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1 | @c -*-texinfo-*- |
2 | @c This is part of the GNU Emacs Lisp Reference Manual. | |
facf1bca LT |
3 | @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, |
4 | @c 2001, 2004 | |
177c0ea7 | 5 | @c Free Software Foundation, Inc. |
3e01fd9d RS |
6 | @c See the file elisp.texi for copying conditions. |
7 | @setfilename ../info/minibuf | |
3e099569 | 8 | @node Minibuffers, Command Loop, Read and Print, Top |
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9 | @chapter Minibuffers |
10 | @cindex arguments, reading | |
11 | @cindex complex arguments | |
12 | @cindex minibuffer | |
13 | ||
14 | A @dfn{minibuffer} is a special buffer that Emacs commands use to read | |
15 | arguments more complicated than the single numeric prefix argument. | |
16 | These arguments include file names, buffer names, and command names (as | |
17 | in @kbd{M-x}). The minibuffer is displayed on the bottom line of the | |
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18 | frame, in the same place as the echo area, but only while it is in use |
19 | for reading an argument. | |
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20 | |
21 | @menu | |
22 | * Intro to Minibuffers:: Basic information about minibuffers. | |
23 | * Text from Minibuffer:: How to read a straight text string. | |
24 | * Object from Minibuffer:: How to read a Lisp object or expression. | |
25 | * Minibuffer History:: Recording previous minibuffer inputs | |
26 | so the user can reuse them. | |
79467ffe | 27 | * Initial Input:: Specifying initial contents for the minibuffer. |
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28 | * Completion:: How to invoke and customize completion. |
29 | * Yes-or-No Queries:: Asking a question with a simple answer. | |
30 | * Multiple Queries:: Asking a series of similar questions. | |
e75ecfec | 31 | * Reading a Password:: Reading a password from the terminal. |
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32 | * Minibuffer Misc:: Various customization hooks and variables. |
33 | @end menu | |
34 | ||
35 | @node Intro to Minibuffers | |
36 | @section Introduction to Minibuffers | |
37 | ||
38 | In most ways, a minibuffer is a normal Emacs buffer. Most operations | |
39 | @emph{within} a buffer, such as editing commands, work normally in a | |
40 | minibuffer. However, many operations for managing buffers do not apply | |
41 | to minibuffers. The name of a minibuffer always has the form @w{@samp{ | |
56bd69df | 42 | *Minibuf-@var{number}*}}, and it cannot be changed. Minibuffers are |
3e01fd9d | 43 | displayed only in special windows used only for minibuffers; these |
1911e6e5 | 44 | windows always appear at the bottom of a frame. (Sometimes frames have |
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45 | no minibuffer window, and sometimes a special kind of frame contains |
46 | nothing but a minibuffer window; see @ref{Minibuffers and Frames}.) | |
47 | ||
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48 | The text in the minibuffer always starts with the @dfn{prompt string}, |
49 | the text that was specified by the program that is using the minibuffer | |
50 | to tell the user what sort of input to type. This text is marked | |
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51 | read-only so you won't accidentally delete or change it. It is also |
52 | marked as a field (@pxref{Fields}), so that certain motion functions, | |
53 | including @code{beginning-of-line}, @code{forward-word}, | |
54 | @code{forward-sentence}, and @code{forward-paragraph}, stop at the | |
55 | boundary between the prompt and the actual text. (In older Emacs | |
56 | versions, the prompt was displayed using a special mechanism and was not | |
57 | part of the buffer contents.) | |
58 | ||
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59 | The minibuffer's window is normally a single line; it grows |
60 | automatically if necessary if the contents require more space. You can | |
61 | explicitly resize it temporarily with the window sizing commands; it | |
62 | reverts to its normal size when the minibuffer is exited. You can | |
63 | resize it permanently by using the window sizing commands in the frame's | |
