guile/<GUILE_EFFECTIVE_VERSION>}, for example: | |
88 | @file{/usr/local/share/guile/1.6}. | |
89 | @end deffn | |
90 | ||
91 | @deffn {Scheme Procedure} %site-dir | |
92 | @deffnx {C Function} scm_sys_site_dir () | |
93 | Return the name of the directory where Guile Scheme files specific to | |
94 | your site should be installed. On Unix-like systems, this is usually | |
95 | @file{/usr/local/share/guile/site} or @file{/usr/share/guile/site}. | |
96 | @end deffn | |
97 | ||
98 | @cindex GUILE_LOAD_PATH | |
99 | @defvar %load-path | |
100 | List of directories which should be searched for Scheme modules and | |
101 | libraries. @code{%load-path} is initialized when Guile starts up to | |
102 | @code{(list (%site-dir) (%library-dir) (%package-data-dir) ".")}, | |
103 | prepended with the contents of the GUILE_LOAD_PATH environment variable, | |
104 | if it is set. | |
105 | @end defvar | |
106 | ||
107 | @deffn {Scheme Procedure} parse-path path [tail] | |
108 | @deffnx {C Function} scm_parse_path (path, tail) | |
109 | Parse @var{path}, which is expected to be a colon-separated | |
110 | string, into a list and return the resulting list with | |
111 | @var{tail} appended. If @var{path} is @code{#f}, @var{tail} | |
112 | is returned. | |
113 | @end deffn | |
114 | ||
115 | @deffn {Scheme Procedure} search-path path filename [extensions] | |
116 | @deffnx {C Function} scm_search_path (path, filename, extensions) | |
117 | Search @var{path} for a directory containing a file named | |
118 | @var{filename}. The file must be readable, and not a directory. | |
119 | If we find one, return its full filename; otherwise, return | |
120 | @code{#f}. If @var{filename} is absolute, return it unchanged. | |
121 | If given, @var{extensions} is a list of strings; for each | |
122 | directory in @var{path}, we search for @var{filename} | |
123 | concatenated with each @var{extension}. | |
124 | @end deffn | |
125 | ||
126 | @defvar %guile-build-info | |
127 | Alist of information collected during the building of a particular | |
128 | Guile. Entries can be grouped into one of several categories: | |
129 | directories, env vars, and versioning info. | |
130 | ||
131 | Briefly, here are the keys in @code{%guile-build-info}, by group: | |
132 | ||
133 | @cindex @code{srcdir} | |
134 | @cindex @code{top_srcdir} | |
135 | @cindex @code{prefix} | |
136 | @cindex @code{exec_prefix} | |
137 | @cindex @code{bindir} | |
138 | @cindex @code{sbindir} | |
139 | @cindex @code{libexecdir} | |
140 | @cindex @code{datadir} | |
141 | @cindex @code{sysconfdir} | |
142 | @cindex @code{sharedstatedir} | |
143 | @cindex @code{localstatedir} | |
144 | @cindex @code{libdir} | |
145 | @cindex @code{infodir} | |
146 | @cindex @code{mandir} | |
147 | @cindex @code{includedir} | |
148 | @cindex @code{pkgdatadir} | |
149 | @cindex @code{pkglibdir} | |
150 | @cindex @code{pkgincludedir} | |
151 | @table @asis | |
152 | @item directories | |
153 | srcdir, top_srcdir, prefix, exec_prefix, bindir, sbindir, libexecdir, | |
154 | datadir, sysconfdir, sharedstatedir, localstatedir, libdir, infodir, | |
155 | mandir, includedir, pkgdatadir, pkglibdir, pkgincludedir | |
156 | @cindex @code{LIBS} | |
157 | @item env vars | |
158 | LIBS | |
159 | @cindex @code{guileversion} | |
160 | @cindex @code{libguileinterface} | |
161 | @cindex @code{buildstamp} | |
162 | @item versioning info | |
163 | guileversion, libguileinterface, buildstamp | |
164 | @end table | |
165 | ||
166 | Values are all strings. The value for @code{LIBS} is typically found | |
167 | also as a part of "guile-config link" output. The value for | |
168 | @code{guileversion} has form X.Y.Z, and should be the same as returned | |
