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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
c0d8ceaa | 2 | @c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 2000 Free Software Foundation, Inc. |
6bf7aab6 DL |
3 | @c See file emacs.texi for copying conditions. |
4 | @node Building, Abbrevs, Programs, Top | |
5 | @chapter Compiling and Testing Programs | |
6 | @cindex building programs | |
7 | @cindex program building | |
8 | @cindex running Lisp functions | |
9 | ||
10 | The previous chapter discusses the Emacs commands that are useful for | |
11 | making changes in programs. This chapter deals with commands that assist | |
12 | in the larger process of developing and maintaining programs. | |
13 | ||
14 | @menu | |
15 | * Compilation:: Compiling programs in languages other | |
16 | than Lisp (C, Pascal, etc.). | |
17 | * Grep Searching:: Running grep as if it were a compiler. | |
18 | * Compilation Mode:: The mode for visiting compiler errors. | |
19 | * Compilation Shell:: Customizing your shell properly | |
20 | for use in the compilation buffer. | |
21 | * Debuggers:: Running symbolic debuggers for non-Lisp programs. | |
22 | * Executing Lisp:: Various modes for editing Lisp programs, | |
23 | with different facilities for running | |
24 | the Lisp programs. | |
25 | * Libraries: Lisp Libraries. Creating Lisp programs to run in Emacs. | |
26 | * Interaction: Lisp Interaction. Executing Lisp in an Emacs buffer. | |
27 | * Eval: Lisp Eval. Executing a single Lisp expression in Emacs. | |
28 | * External Lisp:: Communicating through Emacs with a separate Lisp. | |
29 | @end menu | |
30 | ||
31 | @node Compilation | |
32 | @section Running Compilations under Emacs | |
33 | @cindex inferior process | |
34 | @cindex make | |
35 | @cindex compilation errors | |
36 | @cindex error log | |
37 | ||
38 | Emacs can run compilers for noninteractive languages such as C and | |
39 | Fortran as inferior processes, feeding the error log into an Emacs buffer. | |
40 | It can also parse the error messages and show you the source lines where | |
41 | compilation errors occurred. | |
42 | ||
43 | @table @kbd | |
44 | @item M-x compile | |
45 | Run a compiler asynchronously under Emacs, with error messages to | |
46 | @samp{*compilation*} buffer. | |
47 | @item M-x grep | |
48 | Run @code{grep} asynchronously under Emacs, with matching lines | |
49 | listed in the buffer named @samp{*grep*}. | |
50 | @item M-x grep-find | |
51 | Run @code{grep} via @code{find}, with user-specified arguments, and | |
52 | collect output in the buffer named @samp{*grep*}. | |
53 | @item M-x kill-compilation | |
54 | @itemx M-x kill-grep | |
55 | Kill the running compilation or @code{grep} subprocess. | |
56 | @end table | |
57 | ||
58 | @findex compile | |
59 | To run @code{make} or another compilation command, do @kbd{M-x | |
60 | compile}. This command reads a shell command line using the minibuffer, | |
61 | and then executes the command in an inferior shell, putting output in | |
62 | the buffer named @samp{*compilation*}. The current buffer's default | |
63 | directory is used as the working directory for the execution of the | |
64 | command; normally, therefore, the compilation happens in this | |
65 | directory. | |
66 | ||
67 | @vindex compile-command | |
68 | When the shell command line is read, the minibuffer appears containing | |
69 | a default command line, which is the command you used the last time you | |
70 | did @kbd{M-x compile}. If you type just @key{RET}, the same command | |
71 | line is used again. For the first @kbd{M-x compile}, the default is | |
72 | @samp{make -k}. The default compilation command comes from the variable | |
73 | @code{compile-command}; if the appropriate compilation command for a | |
74 | file is something other than @samp{make -k}, it can be useful for the | |
75 | file to specify a local value for @code{compile-command} (@pxref{File | |
76 | Variables}). | |
77 | ||
78 | Starting a compilation displays the buffer @samp{*compilation*} in | |
79 | another window but does not select it. The buffer's mode line tells you | |
80 | whether compilation is finished, with the word @samp{run} or @samp{exit} | |
81 | inside the parentheses. You do not have to keep this buffer visible; | |
82 | compilation continues in any case. While a compilation is going on, the | |
83 | string @samp{Compiling} appears in the mode lines of all windows. When | |
84 | this string disappears, the compilation is finished. | |
85 | ||
86 | If you want to watch the compilation transcript as it appears, switch | |
87 | to the @samp{*compilation*} buffer and move point to the end of the | |
88 | buffer. When point is at the end, new compilation output is inserted | |
89 | above point, which remains at the end. If point is not at the end of | |
90 | the buffer, it remains fixed while more compilation output is added at | |
91 | the end of the buffer. | |
92 | ||
09e58ba6 | 93 | @cindex compilation buffer, keeping current position at the end |
6bf7aab6 DL |
94 | @vindex compilation-scroll-output |
95 | If you set the variable @code{compilation-scroll-output} to a | |
96 | non-@code{nil} value, then the compilation buffer always scrolls to | |
97 | follow output as it comes in. | |
98 | ||
99 | @findex kill-compilation | |