64 | other window, when the minibuffer is not active. If the frame contains | |
65 | just a minibuffer, you can change the minibuffer's size by changing the | |
66 | frame's size. | |
3e01fd9d | 67 | |
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68 | Use of the minibuffer reads input events, and that alters the values |
69 | of variables such as @code{this-command} and @code{last-command} | |
70 | (@pxref{Command Loop Info}). Your program should bind them around the | |
71 | code that uses the minibuffer, if you do not want that to change them. | |
72 | ||
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73 | If a command uses a minibuffer while there is an active minibuffer, |
74 | this is called a @dfn{recursive minibuffer}. The first minibuffer is | |
75 | named @w{@samp{ *Minibuf-0*}}. Recursive minibuffers are named by | |
76 | incrementing the number at the end of the name. (The names begin with a | |
77 | space so that they won't show up in normal buffer lists.) Of several | |
78 | recursive minibuffers, the innermost (or most recently entered) is the | |
79 | active minibuffer. We usually call this ``the'' minibuffer. You can | |
80 | permit or forbid recursive minibuffers by setting the variable | |
81 | @code{enable-recursive-minibuffers} or by putting properties of that | |
82 | name on command symbols (@pxref{Minibuffer Misc}). | |
83 | ||
84 | Like other buffers, a minibuffer may use any of several local keymaps | |
85 | (@pxref{Keymaps}); these contain various exit commands and in some cases | |
bfe721d1 | 86 | completion commands (@pxref{Completion}). |
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87 | |
88 | @itemize @bullet | |
89 | @item | |
90 | @code{minibuffer-local-map} is for ordinary input (no completion). | |
91 | ||
92 | @item | |
93 | @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits | |
4ff1926e | 94 | just like @key{RET}. |
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95 | |
96 | @item | |
97 | @code{minibuffer-local-completion-map} is for permissive completion. | |
98 | ||
99 | @item | |
100 | @code{minibuffer-local-must-match-map} is for strict completion and | |
101 | for cautious completion. | |
102 | @end itemize | |
103 | ||
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104 | When Emacs is running in batch mode, any request to read from the |
105 | minibuffer actually reads a line from the standard input descriptor that | |
106 | was supplied when Emacs was started. | |
107 | ||
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108 | @node Text from Minibuffer |
109 | @section Reading Text Strings with the Minibuffer | |
110 | ||
793da230 RS |
111 | Most often, the minibuffer is used to read text as a string. It can |
112 | also be used to read a Lisp object in textual form. The most basic | |
113 | primitive for minibuffer input is @code{read-from-minibuffer}; it can do | |
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114 | either one. There are also specialized commands for reading |
115 | commands, variables, file names, etc. (@pxref{Completion}). | |
3e01fd9d | 116 | |
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117 | In most cases, you should not call minibuffer input functions in the |
118 | middle of a Lisp function. Instead, do all minibuffer input as part of | |
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119 | reading the arguments for a command, in the @code{interactive} |
120 | specification. @xref{Defining Commands}. | |
bfe721d1 | 121 | |
4d19f455 | 122 | @defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method keep-all |
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123 | This function is the most general way to get input through the |
124 | minibuffer. By default, it accepts arbitrary text and returns it as a | |
125 | string; however, if @var{read} is non-@code{nil}, then it uses | |
126 | @code{read} to convert the text into a Lisp object (@pxref{Input | |
127 | Functions}). | |
128 | ||
969fe9b5 | 129 | The first thing this function does is to activate a minibuffer and |
3e01fd9d | 130 | display it with @var{prompt-string} as the prompt. This value must be a |
969fe9b5 | 131 | string. Then the user can edit text in the minibuffer. |
3e01fd9d | 132 | |