73e46534 KR |
169 | by @code{(version)}. The value for @code{libguileinterface} is |
170 | libtool compatible and has form CURRENT:REVISION:AGE | |
171 | (@pxref{Versioning,, Library interface versions, libtool, GNU | |
172 | Libtool}). The value for @code{buildstamp} is the output of the | |
173 | date(1) command. | |
07d83abe MV |
174 | |
175 | In the source, @code{%guile-build-info} is initialized from | |
176 | libguile/libpath.h, which is completely generated, so deleting this file | |
177 | before a build guarantees up-to-date values for that build. | |
178 | @end defvar | |
179 | ||
180 | ||
181 | @node Feature Tracking | |
182 | @subsection Feature Tracking | |
183 | ||
184 | Guile has a Scheme level variable @code{*features*} that keeps track to | |
185 | some extent of the features that are available in a running Guile. | |
186 | @code{*features*} is a list of symbols, for example @code{threads}, each | |
187 | of which describes a feature of the running Guile process. | |
188 | ||
189 | @defvar *features* | |
190 | A list of symbols describing available features of the Guile process. | |
191 | @end defvar | |
192 | ||
193 | You shouldn't modify the @code{*features*} variable directly using | |
194 | @code{set!}. Instead, see the procedures that are provided for this | |
195 | purpose in the following subsection. | |
196 | ||
197 | @menu | |
198 | * Feature Manipulation:: Checking for and advertising features. | |
199 | * Common Feature Symbols:: Commonly available features. | |
200 | @end menu | |
201 | ||
202 | ||
203 | @node Feature Manipulation | |
204 | @subsubsection Feature Manipulation | |
205 | ||
206 | To check whether a particular feature is available, use the | |
207 | @code{provided?} procedure: | |
208 | ||
209 | @deffn {Scheme Procedure} provided? feature | |
210 | @deffnx {Deprecated Scheme Procedure} feature? feature | |
211 | Return @code{#t} if the specified @var{feature} is available, otherwise | |
212 | @code{#f}. | |
213 | @end deffn | |
214 | ||
215 | To advertise a feature from your own Scheme code, you can use the | |
216 | @code{provide} procedure: | |
217 | ||
218 | @deffn {Scheme Procedure} provide feature | |
219 | Add @var{feature} to the list of available features in this Guile | |
220 | process. | |
221 | @end deffn | |
222 | ||
223 | For C code, the equivalent function takes its feature name as a | |
224 | @code{char *} argument for convenience: | |
225 | ||
226 | @deftypefn {C Function} void scm_add_feature (const char *str) | |
227 | Add a symbol with name @var{str} to the list of available features in | |
228 | this Guile process. | |
229 | @end deftypefn | |
230 | ||
231 | ||
232 | @node Common Feature Symbols | |
233 | @subsubsection Common Feature Symbols | |
234 | ||
235 | In general, a particular feature may be available for one of two | |
236 | reasons. Either because the Guile library was configured and compiled | |
237 | with that feature enabled --- i.e. the feature is built into the library | |
238 | on your system. Or because some C or Scheme code that was dynamically | |
239 | loaded by Guile has added that feature to the list. | |
240 | ||
241 | In the first category, here are the features that the current version of | |
242 | Guile may define (depending on how it is built), and what they mean. | |
243 | ||
244 | @table @code | |
245 | @item array | |
246 | Indicates support for arrays (@pxref{Arrays}). | |
247 | ||
248 | @item array-for-each | |
249 | Indicates availability of @code{array-for-each} and other array mapping | |
40499598 | 250 | procedures (@pxref{Arrays}). |
07d83abe MV |
251 | |
252 | @item char-ready? | |
253 | Indicates that the @code{char-ready?} function is available | |
