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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
b3b044f2 | 3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001 |
177c0ea7 | 4 | @c Free Software Foundation, Inc. |
3e01fd9d RS |
5 | @c See the file elisp.texi for copying conditions. |
6 | @setfilename ../info/minibuf | |
3e099569 | 7 | @node Minibuffers, Command Loop, Read and Print, Top |
3e01fd9d RS |
8 | @chapter Minibuffers |
9 | @cindex arguments, reading | |
10 | @cindex complex arguments | |
11 | @cindex minibuffer | |
12 | ||
13 | A @dfn{minibuffer} is a special buffer that Emacs commands use to read | |
14 | arguments more complicated than the single numeric prefix argument. | |
15 | These arguments include file names, buffer names, and command names (as | |
16 | in @kbd{M-x}). The minibuffer is displayed on the bottom line of the | |
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17 | frame, in the same place as the echo area, but only while it is in use |
18 | for reading an argument. | |
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19 | |
20 | @menu | |
21 | * Intro to Minibuffers:: Basic information about minibuffers. | |
22 | * Text from Minibuffer:: How to read a straight text string. | |
23 | * Object from Minibuffer:: How to read a Lisp object or expression. | |
24 | * Minibuffer History:: Recording previous minibuffer inputs | |
25 | so the user can reuse them. | |
26 | * Completion:: How to invoke and customize completion. | |
27 | * Yes-or-No Queries:: Asking a question with a simple answer. | |
28 | * Multiple Queries:: Asking a series of similar questions. | |
e75ecfec | 29 | * Reading a Password:: Reading a password from the terminal. |
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30 | * Minibuffer Misc:: Various customization hooks and variables. |
31 | @end menu | |
32 | ||
33 | @node Intro to Minibuffers | |
34 | @section Introduction to Minibuffers | |
35 | ||
36 | In most ways, a minibuffer is a normal Emacs buffer. Most operations | |
37 | @emph{within} a buffer, such as editing commands, work normally in a | |
38 | minibuffer. However, many operations for managing buffers do not apply | |
39 | to minibuffers. The name of a minibuffer always has the form @w{@samp{ | |
56bd69df | 40 | *Minibuf-@var{number}*}}, and it cannot be changed. Minibuffers are |
3e01fd9d | 41 | displayed only in special windows used only for minibuffers; these |
1911e6e5 | 42 | windows always appear at the bottom of a frame. (Sometimes frames have |
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43 | no minibuffer window, and sometimes a special kind of frame contains |
44 | nothing but a minibuffer window; see @ref{Minibuffers and Frames}.) | |
45 | ||
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46 | The text in the minibuffer always starts with the @dfn{prompt string}, |
47 | the text that was specified by the program that is using the minibuffer | |
48 | to tell the user what sort of input to type. This text is marked | |
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49 | read-only so you won't accidentally delete or change it. It is also |
50 | marked as a field (@pxref{Fields}), so that certain motion functions, | |
51 | including @code{beginning-of-line}, @code{forward-word}, | |
52 | @code{forward-sentence}, and @code{forward-paragraph}, stop at the | |
53 | boundary between the prompt and the actual text. (In older Emacs | |
54 | versions, the prompt was displayed using a special mechanism and was not | |
55 | part of the buffer contents.) | |
56 | ||
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57 | The minibuffer's window is normally a single line; it grows |
58 | automatically if necessary if the contents require more space. You can | |
59 | explicitly resize it temporarily with the window sizing commands; it | |
60 | reverts to its normal size when the minibuffer is exited. You can | |
61 | resize it permanently by using the window sizing commands in the frame's | |
62 | other window, when the minibuffer is not active. If the frame contains | |
63 | just a minibuffer, you can change the minibuffer's size by changing the | |
64 | frame's size. | |
3e01fd9d | 65 | |
f460db36 RS |
66 | Use of the minibuffer reads input events, and that alters the values |
67 | of variables such as @code{this-command} and @code{last-command} | |
68 | (@pxref{Command Loop Info}). Your program should bind them around the | |
69 | code that uses the minibuffer, if you do not want that to change them. | |
70 | ||
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71 | If a command uses a minibuffer while there is an active minibuffer, |
72 | this is called a @dfn{recursive minibuffer}. The first minibuffer is | |
73 | named @w{@samp{ *Minibuf-0*}}. Recursive minibuffers are named by | |
74 | incrementing the number at the end of the name. (The names begin with a | |
75 | space so that they won't show up in normal buffer lists.) Of several | |
76 | recursive minibuffers, the innermost (or most recently entered) is the | |
77 | active minibuffer. We usually call this ``the'' minibuffer. You can | |
78 | permit or forbid recursive minibuffers by setting the variable | |
79 | @code{enable-recursive-minibuffers} or by putting properties of that | |
80 | name on command symbols (@pxref{Minibuffer Misc}). | |
81 | ||
82 | Like other buffers, a minibuffer may use any of several local keymaps | |
83 | (@pxref{Keymaps}); these contain various exit commands and in some cases | |
bfe721d1 | 84 | completion commands (@pxref{Completion}). |
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85 | |
86 | @itemize @bullet | |
87 | @item | |
88 | @code{minibuffer-local-map} is for ordinary input (no completion). | |
89 | ||
90 | @item | |
91 | @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits | |
4ff1926e | 92 | just like @key{RET}. |
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93 | |
94 | @item | |
95 | @code{minibuffer-local-completion-map} is for permissive completion. | |
96 | ||
97 | @item | |
98 | @code{minibuffer-local-must-match-map} is for strict completion and | |
99 | for cautious completion. | |
100 | @end itemize | |
101 | ||
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102 | When Emacs is running in batch mode, any request to read from the |
103 | minibuffer actually reads a line from the standard input descriptor that | |
104 | was supplied when Emacs was started. | |
105 | ||
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106 | @node Text from Minibuffer |
107 | @section Reading Text Strings with the Minibuffer | |
108 | ||
793da230 RS |
109 | Most often, the minibuffer is used to read text as a string. It can |
110 | also be used to read a Lisp object in textual form. The most basic | |
111 | primitive for minibuffer input is @code{read-from-minibuffer}; it can do | |
112 | either one. | |
3e01fd9d | 113 | |
bfe721d1 KH |
114 | In most cases, you should not call minibuffer input functions in the |
115 | middle of a Lisp function. Instead, do all minibuffer input as part of | |
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116 | reading the arguments for a command, in the @code{interactive} |
117 | specification. @xref{Defining Commands}. | |
bfe721d1 | 118 | |
f9f59935 | 119 | @defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method |
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120 | This function is the most general way to get input through the |
121 | minibuffer. By default, it accepts arbitrary text and returns it as a | |
122 | string; however, if @var{read} is non-@code{nil}, then it uses | |
123 | @code{read} to convert the text into a Lisp object (@pxref{Input | |
124 | Functions}). | |
125 | ||
969fe9b5 | 126 | The first thing this function does is to activate a minibuffer and |
3e01fd9d | 127 | display it with @var{prompt-string} as the prompt. This value must be a |
969fe9b5 | 128 | string. Then the user can edit text in the minibuffer. |
3e01fd9d | 129 | |
969fe9b5 RS |
130 | When the user types a command to exit the minibuffer, |
131 | @code{read-from-minibuffer} constructs the return value from the text in | |
132 | the minibuffer. Normally it returns a string containing that text. | |
133 | However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer} | |
134 | reads the text and returns the resulting Lisp object, unevaluated. | |
135 | (@xref{Input Functions}, for information about reading.) | |
f9f59935 | 136 | |
969fe9b5 RS |
137 | The argument @var{default} specifies a default value to make available |
138 | through the history commands. It should be a string, or @code{nil}. If | |
139 | @var{read} is non-@code{nil}, then @var{default} is also used as the | |
140 | input to @code{read}, if the user enters empty input. However, in the | |
a9f0a989 | 141 | usual case (where @var{read} is @code{nil}), @code{read-from-minibuffer} |
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142 | does not return @var{default} when the user enters empty input; it |
143 | returns an empty string, @code{""}. In this respect, it is different | |
144 | from all the other minibuffer input functions in this chapter. | |
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145 | |
146 | If @var{keymap} is non-@code{nil}, that keymap is the local keymap to | |
147 | use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the | |
148 | value of @code{minibuffer-local-map} is used as the keymap. Specifying | |
149 | a keymap is the most important way to customize the minibuffer for | |
150 | various applications such as completion. | |
151 | ||
152 | The argument @var{hist} specifies which history list variable to use | |
153 | for saving the input and for history commands used in the minibuffer. | |
154 | It defaults to @code{minibuffer-history}. @xref{Minibuffer History}. | |
155 | ||
f9f59935 RS |
156 | If the variable @code{minibuffer-allow-text-properties} is |
157 | non-@code{nil}, then the string which is returned includes whatever text | |
158 | properties were present in the minibuffer. Otherwise all the text | |
159 | properties are stripped when the value is returned. | |
160 | ||
f9f59935 | 161 | If the argument @var{inherit-input-method} is non-@code{nil}, then the |
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162 | minibuffer inherits the current input method (@pxref{Input Methods}) and |
163 | the setting of @code{enable-multibyte-characters} (@pxref{Text | |
164 | Representations}) from whichever buffer was current before entering the | |
165 | minibuffer. | |
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166 | |
167 | If @var{initial-contents} is a string, @code{read-from-minibuffer} | |