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133 | When the user types a command to exit the minibuffer, |
134 | @code{read-from-minibuffer} constructs the return value from the text in | |
135 | the minibuffer. Normally it returns a string containing that text. | |
136 | However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer} | |
137 | reads the text and returns the resulting Lisp object, unevaluated. | |
138 | (@xref{Input Functions}, for information about reading.) | |
f9f59935 | 139 | |
969fe9b5 | 140 | The argument @var{default} specifies a default value to make available |
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141 | through the history commands. It should be a string, or @code{nil}. |
142 | If non-@code{nil}, the user can access it using | |
143 | @code{next-history-element}, usually bound in the minibuffer to | |
144 | @kbd{M-n}. If @var{read} is non-@code{nil}, then @var{default} is | |
145 | also used as the input to @code{read}, if the user enters empty input. | |
146 | (If @var{read} is non-@code{nil} and @var{default} is @code{nil}, empty | |
147 | input results in an @code{end-of-file} error.) However, in the usual | |
148 | case (where @var{read} is @code{nil}), @code{read-from-minibuffer} | |
149 | ignores @var{default} when the user enters empty input and returns an | |
150 | empty string, @code{""}. In this respect, it is different from all | |
151 | the other minibuffer input functions in this chapter. | |
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152 | |
153 | If @var{keymap} is non-@code{nil}, that keymap is the local keymap to | |
154 | use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the | |
155 | value of @code{minibuffer-local-map} is used as the keymap. Specifying | |
156 | a keymap is the most important way to customize the minibuffer for | |
157 | various applications such as completion. | |
158 | ||
159 | The argument @var{hist} specifies which history list variable to use | |
160 | for saving the input and for history commands used in the minibuffer. | |
161 | It defaults to @code{minibuffer-history}. @xref{Minibuffer History}. | |
162 | ||
f9f59935 RS |
163 | If the variable @code{minibuffer-allow-text-properties} is |
164 | non-@code{nil}, then the string which is returned includes whatever text | |
165 | properties were present in the minibuffer. Otherwise all the text | |
166 | properties are stripped when the value is returned. | |
167 | ||
f9f59935 | 168 | If the argument @var{inherit-input-method} is non-@code{nil}, then the |
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169 | minibuffer inherits the current input method (@pxref{Input Methods}) and |
170 | the setting of @code{enable-multibyte-characters} (@pxref{Text | |
171 | Representations}) from whichever buffer was current before entering the | |
172 | minibuffer. | |
969fe9b5 | 173 | |
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174 | If @var{keep-all} is non-@code{nil}, even empty and duplicate inputs |
175 | are added to the history list. | |
176 | ||
79467ffe RS |
177 | Use of @var{initial-contents} is mostly deprecated; we recommend using |
178 | a non-@code{nil} value only in conjunction with specifying a cons cell | |
179 | for @var{hist}. @xref{Initial Input}. | |
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180 | @end defun |
181 | ||
f9f59935 | 182 | @defun read-string prompt &optional initial history default inherit-input-method |
3e01fd9d | 183 | This function reads a string from the minibuffer and returns it. The |
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184 | arguments @var{prompt}, @var{initial}, @var{history} and |
185 | @var{inherit-input-method} are used as in @code{read-from-minibuffer}. | |
186 | The keymap used is @code{minibuffer-local-map}. | |
3e01fd9d | 187 | |
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188 | The optional argument @var{default} is used as in |
189 | @code{read-from-minibuffer}, except that, if non-@code{nil}, it also | |
190 | specifies a default value to return if the user enters null input. As | |
191 | in @code{read-from-minibuffer} it should be a string, or @code{nil}, | |
192 | which is equivalent to an empty string. | |
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193 | |