100 | To kill the compilation process, do @kbd{M-x kill-compilation}. When | |
101 | the compiler process terminates, the mode line of the | |
102 | @samp{*compilation*} buffer changes to say @samp{signal} instead of | |
103 | @samp{run}. Starting a new compilation also kills any running | |
104 | compilation, as only one can exist at any time. However, @kbd{M-x | |
105 | compile} asks for confirmation before actually killing a compilation | |
106 | that is running. | |
107 | ||
108 | @node Grep Searching | |
109 | @section Searching with Grep under Emacs | |
110 | ||
111 | @findex grep | |
112 | Just as you can run a compiler from Emacs and then visit the lines | |
113 | where there were compilation errors, you can also run @code{grep} and | |
114 | then visit the lines on which matches were found. This works by | |
115 | treating the matches reported by @code{grep} as if they were ``errors.'' | |
116 | ||
117 | To do this, type @kbd{M-x grep}, then enter a command line that | |
118 | specifies how to run @code{grep}. Use the same arguments you would give | |
119 | @code{grep} when running it normally: a @code{grep}-style regexp | |
120 | (usually in single-quotes to quote the shell's special characters) | |
121 | followed by file names, which may use wildcards. The output from | |
122 | @code{grep} goes in the @samp{*grep*} buffer. You can find the | |
123 | corresponding lines in the original files using @kbd{C-x `} and | |
124 | @key{RET}, as with compilation errors. | |
125 | ||
126 | If you specify a prefix argument for @kbd{M-x grep}, it figures out | |
127 | the tag (@pxref{Tags}) around point, and puts that into the default | |
128 | @code{grep} command. | |
129 | ||
130 | @findex grep-find | |
131 | The command @kbd{M-x grep-find} is similar to @kbd{M-x grep}, but it | |
132 | supplies a different initial default for the command---one that runs | |
133 | both @code{find} and @code{grep}, so as to search every file in a | |
134 | directory tree. See also the @code{find-grep-dired} command, | |
135 | in @ref{Dired and Find}. | |
136 | ||
137 | @node Compilation Mode | |
138 | @section Compilation Mode | |
139 | ||
140 | @findex compile-goto-error | |
141 | @cindex Compilation mode | |
142 | @cindex mode, Compilation | |
143 | The @samp{*compilation*} buffer uses a special major mode, Compilation | |
144 | mode, whose main feature is to provide a convenient way to look at the | |
145 | source line where the error happened. | |
146 | ||
09e58ba6 EZ |
147 | If you set the variable @code{compilation-scroll-output} to a |
148 | non-@code{nil} value, then the compilation buffer always scrolls to | |
149 | follow output as it comes in. | |
150 | ||
6bf7aab6 DL |
151 | @table @kbd |
152 | @item C-x ` | |
153 | Visit the locus of the next compiler error message or @code{grep} match. | |
154 | @item @key{RET} | |
155 | Visit the locus of the error message that point is on. | |
156 | This command is used in the compilation buffer. | |
157 | @item Mouse-2 | |
158 | Visit the locus of the error message that you click on. | |
159 | @end table | |
160 | ||
161 | @kindex C-x ` | |
162 | @findex next-error | |
163 | You can visit the source for any particular error message by moving | |
164 | point in @samp{*compilation*} to that error message and typing @key{RET} | |
165 | (@code{compile-goto-error}). Or click @kbd{Mouse-2} on the error message; | |
166 | you need not switch to the @samp{*compilation*} buffer first. | |
167 | ||
168 | To parse the compiler error messages sequentially, type @kbd{C-x `} | |
169 | (@code{next-error}). The character following the @kbd{C-x} is the | |
170 | backquote or ``grave accent,'' not the single-quote. This command is | |
171 | available in all buffers, not just in @samp{*compilation*}; it displays | |
172 | the next error message at the top of one window and source location of | |
173 | the error in another window. | |
174 | ||
175 | The first time @kbd{C-x `} is used after the start of a compilation, | |
176 | it moves to the first error's location. Subsequent uses of @kbd{C-x `} | |
177 | advance down to subsequent errors. If you visit a specific error | |
178 | message with @key{RET} or @kbd{Mouse-2}, subsequent @kbd{C-x `} | |
179 | commands advance from there. When @kbd{C-x `} gets to the end of the | |
180 | buffer and finds no more error messages to visit, it fails and signals | |
181 | an Emacs error. | |
182 | ||
183 | @kbd{C-u C-x `} starts scanning from the beginning of the compilation | |
184 | buffer. This is one way to process the same set of errors again. | |
185 | ||
186 | Compilation mode also redefines the keys @key{SPC} and @key{DEL} to | |
187 | scroll by screenfuls, and @kbd{M-n} and @kbd{M-p} to move to the next or | |
188 | previous error message. You can also use @kbd{M-@{} and @kbd{M-@}} to | |
189 | move up or down to an error message for a different source file. | |
190 | ||
191 | The features of Compilation mode are also available in a minor mode | |
192 | called Compilation Minor mode. This lets you parse error messages in | |
193 | any buffer, not just a normal compilation output buffer. Type @kbd{M-x | |
194 | compilation-minor-mode} to enable the minor mode. This defines the keys | |
195 | @key{RET} and @kbd{Mouse-2}, as in the Compilation major mode. | |