254 | (@pxref{Reading}). | |
255 | ||
256 | @item complex | |
257 | Indicates support for complex numbers. | |
258 | ||
259 | @item current-time | |
260 | Indicates availability of time-related functions: @code{times}, | |
261 | @code{get-internal-run-time} and so on (@pxref{Time}). | |
262 | ||
263 | @item debug-extensions | |
264 | Indicates that the debugging evaluator is available, together with the | |
265 | options for controlling it. | |
266 | ||
267 | @item delay | |
268 | Indicates support for promises (@pxref{Delayed Evaluation}). | |
269 | ||
270 | @item EIDs | |
271 | Indicates that the @code{geteuid} and @code{getegid} really return | |
272 | effective user and group IDs (@pxref{Processes}). | |
273 | ||
274 | @item inexact | |
275 | Indicates support for inexact numbers. | |
276 | ||
277 | @item i/o-extensions | |
278 | Indicates availability of the following extended I/O procedures: | |
279 | @code{ftell}, @code{redirect-port}, @code{dup->fdes}, @code{dup2}, | |
280 | @code{fileno}, @code{isatty?}, @code{fdopen}, | |
281 | @code{primitive-move->fdes} and @code{fdes->ports} (@pxref{Ports and | |
282 | File Descriptors}). | |
283 | ||
284 | @item net-db | |
285 | Indicates availability of network database functions: | |
286 | @code{scm_gethost}, @code{scm_getnet}, @code{scm_getproto}, | |
287 | @code{scm_getserv}, @code{scm_sethost}, @code{scm_setnet}, @code{scm_setproto}, | |
288 | @code{scm_setserv}, and their `byXXX' variants (@pxref{Network | |
289 | Databases}). | |
290 | ||
291 | @item posix | |
292 | Indicates support for POSIX functions: @code{pipe}, @code{getgroups}, | |
293 | @code{kill}, @code{execl} and so on (@pxref{POSIX}). | |
294 | ||
295 | @item random | |
296 | Indicates availability of random number generation functions: | |
297 | @code{random}, @code{copy-random-state}, @code{random-uniform} and so on | |
298 | (@pxref{Random}). | |
299 | ||
300 | @item reckless | |
301 | Indicates that Guile was built with important checks omitted --- you | |
302 | should never see this! | |
303 | ||
304 | @item regex | |
305 | Indicates support for POSIX regular expressions using | |
306 | @code{make-regexp}, @code{regexp-exec} and friends (@pxref{Regexp | |
307 | Functions}). | |
308 | ||
309 | @item socket | |
310 | Indicates availability of socket-related functions: @code{socket}, | |
311 | @code{bind}, @code{connect} and so on (@pxref{Network Sockets and | |
312 | Communication}). | |
313 | ||
314 | @item sort | |
315 | Indicates availability of sorting and merging functions | |
316 | (@pxref{Sorting}). | |
317 | ||
318 | @item system | |
319 | Indicates that the @code{system} function is available | |
320 | (@pxref{Processes}). | |
321 | ||
322 | @item threads | |
323 | Indicates support for multithreading (@pxref{Threads}). | |
324 | ||
325 | @item values | |
326 | Indicates support for multiple return values using @code{values} and | |
327 | @code{call-with-values} (@pxref{Multiple Values}). | |
328 | @end table | |
329 | ||
330 | Available features in the second category depend, by definition, on what | |
331 | additional code your Guile process has loaded in. The following table | |
332 | lists features that you might encounter for this reason. | |
333 | ||
334 | @table @code | |
335 | @item defmacro | |
336 | Indicates that the @code{defmacro} macro is available (@pxref{Macros}). | |
337 | ||
338 | @item describe | |
339 | Indicates that the @code{(oop goops describe)} module has been loaded, | |
340 | which provides a procedure for describing the contents of GOOPS | |
341 | instances. | |
342 | ||
343 | @item readline | |
344 | Indicates that Guile has loaded in Readline support, for command line | |