194 | This function is a simplified interface to the | |
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195 | @code{read-from-minibuffer} function: |
196 | ||
197 | @smallexample | |
198 | @group | |
f9f59935 | 199 | (read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit}) |
3e01fd9d | 200 | @equiv{} |
969fe9b5 RS |
201 | (let ((value |
202 | (read-from-minibuffer @var{prompt} @var{initial} nil nil | |
203 | @var{history} @var{default} @var{inherit}))) | |
4b574f3d | 204 | (if (and (equal value "") @var{default}) |
969fe9b5 RS |
205 | @var{default} |
206 | value)) | |
3e01fd9d RS |
207 | @end group |
208 | @end smallexample | |
209 | @end defun | |
210 | ||
f9f59935 | 211 | @defvar minibuffer-allow-text-properties |
1911e6e5 RS |
212 | If this variable is @code{nil}, then @code{read-from-minibuffer} strips |
213 | all text properties from the minibuffer input before returning it. | |
4b574f3d LT |
214 | This variable also affects @code{read-string}. However, |
215 | @code{read-no-blanks-input} (see below), as well as | |
216 | @code{read-minibuffer} and related functions (@pxref{Object from | |
217 | Minibuffer,, Reading Lisp Objects With the Minibuffer}), and all | |
218 | functions that do minibuffer input with completion, discard text | |
219 | properties unconditionally, regardless of the value of this variable. | |
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220 | @end defvar |
221 | ||
3e01fd9d | 222 | @defvar minibuffer-local-map |
facf1bca | 223 | @anchor{Definition of minibuffer-local-map} |
3e01fd9d RS |
224 | This is the default local keymap for reading from the minibuffer. By |
225 | default, it makes the following bindings: | |
226 | ||
227 | @table @asis | |
969fe9b5 | 228 | @item @kbd{C-j} |
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229 | @code{exit-minibuffer} |
230 | ||
231 | @item @key{RET} | |
232 | @code{exit-minibuffer} | |
233 | ||
234 | @item @kbd{C-g} | |
235 | @code{abort-recursive-edit} | |
236 | ||
237 | @item @kbd{M-n} | |
e37d6e4c | 238 | @itemx @key{DOWN} |
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239 | @code{next-history-element} |
240 | ||
241 | @item @kbd{M-p} | |
e37d6e4c | 242 | @itemx @key{UP} |
3e01fd9d RS |
243 | @code{previous-history-element} |
244 | ||
4b574f3d | 245 | @item @kbd{M-s} |
3e01fd9d RS |
246 | @code{next-matching-history-element} |
247 | ||
4b574f3d | 248 | @item @kbd{M-r} |
3e01fd9d RS |
249 | @code{previous-matching-history-element} |
250 | @end table | |
251 | @end defvar | |
252 | ||
253 | @c In version 18, initial is required | |
254 | @c Emacs 19 feature | |
f9f59935 | 255 | @defun read-no-blanks-input prompt &optional initial inherit-input-method |
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256 | This function reads a string from the minibuffer, but does not allow |
257 | whitespace characters as part of the input: instead, those characters | |
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258 | terminate the input. The arguments @var{prompt}, @var{initial}, and |
259 | @var{inherit-input-method} are used as in @code{read-from-minibuffer}. | |
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260 | |
261 | This is a simplified interface to the @code{read-from-minibuffer} | |
262 | function, and passes the value of the @code{minibuffer-local-ns-map} | |
263 | keymap as the @var{keymap} argument for that function. Since the keymap | |
264 | @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is} | |
265 | possible to put a space into the string, by quoting it. | |
266 | ||
4b574f3d LT |
267 | This function discards text properties, regardless of the value of |
268 | @code{minibuffer-allow-text-properties}. | |
269 | ||
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270 | @smallexample |
271 | @group | |
272 | (read-no-blanks-input @var{prompt} @var{initial}) | |
273 | @equiv{} | |
4b574f3d LT |
274 | (let (minibuffer-allow-text-properties) |
275 | (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map)) | |
3e01fd9d RS |
276 | @end group |
277 | @end smallexample | |
278 | @end defun | |
279 | ||
280 | @defvar minibuffer-local-ns-map | |
281 | This built-in variable is the keymap used as the minibuffer local keymap | |