196 | ||
197 | Compilation minor mode works in any buffer, as long as the contents | |
198 | are in a format that it understands. In an Rlogin buffer (@pxref{Remote | |
199 | Host}), Compilation minor mode automatically accesses remote source | |
200 | files by FTP (@pxref{File Names}). | |
201 | ||
202 | @node Compilation Shell | |
203 | @section Subshells for Compilation | |
204 | ||
205 | Emacs uses a shell to run the compilation command, but specifies | |
206 | the option for a noninteractive shell. This means, in particular, that | |
207 | the shell should start with no prompt. If you find your usual shell | |
208 | prompt making an unsightly appearance in the @samp{*compilation*} | |
209 | buffer, it means you have made a mistake in your shell's init file by | |
210 | setting the prompt unconditionally. (This init file's name may be | |
211 | @file{.bashrc}, @file{.profile}, @file{.cshrc}, @file{.shrc}, or various | |
212 | other things, depending on the shell you use.) The shell init file | |
213 | should set the prompt only if there already is a prompt. In csh, here | |
214 | is how to do it: | |
215 | ||
216 | @example | |
217 | if ($?prompt) set prompt = @dots{} | |
218 | @end example | |
219 | ||
220 | @noindent | |
221 | And here's how to do it in bash: | |
222 | ||
223 | @example | |
224 | if [ "$@{PS1+set@}" = set ] | |
225 | then PS1=@dots{} | |
226 | fi | |
227 | @end example | |
228 | ||
229 | There may well be other things that your shell's init file | |
230 | ought to do only for an interactive shell. You can use the same | |
231 | method to conditionalize them. | |
232 | ||
233 | The MS-DOS ``operating system'' does not support asynchronous | |
234 | subprocesses; to work around this lack, @kbd{M-x compile} runs the | |
235 | compilation command synchronously on MS-DOS. As a consequence, you must | |
236 | wait until the command finishes before you can do anything else in | |
237 | Emacs. @xref{MS-DOS}. | |
238 | ||
239 | @node Debuggers | |
240 | @section Running Debuggers Under Emacs | |
241 | @cindex debuggers | |
242 | @cindex GUD library | |
243 | @cindex GDB | |
244 | @cindex DBX | |
245 | @cindex SDB | |
246 | @cindex XDB | |
247 | @cindex Perldb | |
248 | @cindex JDB | |
249 | @cindex PDB | |
250 | ||
251 | @c Do you believe in GUD? | |
252 | The GUD (Grand Unified Debugger) library provides an interface to | |
253 | various symbolic debuggers from within Emacs. We recommend the debugger | |
254 | GDB, which is free software, but you can also run DBX, SDB or XDB if you | |
255 | have them. GUD can also serve as an interface to the Perl's debugging | |
256 | mode, the Python debugger PDB, and to JDB, the Java Debugger. | |
d952abde RS |
257 | @xref{Debugger,, The Lisp Debugger, elisp, the Emacs Lisp Reference Manual}, |
258 | for information on debugging Emacs Lisp programs. | |
6bf7aab6 DL |
259 | |
260 | @menu | |
261 | * Starting GUD:: How to start a debugger subprocess. | |
262 | * Debugger Operation:: Connection between the debugger and source buffers. | |
263 | * Commands of GUD:: Key bindings for common commands. | |
264 | * GUD Customization:: Defining your own commands for GUD. | |
c0d8ceaa | 265 | * GUD Tooltips:: Showing variable values by pointing with the mouse. |
6bf7aab6 DL |
266 | @end menu |
267 | ||
268 | @node Starting GUD | |
269 | @subsection Starting GUD | |
270 | ||
271 | There are several commands for starting a debugger, each corresponding | |
272 | to a particular debugger program. | |
273 | ||
274 | @table @kbd | |
275 | @item M-x gdb @key{RET} @var{file} @key{RET} | |
276 | @findex gdb | |
277 | Run GDB as a subprocess of Emacs. This command creates a buffer for | |
278 | input and output to GDB, and switches to it. If a GDB buffer already | |
279 | exists, it just switches to that buffer. | |
280 | ||
281 | @item M-x dbx @key{RET} @var{file} @key{RET} | |
282 | @findex dbx | |
283 | Similar, but run DBX instead of GDB. | |
284 | ||
285 | @item M-x xdb @key{RET} @var{file} @key{RET} | |
286 | @findex xdb | |
287 | @vindex gud-xdb-directories | |
288 | Similar, but run XDB instead of GDB. Use the variable | |
289 | @code{gud-xdb-directories} to specify directories to search for source | |
290 | files. | |
291 | ||
292 | @item M-x sdb @key{RET} @var{file} @key{RET} | |
293 | @findex sdb | |
294 | Similar, but run SDB instead of GDB. | |
295 | ||
296 | Some versions of SDB do not mention source file names in their | |
297 | messages. When you use them, you need to have a valid tags table | |
298 | (@pxref{Tags}) in order for GUD to find functions in the source code. | |
299 | If you have not visited a tags table or the tags table doesn't list one | |
300 | of the functions, you get a message saying @samp{The sdb support | |
301 | requires a valid tags table to work}. If this happens, generate a valid | |
302 | tags table in the working directory and try again. | |
303 | ||
304 | @item M-x perldb @key{RET} @var{file} @key{RET} | |
305 | @findex perldb | |
306 | Run the Perl interpreter in debug mode to debug @var{file}, a Perl program. | |
307 | ||
308 | @item M-x jdb @key{RET} @var{file} @key{RET} | |
309 | @findex jdb | |
310 | Run the Java debugger to debug @var{file}. | |
311 | ||
312 | @item M-x pdb @key{RET} @var{file} @key{RET} | |
313 | @findex pdb | |