168 | inserts it into the minibuffer, leaving point at the end, before the | |
169 | user starts to edit the text. The minibuffer appears with this text as | |
170 | its initial contents. | |
171 | ||
172 | Alternatively, @var{initial-contents} can be a cons cell of the form | |
173 | @code{(@var{string} . @var{position})}. This means to insert | |
174 | @var{string} in the minibuffer but put point @var{position} characters | |
175 | from the beginning, rather than at the end. | |
176 | ||
177 | @strong{Usage note:} The @var{initial-contents} argument and the | |
178 | @var{default} argument are two alternative features for more or less the | |
179 | same job. It does not make sense to use both features in a single call | |
180 | to @code{read-from-minibuffer}. In general, we recommend using | |
181 | @var{default}, since this permits the user to insert the default value | |
182 | when it is wanted, but does not burden the user with deleting it from | |
183 | the minibuffer on other occasions. | |
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184 | @end defun |
185 | ||
f9f59935 | 186 | @defun read-string prompt &optional initial history default inherit-input-method |
3e01fd9d RS |
187 | This function reads a string from the minibuffer and returns it. The |
188 | arguments @var{prompt} and @var{initial} are used as in | |
189 | @code{read-from-minibuffer}. The keymap used is | |
190 | @code{minibuffer-local-map}. | |
191 | ||
6fe50867 RS |
192 | The optional argument @var{history}, if non-@code{nil}, specifies a |
193 | history list and optionally the initial position in the list. The | |
194 | optional argument @var{default} specifies a default value to return if | |
195 | the user enters null input; it should be a string. The optional | |
196 | argument @var{inherit-input-method} specifies whether to inherit the | |
197 | current buffer's input method. | |
f9f59935 RS |
198 | |
199 | This function is a simplified interface to the | |
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200 | @code{read-from-minibuffer} function: |
201 | ||
202 | @smallexample | |
203 | @group | |
f9f59935 | 204 | (read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit}) |
3e01fd9d | 205 | @equiv{} |
969fe9b5 RS |
206 | (let ((value |
207 | (read-from-minibuffer @var{prompt} @var{initial} nil nil | |
208 | @var{history} @var{default} @var{inherit}))) | |
209 | (if (equal value "") | |
210 | @var{default} | |
211 | value)) | |
3e01fd9d RS |
212 | @end group |
213 | @end smallexample | |
214 | @end defun | |
215 | ||
f9f59935 | 216 | @defvar minibuffer-allow-text-properties |
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217 | If this variable is @code{nil}, then @code{read-from-minibuffer} strips |
218 | all text properties from the minibuffer input before returning it. | |
f9f59935 RS |
219 | Since all minibuffer input uses @code{read-from-minibuffer}, this |
220 | variable applies to all minibuffer input. | |
1911e6e5 RS |
221 | |
222 | Note that the completion functions discard text properties unconditionally, | |
223 | regardless of the value of this variable. | |
f9f59935 RS |
224 | @end defvar |
225 | ||
3e01fd9d RS |
226 | @defvar minibuffer-local-map |
227 | This is the default local keymap for reading from the minibuffer. By | |
228 | default, it makes the following bindings: | |
229 | ||
230 | @table @asis | |
969fe9b5 | 231 | @item @kbd{C-j} |
3e01fd9d RS |
232 | @code{exit-minibuffer} |
233 | ||
234 | @item @key{RET} | |
235 | @code{exit-minibuffer} | |
236 | ||
237 | @item @kbd{C-g} | |
238 | @code{abort-recursive-edit} | |
239 | ||
240 | @item @kbd{M-n} | |
241 | @code{next-history-element} | |
242 | ||
243 | @item @kbd{M-p} | |
244 | @code{previous-history-element} | |
245 | ||
246 | @item @kbd{M-r} | |
247 | @code{next-matching-history-element} | |
248 | ||
249 | @item @kbd{M-s} | |
250 | @code{previous-matching-history-element} | |
251 | @end table | |
252 | @end defvar | |
253 | ||
254 | @c In version 18, initial is required | |
255 | @c Emacs 19 feature | |
f9f59935 | 256 | @defun read-no-blanks-input prompt &optional initial inherit-input-method |
3e01fd9d RS |
257 | This function reads a string from the minibuffer, but does not allow |
258 | whitespace characters as part of the input: instead, those characters | |
f9f59935 RS |
259 | terminate the input. The arguments @var{prompt}, @var{initial}, and |
260 | @var{inherit-input-method} are used as in @code{read-from-minibuffer}. | |
3e01fd9d RS |
261 | |
262 | This is a simplified interface to the @code{read-from-minibuffer} | |
263 | function, and passes the value of the @code{minibuffer-local-ns-map} | |
264 | keymap as the @var{keymap} argument for that function. Since the keymap | |
265 | @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is} | |
266 | possible to put a space into the string, by quoting it. | |
267 | ||
268 | @smallexample | |
269 | @group | |
270 | (read-no-blanks-input @var{prompt} @var{initial}) | |
271 | @equiv{} | |
272 | (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map) | |
273 | @end group | |
274 | @end smallexample | |
275 | @end defun | |
276 | ||
277 | @defvar minibuffer-local-ns-map | |
278 | This built-in variable is the keymap used as the minibuffer local keymap | |
279 | in the function @code{read-no-blanks-input}. By default, it makes the | |
bfe721d1 | 280 | following bindings, in addition to those of @code{minibuffer-local-map}: |
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281 | |
282 | @table @asis | |
3e01fd9d RS |
283 | @item @key{SPC} |
284 | @cindex @key{SPC} in minibuffer | |
285 | @code{exit-minibuffer} | |
286 | ||
287 | @item @key{TAB} | |
288 | @cindex @key{TAB} in minibuffer | |
289 | @code{exit-minibuffer} | |
290 | ||
3e01fd9d RS |
291 | @item @kbd{?} |
292 | @cindex @kbd{?} in minibuffer | |
293 | @code{self-insert-and-exit} | |
3e01fd9d RS |
294 | @end table |
295 | @end defvar | |
296 | ||
297 | @node Object from Minibuffer | |
298 | @section Reading Lisp Objects with the Minibuffer | |
299 | ||
300 | This section describes functions for reading Lisp objects with the | |
301 | minibuffer. | |
302 | ||
303 | @defun read-minibuffer prompt &optional initial | |
f9f59935 | 304 | This function reads a Lisp object using the minibuffer, and returns it |
3e01fd9d | 305 | without evaluating it. The arguments @var{prompt} and @var{initial} are |
793da230 | 306 | used as in @code{read-from-minibuffer}. |
3e01fd9d | 307 | |
793da230 | 308 | This is a simplified interface to the |
3e01fd9d RS |
309 | @code{read-from-minibuffer} function: |
310 | ||
311 | @smallexample | |
312 | @group | |
313 | (read-minibuffer @var{prompt} @var{initial}) | |
314 | @equiv{} | |
315 | (read-from-minibuffer @var{prompt} @var{initial} nil t) | |
316 | @end group | |
317 | @end smallexample | |
318 | ||
319 | Here is an example in which we supply the string @code{"(testing)"} as | |
320 | initial input: | |
321 | ||
322 | @smallexample | |
323 | @group | |
324 | (read-minibuffer | |
325 | "Enter an expression: " (format "%s" '(testing))) | |
326 | ||
327 | ;; @r{Here is how the minibuffer is displayed:} | |
328 | @end group | |
329 | ||
330 | @group | |
331 | ---------- Buffer: Minibuffer ---------- | |
332 | Enter an expression: (testing)@point{} | |
333 | ---------- Buffer: Minibuffer ---------- | |
334 | @end group | |
335 | @end smallexample | |
336 | ||
337 | @noindent | |
338 | The user can type @key{RET} immediately to use the initial input as a | |
339 | default, or can edit the input. | |
340 | @end defun | |
341 | ||
342 | @defun eval-minibuffer prompt &optional initial | |
f9f59935 RS |
343 | This function reads a Lisp expression using the minibuffer, evaluates |
344 | it, then returns the result. The arguments @var{prompt} and | |
345 | @var{initial} are used as in @code{read-from-minibuffer}. | |
3e01fd9d | 346 | |
793da230 | 347 | This function simply evaluates the result of a call to |
3e01fd9d RS |
348 | @code{read-minibuffer}: |
349 | ||
350 | @smallexample | |
351 | @group | |
352 | (eval-minibuffer @var{prompt} @var{initial}) | |
353 | @equiv{} | |
354 | (eval (read-minibuffer @var{prompt} @var{initial})) | |
355 | @end group | |
356 | @end smallexample | |
357 | @end defun | |
358 | ||
359 | @defun edit-and-eval-command prompt form | |
793da230 | 360 | This function reads a Lisp expression in the minibuffer, and then |
3e01fd9d RS |
361 | evaluates it. The difference between this command and |
362 | @code{eval-minibuffer} is that here the initial @var{form} is not | |
363 | optional and it is treated as a Lisp object to be converted to printed | |
364 | representation rather than as a string of text. It is printed with | |
365 | @code{prin1}, so if it is a string, double-quote characters (@samp{"}) | |
366 | appear in the initial text. @xref{Output Functions}. | |
367 | ||
793da230 | 368 | The first thing @code{edit-and-eval-command} does is to activate the |
3e01fd9d | 369 | minibuffer with @var{prompt} as the prompt. Then it inserts the printed |
f9f59935 | 370 | representation of @var{form} in the minibuffer, and lets the user edit it. |
3e01fd9d RS |
371 | When the user exits the minibuffer, the edited text is read with |
372 | @code{read} and then evaluated. The resulting value becomes the value | |
373 | of @code{edit-and-eval-command}. | |
374 | ||
793da230 | 375 | In the following example, we offer the user an expression with initial |
3e01fd9d RS |
376 | text which is a valid form already: |
377 | ||
378 | @smallexample | |
379 | @group | |
380 | (edit-and-eval-command "Please edit: " '(forward-word 1)) | |
381 | ||
177c0ea7 | 382 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
383 | ;; @r{the following appears in the minibuffer:} |
384 | @end group | |
385 | ||
386 | @group | |
387 | ---------- Buffer: Minibuffer ---------- | |
388 | Please edit: (forward-word 1)@point{} | |
389 | ---------- Buffer: Minibuffer ---------- | |
390 | @end group | |
391 | @end smallexample | |
392 | ||
393 | @noindent | |
394 | Typing @key{RET} right away would exit the minibuffer and evaluate the | |
395 | expression, thus moving point forward one word. | |
396 | @code{edit-and-eval-command} returns @code{nil} in this example. | |
397 | @end defun | |
398 | ||
399 | @node Minibuffer History | |
400 | @section Minibuffer History | |
401 | @cindex minibuffer history | |
402 | @cindex history list | |
403 | ||
969fe9b5 | 404 | A @dfn{minibuffer history list} records previous minibuffer inputs so |
793da230 RS |
405 | the user can reuse them conveniently. A history list is actually a |
406 | symbol, not a list; it is a variable whose value is a list of strings | |
407 | (previous inputs), most recent first. | |
3e01fd9d | 408 | |