282 | in the function @code{read-no-blanks-input}. By default, it makes the | |
bfe721d1 | 283 | following bindings, in addition to those of @code{minibuffer-local-map}: |
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284 | |
285 | @table @asis | |
3e01fd9d RS |
286 | @item @key{SPC} |
287 | @cindex @key{SPC} in minibuffer | |
288 | @code{exit-minibuffer} | |
289 | ||
290 | @item @key{TAB} | |
291 | @cindex @key{TAB} in minibuffer | |
292 | @code{exit-minibuffer} | |
293 | ||
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294 | @item @kbd{?} |
295 | @cindex @kbd{?} in minibuffer | |
296 | @code{self-insert-and-exit} | |
3e01fd9d RS |
297 | @end table |
298 | @end defvar | |
299 | ||
300 | @node Object from Minibuffer | |
301 | @section Reading Lisp Objects with the Minibuffer | |
302 | ||
303 | This section describes functions for reading Lisp objects with the | |
304 | minibuffer. | |
305 | ||
306 | @defun read-minibuffer prompt &optional initial | |
f9f59935 | 307 | This function reads a Lisp object using the minibuffer, and returns it |
3e01fd9d | 308 | without evaluating it. The arguments @var{prompt} and @var{initial} are |
793da230 | 309 | used as in @code{read-from-minibuffer}. |
3e01fd9d | 310 | |
793da230 | 311 | This is a simplified interface to the |
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312 | @code{read-from-minibuffer} function: |
313 | ||
314 | @smallexample | |
315 | @group | |
316 | (read-minibuffer @var{prompt} @var{initial}) | |
317 | @equiv{} | |
4b574f3d LT |
318 | (let (minibuffer-allow-text-properties) |
319 | (read-from-minibuffer @var{prompt} @var{initial} nil t)) | |
3e01fd9d RS |
320 | @end group |
321 | @end smallexample | |
322 | ||
323 | Here is an example in which we supply the string @code{"(testing)"} as | |
324 | initial input: | |
325 | ||
326 | @smallexample | |
327 | @group | |
328 | (read-minibuffer | |
329 | "Enter an expression: " (format "%s" '(testing))) | |
330 | ||
331 | ;; @r{Here is how the minibuffer is displayed:} | |
332 | @end group | |
333 | ||
334 | @group | |
335 | ---------- Buffer: Minibuffer ---------- | |
336 | Enter an expression: (testing)@point{} | |
337 | ---------- Buffer: Minibuffer ---------- | |
338 | @end group | |
339 | @end smallexample | |
340 | ||
341 | @noindent | |
342 | The user can type @key{RET} immediately to use the initial input as a | |
343 | default, or can edit the input. | |
344 | @end defun | |
345 | ||
346 | @defun eval-minibuffer prompt &optional initial | |
f9f59935 RS |
347 | This function reads a Lisp expression using the minibuffer, evaluates |
348 | it, then returns the result. The arguments @var{prompt} and | |
349 | @var{initial} are used as in @code{read-from-minibuffer}. | |
3e01fd9d | 350 | |
793da230 | 351 | This function simply evaluates the result of a call to |
3e01fd9d RS |
352 | @code{read-minibuffer}: |
353 | ||
354 | @smallexample | |
355 | @group | |
356 | (eval-minibuffer @var{prompt} @var{initial}) | |
357 | @equiv{} | |
358 | (eval (read-minibuffer @var{prompt} @var{initial})) | |
359 | @end group | |
360 | @end smallexample | |
361 | @end defun | |
362 | ||
363 | @defun edit-and-eval-command prompt form | |
793da230 | 364 | This function reads a Lisp expression in the minibuffer, and then |
3e01fd9d RS |
365 | evaluates it. The difference between this command and |
366 | @code{eval-minibuffer} is that here the initial @var{form} is not | |
367 | optional and it is treated as a Lisp object to be converted to printed | |
368 | representation rather than as a string of text. It is printed with | |
369 | @code{prin1}, so if it is a string, double-quote characters (@samp{"}) | |
370 | appear in the initial text. @xref{Output Functions}. | |
371 | ||
793da230 | 372 | The first thing @code{edit-and-eval-command} does is to activate the |
3e01fd9d | 373 | minibuffer with @var{prompt} as the prompt. Then it inserts the printed |
f9f59935 | 374 | representation of @var{form} in the minibuffer, and lets the user edit it. |
3e01fd9d RS |
375 | When the user exits the minibuffer, the edited text is read with |
376 | @code{read} and then evaluated. The resulting value becomes the value | |
377 | of @code{edit-and-eval-command}. | |
378 | ||