314 | Run the Python debugger to debug @var{file}. | |
315 | @end table | |
316 | ||
317 | Each of these commands takes one argument: a command line to invoke | |
318 | the debugger. In the simplest case, specify just the name of the | |
319 | executable file you want to debug. You may also use options that the | |
320 | debugger supports. However, shell wildcards and variables are not | |
321 | allowed. GUD assumes that the first argument not starting with a | |
322 | @samp{-} is the executable file name. | |
323 | ||
324 | Emacs can only run one debugger process at a time. | |
325 | ||
326 | @node Debugger Operation | |
327 | @subsection Debugger Operation | |
328 | ||
329 | When you run a debugger with GUD, the debugger uses an Emacs buffer | |
330 | for its ordinary input and output. This is called the GUD buffer. The | |
331 | debugger displays the source files of the program by visiting them in | |
332 | Emacs buffers. An arrow (@samp{=>}) in one of these buffers indicates | |
9c8599ca DL |
333 | the current execution line.@footnote{Under a window system the arrow is |
334 | displayed in the marginal area of the Emacs window.} Moving point in | |
335 | this buffer does not move the arrow. | |
6bf7aab6 DL |
336 | |
337 | You can start editing these source files at any time in the buffers | |
338 | that were made to display them. The arrow is not part of the file's | |
339 | text; it appears only on the screen. If you do modify a source file, | |
340 | keep in mind that inserting or deleting lines will throw off the arrow's | |
341 | positioning; GUD has no way of figuring out which line corresponded | |
342 | before your changes to the line number in a debugger message. Also, | |
343 | you'll typically have to recompile and restart the program for your | |
344 | changes to be reflected in the debugger's tables. | |
345 | ||
346 | If you wish, you can control your debugger process entirely through the | |
347 | debugger buffer, which uses a variant of Shell mode. All the usual | |
348 | commands for your debugger are available, and you can use the Shell mode | |
349 | history commands to repeat them. @xref{Shell Mode}. | |
350 | ||
351 | @node Commands of GUD | |
352 | @subsection Commands of GUD | |
353 | ||
354 | The GUD interaction buffer uses a variant of Shell mode, so the | |
355 | commands of Shell mode are available (@pxref{Shell Mode}). GUD mode | |
356 | also provides commands for setting and clearing breakpoints, for | |
357 | selecting stack frames, and for stepping through the program. These | |
358 | commands are available both in the GUD buffer and globally, but with | |
359 | different key bindings. | |
360 | ||
361 | The breakpoint commands are usually used in source file buffers, | |
362 | because that is the way to specify where to set or clear the breakpoint. | |
363 | Here's the global command to set a breakpoint: | |
364 | ||
365 | @table @kbd | |
366 | @item C-x @key{SPC} | |
367 | @kindex C-x SPC | |
368 | Set a breakpoint on the source line that point is on. | |
369 | @end table | |
370 | ||
371 | @kindex C-x C-a @r{(GUD)} | |
372 | Here are the other special commands provided by GUD. The keys | |
373 | starting with @kbd{C-c} are available only in the GUD interaction | |
374 | buffer. The key bindings that start with @kbd{C-x C-a} are available in | |
375 | the GUD interaction buffer and also in source files. | |
376 | ||
377 | @table @kbd | |
378 | @item C-c C-l | |
379 | @kindex C-c C-l @r{(GUD)} | |
380 | @itemx C-x C-a C-l | |
381 | @findex gud-refresh | |
382 | Display in another window the last line referred to in the GUD | |
383 | buffer (that is, the line indicated in the last location message). | |
384 | This runs the command @code{gud-refresh}. | |
385 | ||
386 | @item C-c C-s | |
387 | @kindex C-c C-s @r{(GUD)} | |
388 | @itemx C-x C-a C-s | |
389 | @findex gud-step | |
390 | Execute a single line of code (@code{gud-step}). If the line contains | |
391 | a function call, execution stops after entering the called function. | |
392 | ||
393 | @item C-c C-n | |
394 | @kindex C-c C-n @r{(GUD)} | |
395 | @itemx C-x C-a C-n | |
396 | @findex gud-next | |
397 | Execute a single line of code, stepping across entire function calls | |
398 | at full speed (@code{gud-next}). | |
399 | ||
400 | @item C-c C-i | |
401 | @kindex C-c C-i @r{(GUD)} | |
402 | @itemx C-x C-a C-i | |
403 | @findex gud-stepi | |
404 | Execute a single machine instruction (@code{gud-stepi}). | |
405 | ||
406 | @need 3000 | |
407 | @item C-c C-r | |
408 | @kindex C-c C-r @r{(GUD)} | |
409 | @itemx C-x C-a C-r | |
410 | @findex gud-cont | |
411 | Continue execution without specifying any stopping point. The program | |
412 | will run until it hits a breakpoint, terminates, or gets a signal that | |
413 | the debugger is checking for (@code{gud-cont}). | |
414 | ||
415 | @need 1000 | |
416 | @item C-c C-d | |
417 | @kindex C-c C-d @r{(GUD)} | |
418 | @itemx C-x C-a C-d | |
419 | @findex gud-remove | |
420 | Delete the breakpoint(s) on the current source line, if any | |
421 | (@code{gud-remove}). If you use this command in the GUD interaction | |
422 | buffer, it applies to the line where the program last stopped. | |
423 | ||
424 | @item C-c C-t | |
425 | @kindex C-c C-t @r{(GUD)} | |
426 | @itemx C-x C-a C-t | |