969fe9b5 | 409 | There are many separate history lists, used for different kinds of |
3e01fd9d RS |
410 | inputs. It's the Lisp programmer's job to specify the right history |
411 | list for each use of the minibuffer. | |
412 | ||
969fe9b5 | 413 | The basic minibuffer input functions @code{read-from-minibuffer} and |
3e01fd9d RS |
414 | @code{completing-read} both accept an optional argument named @var{hist} |
415 | which is how you specify the history list. Here are the possible | |
416 | values: | |
417 | ||
418 | @table @asis | |
419 | @item @var{variable} | |
420 | Use @var{variable} (a symbol) as the history list. | |
421 | ||
422 | @item (@var{variable} . @var{startpos}) | |
423 | Use @var{variable} (a symbol) as the history list, and assume that the | |
424 | initial history position is @var{startpos} (an integer, counting from | |
425 | zero which specifies the most recent element of the history). | |
426 | ||
427 | If you specify @var{startpos}, then you should also specify that element | |
428 | of the history as the initial minibuffer contents, for consistency. | |
429 | @end table | |
430 | ||
969fe9b5 | 431 | If you don't specify @var{hist}, then the default history list |
3e01fd9d RS |
432 | @code{minibuffer-history} is used. For other standard history lists, |
433 | see below. You can also create your own history list variable; just | |
434 | initialize it to @code{nil} before the first use. | |
435 | ||
969fe9b5 | 436 | Both @code{read-from-minibuffer} and @code{completing-read} add new |
3e01fd9d RS |
437 | elements to the history list automatically, and provide commands to |
438 | allow the user to reuse items on the list. The only thing your program | |
439 | needs to do to use a history list is to initialize it and to pass its | |
440 | name to the input functions when you wish. But it is safe to modify the | |
441 | list by hand when the minibuffer input functions are not using it. | |
442 | ||
ff306b60 RS |
443 | Emacs functions that add a new element to a history list can also |
444 | delete old elements if the list gets too long. The variable | |
445 | @code{history-length} specifies the maximum length for most history | |
446 | lists. To specify a different maximum length for a particular history | |
447 | list, put the length in the @code{history-length} property of the | |
448 | history list symbol. | |
449 | ||
450 | @defvar history-length | |
451 | The value of this variable specifies the maximum length for all | |
452 | history lists that don't specify their own maximum lengths. If the | |
453 | value is @code{t}, that means there no maximum (don't delete old | |
454 | elements). | |
455 | @end defvar | |
456 | ||
969fe9b5 RS |
457 | Here are some of the standard minibuffer history list variables: |
458 | ||
3e01fd9d RS |
459 | @defvar minibuffer-history |
460 | The default history list for minibuffer history input. | |
461 | @end defvar | |
462 | ||
463 | @defvar query-replace-history | |
464 | A history list for arguments to @code{query-replace} (and similar | |
465 | arguments to other commands). | |
466 | @end defvar | |
467 | ||
468 | @defvar file-name-history | |
a9f0a989 RS |
469 | A history list for file-name arguments. |
470 | @end defvar | |
471 | ||
472 | @defvar buffer-name-history | |
a9f0a989 | 473 | A history list for buffer-name arguments. |
3e01fd9d RS |
474 | @end defvar |
475 | ||
476 | @defvar regexp-history | |
477 | A history list for regular expression arguments. | |
478 | @end defvar | |
479 | ||
480 | @defvar extended-command-history | |
481 | A history list for arguments that are names of extended commands. | |
482 | @end defvar | |
483 | ||
484 | @defvar shell-command-history | |
485 | A history list for arguments that are shell commands. | |
486 | @end defvar | |
487 | ||
488 | @defvar read-expression-history | |
489 | A history list for arguments that are Lisp expressions to evaluate. | |
490 | @end defvar | |
491 | ||
492 | @node Completion | |
493 | @section Completion | |
494 | @cindex completion | |
495 | ||
496 | @dfn{Completion} is a feature that fills in the rest of a name | |
497 | starting from an abbreviation for it. Completion works by comparing the | |
498 | user's input against a list of valid names and determining how much of | |
499 | the name is determined uniquely by what the user has typed. For | |
500 | example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then | |
501 | type the first few letters of the name of the buffer to which you wish | |
502 | to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs | |
503 | extends the name as far as it can. | |
504 | ||
505 | Standard Emacs commands offer completion for names of symbols, files, | |
506 | buffers, and processes; with the functions in this section, you can | |
507 | implement completion for other kinds of names. | |
508 | ||
509 | The @code{try-completion} function is the basic primitive for | |
510 | completion: it returns the longest determined completion of a given | |
511 | initial string, with a given set of strings to match against. | |
512 | ||
513 | The function @code{completing-read} provides a higher-level interface | |
514 | for completion. A call to @code{completing-read} specifies how to | |
515 | determine the list of valid names. The function then activates the | |
516 | minibuffer with a local keymap that binds a few keys to commands useful | |
517 | for completion. Other functions provide convenient simple interfaces | |
518 | for reading certain kinds of names with completion. | |
519 | ||
520 | @menu | |
521 | * Basic Completion:: Low-level functions for completing strings. | |
522 | (These are too low level to use the minibuffer.) | |
523 | * Minibuffer Completion:: Invoking the minibuffer with completion. | |
524 | * Completion Commands:: Minibuffer commands that do completion. | |
525 | * High-Level Completion:: Convenient special cases of completion | |
526 | (reading buffer name, file name, etc.) | |
527 | * Reading File Names:: Using completion to read file names. | |
4ff1926e | 528 | * Programmed Completion:: Writing your own completion-function. |
3e01fd9d RS |
529 | @end menu |
530 | ||
531 | @node Basic Completion | |
532 | @subsection Basic Completion Functions | |
533 | ||
7370e0a8 RS |
534 | The functions @code{try-completion}, @code{all-completions} and |
535 | @code{test-completion} have nothing in themselves to do with | |
536 | minibuffers. We describe them in this chapter so as to keep them near | |
537 | the higher-level completion features that do use the minibuffer. | |
793da230 | 538 | |
3e01fd9d RS |
539 | @defun try-completion string collection &optional predicate |
540 | This function returns the longest common substring of all possible | |
541 | completions of @var{string} in @var{collection}. The value of | |
7370e0a8 RS |
542 | @var{collection} must be a list of strings, an alist, an obarray, or a |
543 | function that implements a virtual set of strings (see below). | |
3e01fd9d RS |
544 | |
545 | Completion compares @var{string} against each of the permissible | |
546 | completions specified by @var{collection}; if the beginning of the | |
547 | permissible completion equals @var{string}, it matches. If no permissible | |
548 | completions match, @code{try-completion} returns @code{nil}. If only | |
549 | one permissible completion matches, and the match is exact, then | |
550 | @code{try-completion} returns @code{t}. Otherwise, the value is the | |
551 | longest initial sequence common to all the permissible completions that | |
552 | match. | |
553 | ||
554 | If @var{collection} is an alist (@pxref{Association Lists}), the | |
555 | @sc{car}s of the alist elements form the set of permissible completions. | |
556 | ||
557 | @cindex obarray in completion | |
558 | If @var{collection} is an obarray (@pxref{Creating Symbols}), the names | |
559 | of all symbols in the obarray form the set of permissible completions. The | |
560 | global variable @code{obarray} holds an obarray containing the names of | |
561 | all interned Lisp symbols. | |
562 | ||
563 | Note that the only valid way to make a new obarray is to create it | |
564 | empty and then add symbols to it one by one using @code{intern}. | |
565 | Also, you cannot intern a given symbol in more than one obarray. | |
566 | ||
793da230 RS |
567 | You can also use a symbol that is a function as @var{collection}. Then |
568 | the function is solely responsible for performing completion; | |
3e01fd9d RS |
569 | @code{try-completion} returns whatever this function returns. The |
570 | function is called with three arguments: @var{string}, @var{predicate} | |
571 | and @code{nil}. (The reason for the third argument is so that the same | |
572 | function can be used in @code{all-completions} and do the appropriate | |
573 | thing in either case.) @xref{Programmed Completion}. | |
574 | ||
7370e0a8 RS |
575 | If the argument @var{predicate} is non-@code{nil}, then it must be a |
576 | function of one argument. It is used to test each possible match, and | |
577 | the match is accepted only if @var{predicate} returns non-@code{nil}. | |
578 | The argument given to @var{predicate} is either a string from the | |
579 | list, a cons cell from the alist (the @sc{car} of which is a string) | |
580 | or a symbol (@emph{not} a symbol name) from the obarray. | |
581 | ||
3e01fd9d RS |
582 | In the first of the following examples, the string @samp{foo} is |
583 | matched by three of the alist @sc{car}s. All of the matches begin with | |
584 | the characters @samp{fooba}, so that is the result. In the second | |
585 | example, there is only one possible match, and it is exact, so the value | |
586 | is @code{t}. | |
587 | ||
588 | @smallexample | |
589 | @group | |
177c0ea7 | 590 | (try-completion |
3e01fd9d RS |
591 | "foo" |
592 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))) | |
593 | @result{} "fooba" | |
594 | @end group | |
595 | ||
596 | @group | |
597 | (try-completion "foo" '(("barfoo" 2) ("foo" 3))) | |
598 | @result{} t | |
599 | @end group | |
600 | @end smallexample | |
601 | ||
602 | In the following example, numerous symbols begin with the characters | |
603 | @samp{forw}, and all of them begin with the word @samp{forward}. In | |
604 | most of the symbols, this is followed with a @samp{-}, but not in all, | |
605 | so no more than @samp{forward} can be completed. | |
606 | ||
607 | @smallexample | |
608 | @group | |
609 | (try-completion "forw" obarray) | |
610 | @result{} "forward" | |
611 | @end group | |
612 | @end smallexample | |
613 | ||
614 | Finally, in the following example, only two of the three possible | |
615 | matches pass the predicate @code{test} (the string @samp{foobaz} is | |