345 | editing (@pxref{Readline Support}). | |
346 | ||
347 | @item record | |
348 | Indicates support for record definition using @code{make-record-type} | |
349 | and friends (@pxref{Records}). | |
350 | @end table | |
351 | ||
352 | Although these tables may seem exhaustive, it is probably unwise in | |
353 | practice to rely on them, as the correspondences between feature symbols | |
354 | and available procedures/behaviour are not strictly defined. If you are | |
355 | writing code that needs to check for the existence of some procedure, it | |
356 | is probably safer to do so directly using the @code{defined?} procedure | |
357 | than to test for the corresponding feature using @code{provided?}. | |
358 | ||
359 | ||
360 | @node Runtime Options | |
361 | @subsection Runtime Options | |
362 | ||
363 | Guile's runtime behaviour can be modified by setting options. For | |
364 | example, is the language that Guile accepts case sensitive, or should | |
365 | the debugger automatically show a backtrace on error? | |
366 | ||
367 | Guile has two levels of interface for managing options: a low-level | |
368 | control interface, and a user-level interface which allows the enabling | |
369 | or disabling of options. | |
370 | ||
371 | Moreover, the options are classified in groups according to whether they | |
372 | configure @emph{reading}, @emph{printing}, @emph{debugging} or | |
373 | @emph{evaluating}. | |
374 | ||
375 | @menu | |
376 | * Low level options interfaces:: | |
377 | * User level options interfaces:: | |
378 | * Reader options:: | |
379 | * Printing options:: | |
380 | * Debugger options:: | |
381 | * Evaluator options:: | |
382 | * Evaluator trap options:: | |
383 | * Examples of option use:: | |
384 | @end menu | |
385 | ||
386 | ||
387 | @node Low level options interfaces | |
388 | @subsubsection Low Level Options Interfaces | |
389 | ||
390 | @deffn {Scheme Procedure} read-options-interface [setting] | |
391 | @deffnx {Scheme Procedure} eval-options-interface [setting] | |
392 | @deffnx {Scheme Procedure} print-options-interface [setting] | |
393 | @deffnx {Scheme Procedure} debug-options-interface [setting] | |
394 | @deffnx {Scheme Procedure} evaluator-traps-interface [setting] | |
395 | @deffnx {C Function} scm_read_options (setting) | |
396 | @deffnx {C Function} scm_eval_options_interface (setting) | |
397 | @deffnx {C Function} scm_print_options (setting) | |
398 | @deffnx {C Function} scm_debug_options (setting) | |
399 | @deffnx {C Function} scm_evaluator_traps (setting) | |
400 | If one of these procedures is called with no arguments (or with | |
401 | @code{setting == SCM_UNDEFINED} in C code), it returns a list describing | |
402 | the current setting of the read, eval, print, debug or evaluator traps | |
403 | options respectively. The setting of a boolean option is indicated | |
404 | simply by the presence or absence of the option symbol in the list. The | |
405 | setting of a non-boolean option is indicated by the presence of the | |
406 | option symbol immediately followed by the option's current value. | |
407 | ||
408 | If called with a list argument, these procedures interpret the list as | |
409 | an option setting and modify the relevant options accordingly. [FIXME | |
410 | --- this glosses over a lot of details!] | |
411 | ||
412 | If called with any other argument, such as @code{'help}, these | |
413 | procedures return a list of entries like @code{(@var{OPTION-SYMBOL} | |
414 | @var{DEFAULT-VALUE} @var{DOC-STRING})}, with each entry giving the | |
415 | default value and documentation for each option symbol in the relevant | |
416 | set of options. | |