427 | @findex gud-tbreak | |
428 | Set a temporary breakpoint on the current source line, if any. | |
429 | If you use this command in the GUD interaction buffer, | |
430 | it applies to the line where the program last stopped. | |
431 | @end table | |
432 | ||
433 | The above commands are common to all supported debuggers. If you are | |
434 | using GDB or (some versions of) DBX, these additional commands are available: | |
435 | ||
436 | @table @kbd | |
437 | @item C-c < | |
438 | @kindex C-c < @r{(GUD)} | |
439 | @itemx C-x C-a < | |
440 | @findex gud-up | |
441 | Select the next enclosing stack frame (@code{gud-up}). This is | |
442 | equivalent to the @samp{up} command. | |
443 | ||
444 | @item C-c > | |
445 | @kindex C-c > @r{(GUD)} | |
446 | @itemx C-x C-a > | |
447 | @findex gud-down | |
448 | Select the next inner stack frame (@code{gud-down}). This is | |
449 | equivalent to the @samp{down} command. | |
450 | @end table | |
451 | ||
452 | If you are using GDB, these additional key bindings are available: | |
453 | ||
454 | @table @kbd | |
455 | @item @key{TAB} | |
456 | @kindex TAB @r{(GUD)} | |
457 | @findex gud-gdb-complete-command | |
458 | With GDB, complete a symbol name (@code{gud-gdb-complete-command}). | |
459 | This key is available only in the GUD interaction buffer, and requires | |
460 | GDB versions 4.13 and later. | |
461 | ||
462 | @item C-c C-f | |
463 | @kindex C-c C-f @r{(GUD)} | |
464 | @itemx C-x C-a C-f | |
465 | @findex gud-finish | |
466 | Run the program until the selected stack frame returns (or until it | |
467 | stops for some other reason). | |
468 | @end table | |
469 | ||
470 | These commands interpret a numeric argument as a repeat count, when | |
471 | that makes sense. | |
472 | ||
473 | Because @key{TAB} serves as a completion command, you can't use it to | |
474 | enter a tab as input to the program you are debugging with GDB. | |
475 | Instead, type @kbd{C-q @key{TAB}} to enter a tab. | |
476 | ||
477 | @node GUD Customization | |
478 | @subsection GUD Customization | |
479 | ||
480 | @vindex gdb-mode-hook | |
481 | @vindex dbx-mode-hook | |
482 | @vindex sdb-mode-hook | |
483 | @vindex xdb-mode-hook | |
484 | @vindex perldb-mode-hook | |
485 | @vindex pdb-mode-hook | |
486 | @vindex jdb-mode-hook | |
487 | On startup, GUD runs one of the following hooks: @code{gdb-mode-hook}, | |
488 | if you are using GDB; @code{dbx-mode-hook}, if you are using DBX; | |
489 | @code{sdb-mode-hook}, if you are using SDB; @code{xdb-mode-hook}, if you | |
490 | are using XDB; @code{perldb-mode-hook}, for Perl debugging mode; | |
491 | @code{jdb-mode-hook}, for PDB; @code{jdb-mode-hook}, for JDB. You can | |
492 | use these hooks to define custom key bindings for the debugger | |
493 | interaction buffer. @xref{Hooks}. | |
494 | ||
495 | Here is a convenient way to define a command that sends a particular | |
496 | command string to the debugger, and set up a key binding for it in the | |
497 | debugger interaction buffer: | |
498 | ||
499 | @findex gud-def | |
500 | @example | |
501 | (gud-def @var{function} @var{cmdstring} @var{binding} @var{docstring}) | |
502 | @end example | |
503 | ||
504 | This defines a command named @var{function} which sends | |
505 | @var{cmdstring} to the debugger process, and gives it the documentation | |
506 | string @var{docstring}. You can use the command thus defined in any | |
507 | buffer. If @var{binding} is non-@code{nil}, @code{gud-def} also binds | |
508 | the command to @kbd{C-c @var{binding}} in the GUD buffer's mode and to | |
509 | @kbd{C-x C-a @var{binding}} generally. | |
510 | ||
511 | The command string @var{cmdstring} may contain certain | |
512 | @samp{%}-sequences that stand for data to be filled in at the time | |
513 | @var{function} is called: | |
514 | ||
515 | @table @samp | |
516 | @item %f | |
517 | The name of the current source file. If the current buffer is the GUD | |
518 | buffer, then the ``current source file'' is the file that the program | |
519 | stopped in. | |
520 | @c This said, ``the name of the file the program counter was in at the last breakpoint.'' | |
521 | @c But I suspect it is really the last stop file. | |
522 | ||
523 | @item %l | |
524 | The number of the current source line. If the current buffer is the GUD | |
525 | buffer, then the ``current source line'' is the line that the program | |
526 | stopped in. | |
527 | ||
528 | @item %e | |
529 | The text of the C lvalue or function-call expression at or adjacent to point. | |
530 | ||
531 | @item %a | |
532 | The text of the hexadecimal address at or adjacent to point. | |
533 | ||
534 | @item %p | |
535 | The numeric argument of the called function, as a decimal number. If | |
536 | the command is used without a numeric argument, @samp{%p} stands for the | |
537 | empty string. | |
538 | ||
539 | If you don't use @samp{%p} in the command string, the command you define | |
540 | ignores any numeric argument. | |
541 | @end table | |
542 | ||
c0d8ceaa DL |
543 | @node GUD Tooltips |
544 | @subsection GUD Tooltips | |
545 | ||
546 | @cindex tooltips with GUD | |
547 | The Tooltip facility (@pxref{Tooltips}) provides support for GUD@. If | |
548 | GUD support is activated by customizing the @code{tooltip} group, | |
549 | variable values can be displayed in tooltips by pointing at them with | |