793da230 | 379 | In the following example, we offer the user an expression with initial |
3e01fd9d RS |
380 | text which is a valid form already: |
381 | ||
382 | @smallexample | |
383 | @group | |
384 | (edit-and-eval-command "Please edit: " '(forward-word 1)) | |
385 | ||
177c0ea7 | 386 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
387 | ;; @r{the following appears in the minibuffer:} |
388 | @end group | |
389 | ||
390 | @group | |
391 | ---------- Buffer: Minibuffer ---------- | |
392 | Please edit: (forward-word 1)@point{} | |
393 | ---------- Buffer: Minibuffer ---------- | |
394 | @end group | |
395 | @end smallexample | |
396 | ||
397 | @noindent | |
398 | Typing @key{RET} right away would exit the minibuffer and evaluate the | |
399 | expression, thus moving point forward one word. | |
400 | @code{edit-and-eval-command} returns @code{nil} in this example. | |
401 | @end defun | |
402 | ||
403 | @node Minibuffer History | |
404 | @section Minibuffer History | |
405 | @cindex minibuffer history | |
406 | @cindex history list | |
407 | ||
969fe9b5 | 408 | A @dfn{minibuffer history list} records previous minibuffer inputs so |
793da230 RS |
409 | the user can reuse them conveniently. A history list is actually a |
410 | symbol, not a list; it is a variable whose value is a list of strings | |
411 | (previous inputs), most recent first. | |
3e01fd9d | 412 | |
969fe9b5 | 413 | There are many separate history lists, used for different kinds of |
3e01fd9d RS |
414 | inputs. It's the Lisp programmer's job to specify the right history |
415 | list for each use of the minibuffer. | |
416 | ||
969fe9b5 | 417 | The basic minibuffer input functions @code{read-from-minibuffer} and |
3e01fd9d RS |
418 | @code{completing-read} both accept an optional argument named @var{hist} |
419 | which is how you specify the history list. Here are the possible | |
420 | values: | |
421 | ||
422 | @table @asis | |
423 | @item @var{variable} | |
424 | Use @var{variable} (a symbol) as the history list. | |
425 | ||
426 | @item (@var{variable} . @var{startpos}) | |
427 | Use @var{variable} (a symbol) as the history list, and assume that the | |
4b574f3d LT |
428 | initial history position is @var{startpos} (a nonnegative integer). |
429 | ||
430 | Specifying 0 for @var{startpos} is equivalent to just specifying the | |
431 | symbol @var{variable}. @code{previous-history-element} will display | |
432 | the most recent element of the history list in the minibuffer. If you | |
433 | specify a positive @var{startpos}, the minibuffer history functions | |
434 | behave as if @code{(elt @var{variable} (1- @var{STARTPOS}))} were the | |
79467ffe RS |
435 | history element currently shown in the minibuffer. |
436 | ||
437 | For consistency, you should also specify that element of the history | |
438 | as the initial minibuffer contents, using the @var{initial} argument | |
439 | to the minibuffer input function (@pxref{Initial Input}). | |
3e01fd9d RS |
440 | @end table |
441 | ||
969fe9b5 | 442 | If you don't specify @var{hist}, then the default history list |
3e01fd9d RS |
443 | @code{minibuffer-history} is used. For other standard history lists, |
444 | see below. You can also create your own history list variable; just | |
445 | initialize it to @code{nil} before the first use. | |
446 | ||
969fe9b5 | 447 | Both @code{read-from-minibuffer} and @code{completing-read} add new |
3e01fd9d RS |
448 | elements to the history list automatically, and provide commands to |
449 | allow the user to reuse items on the list. The only thing your program | |
450 | needs to do to use a history list is to initialize it and to pass its | |
451 | name to the input functions when you wish. But it is safe to modify the | |
452 | list by hand when the minibuffer input functions are not using it. | |
453 | ||
ff306b60 RS |
454 | Emacs functions that add a new element to a history list can also |
455 | delete old elements if the list gets too long. The variable | |
456 | @code{history-length} specifies the maximum length for most history | |
457 | lists. To specify a different maximum length for a particular history | |
458 | list, put the length in the @code{history-length} property of the | |
fbb2f03d JL |
459 | history list symbol. The variable @code{history-delete-duplicates} |