616 | too short). Both of those begin with the string @samp{foobar}. | |
617 | ||
618 | @smallexample | |
619 | @group | |
177c0ea7 | 620 | (defun test (s) |
3e01fd9d RS |
621 | (> (length (car s)) 6)) |
622 | @result{} test | |
623 | @end group | |
624 | @group | |
177c0ea7 | 625 | (try-completion |
3e01fd9d | 626 | "foo" |
177c0ea7 | 627 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) |
793da230 | 628 | 'test) |
3e01fd9d RS |
629 | @result{} "foobar" |
630 | @end group | |
631 | @end smallexample | |
632 | @end defun | |
633 | ||
22697dac | 634 | @defun all-completions string collection &optional predicate nospace |
3e01fd9d | 635 | This function returns a list of all possible completions of |
72821190 RS |
636 | @var{string}. The arguments to this function (aside from @var{nospace}) |
637 | are the same as those of @code{try-completion}. If @var{nospace} is | |
638 | non-@code{nil}, completions that start with a space are ignored unless | |
639 | @var{string} also starts with a space. | |
3e01fd9d RS |
640 | |
641 | If @var{collection} is a function, it is called with three arguments: | |
642 | @var{string}, @var{predicate} and @code{t}; then @code{all-completions} | |
643 | returns whatever the function returns. @xref{Programmed Completion}. | |
644 | ||
645 | Here is an example, using the function @code{test} shown in the | |
646 | example for @code{try-completion}: | |
647 | ||
648 | @smallexample | |
649 | @group | |
177c0ea7 | 650 | (defun test (s) |
3e01fd9d RS |
651 | (> (length (car s)) 6)) |
652 | @result{} test | |
653 | @end group | |
654 | ||
655 | @group | |
177c0ea7 | 656 | (all-completions |
3e01fd9d RS |
657 | "foo" |
658 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) | |
793da230 | 659 | 'test) |
3e01fd9d RS |
660 | @result{} ("foobar1" "foobar2") |
661 | @end group | |
662 | @end smallexample | |
663 | @end defun | |
664 | ||
7370e0a8 RS |
665 | @defun test-completion string collection &optional predicate |
666 | This function returns non-@code{nil} if @var{string} is a valid | |
667 | completion possibility specified by @var{collection} and | |
668 | @var{predicate}. The other arguments are the same as in | |
669 | @code{try-completion}. For instance, if @var{collection} is a list, | |
670 | this is true if @var{string} appears in the list and @var{predicate} | |
671 | is satisfied. | |
672 | ||
673 | If @var{collection} is a function, it is called with three arguments, | |
674 | the values @var{string}, @var{predicate} and @code{lambda}; whatever | |
675 | it returns, @code{test-completion} returns in turn. | |
676 | @end defun | |
677 | ||
3e01fd9d | 678 | @defvar completion-ignore-case |
7370e0a8 RS |
679 | If the value of this variable is non-@code{nil}, Emacs does not |
680 | consider case significant in completion. | |
3e01fd9d RS |
681 | @end defvar |
682 | ||
4ff1926e RS |
683 | @defmac lazy-completion-table var fun &rest args |
684 | This macro provides a way to initialize the variable @var{var} as a | |
7370e0a8 RS |
685 | collection for completion in a lazy way, not computing its actual |
686 | contents until they are first needed. You use this macro to produce a | |
687 | value that you store in @var{var}. The actual computation of the | |
688 | proper value is done the first time you do completion using @var{var}. | |
689 | It is done by calling @var{fun} with the arguments @var{args}. The | |
690 | value @var{fun} returns becomes the permanent value of @var{var}. | |
691 | ||
692 | Here are two examples of use: | |
4ff1926e RS |
693 | |
694 | @example | |
695 | (defvar foo (lazy-completion-table foo make-my-alist 'global)) | |
7370e0a8 | 696 | |
4ff1926e RS |
697 | (make-local-variable 'bar) |
698 | (setq bar (lazy-completion-table foo make-my-alist 'local) | |
699 | @end example | |
700 | @end defmac | |
701 | ||
3e01fd9d RS |
702 | @node Minibuffer Completion |
703 | @subsection Completion and the Minibuffer | |
704 | ||
705 | This section describes the basic interface for reading from the | |
706 | minibuffer with completion. | |
707 | ||
f9f59935 | 708 | @defun completing-read prompt collection &optional predicate require-match initial hist default inherit-input-method |
3e01fd9d RS |
709 | This function reads a string in the minibuffer, assisting the user by |
710 | providing completion. It activates the minibuffer with prompt | |
969fe9b5 | 711 | @var{prompt}, which must be a string. |
3e01fd9d RS |
712 | |
713 | The actual completion is done by passing @var{collection} and | |
714 | @var{predicate} to the function @code{try-completion}. This happens in | |
715 | certain commands bound in the local keymaps used for completion. | |
716 | ||
f9f59935 RS |
717 | If @var{require-match} is @code{nil}, the exit commands work regardless |
718 | of the input in the minibuffer. If @var{require-match} is @code{t}, the | |
719 | usual minibuffer exit commands won't exit unless the input completes to | |
720 | an element of @var{collection}. If @var{require-match} is neither | |
721 | @code{nil} nor @code{t}, then the exit commands won't exit unless the | |
722 | input already in the buffer matches an element of @var{collection}. | |
723 | ||
724 | However, empty input is always permitted, regardless of the value of | |
725 | @var{require-match}; in that case, @code{completing-read} returns | |
969fe9b5 RS |
726 | @var{default}. The value of @var{default} (if non-@code{nil}) is also |
727 | available to the user through the history commands. | |
3e01fd9d | 728 | |
ece23c27 | 729 | The user can exit with null input by typing @key{RET} with an empty |
6ecb21f1 RS |
730 | minibuffer. Then @code{completing-read} returns @code{""}. This is how |
731 | the user requests whatever default the command uses for the value being | |
732 | read. The user can return using @key{RET} in this way regardless of the | |
733 | value of @var{require-match}, and regardless of whether the empty string | |
734 | is included in @var{collection}. | |
ece23c27 | 735 | |
3e01fd9d RS |
736 | The function @code{completing-read} works by calling |
737 | @code{read-minibuffer}. It uses @code{minibuffer-local-completion-map} | |
738 | as the keymap if @var{require-match} is @code{nil}, and uses | |
739 | @code{minibuffer-local-must-match-map} if @var{require-match} is | |
793da230 | 740 | non-@code{nil}. @xref{Completion Commands}. |
3e01fd9d RS |
741 | |
742 | The argument @var{hist} specifies which history list variable to use for | |
743 | saving the input and for minibuffer history commands. It defaults to | |
744 | @code{minibuffer-history}. @xref{Minibuffer History}. | |
745 | ||
969fe9b5 RS |
746 | If @var{initial} is non-@code{nil}, @code{completing-read} inserts it |
747 | into the minibuffer as part of the input. Then it allows the user to | |
748 | edit the input, providing several commands to attempt completion. | |
749 | In most cases, we recommend using @var{default}, and not @var{initial}. | |
f9f59935 | 750 | |
70c750c0 RS |
751 | @strong{We discourage use of a non-@code{nil} value for |
752 | @var{initial}}, because it is an intrusive interface. The history | |
b9332010 RS |
753 | list feature (which did not exist when we introduced @var{initial}) |
754 | offers a far more convenient and general way for the user to get the | |
755 | default and edit it, and it is always available. | |
70c750c0 | 756 | |
f9f59935 | 757 | If the argument @var{inherit-input-method} is non-@code{nil}, then the |
1911e6e5 | 758 | minibuffer inherits the current input method (@pxref{Input |
a9f0a989 RS |
759 | Methods}) and the setting of @code{enable-multibyte-characters} |
760 | (@pxref{Text Representations}) from whichever buffer was current before | |
761 | entering the minibuffer. | |
f9f59935 | 762 | |
3e01fd9d RS |
763 | Completion ignores case when comparing the input against the possible |
764 | matches, if the built-in variable @code{completion-ignore-case} is | |
765 | non-@code{nil}. @xref{Basic Completion}. | |
766 | ||
767 | Here's an example of using @code{completing-read}: | |
768 | ||
769 | @smallexample | |
770 | @group | |
771 | (completing-read | |
772 | "Complete a foo: " | |
773 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) | |
774 | nil t "fo") | |
775 | @end group | |
776 | ||
777 | @group | |
177c0ea7 | 778 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
779 | ;; @r{the following appears in the minibuffer:} |
780 | ||
781 | ---------- Buffer: Minibuffer ---------- | |
782 | Complete a foo: fo@point{} | |
783 | ---------- Buffer: Minibuffer ---------- | |
784 | @end group | |
785 | @end smallexample | |
786 | ||
787 | @noindent | |
788 | If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}}, | |
789 | @code{completing-read} returns @code{barfoo}. | |
790 | ||
791 | The @code{completing-read} function binds three variables to pass | |
793da230 RS |
792 | information to the commands that actually do completion. These |
793 | variables are @code{minibuffer-completion-table}, | |
794 | @code{minibuffer-completion-predicate} and | |
795 | @code{minibuffer-completion-confirm}. For more information about them, | |
796 | see @ref{Completion Commands}. | |
3e01fd9d RS |
797 | @end defun |
798 | ||
799 | @node Completion Commands | |
8241495d | 800 | @subsection Minibuffer Commands that Do Completion |
3e01fd9d RS |
801 | |
802 | This section describes the keymaps, commands and user options used in | |
803 | the minibuffer to do completion. | |
804 | ||
805 | @defvar minibuffer-local-completion-map | |
793da230 | 806 | @code{completing-read} uses this value as the local keymap when an |
3e01fd9d RS |
807 | exact match of one of the completions is not required. By default, this |
808 | keymap makes the following bindings: | |
809 | ||
810 | @table @asis | |
811 | @item @kbd{?} | |
812 | @code{minibuffer-completion-help} | |
813 | ||
814 | @item @key{SPC} | |
815 | @code{minibuffer-complete-word} | |
816 | ||
817 | @item @key{TAB} | |
818 | @code{minibuffer-complete} | |
819 | @end table | |
820 | ||
821 | @noindent | |
793da230 RS |
822 | with other characters bound as in @code{minibuffer-local-map} |
823 | (@pxref{Text from Minibuffer}). | |
3e01fd9d RS |
824 | @end defvar |
825 | ||
826 | @defvar minibuffer-local-must-match-map | |
827 | @code{completing-read} uses this value as the local keymap when an | |
828 | exact match of one of the completions is required. Therefore, no keys | |
793da230 | 829 | are bound to @code{exit-minibuffer}, the command that exits the |
3e01fd9d RS |
830 | minibuffer unconditionally. By default, this keymap makes the following |
831 | bindings: | |
832 | ||
833 | @table @asis | |
834 | @item @kbd{?} | |
835 | @code{minibuffer-completion-help} | |
836 | ||