550 | the mouse in the GUD buffer or in source buffers with major modes in the | |
551 | customizable list @code{tooltip-gud-modes}. | |
552 | ||
6bf7aab6 DL |
553 | @node Executing Lisp |
554 | @section Executing Lisp Expressions | |
555 | ||
556 | Emacs has several different major modes for Lisp and Scheme. They are | |
557 | the same in terms of editing commands, but differ in the commands for | |
558 | executing Lisp expressions. Each mode has its own purpose. | |
559 | ||
560 | @table @asis | |
561 | @item Emacs-Lisp mode | |
562 | The mode for editing source files of programs to run in Emacs Lisp. | |
563 | This mode defines @kbd{C-M-x} to evaluate the current defun. | |
564 | @xref{Lisp Libraries}. | |
565 | @item Lisp Interaction mode | |
566 | The mode for an interactive session with Emacs Lisp. It defines | |
567 | @kbd{C-j} to evaluate the sexp before point and insert its value in the | |
568 | buffer. @xref{Lisp Interaction}. | |
569 | @item Lisp mode | |
570 | The mode for editing source files of programs that run in Lisps other | |
571 | than Emacs Lisp. This mode defines @kbd{C-M-x} to send the current defun | |
572 | to an inferior Lisp process. @xref{External Lisp}. | |
573 | @item Inferior Lisp mode | |
574 | The mode for an interactive session with an inferior Lisp process. | |
575 | This mode combines the special features of Lisp mode and Shell mode | |
576 | (@pxref{Shell Mode}). | |
577 | @item Scheme mode | |
578 | Like Lisp mode but for Scheme programs. | |
579 | @item Inferior Scheme mode | |
580 | The mode for an interactive session with an inferior Scheme process. | |
581 | @end table | |
582 | ||
583 | Most editing commands for working with Lisp programs are in fact | |
584 | available globally. @xref{Programs}. | |
585 | ||
586 | @node Lisp Libraries | |
587 | @section Libraries of Lisp Code for Emacs | |
588 | @cindex libraries | |
589 | @cindex loading Lisp code | |
590 | ||
591 | Lisp code for Emacs editing commands is stored in files whose names | |
592 | conventionally end in @file{.el}. This ending tells Emacs to edit them in | |
593 | Emacs-Lisp mode (@pxref{Executing Lisp}). | |
594 | ||
595 | @findex load-file | |
596 | To execute a file of Emacs Lisp code, use @kbd{M-x load-file}. This | |
597 | command reads a file name using the minibuffer and then executes the | |
598 | contents of that file as Lisp code. It is not necessary to visit the | |
599 | file first; in any case, this command reads the file as found on disk, | |
600 | not text in an Emacs buffer. | |
601 | ||
602 | @findex load | |
603 | @findex load-library | |
604 | Once a file of Lisp code is installed in the Emacs Lisp library | |
605 | directories, users can load it using @kbd{M-x load-library}. Programs can | |
606 | load it by calling @code{load-library}, or with @code{load}, a more primitive | |
607 | function that is similar but accepts some additional arguments. | |
608 | ||
609 | @kbd{M-x load-library} differs from @kbd{M-x load-file} in that it | |
610 | searches a sequence of directories and tries three file names in each | |
611 | directory. Suppose your argument is @var{lib}; the three names are | |
612 | @file{@var{lib}.elc}, @file{@var{lib}.el}, and lastly just | |
613 | @file{@var{lib}}. If @file{@var{lib}.elc} exists, it is by convention | |
614 | the result of compiling @file{@var{lib}.el}; it is better to load the | |
615 | compiled file, since it will load and run faster. | |
616 | ||
617 | If @code{load-library} finds that @file{@var{lib}.el} is newer than | |
618 | @file{@var{lib}.elc} file, it prints a warning, because it's likely that | |
619 | somebody made changes to the @file{.el} file and forgot to recompile | |
620 | it. | |
621 | ||
622 | Because the argument to @code{load-library} is usually not in itself | |
623 | a valid file name, file name completion is not available. Indeed, when | |
624 | using this command, you usually do not know exactly what file name | |
625 | will be used. | |
626 | ||
627 | @vindex load-path | |
628 | The sequence of directories searched by @kbd{M-x load-library} is | |
629 | specified by the variable @code{load-path}, a list of strings that are | |
630 | directory names. The default value of the list contains the directory where | |
631 | the Lisp code for Emacs itself is stored. If you have libraries of | |
632 | your own, put them in a single directory and add that directory | |
633 | to @code{load-path}. @code{nil} in this list stands for the current default | |
634 | directory, but it is probably not a good idea to put @code{nil} in the | |
635 | list. If you find yourself wishing that @code{nil} were in the list, | |
636 | most likely what you really want to do is use @kbd{M-x load-file} | |
637 | this once. | |
638 | ||
639 | @cindex autoload | |
640 | Often you do not have to give any command to load a library, because | |
641 | the commands defined in the library are set up to @dfn{autoload} that | |
642 | library. Trying to run any of those commands calls @code{load} to load | |
643 | the library; this replaces the autoload definitions with the real ones | |
644 | from the library. | |
645 | ||
646 | @cindex byte code | |
647 | Emacs Lisp code can be compiled into byte-code which loads faster, | |