417 | @end deffn | |
418 | ||
419 | ||
420 | @node User level options interfaces | |
421 | @subsubsection User Level Options Interfaces | |
422 | ||
423 | @c @deftp {Data type} scm_option | |
424 | @c @code{scm_option} is used to represent run time options. It can be a | |
425 | @c @emph{boolean} type, in which case the option will be set by the strings | |
426 | @c @code{"yes"} and @code{"no"}. It can be a | |
427 | @c @end deftp | |
428 | ||
429 | @c NJFIXME | |
430 | @deffn {Scheme Procedure} <group>-options [arg] | |
431 | @deffnx {Scheme Procedure} read-options [arg] | |
432 | @deffnx {Scheme Procedure} print-options [arg] | |
433 | @deffnx {Scheme Procedure} debug-options [arg] | |
434 | @deffnx {Scheme Procedure} traps [arg] | |
435 | These functions list the options in their group. The optional argument | |
436 | @var{arg} is a symbol which modifies the form in which the options are | |
437 | presented. | |
438 | ||
439 | With no arguments, @code{<group>-options} returns the values of the | |
440 | options in that particular group. If @var{arg} is @code{'help}, a | |
441 | description of each option is given. If @var{arg} is @code{'full}, | |
442 | programmers' options are also shown. | |
443 | ||
444 | @var{arg} can also be a list representing the state of all options. In | |
445 | this case, the list contains single symbols (for enabled boolean | |
446 | options) and symbols followed by values. | |
447 | @end deffn | |
448 | [FIXME: I don't think 'full is ever any different from 'help. What's | |
449 | up?] | |
450 | ||
451 | @c NJFIXME | |
452 | @deffn {Scheme Procedure} <group>-enable option-symbol | |
453 | @deffnx {Scheme Procedure} read-enable option-symbol | |
454 | @deffnx {Scheme Procedure} print-enable option-symbol | |
455 | @deffnx {Scheme Procedure} debug-enable option-symbol | |
456 | @deffnx {Scheme Procedure} trap-enable option-symbol | |
457 | These functions set the specified @var{option-symbol} in their options | |
458 | group. They only work if the option is boolean, and throw an error | |
459 | otherwise. | |
460 | @end deffn | |
461 | ||
462 | @c NJFIXME | |
463 | @deffn {Scheme Procedure} <group>-disable option-symbol | |
464 | @deffnx {Scheme Procedure} read-disable option-symbol | |
465 | @deffnx {Scheme Procedure} print-disable option-symbol | |
466 | @deffnx {Scheme Procedure} debug-disable option-symbol | |
467 | @deffnx {Scheme Procedure} trap-disable option-symbol | |
468 | These functions turn off the specified @var{option-symbol} in their | |
469 | options group. They only work if the option is boolean, and throw an | |
470 | error otherwise. | |
471 | @end deffn | |
472 | ||
473 | @c NJFIXME | |
474 | @deffn syntax <group>-set! option-symbol value | |
475 | @deffnx syntax read-set! option-symbol value | |
476 | @deffnx syntax print-set! option-symbol value | |
477 | @deffnx syntax debug-set! option-symbol value | |
478 | @deffnx syntax trap-set! option-symbol value | |
479 | These functions set a non-boolean @var{option-symbol} to the specified | |
480 | @var{value}. | |
481 | @end deffn | |
482 | ||
483 | ||
484 | @node Reader options | |
485 | @subsubsection Reader options | |
486 | @cindex options - read | |
487 | @cindex read options | |
488 | ||
489 | Here is the list of reader options generated by typing | |
490 | @code{(read-options 'full)} in Guile. You can also see the default | |
491 | values. | |
492 | ||
493 | @smalllisp | |
ef4cbc08 | 494 | keywords #f Style of keyword recognition: #f, 'prefix or 'postfix |
07d83abe MV |
495 | case-insensitive no Convert symbols to lower case. |
496 | positions yes Record positions of source code expressions. | |
497 | copy no Copy source code expressions. | |