837 | @item @key{SPC} | |
838 | @code{minibuffer-complete-word} | |
839 | ||
840 | @item @key{TAB} | |
841 | @code{minibuffer-complete} | |
842 | ||
969fe9b5 | 843 | @item @kbd{C-j} |
3e01fd9d RS |
844 | @code{minibuffer-complete-and-exit} |
845 | ||
846 | @item @key{RET} | |
847 | @code{minibuffer-complete-and-exit} | |
848 | @end table | |
849 | ||
850 | @noindent | |
851 | with other characters bound as in @code{minibuffer-local-map}. | |
852 | @end defvar | |
853 | ||
854 | @defvar minibuffer-completion-table | |
855 | The value of this variable is the alist or obarray used for completion | |
856 | in the minibuffer. This is the global variable that contains what | |
857 | @code{completing-read} passes to @code{try-completion}. It is used by | |
858 | minibuffer completion commands such as @code{minibuffer-complete-word}. | |
859 | @end defvar | |
860 | ||
861 | @defvar minibuffer-completion-predicate | |
862 | This variable's value is the predicate that @code{completing-read} | |
863 | passes to @code{try-completion}. The variable is also used by the other | |
864 | minibuffer completion functions. | |
865 | @end defvar | |
866 | ||
867 | @deffn Command minibuffer-complete-word | |
868 | This function completes the minibuffer contents by at most a single | |
869 | word. Even if the minibuffer contents have only one completion, | |
870 | @code{minibuffer-complete-word} does not add any characters beyond the | |
871 | first character that is not a word constituent. @xref{Syntax Tables}. | |
872 | @end deffn | |
873 | ||
874 | @deffn Command minibuffer-complete | |
875 | This function completes the minibuffer contents as far as possible. | |
876 | @end deffn | |
877 | ||
878 | @deffn Command minibuffer-complete-and-exit | |
879 | This function completes the minibuffer contents, and exits if | |
880 | confirmation is not required, i.e., if | |
2770e862 | 881 | @code{minibuffer-completion-confirm} is @code{nil}. If confirmation |
793da230 RS |
882 | @emph{is} required, it is given by repeating this command |
883 | immediately---the command is programmed to work without confirmation | |
884 | when run twice in succession. | |
3e01fd9d RS |
885 | @end deffn |
886 | ||
887 | @defvar minibuffer-completion-confirm | |
888 | When the value of this variable is non-@code{nil}, Emacs asks for | |
889 | confirmation of a completion before exiting the minibuffer. The | |
890 | function @code{minibuffer-complete-and-exit} checks the value of this | |
891 | variable before it exits. | |
892 | @end defvar | |
893 | ||
894 | @deffn Command minibuffer-completion-help | |
895 | This function creates a list of the possible completions of the | |
896 | current minibuffer contents. It works by calling @code{all-completions} | |
897 | using the value of the variable @code{minibuffer-completion-table} as | |
898 | the @var{collection} argument, and the value of | |
899 | @code{minibuffer-completion-predicate} as the @var{predicate} argument. | |
900 | The list of completions is displayed as text in a buffer named | |
901 | @samp{*Completions*}. | |
902 | @end deffn | |
903 | ||
904 | @defun display-completion-list completions | |
905 | This function displays @var{completions} to the stream in | |
3e099569 | 906 | @code{standard-output}, usually a buffer. (@xref{Read and Print}, for more |
3e01fd9d RS |
907 | information about streams.) The argument @var{completions} is normally |
908 | a list of completions just returned by @code{all-completions}, but it | |
909 | does not have to be. Each element may be a symbol or a string, either | |
910 | of which is simply printed, or a list of two strings, which is printed | |
911 | as if the strings were concatenated. | |
912 | ||
913 | This function is called by @code{minibuffer-completion-help}. The | |
914 | most common way to use it is together with | |
915 | @code{with-output-to-temp-buffer}, like this: | |
916 | ||
917 | @example | |
918 | (with-output-to-temp-buffer "*Completions*" | |
919 | (display-completion-list | |
920 | (all-completions (buffer-string) my-alist))) | |
921 | @end example | |
922 | @end defun | |
923 | ||
924 | @defopt completion-auto-help | |
925 | If this variable is non-@code{nil}, the completion commands | |
926 | automatically display a list of possible completions whenever nothing | |
927 | can be completed because the next character is not uniquely determined. | |
928 | @end defopt | |
929 | ||
930 | @node High-Level Completion | |
931 | @subsection High-Level Completion Functions | |
932 | ||
933 | This section describes the higher-level convenient functions for | |
934 | reading certain sorts of names with completion. | |
935 | ||
bfe721d1 KH |
936 | In most cases, you should not call these functions in the middle of a |
937 | Lisp function. When possible, do all minibuffer input as part of | |
a9f0a989 RS |
938 | reading the arguments for a command, in the @code{interactive} |
939 | specification. @xref{Defining Commands}. | |
bfe721d1 | 940 | |
3e01fd9d RS |
941 | @defun read-buffer prompt &optional default existing |
942 | This function reads the name of a buffer and returns it as a string. | |
943 | The argument @var{default} is the default name to use, the value to | |
944 | return if the user exits with an empty minibuffer. If non-@code{nil}, | |
945 | it should be a string or a buffer. It is mentioned in the prompt, but | |
946 | is not inserted in the minibuffer as initial input. | |
947 | ||
948 | If @var{existing} is non-@code{nil}, then the name specified must be | |
793da230 RS |
949 | that of an existing buffer. The usual commands to exit the minibuffer |
950 | do not exit if the text is not valid, and @key{RET} does completion to | |
951 | attempt to find a valid name. (However, @var{default} is not checked | |
952 | for validity; it is returned, whatever it is, if the user exits with the | |
953 | minibuffer empty.) | |
3e01fd9d RS |
954 | |
955 | In the following example, the user enters @samp{minibuffer.t}, and | |
956 | then types @key{RET}. The argument @var{existing} is @code{t}, and the | |
957 | only buffer name starting with the given input is | |
958 | @samp{minibuffer.texi}, so that name is the value. | |
959 | ||
960 | @example | |
961 | (read-buffer "Buffer name? " "foo" t) | |
962 | @group | |
177c0ea7 | 963 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
964 | ;; @r{the following prompt appears,} |
965 | ;; @r{with an empty minibuffer:} | |
966 | @end group | |
967 | ||
968 | @group | |
969 | ---------- Buffer: Minibuffer ---------- | |
970 | Buffer name? (default foo) @point{} | |
971 | ---------- Buffer: Minibuffer ---------- | |
972 | @end group | |
973 | ||
974 | @group | |
975 | ;; @r{The user types @kbd{minibuffer.t @key{RET}}.} | |
976 | @result{} "minibuffer.texi" | |
977 | @end group | |
978 | @end example | |
979 | @end defun | |
980 | ||
f9f59935 RS |
981 | @defvar read-buffer-function |
982 | This variable specifies how to read buffer names. For example, if you | |
983 | set this variable to @code{iswitchb-read-buffer}, all Emacs commands | |
984 | that call @code{read-buffer} to read a buffer name will actually use the | |
985 | @code{iswitchb} package to read it. | |
986 | @end defvar | |
987 | ||
988 | @defun read-command prompt &optional default | |
3e01fd9d RS |
989 | This function reads the name of a command and returns it as a Lisp |
990 | symbol. The argument @var{prompt} is used as in | |
991 | @code{read-from-minibuffer}. Recall that a command is anything for | |
992 | which @code{commandp} returns @code{t}, and a command name is a symbol | |
993 | for which @code{commandp} returns @code{t}. @xref{Interactive Call}. | |
994 | ||
f9f59935 | 995 | The argument @var{default} specifies what to return if the user enters |
969fe9b5 RS |
996 | null input. It can be a symbol or a string; if it is a string, |
997 | @code{read-command} interns it before returning it. If @var{default} is | |
998 | @code{nil}, that means no default has been specified; then if the user | |
999 | enters null input, the return value is @code{nil}. | |
f9f59935 | 1000 | |
3e01fd9d RS |
1001 | @example |
1002 | (read-command "Command name? ") | |
1003 | ||
1004 | @group | |
177c0ea7 | 1005 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
1006 | ;; @r{the following prompt appears with an empty minibuffer:} |
1007 | @end group | |
1008 | ||
1009 | @group | |
177c0ea7 JB |
1010 | ---------- Buffer: Minibuffer ---------- |
1011 | Command name? | |
3e01fd9d RS |
1012 | ---------- Buffer: Minibuffer ---------- |
1013 | @end group | |
1014 | @end example | |
1015 | ||
1016 | @noindent | |
1017 | If the user types @kbd{forward-c @key{RET}}, then this function returns | |
1018 | @code{forward-char}. | |
1019 | ||
9e2b495b RS |
1020 | The @code{read-command} function is a simplified interface to |
1021 | @code{completing-read}. It uses the variable @code{obarray} so as to | |
1022 | complete in the set of extant Lisp symbols, and it uses the | |
3e01fd9d RS |
1023 | @code{commandp} predicate so as to accept only command names: |
1024 | ||
1025 | @cindex @code{commandp} example | |
1026 | @example | |
1027 | @group | |
1028 | (read-command @var{prompt}) | |
1029 | @equiv{} | |
177c0ea7 | 1030 | (intern (completing-read @var{prompt} obarray |
3e01fd9d RS |
1031 | 'commandp t nil)) |
1032 | @end group | |
1033 | @end example | |
1034 | @end defun | |
1035 | ||
f9f59935 | 1036 | @defun read-variable prompt &optional default |
3e01fd9d RS |
1037 | This function reads the name of a user variable and returns it as a |
1038 | symbol. | |
1039 | ||
f9f59935 | 1040 | The argument @var{default} specifies what to return if the user enters |
969fe9b5 RS |
1041 | null input. It can be a symbol or a string; if it is a string, |
1042 | @code{read-variable} interns it before returning it. If @var{default} | |
1043 | is @code{nil}, that means no default has been specified; then if the | |
1044 | user enters null input, the return value is @code{nil}. | |
f9f59935 | 1045 | |
3e01fd9d RS |
1046 | @example |
1047 | @group | |
1048 | (read-variable "Variable name? ") | |
1049 | ||
177c0ea7 JB |
1050 | ;; @r{After evaluation of the preceding expression,} |
1051 | ;; @r{the following prompt appears,} | |
3e01fd9d RS |
1052 | ;; @r{with an empty minibuffer:} |
1053 | @end group | |
1054 | ||
1055 | @group | |
1056 | ---------- Buffer: Minibuffer ---------- | |
1057 | Variable name? @point{} | |
1058 | ---------- Buffer: Minibuffer ---------- | |
1059 | @end group | |
1060 | @end example | |
1061 | ||
1062 | @noindent | |
1063 | If the user then types @kbd{fill-p @key{RET}}, @code{read-variable} | |
1064 | returns @code{fill-prefix}. | |
1065 | ||
1066 | This function is similar to @code{read-command}, but uses the | |