648 | takes up less space when loaded, and executes faster. @xref{Byte | |
649 | Compilation,, Byte Compilation, elisp, the Emacs Lisp Reference Manual}. | |
650 | By convention, the compiled code for a library goes in a separate file | |
651 | whose name consists of the library source file with @samp{c} appended. | |
652 | Thus, the compiled code for @file{foo.el} goes in @file{foo.elc}. | |
653 | That's why @code{load-library} searches for @samp{.elc} files first. | |
654 | ||
493c59e0 EZ |
655 | @vindex load-dangerous-libraries |
656 | @cindex Lisp files byte-compiled by XEmacs | |
a50c7a80 RS |
657 | By default, Emacs refuses to load compiled Lisp files which were |
658 | compiled with XEmacs, a modified versions of Emacs---they can cause | |
659 | Emacs to crash. Set the variable @code{load-dangerous-libraries} to | |
660 | @code{t} if you want to try loading them. | |
493c59e0 | 661 | |
6bf7aab6 DL |
662 | @node Lisp Eval |
663 | @section Evaluating Emacs-Lisp Expressions | |
664 | @cindex Emacs-Lisp mode | |
665 | @cindex mode, Emacs-Lisp | |
666 | ||
667 | @findex emacs-lisp-mode | |
668 | Lisp programs intended to be run in Emacs should be edited in | |
669 | Emacs-Lisp mode; this happens automatically for file names ending in | |
670 | @file{.el}. By contrast, Lisp mode itself is used for editing Lisp | |
671 | programs intended for other Lisp systems. To switch to Emacs-Lisp mode | |
672 | explicitly, use the command @kbd{M-x emacs-lisp-mode}. | |
673 | ||
674 | For testing of Lisp programs to run in Emacs, it is often useful to | |
675 | evaluate part of the program as it is found in the Emacs buffer. For | |
676 | example, after changing the text of a Lisp function definition, | |
677 | evaluating the definition installs the change for future calls to the | |
678 | function. Evaluation of Lisp expressions is also useful in any kind of | |
679 | editing, for invoking noninteractive functions (functions that are | |
680 | not commands). | |
681 | ||
682 | @table @kbd | |
683 | @item M-: | |
684 | Read a single Lisp expression in the minibuffer, evaluate it, and print | |
685 | the value in the echo area (@code{eval-expression}). | |
686 | @item C-x C-e | |
687 | Evaluate the Lisp expression before point, and print the value in the | |
688 | echo area (@code{eval-last-sexp}). | |
689 | @item C-M-x | |
690 | Evaluate the defun containing or after point, and print the value in | |
691 | the echo area (@code{eval-defun}). | |
692 | @item M-x eval-region | |
693 | Evaluate all the Lisp expressions in the region. | |
694 | @item M-x eval-current-buffer | |
695 | Evaluate all the Lisp expressions in the buffer. | |
696 | @end table | |
697 | ||
698 | @kindex M-: | |
699 | @findex eval-expression | |
700 | @kbd{M-:} (@code{eval-expression}) is the most basic command for evaluating | |
701 | a Lisp expression interactively. It reads the expression using the | |
702 | minibuffer, so you can execute any expression on a buffer regardless of | |
703 | what the buffer contains. When the expression is evaluated, the current | |
704 | buffer is once again the buffer that was current when @kbd{M-:} was | |
705 | typed. | |
706 | ||
707 | @kindex C-M-x @r{(Emacs-Lisp mode)} | |
708 | @findex eval-defun | |
709 | In Emacs-Lisp mode, the key @kbd{C-M-x} is bound to the command | |
710 | @code{eval-defun}, which parses the defun containing or following point | |
711 | as a Lisp expression and evaluates it. The value is printed in the echo | |
712 | area. This command is convenient for installing in the Lisp environment | |
713 | changes that you have just made in the text of a function definition. | |
714 | ||
715 | @kbd{C-M-x} treats @code{defvar} expressions specially. Normally, | |
716 | evaluating a @code{defvar} expression does nothing if the variable it | |
717 | defines already has a value. But @kbd{C-M-x} unconditionally resets the | |
718 | variable to the initial value specified in the @code{defvar} expression. | |
9c8599ca | 719 | @code{defcustom} expressions are treated similarly. |
6bf7aab6 DL |
720 | This special feature is convenient for debugging Lisp programs. |
721 | ||
722 | @kindex C-x C-e | |
723 | @findex eval-last-sexp | |
724 | The command @kbd{C-x C-e} (@code{eval-last-sexp}) evaluates the Lisp | |
725 | expression preceding point in the buffer, and displays the value in the | |
726 | echo area. It is available in all major modes, not just Emacs-Lisp | |
727 | mode. It does not treat @code{defvar} specially. | |
728 | ||
729 | If @kbd{C-M-x}, @kbd{C-x C-e}, or @kbd{M-:} is given a numeric | |
730 | argument, it inserts the value into the current buffer at point, rather | |
731 | than displaying it in the echo area. The argument's value does not | |
732 | matter. | |
733 | ||
734 | @findex eval-region | |
735 | @findex eval-current-buffer | |
736 | The most general command for evaluating Lisp expressions from a buffer | |
737 | is @code{eval-region}. @kbd{M-x eval-region} parses the text of the | |
738 | region as one or more Lisp expressions, evaluating them one by one. | |
739 | @kbd{M-x eval-current-buffer} is similar but evaluates the entire | |
740 | buffer. This is a reasonable way to install the contents of a file of | |
741 | Lisp code that you are just ready to test. Later, as you find bugs and | |