498 | @end smalllisp | |
499 | ||
500 | Notice that while Standard Scheme is case insensitive, to ease | |
501 | translation of other Lisp dialects, notably Emacs Lisp, into Guile, | |
502 | Guile is case-sensitive by default. | |
503 | ||
504 | To make Guile case insensitive, you can type | |
505 | ||
506 | @smalllisp | |
507 | (read-enable 'case-insensitive) | |
508 | @end smalllisp | |
509 | ||
510 | @node Printing options | |
511 | @subsubsection Printing options | |
512 | ||
513 | Here is the list of print options generated by typing | |
514 | @code{(print-options 'full)} in Guile. You can also see the default | |
515 | values. | |
516 | ||
517 | @smallexample | |
227eafdb MV |
518 | quote-keywordish-symbols reader How to print symbols that have a colon |
519 | as their first or last character. The | |
520 | value '#f' does not quote the colons; | |
521 | '#t' quotes them; 'reader' quotes | |
522 | them when the reader option | |
523 | 'keywords' is not '#f'. | |
524 | ||
525 | highlight-prefix @{ The string to print before highlighted values. | |
526 | highlight-suffix @} The string to print after highlighted values. | |
527 | ||
528 | source no Print closures with source. | |
529 | closure-hook #f Hook for printing closures. | |
07d83abe MV |
530 | @end smallexample |
531 | ||
532 | ||
533 | @node Evaluator options | |
534 | @subsubsection Evaluator options | |
535 | ||
536 | These are the evaluator options with their default values, as they are | |
537 | printed by typing @code{(eval-options 'full)} in Guile. | |
538 | ||
539 | @smallexample | |
540 | stack 22000 Size of thread stacks (in machine words). | |
541 | @end smallexample | |
542 | ||
543 | ||
544 | @node Evaluator trap options | |
545 | @subsubsection Evaluator trap options | |
546 | [FIXME: These flags, together with their corresponding handlers, are not | |
547 | user level options. Probably this entire section should be moved to the | |
548 | documentation about the low-level programmer debugging interface.] | |
549 | ||
550 | Here is the list of evaluator trap options generated by typing | |
551 | @code{(traps 'full)} in Guile. You can also see the default values. | |
552 | ||
553 | @smallexample | |
554 | exit-frame no Trap when exiting eval or apply. | |
555 | apply-frame no Trap when entering apply. | |
556 | enter-frame no Trap when eval enters new frame. | |
19ab431e | 557 | memoize-symbol no Trap when eval memoizes a symbol's value |
07d83abe MV |
558 | traps yes Enable evaluator traps. |
559 | @end smallexample | |
560 | ||
561 | @deffn apply-frame-handler key cont tailp | |
562 | Called when a procedure is being applied. | |
563 | ||
564 | Called if: | |
565 | ||
566 | @itemize @bullet | |
567 | @item | |
568 | evaluator traps are enabled [traps interface], and | |
569 | @item | |
570 | either | |
571 | @itemize @minus | |
572 | @item | |
573 | @code{apply-frame} is enabled [traps interface], or | |
574 | @item | |
575 | trace mode is on [debug-options interface], and the procedure being | |
576 | called has the trace property enabled. | |
577 | @end itemize | |
578 | @end itemize | |
579 | ||
31e2cc50 NJ |
580 | @var{cont} is a ``debug object'', which means that it can be passed to |
581 | @code{make-stack} to discover the stack at the point of the trap. The | |
582 | apply frame handler's code can capture a restartable continuation if it | |
583 | wants to by using @code{call-with-current-continuation} in the usual way. | |
07d83abe MV |
584 | |
585 | @var{tailp} is true if this is a tail call | |
586 | @end deffn | |
587 | ||
588 | @deffn exit-frame-handler key cont retval | |
589 | Called when a value is returned from a procedure. | |