1067 | predicate @code{user-variable-p} instead of @code{commandp}: | |
1068 | ||
1069 | @cindex @code{user-variable-p} example | |
1070 | @example | |
1071 | @group | |
1072 | (read-variable @var{prompt}) | |
1073 | @equiv{} | |
1074 | (intern | |
1075 | (completing-read @var{prompt} obarray | |
1076 | 'user-variable-p t nil)) | |
1077 | @end group | |
1078 | @end example | |
1079 | @end defun | |
1080 | ||
969fe9b5 | 1081 | See also the functions @code{read-coding-system} and |
1911e6e5 | 1082 | @code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems}. |
f9f59935 | 1083 | |
3e01fd9d RS |
1084 | @node Reading File Names |
1085 | @subsection Reading File Names | |
1086 | ||
1087 | Here is another high-level completion function, designed for reading a | |
1088 | file name. It provides special features including automatic insertion | |
1089 | of the default directory. | |
1090 | ||
1c7cdff5 | 1091 | @defun read-file-name prompt &optional directory default existing initial predicate |
3e01fd9d RS |
1092 | This function reads a file name in the minibuffer, prompting with |
1093 | @var{prompt} and providing completion. If @var{default} is | |
1094 | non-@code{nil}, then the function returns @var{default} if the user just | |
793da230 RS |
1095 | types @key{RET}. @var{default} is not checked for validity; it is |
1096 | returned, whatever it is, if the user exits with the minibuffer empty. | |
3e01fd9d | 1097 | |
793da230 RS |
1098 | If @var{existing} is non-@code{nil}, then the user must specify the name |
1099 | of an existing file; @key{RET} performs completion to make the name | |
1100 | valid if possible, and then refuses to exit if it is not valid. If the | |
1101 | value of @var{existing} is neither @code{nil} nor @code{t}, then | |
1102 | @key{RET} also requires confirmation after completion. If | |
1103 | @var{existing} is @code{nil}, then the name of a nonexistent file is | |
1104 | acceptable. | |
3e01fd9d RS |
1105 | |
1106 | The argument @var{directory} specifies the directory to use for | |
793da230 RS |
1107 | completion of relative file names. If @code{insert-default-directory} |
1108 | is non-@code{nil}, @var{directory} is also inserted in the minibuffer as | |
1109 | initial input. It defaults to the current buffer's value of | |
1110 | @code{default-directory}. | |
3e01fd9d RS |
1111 | |
1112 | @c Emacs 19 feature | |
6142d1d0 RS |
1113 | If you specify @var{initial}, that is an initial file name to insert |
1114 | in the buffer (after @var{directory}, if that is inserted). In this | |
793da230 RS |
1115 | case, point goes at the beginning of @var{initial}. The default for |
1116 | @var{initial} is @code{nil}---don't insert any file name. To see what | |
6142d1d0 RS |
1117 | @var{initial} does, try the command @kbd{C-x C-v}. @strong{Please |
1118 | note:} we recommend using @var{default} rather than @var{initial} in | |
1119 | most cases. | |
3e01fd9d | 1120 | |
1c7cdff5 RS |
1121 | If @var{predicate} is non-@code{nil}, it specifies a function of one |
1122 | argument that decides which file names are acceptable completion | |
1123 | possibilities. A file name is an acceptable value if @var{predicate} | |
1124 | returns non-@code{nil} for it. | |
1125 | ||
177c0ea7 | 1126 | Here is an example: |
3e01fd9d RS |
1127 | |
1128 | @example | |
1129 | @group | |
1130 | (read-file-name "The file is ") | |
1131 | ||
177c0ea7 | 1132 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
1133 | ;; @r{the following appears in the minibuffer:} |
1134 | @end group | |
1135 | ||
1136 | @group | |
1137 | ---------- Buffer: Minibuffer ---------- | |
1138 | The file is /gp/gnu/elisp/@point{} | |
1139 | ---------- Buffer: Minibuffer ---------- | |
1140 | @end group | |
1141 | @end example | |
1142 | ||
1143 | @noindent | |
1144 | Typing @kbd{manual @key{TAB}} results in the following: | |
1145 | ||
1146 | @example | |
1147 | @group | |
1148 | ---------- Buffer: Minibuffer ---------- | |
1149 | The file is /gp/gnu/elisp/manual.texi@point{} | |
1150 | ---------- Buffer: Minibuffer ---------- | |
1151 | @end group | |
1152 | @end example | |
1153 | ||
1154 | @c Wordy to avoid overfull hbox in smallbook mode. | |
1155 | @noindent | |
1156 | If the user types @key{RET}, @code{read-file-name} returns the file name | |
1157 | as the string @code{"/gp/gnu/elisp/manual.texi"}. | |
1158 | @end defun | |
1159 | ||
1c7cdff5 RS |
1160 | @defun read-directory-name prompt &optional directory default existing initial |
1161 | This function is like @code{read-file-name} but allows only directory | |
1162 | names as completion possibilities. | |
1163 | @end defun | |
1164 | ||
3e01fd9d RS |
1165 | @defopt insert-default-directory |
1166 | This variable is used by @code{read-file-name}. Its value controls | |
1167 | whether @code{read-file-name} starts by placing the name of the default | |
1168 | directory in the minibuffer, plus the initial file name if any. If the | |
1169 | value of this variable is @code{nil}, then @code{read-file-name} does | |
bfe721d1 KH |
1170 | not place any initial input in the minibuffer (unless you specify |
1171 | initial input with the @var{initial} argument). In that case, the | |
3e01fd9d RS |
1172 | default directory is still used for completion of relative file names, |
1173 | but is not displayed. | |
1174 | ||
1175 | For example: | |
1176 | ||
1177 | @example | |
1178 | @group | |
1179 | ;; @r{Here the minibuffer starts out with the default directory.} | |
1180 | (let ((insert-default-directory t)) | |
1181 | (read-file-name "The file is ")) | |
1182 | @end group | |
1183 | ||
1184 | @group | |
1185 | ---------- Buffer: Minibuffer ---------- | |
1186 | The file is ~lewis/manual/@point{} | |
1187 | ---------- Buffer: Minibuffer ---------- | |
1188 | @end group | |
1189 | ||
1190 | @group | |
1191 | ;; @r{Here the minibuffer is empty and only the prompt} | |
1192 | ;; @r{appears on its line.} | |
1193 | (let ((insert-default-directory nil)) | |
1194 | (read-file-name "The file is ")) | |
1195 | @end group | |
1196 | ||
1197 | @group | |
1198 | ---------- Buffer: Minibuffer ---------- | |
1199 | The file is @point{} | |
1200 | ---------- Buffer: Minibuffer ---------- | |
1201 | @end group | |
1202 | @end example | |
1203 | @end defopt | |
1204 | ||
1205 | @node Programmed Completion | |
1206 | @subsection Programmed Completion | |
1207 | @cindex programmed completion | |
1208 | ||
1209 | Sometimes it is not possible to create an alist or an obarray | |
1210 | containing all the intended possible completions. In such a case, you | |
1211 | can supply your own function to compute the completion of a given string. | |
1212 | This is called @dfn{programmed completion}. | |
1213 | ||
1214 | To use this feature, pass a symbol with a function definition as the | |
793da230 RS |
1215 | @var{collection} argument to @code{completing-read}. The function |
1216 | @code{completing-read} arranges to pass your completion function along | |
1217 | to @code{try-completion} and @code{all-completions}, which will then let | |
1218 | your function do all the work. | |
3e01fd9d RS |
1219 | |
1220 | The completion function should accept three arguments: | |
1221 | ||
1222 | @itemize @bullet | |
1223 | @item | |
1224 | The string to be completed. | |
1225 | ||
1226 | @item | |
1227 | The predicate function to filter possible matches, or @code{nil} if | |
1228 | none. Your function should call the predicate for each possible match, | |
1229 | and ignore the possible match if the predicate returns @code{nil}. | |
1230 | ||
1231 | @item | |
1232 | A flag specifying the type of operation. | |
1233 | @end itemize | |
1234 | ||
1235 | There are three flag values for three operations: | |
1236 | ||
1237 | @itemize @bullet | |
1238 | @item | |
1239 | @code{nil} specifies @code{try-completion}. The completion function | |
1240 | should return the completion of the specified string, or @code{t} if the | |
d595eca0 RS |
1241 | string is a unique and exact match already, or @code{nil} if the string |
1242 | matches no possibility. | |
1243 | ||
1244 | If the string is an exact match for one possibility, but also matches | |
969fe9b5 | 1245 | other longer possibilities, the function should return the string, not |
d595eca0 | 1246 | @code{t}. |
3e01fd9d RS |
1247 | |
1248 | @item | |
1249 | @code{t} specifies @code{all-completions}. The completion function | |
1250 | should return a list of all possible completions of the specified | |
1251 | string. | |
1252 | ||
1253 | @item | |
7370e0a8 | 1254 | @code{lambda} specifies @code{test-completion}. The completion |
3e01fd9d RS |
1255 | function should return @code{t} if the specified string is an exact |
1256 | match for some possibility; @code{nil} otherwise. | |
1257 | @end itemize | |
1258 | ||
1259 | It would be consistent and clean for completion functions to allow | |
bfe721d1 | 1260 | lambda expressions (lists that are functions) as well as function |
3e01fd9d | 1261 | symbols as @var{collection}, but this is impossible. Lists as |
7370e0a8 RS |
1262 | completion tables already have other meanings, and it would be |
1263 | unreliable to treat one differently just because it is also a possible | |
1264 | function. So you must arrange for any function you wish to use for | |
1265 | completion to be encapsulated in a symbol. | |
3e01fd9d RS |
1266 | |
1267 | Emacs uses programmed completion when completing file names. | |
1268 | @xref{File Name Completion}. | |
1269 | ||
4ff1926e RS |
1270 | @defmac dynamic-completion-table function |
1271 | This macro is a convenient way to write a function that can act as | |
1272 | programmed completion function. The argument @var{function} should be | |
1273 | a function that takes one argument, a string, and returns an alist of | |
1274 | possible completions of it. You can think of | |
1275 | @code{dynamic-completion-table} as a transducer between that interface | |
1276 | and the interface for programmed completion functions. | |
1277 | @end defmac | |
1278 | ||
3e01fd9d RS |
1279 | @node Yes-or-No Queries |
1280 | @section Yes-or-No Queries | |
1281 | @cindex asking the user questions | |
1282 | @cindex querying the user | |
1283 | @cindex yes-or-no questions | |
1284 | ||
1285 | This section describes functions used to ask the user a yes-or-no | |
1286 | question. The function @code{y-or-n-p} can be answered with a single | |
1287 | character; it is useful for questions where an inadvertent wrong answer | |
1288 | will not have serious consequences. @code{yes-or-no-p} is suitable for | |
1289 | more momentous questions, since it requires three or four characters to | |
1290 | answer. | |
1291 | ||
3e099569 RS |