742 | change individual functions, use @kbd{C-M-x} on each function that you | |
743 | change. This keeps the Lisp world in step with the source file. | |
744 | ||
9c8599ca DL |
745 | @vindex eval-expression-print-level |
746 | @vindex eval-expression-print-length | |
747 | @vindex eval-expression-debug-on-error | |
748 | The customizable variables @code{eval-expression-print-level} and | |
749 | @code{eval-expression-print-length} control the maximum depth and length | |
750 | of lists to print in the result of the evaluation commands before | |
751 | abbreviating them. @code{eval-expression-debug-on-error} controls | |
752 | whether evaluation errors invoke the debugger when these commands are | |
753 | used. | |
754 | ||
6bf7aab6 DL |
755 | @node Lisp Interaction |
756 | @section Lisp Interaction Buffers | |
757 | ||
758 | The buffer @samp{*scratch*} which is selected when Emacs starts up is | |
759 | provided for evaluating Lisp expressions interactively inside Emacs. | |
760 | ||
761 | The simplest way to use the @samp{*scratch*} buffer is to insert Lisp | |
762 | expressions and type @kbd{C-j} after each expression. This command | |
763 | reads the Lisp expression before point, evaluates it, and inserts the | |
764 | value in printed representation before point. The result is a complete | |
765 | typescript of the expressions you have evaluated and their values. | |
766 | ||
767 | The @samp{*scratch*} buffer's major mode is Lisp Interaction mode, which | |
768 | is the same as Emacs-Lisp mode except for the binding of @kbd{C-j}. | |
769 | ||
770 | @findex lisp-interaction-mode | |
771 | The rationale for this feature is that Emacs must have a buffer when | |
772 | it starts up, but that buffer is not useful for editing files since a | |
773 | new buffer is made for every file that you visit. The Lisp interpreter | |
774 | typescript is the most useful thing I can think of for the initial | |
775 | buffer to do. Type @kbd{M-x lisp-interaction-mode} to put the current | |
776 | buffer in Lisp Interaction mode. | |
777 | ||
778 | @findex ielm | |
779 | An alternative way of evaluating Emacs Lisp expressions interactively | |
780 | is to use Inferior Emacs-Lisp mode, which provides an interface rather | |
781 | like Shell mode (@pxref{Shell Mode}) for evaluating Emacs Lisp | |
782 | expressions. Type @kbd{M-x ielm} to create an @samp{*ielm*} buffer | |
783 | which uses this mode. | |
784 | ||
785 | @node External Lisp | |
786 | @section Running an External Lisp | |
787 | ||
788 | Emacs has facilities for running programs in other Lisp systems. You can | |
789 | run a Lisp process as an inferior of Emacs, and pass expressions to it to | |
790 | be evaluated. You can also pass changed function definitions directly from | |
791 | the Emacs buffers in which you edit the Lisp programs to the inferior Lisp | |
792 | process. | |
793 | ||
794 | @findex run-lisp | |
795 | @vindex inferior-lisp-program | |
796 | @kindex C-x C-z | |
797 | To run an inferior Lisp process, type @kbd{M-x run-lisp}. This runs | |
798 | the program named @code{lisp}, the same program you would run by typing | |
799 | @code{lisp} as a shell command, with both input and output going through | |
800 | an Emacs buffer named @samp{*lisp*}. That is to say, any ``terminal | |
801 | output'' from Lisp will go into the buffer, advancing point, and any | |
802 | ``terminal input'' for Lisp comes from text in the buffer. (You can | |
803 | change the name of the Lisp executable file by setting the variable | |
804 | @code{inferior-lisp-program}.) | |
805 | ||
806 | To give input to Lisp, go to the end of the buffer and type the input, | |
807 | terminated by @key{RET}. The @samp{*lisp*} buffer is in Inferior Lisp | |
808 | mode, which combines the special characteristics of Lisp mode with most | |
809 | of the features of Shell mode (@pxref{Shell Mode}). The definition of | |
810 | @key{RET} to send a line to a subprocess is one of the features of Shell | |
811 | mode. | |
812 | ||
813 | @findex lisp-mode | |
814 | For the source files of programs to run in external Lisps, use Lisp | |
815 | mode. This mode can be selected with @kbd{M-x lisp-mode}, and is used | |
816 | automatically for files whose names end in @file{.l}, @file{.lsp}, or | |
817 | @file{.lisp}, as most Lisp systems usually expect. | |
818 | ||
819 | @kindex C-M-x @r{(Lisp mode)} | |
820 | @findex lisp-eval-defun | |
821 | When you edit a function in a Lisp program you are running, the easiest | |
822 | way to send the changed definition to the inferior Lisp process is the key | |
823 | @kbd{C-M-x}. In Lisp mode, this runs the function @code{lisp-eval-defun}, | |
824 | which finds the defun around or following point and sends it as input to | |
825 | the Lisp process. (Emacs can send input to any inferior process regardless | |
826 | of what buffer is current.) | |
827 | ||
828 | Contrast the meanings of @kbd{C-M-x} in Lisp mode (for editing programs | |
829 | to be run in another Lisp system) and Emacs-Lisp mode (for editing Lisp | |
830 | programs to be run in Emacs): in both modes it has the effect of installing | |
831 | the function definition that point is in, but the way of doing so is | |
832 | different according to where the relevant Lisp environment is found. | |
833 | @xref{Executing Lisp}. |