590 | ||
591 | Called if: | |
592 | ||
593 | @itemize @bullet | |
594 | @item | |
595 | evaluator traps are enabled [traps interface], and | |
596 | @item | |
597 | either | |
598 | @itemize @minus | |
599 | @item | |
600 | @code{exit-frame} is enabled [traps interface], or | |
601 | @item | |
602 | trace mode is on [debug-options interface], and the procedure being | |
603 | called has the trace property enabled. | |
604 | @end itemize | |
605 | @end itemize | |
606 | ||
31e2cc50 NJ |
607 | @var{cont} is a ``debug object'', which means that it can be passed to |
608 | @code{make-stack} to discover the stack at the point of the trap. The | |
609 | exit frame handler's code can capture a restartable continuation if it | |
610 | wants to by using @code{call-with-current-continuation} in the usual | |
611 | way. | |
07d83abe MV |
612 | |
613 | @var{retval} is the return value. | |
614 | @end deffn | |
615 | ||
19ab431e HWN |
616 | @deffn memoize-symbol-handler key cont expression env |
617 | Called when the evaluator memoizes the value of a procedure symbol | |
618 | ||
619 | @var{cont} is a ``debug object'', which means that it can be passed to | |
620 | @code{make-stack} to discover the stack at the point of the trap. The | |
621 | exit frame handler's code can capture a restartable continuation if it | |
622 | wants to by using @code{call-with-current-continuation} in the usual | |
623 | way. | |
624 | ||
625 | @var{retval} is the return value. | |
626 | @end deffn | |
627 | ||
24dbb5ed NJ |
628 | @deffn {Scheme Procedure} with-traps thunk |
629 | @deffnx {C Function} scm_with_traps (thunk) | |
630 | Call @var{thunk} with traps enabled. | |
631 | @end deffn | |
632 | ||
633 | @deffn {Scheme Procedure} debug-object? obj | |
634 | @deffnx {C Function} scm_debug_object_p (obj) | |
635 | Return @code{#t} if @var{obj} is a debug object. | |
636 | @end deffn | |
637 | ||
19ab431e | 638 | |
07d83abe MV |
639 | @node Debugger options |
640 | @subsubsection Debugger options | |
641 | ||
642 | Here is the list of print options generated by typing | |
643 | @code{(debug-options 'full)} in Guile. You can also see the default | |
644 | values. | |
645 | ||
646 | @smallexample | |
647 | stack 20000 Stack size limit (0 = no check). | |
648 | debug yes Use the debugging evaluator. | |
649 | backtrace no Show backtrace on error. | |
650 | depth 20 Maximal length of printed backtrace. | |
651 | maxdepth 1000 Maximal number of stored backtrace frames. | |
652 | frames 3 Maximum number of tail-recursive frames in backtrace. | |
653 | indent 10 Maximal indentation in backtrace. | |
654 | backwards no Display backtrace in anti-chronological order. | |
655 | procnames yes Record procedure names at definition. | |
656 | trace no *Trace mode. | |
657 | breakpoints no *Check for breakpoints. | |
31e2cc50 | 658 | cheap yes *This option is now obsolete. Setting it has no effect. |
07d83abe MV |
659 | @end smallexample |
660 | ||
661 | @subsubheading Stack overflow | |
662 | ||
663 | @cindex overflow, stack | |
664 | @cindex stack overflow | |
665 | Stack overflow errors are caused by a computation trying to use more | |
666 | stack space than has been enabled by the @code{stack} option. They are | |
667 | reported like this: | |
668 | ||
669 | @lisp | |
670 | (non-tail-recursive-factorial 500) | |
671 | @print{} | |
672 | ERROR: Stack overflow | |
673 | ABORT: (stack-overflow) | |
674 | @end lisp | |
675 | ||
676 | If you get an error like this, you can either try rewriting your code to | |
677 | use less stack space, or increase the maximum stack size. To increase | |
678 | the maximum stack size, use @code{debug-set!}, for example: | |
679 | ||
680 | @lisp | |