1292 | If either of these functions is called in a command that was invoked |
1293 | using the mouse---more precisely, if @code{last-nonmenu-event} | |
1294 | (@pxref{Command Loop Info}) is either @code{nil} or a list---then it | |
1295 | uses a dialog box or pop-up menu to ask the question. Otherwise, it | |
1296 | uses keyboard input. You can force use of the mouse or use of keyboard | |
1297 | input by binding @code{last-nonmenu-event} to a suitable value around | |
1298 | the call. | |
1299 | ||
3e01fd9d RS |
1300 | Strictly speaking, @code{yes-or-no-p} uses the minibuffer and |
1301 | @code{y-or-n-p} does not; but it seems best to describe them together. | |
1302 | ||
1303 | @defun y-or-n-p prompt | |
793da230 | 1304 | This function asks the user a question, expecting input in the echo |
3e01fd9d RS |
1305 | area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the |
1306 | user types @kbd{n}. This function also accepts @key{SPC} to mean yes | |
1307 | and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like | |
1308 | @kbd{C-g}, because the question might look like a minibuffer and for | |
1309 | that reason the user might try to use @kbd{C-]} to get out. The answer | |
1310 | is a single character, with no @key{RET} needed to terminate it. Upper | |
1311 | and lower case are equivalent. | |
1312 | ||
793da230 | 1313 | ``Asking the question'' means printing @var{prompt} in the echo area, |
3e01fd9d RS |
1314 | followed by the string @w{@samp{(y or n) }}. If the input is not one of |
1315 | the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}}, | |
1316 | @kbd{@key{DEL}}, or something that quits), the function responds | |
1317 | @samp{Please answer y or n.}, and repeats the request. | |
1318 | ||
793da230 | 1319 | This function does not actually use the minibuffer, since it does not |
3e01fd9d RS |
1320 | allow editing of the answer. It actually uses the echo area (@pxref{The |
1321 | Echo Area}), which uses the same screen space as the minibuffer. The | |
1322 | cursor moves to the echo area while the question is being asked. | |
1323 | ||
793da230 | 1324 | The answers and their meanings, even @samp{y} and @samp{n}, are not |
3e01fd9d RS |
1325 | hardwired. The keymap @code{query-replace-map} specifies them. |
1326 | @xref{Search and Replace}. | |
1327 | ||
793da230 | 1328 | In the following example, the user first types @kbd{q}, which is |
3e01fd9d RS |
1329 | invalid. At the next prompt the user types @kbd{y}. |
1330 | ||
1331 | @smallexample | |
1332 | @group | |
1333 | (y-or-n-p "Do you need a lift? ") | |
1334 | ||
177c0ea7 | 1335 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
1336 | ;; @r{the following prompt appears in the echo area:} |
1337 | @end group | |
1338 | ||
1339 | @group | |
1340 | ---------- Echo area ---------- | |
177c0ea7 | 1341 | Do you need a lift? (y or n) |
3e01fd9d RS |
1342 | ---------- Echo area ---------- |
1343 | @end group | |
1344 | ||
1345 | ;; @r{If the user then types @kbd{q}, the following appears:} | |
1346 | ||
1347 | @group | |
1348 | ---------- Echo area ---------- | |
177c0ea7 | 1349 | Please answer y or n. Do you need a lift? (y or n) |
3e01fd9d RS |
1350 | ---------- Echo area ---------- |
1351 | @end group | |
1352 | ||
1353 | ;; @r{When the user types a valid answer,} | |
1354 | ;; @r{it is displayed after the question:} | |
1355 | ||
1356 | @group | |
1357 | ---------- Echo area ---------- | |
1358 | Do you need a lift? (y or n) y | |
1359 | ---------- Echo area ---------- | |
1360 | @end group | |
1361 | @end smallexample | |
1362 | ||
1363 | @noindent | |
1364 | We show successive lines of echo area messages, but only one actually | |
1365 | appears on the screen at a time. | |
1366 | @end defun | |
1367 | ||
48a58303 RS |
1368 | @defun y-or-n-p-with-timeout prompt seconds default-value |
1369 | Like @code{y-or-n-p}, except that if the user fails to answer within | |
1370 | @var{seconds} seconds, this function stops waiting and returns | |
1371 | @var{default-value}. It works by setting up a timer; see @ref{Timers}. | |
1372 | The argument @var{seconds} may be an integer or a floating point number. | |
1373 | @end defun | |
1374 | ||
3e01fd9d | 1375 | @defun yes-or-no-p prompt |
793da230 RS |
1376 | This function asks the user a question, expecting input in the |
1377 | minibuffer. It returns @code{t} if the user enters @samp{yes}, | |
1378 | @code{nil} if the user types @samp{no}. The user must type @key{RET} to | |
1379 | finalize the response. Upper and lower case are equivalent. | |
3e01fd9d | 1380 | |
793da230 | 1381 | @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area, |
3e01fd9d RS |
1382 | followed by @w{@samp{(yes or no) }}. The user must type one of the |
1383 | expected responses; otherwise, the function responds @samp{Please answer | |
1384 | yes or no.}, waits about two seconds and repeats the request. | |
1385 | ||
793da230 | 1386 | @code{yes-or-no-p} requires more work from the user than |
3e01fd9d RS |
1387 | @code{y-or-n-p} and is appropriate for more crucial decisions. |
1388 | ||
3e01fd9d RS |
1389 | Here is an example: |
1390 | ||
1391 | @smallexample | |
1392 | @group | |
1393 | (yes-or-no-p "Do you really want to remove everything? ") | |
1394 | ||
177c0ea7 JB |
1395 | ;; @r{After evaluation of the preceding expression,} |
1396 | ;; @r{the following prompt appears,} | |
3e01fd9d RS |
1397 | ;; @r{with an empty minibuffer:} |
1398 | @end group | |
1399 | ||
1400 | @group | |
1401 | ---------- Buffer: minibuffer ---------- | |
177c0ea7 | 1402 | Do you really want to remove everything? (yes or no) |
3e01fd9d RS |
1403 | ---------- Buffer: minibuffer ---------- |
1404 | @end group | |
1405 | @end smallexample | |
1406 | ||
1407 | @noindent | |
1408 | If the user first types @kbd{y @key{RET}}, which is invalid because this | |
1409 | function demands the entire word @samp{yes}, it responds by displaying | |
1410 | these prompts, with a brief pause between them: | |
1411 | ||
1412 | @smallexample | |
1413 | @group | |
1414 | ---------- Buffer: minibuffer ---------- | |
1415 | Please answer yes or no. | |
1416 | Do you really want to remove everything? (yes or no) | |
1417 | ---------- Buffer: minibuffer ---------- | |
1418 | @end group | |
1419 | @end smallexample | |
1420 | @end defun | |
1421 | ||
1422 | @node Multiple Queries | |
1423 | @section Asking Multiple Y-or-N Questions | |
1424 | ||
793da230 RS |
1425 | When you have a series of similar questions to ask, such as ``Do you |
1426 | want to save this buffer'' for each buffer in turn, you should use | |
1427 | @code{map-y-or-n-p} to ask the collection of questions, rather than | |
1428 | asking each question individually. This gives the user certain | |
1429 | convenient facilities such as the ability to answer the whole series at | |
1430 | once. | |
1431 | ||
2468d0c0 | 1432 | @defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area |
f9f59935 RS |
1433 | This function asks the user a series of questions, reading a |
1434 | single-character answer in the echo area for each one. | |
3e01fd9d RS |
1435 | |
1436 | The value of @var{list} specifies the objects to ask questions about. | |
1437 | It should be either a list of objects or a generator function. If it is | |
1438 | a function, it should expect no arguments, and should return either the | |
1439 | next object to ask about, or @code{nil} meaning stop asking questions. | |
1440 | ||
1441 | The argument @var{prompter} specifies how to ask each question. If | |
1442 | @var{prompter} is a string, the question text is computed like this: | |
1443 | ||
1444 | @example | |
1445 | (format @var{prompter} @var{object}) | |
1446 | @end example | |
1447 | ||
1448 | @noindent | |
1449 | where @var{object} is the next object to ask about (as obtained from | |
1450 | @var{list}). | |
1451 | ||
1452 | If not a string, @var{prompter} should be a function of one argument | |
63ff95ee MW |
1453 | (the next object to ask about) and should return the question text. If |
1454 | the value is a string, that is the question to ask the user. The | |
1455 | function can also return @code{t} meaning do act on this object (and | |
1456 | don't ask the user), or @code{nil} meaning ignore this object (and don't | |
1457 | ask the user). | |
3e01fd9d RS |
1458 | |
1459 | The argument @var{actor} says how to act on the answers that the user | |
1460 | gives. It should be a function of one argument, and it is called with | |
1461 | each object that the user says yes for. Its argument is always an | |
1462 | object obtained from @var{list}. | |
1463 | ||
1464 | If the argument @var{help} is given, it should be a list of this form: | |
1465 | ||
1466 | @example | |
1467 | (@var{singular} @var{plural} @var{action}) | |
1468 | @end example | |
1469 | ||
1470 | @noindent | |
1471 | where @var{singular} is a string containing a singular noun that | |
1472 | describes the objects conceptually being acted on, @var{plural} is the | |
1473 | corresponding plural noun, and @var{action} is a transitive verb | |
1474 | describing what @var{actor} does. | |
1475 | ||
1476 | If you don't specify @var{help}, the default is @code{("object" | |
1477 | "objects" "act on")}. | |
1478 | ||
1479 | Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or | |
1480 | @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip | |
1481 | that object; @kbd{!} to act on all following objects; @key{ESC} or | |
1482 | @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on | |
1483 | the current object and then exit; or @kbd{C-h} to get help. These are | |
1484 | the same answers that @code{query-replace} accepts. The keymap | |
1485 | @code{query-replace-map} defines their meaning for @code{map-y-or-n-p} | |
1486 | as well as for @code{query-replace}; see @ref{Search and Replace}. | |
1487 | ||
1488 | You can use @var{action-alist} to specify additional possible answers | |
1489 | and what they mean. It is an alist of elements of the form | |
1490 | @code{(@var{char} @var{function} @var{help})}, each of which defines one | |
1491 | additional answer. In this element, @var{char} is a character (the | |
1492 | answer); @var{function} is a function of one argument (an object from | |
1493 | @var{list}); @var{help} is a string. | |
1494 | ||
1495 | When the user responds with @var{char}, @code{map-y-or-n-p} calls | |
1496 | @var{function}. If it returns non-@code{nil}, the object is considered | |
1497 | ``acted upon'', and @code{map-y-or-n-p} advances to the next object in | |
1498 | @var{list}. If it returns @code{nil}, the prompt is repeated for the | |
1499 | same object. | |
1500 | ||
2468d0c0 DL |
1501 | Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while |
1502 | prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it | |