681 | (debug-set! stack 200000) | |
682 | @result{} | |
683 | (show-file-name #t stack 200000 debug backtrace depth 20 maxdepth 1000 frames 3 indent 10 width 79 procnames cheap) | |
684 | ||
685 | (non-tail-recursive-factorial 500) | |
686 | @result{} | |
687 | 122013682599111006870123878542304692625357434@dots{} | |
688 | @end lisp | |
689 | ||
690 | If you prefer to try rewriting your code, you may be able to save stack | |
bfc083ec KR |
691 | space by making some of your procedures @dfn{tail recursive} |
692 | (@pxref{Tail Calls}). | |
07d83abe MV |
693 | |
694 | ||
695 | @node Examples of option use | |
696 | @subsubsection Examples of option use | |
697 | ||
698 | Here is an example of a session in which some read and debug option | |
699 | handling procedures are used. In this example, the user | |
700 | ||
701 | @enumerate | |
702 | @item | |
703 | Notices that the symbols @code{abc} and @code{aBc} are not the same | |
704 | @item | |
705 | Examines the @code{read-options}, and sees that @code{case-insensitive} | |
706 | is set to ``no''. | |
707 | @item | |
708 | Enables @code{case-insensitive} | |
709 | @item | |
710 | Verifies that now @code{aBc} and @code{abc} are the same | |
711 | @item | |
712 | Disables @code{case-insensitive} and enables debugging @code{backtrace} | |
713 | @item | |
714 | Reproduces the error of displaying @code{aBc} with backtracing enabled | |
715 | [FIXME: this last example is lame because there is no depth in the | |
716 | backtrace. Need to give a better example, possibly putting debugging | |
717 | option examples in a separate session.] | |
718 | @end enumerate | |
719 | ||
720 | ||
721 | @smalllisp | |
722 | guile> (define abc "hello") | |
723 | guile> abc | |
724 | "hello" | |
725 | guile> aBc | |
726 | ERROR: In expression aBc: | |
727 | ERROR: Unbound variable: aBc | |
728 | ABORT: (misc-error) | |
729 | ||
730 | Type "(backtrace)" to get more information. | |
731 | guile> (read-options 'help) | |
ef4cbc08 | 732 | keywords #f Style of keyword recognition: #f, 'prefix or 'postfix |
07d83abe MV |
733 | case-insensitive no Convert symbols to lower case. |
734 | positions yes Record positions of source code expressions. | |
735 | copy no Copy source code expressions. | |
736 | guile> (debug-options 'help) | |
737 | stack 20000 Stack size limit (0 = no check). | |
738 | debug yes Use the debugging evaluator. | |
739 | backtrace no Show backtrace on error. | |
740 | depth 20 Maximal length of printed backtrace. | |
741 | maxdepth 1000 Maximal number of stored backtrace frames. | |
742 | frames 3 Maximum number of tail-recursive frames in backtrace. | |
743 | indent 10 Maximal indentation in backtrace. | |
744 | backwards no Display backtrace in anti-chronological order. | |
745 | procnames yes Record procedure names at definition. | |
746 | trace no *Trace mode. | |
747 | breakpoints no *Check for breakpoints. | |
31e2cc50 | 748 | cheap yes *This option is now obsolete. Setting it has no effect. |
07d83abe MV |
749 | guile> (read-enable 'case-insensitive) |
750 | (keywords #f case-insensitive positions) | |
751 | guile> aBc | |
752 | "hello" | |
753 | guile> (read-disable 'case-insensitive) | |
754 | (keywords #f positions) | |
755 | guile> (debug-enable 'backtrace) | |
756 | (stack 20000 debug backtrace depth 20 maxdepth 1000 frames 3 indent 10 procnames cheap) | |
757 | guile> aBc | |
758 | ||
759 | Backtrace: | |
760 | 0* aBc | |
761 | ||
762 | ERROR: In expression aBc: | |
763 | ERROR: Unbound variable: aBc | |
764 | ABORT: (misc-error) | |
765 | guile> | |
766 | @end smalllisp | |
767 | ||
768 | ||
769 | @c Local Variables: | |
770 | @c TeX-master: "guile.texi" | |
771 | @c End: |