1503 | does not do that. | |
1504 | ||
3e099569 RS |
1505 | If @code{map-y-or-n-p} is called in a command that was invoked using the |
1506 | mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command | |
1507 | Loop Info}) is either @code{nil} or a list---then it uses a dialog box | |
1508 | or pop-up menu to ask the question. In this case, it does not use | |
1509 | keyboard input or the echo area. You can force use of the mouse or use | |
1510 | of keyboard input by binding @code{last-nonmenu-event} to a suitable | |
1511 | value around the call. | |
1512 | ||
3e01fd9d RS |
1513 | The return value of @code{map-y-or-n-p} is the number of objects acted on. |
1514 | @end defun | |
1515 | ||
e75ecfec KH |
1516 | @node Reading a Password |
1517 | @section Reading a Password | |
1518 | @cindex passwords, reading | |
1519 | ||
1520 | To read a password to pass to another program, you can use the | |
1521 | function @code{read-passwd}. | |
1522 | ||
e75ecfec KH |
1523 | @defun read-passwd prompt &optional confirm default |
1524 | This function reads a password, prompting with @var{prompt}. It does | |
1525 | not echo the password as the user types it; instead, it echoes @samp{.} | |
1526 | for each character in the password. | |
1527 | ||
1528 | The optional argument @var{confirm}, if non-@code{nil}, says to read the | |
1529 | password twice and insist it must be the same both times. If it isn't | |
1530 | the same, the user has to type it over and over until the last two | |
1531 | times match. | |
1532 | ||
1533 | The optional argument @var{default} specifies the default password to | |
1534 | return if the user enters empty input. If @var{default} is @code{nil}, | |
1535 | then @code{read-passwd} returns the null string in that case. | |
1536 | @end defun | |
1537 | ||
3e01fd9d | 1538 | @node Minibuffer Misc |
3e01fd9d RS |
1539 | @section Minibuffer Miscellany |
1540 | ||
1541 | This section describes some basic functions and variables related to | |
1542 | minibuffers. | |
1543 | ||
1544 | @deffn Command exit-minibuffer | |
1545 | This command exits the active minibuffer. It is normally bound to | |
1546 | keys in minibuffer local keymaps. | |
1547 | @end deffn | |
1548 | ||
1549 | @deffn Command self-insert-and-exit | |
1550 | This command exits the active minibuffer after inserting the last | |
1551 | character typed on the keyboard (found in @code{last-command-char}; | |
1552 | @pxref{Command Loop Info}). | |
1553 | @end deffn | |
1554 | ||
1555 | @deffn Command previous-history-element n | |
1556 | This command replaces the minibuffer contents with the value of the | |
1557 | @var{n}th previous (older) history element. | |
1558 | @end deffn | |
1559 | ||
1560 | @deffn Command next-history-element n | |
1561 | This command replaces the minibuffer contents with the value of the | |
1562 | @var{n}th more recent history element. | |
1563 | @end deffn | |
1564 | ||
2468d0c0 | 1565 | @deffn Command previous-matching-history-element pattern n |
3e01fd9d | 1566 | This command replaces the minibuffer contents with the value of the |
2468d0c0 DL |
1567 | @var{n}th previous (older) history element that matches @var{pattern} (a |
1568 | regular expression). | |
3e01fd9d RS |
1569 | @end deffn |
1570 | ||
2468d0c0 DL |
1571 | @deffn Command next-matching-history-element pattern n |
1572 | This command replaces the minibuffer contents with the value of the | |
1573 | @var{n}th next (newer) history element that matches @var{pattern} (a | |
1574 | regular expression). | |
3e01fd9d RS |
1575 | @end deffn |
1576 | ||
bfe721d1 KH |
1577 | @defun minibuffer-prompt |
1578 | This function returns the prompt string of the currently active | |
1579 | minibuffer. If no minibuffer is active, it returns @code{nil}. | |
1580 | @end defun | |
1581 | ||
2468d0c0 | 1582 | @defun minibuffer-prompt-end |
b3b044f2 | 1583 | @tindex minibuffer-prompt-end |
8241495d RS |
1584 | This function, available starting in Emacs 21, returns the current |
1585 | position of the end of the minibuffer prompt, if a minibuffer is | |
b3b044f2 MB |
1586 | current. Otherwise, it returns the minimum valid buffer position. |
1587 | @end defun | |
1588 | ||
1589 | @defun minibuffer-contents | |
1590 | @tindex minibuffer-contents | |
1591 | This function, available starting in Emacs 21, returns the editable | |
1592 | contents of the minibuffer (that is, everything except the prompt) as | |
1593 | a string, if a minibuffer is current. Otherwise, it returns the | |
1594 | entire contents of the current buffer. | |
1595 | @end defun | |
1596 | ||
1597 | @defun minibuffer-contents-no-properties | |
1598 | @tindex minibuffer-contents-no-properties | |
1599 | This is like @code{minibuffer-contents}, except that it does not copy text | |
1600 | properties, just the characters themselves. @xref{Text Properties}. | |
1601 | @end defun | |
1602 | ||
1603 | @defun delete-minibuffer-contents | |
1604 | @tindex delete-minibuffer-contents | |
1605 | This function, available starting in Emacs 21, erases the editable | |
1606 | contents of the minibuffer (that is, everything except the prompt), if | |
1607 | a minibuffer is current. Otherwise, it erases the entire buffer. | |
8241495d RS |
1608 | @end defun |
1609 | ||
42d9d13a | 1610 | @defun minibuffer-prompt-width |
8241495d RS |
1611 | This function returns the current display-width of the minibuffer |
1612 | prompt, if a minibuffer is current. Otherwise, it returns zero. | |
bfe721d1 KH |
1613 | @end defun |
1614 | ||
3e01fd9d RS |
1615 | @defvar minibuffer-setup-hook |
1616 | This is a normal hook that is run whenever the minibuffer is entered. | |
793da230 RS |
1617 | @xref{Hooks}. |
1618 | @end defvar | |
1619 | ||
612b4d5c | 1620 | @defvar minibuffer-exit-hook |
793da230 RS |
1621 | This is a normal hook that is run whenever the minibuffer is exited. |
1622 | @xref{Hooks}. | |
3e01fd9d RS |
1623 | @end defvar |
1624 | ||
1625 | @defvar minibuffer-help-form | |
1626 | The current value of this variable is used to rebind @code{help-form} | |
1627 | locally inside the minibuffer (@pxref{Help Functions}). | |
1628 | @end defvar | |
1629 | ||
7370e0a8 RS |
1630 | @defun minibufferp &optional buffer |
1631 | This function returns non-@code{nil} if @var{buffer} is a minibuffer. | |
1632 | If @var{buffer} is omitted, it tests the current buffer. | |
1633 | @end defun | |
1634 | ||
22697dac KH |
1635 | @defun active-minibuffer-window |
1636 | This function returns the currently active minibuffer window, or | |
1637 | @code{nil} if none is currently active. | |
1638 | @end defun | |
1639 | ||
3e01fd9d | 1640 | @defun minibuffer-window &optional frame |
22697dac KH |
1641 | This function returns the minibuffer window used for frame @var{frame}. |
1642 | If @var{frame} is @code{nil}, that stands for the current frame. Note | |
1643 | that the minibuffer window used by a frame need not be part of that | |
1644 | frame---a frame that has no minibuffer of its own necessarily uses some | |
1645 | other frame's minibuffer window. | |
3e01fd9d RS |
1646 | @end defun |
1647 | ||
41495ddd RS |
1648 | @defun set-minibuffer-window window |
1649 | This function specifies @var{window} as the minibuffer window to use. | |
1650 | This affects where the minibuffer is displayed if you put text in it | |
1651 | without invoking the usual minibuffer commands. It has no effect on | |
1652 | the usual minibuffer input functions because they all start by | |
1653 | choosing the minibuffer window according to the current frame. | |
1654 | @end defun | |
1655 | ||
3e01fd9d RS |
1656 | @c Emacs 19 feature |
1657 | @defun window-minibuffer-p window | |
1658 | This function returns non-@code{nil} if @var{window} is a minibuffer window. | |
1659 | @end defun | |
1660 | ||
1661 | It is not correct to determine whether a given window is a minibuffer by | |
1662 | comparing it with the result of @code{(minibuffer-window)}, because | |
1663 | there can be more than one minibuffer window if there is more than one | |
1664 | frame. | |
1665 | ||
1666 | @defun minibuffer-window-active-p window | |
1667 | This function returns non-@code{nil} if @var{window}, assumed to be | |
1668 | a minibuffer window, is currently active. | |
1669 | @end defun | |
1670 | ||
1671 | @defvar minibuffer-scroll-window | |
1672 | If the value of this variable is non-@code{nil}, it should be a window | |
1673 | object. When the function @code{scroll-other-window} is called in the | |
1674 | minibuffer, it scrolls this window. | |
1675 | @end defvar | |
1676 | ||
f460db36 RS |
1677 | @defun minibuffer-selected-window |
1678 | This function returns the window which was selected when the | |
1679 | minibuffer was entered. If selected window is not a minibuffer | |
1680 | window, it returns @code{nil}. | |
1681 | @end defun | |
1682 | ||
3e01fd9d RS |
1683 | Finally, some functions and variables deal with recursive minibuffers |
1684 | (@pxref{Recursive Editing}): | |
1685 | ||
1686 | @defun minibuffer-depth | |
1687 | This function returns the current depth of activations of the | |
1688 | minibuffer, a nonnegative integer. If no minibuffers are active, it | |
1689 | returns zero. | |
1690 | @end defun | |
1691 | ||
1692 | @defopt enable-recursive-minibuffers | |
1693 | If this variable is non-@code{nil}, you can invoke commands (such as | |
969fe9b5 RS |
1694 | @code{find-file}) that use minibuffers even while the minibuffer window |
1695 | is active. Such invocation produces a recursive editing level for a new | |
3e01fd9d RS |
1696 | minibuffer. The outer-level minibuffer is invisible while you are |
1697 | editing the inner one. | |
1698 | ||
969fe9b5 RS |
1699 | If this variable is @code{nil}, you cannot invoke minibuffer |
1700 | commands when the minibuffer window is active, not even if you switch to | |
1701 | another window to do it. | |
3e01fd9d RS |
1702 | @end defopt |
1703 | ||
1704 | @c Emacs 19 feature | |
1705 | If a command name has a property @code{enable-recursive-minibuffers} | |
793da230 | 1706 | that is non-@code{nil}, then the command can use the minibuffer to read |
3e01fd9d | 1707 | arguments even if it is invoked from the minibuffer. The minibuffer |
bfe721d1 KH |
1708 | command @code{next-matching-history-element} (normally @kbd{M-s} in the |
1709 | minibuffer) uses this feature. | |
9a191eba RS |
1710 | |
1711 | @defun minibuffer-message string &optional timeout | |
1712 | This function displays @var{string} temporarily at the end of the | |
1713 | minibuffer text, for @var{timeout} seconds. (The default is 2 | |
1714 | seconds.) | |
1715 | @end defun | |
ab5796a9 MB |
1716 | |
1717 | @ignore | |
1718 | arch-tag: bba7f945-9078-477f-a2ce-18818a6e1218 | |
1719 | @end ignore |