460 | specifies whether to delete duplicates in history. | |
ff306b60 RS |
461 | |
462 | @defvar history-length | |
463 | The value of this variable specifies the maximum length for all | |
464 | history lists that don't specify their own maximum lengths. If the | |
465 | value is @code{t}, that means there no maximum (don't delete old | |
466 | elements). | |
fbb2f03d JL |
467 | @end defvar |
468 | ||
469 | @defvar history-delete-duplicates | |
470 | If the value of this variable is @code{t}, that means when adding a | |
471 | new history element, all previous identical elements are deleted. | |
ff306b60 RS |
472 | @end defvar |
473 | ||
969fe9b5 RS |
474 | Here are some of the standard minibuffer history list variables: |
475 | ||
3e01fd9d RS |
476 | @defvar minibuffer-history |
477 | The default history list for minibuffer history input. | |
478 | @end defvar | |
479 | ||
480 | @defvar query-replace-history | |
481 | A history list for arguments to @code{query-replace} (and similar | |
482 | arguments to other commands). | |
483 | @end defvar | |
484 | ||
485 | @defvar file-name-history | |
a9f0a989 RS |
486 | A history list for file-name arguments. |
487 | @end defvar | |
488 | ||
489 | @defvar buffer-name-history | |
a9f0a989 | 490 | A history list for buffer-name arguments. |
3e01fd9d RS |
491 | @end defvar |
492 | ||
493 | @defvar regexp-history | |
494 | A history list for regular expression arguments. | |
495 | @end defvar | |
496 | ||
497 | @defvar extended-command-history | |
498 | A history list for arguments that are names of extended commands. | |
499 | @end defvar | |
500 | ||
501 | @defvar shell-command-history | |
502 | A history list for arguments that are shell commands. | |
503 | @end defvar | |
504 | ||
505 | @defvar read-expression-history | |
506 | A history list for arguments that are Lisp expressions to evaluate. | |
507 | @end defvar | |
508 | ||
79467ffe RS |
509 | @node Initial Input |
510 | @section Initial Input | |
511 | ||
512 | Several of the functions for minibuffer input have an argument called | |
513 | @var{initial} or @var{initial-contents}. This is a mostly-deprecated | |
514 | feature for specifiying that the minibuffer should start out with | |
515 | certain text, instead of empty as usual. | |
516 | ||
517 | If @var{initial} is a string, the minibuffer starts out containing the | |
518 | text of the string, with point at the end, when the user starts to | |
519 | edit the text. If the user simply types @key{RET} to exit the | |
520 | minibuffer, it will use the initial input string to determine the | |
521 | value to return. | |
522 | ||
523 | @strong{We discourage use of a non-@code{nil} value for | |
524 | @var{initial}}, because initial input is an intrusive interface. | |
525 | History lists and default values provide a much more convenient method | |
526 | to offer useful default inputs to the user. | |
527 | ||
528 | There is just one situation where you should specify a string for an | |
529 | @var{initial} argument. This is when you specify a cons cell for the | |
530 | @var{hist} or @var{history} argument. @xref{Minibuffer History}. | |
531 | ||
532 | @var{initial} can also be a cons cell of the form @code{(@var{string} | |
533 | . @var{position})}. This means to insert @var{string} in the | |
534 | minibuffer but put point at @var{position} within the string's text. | |
535 | ||
536 | As a historical accident, @var{position} was implemented | |
537 | inconsistently in different functions. In @code{completing-read}, | |
538 | @var{position}'s value is interpreted as origin-zero; that is, a value | |
539 | of 0 means the beginning of the string, 1 means after the first | |
540 | character, etc. In @code{read-minibuffer}, and the other | |
541 | non-completion minibuffer input functions that support this argument, | |
542 | 1 means the beginning of the string 2 means after the first character, | |
543 | etc. | |
544 | ||
545 | Use of a cons cell as the value for @var{initial} arguments is | |
546 | deprecated in user code. | |
facf1bca | 547 | |
3e01fd9d RS |
548 | @node Completion |
549 | @section Completion | |
550 | @cindex completion | |
551 | ||
552 | @dfn{Completion} is a feature that fills in the rest of a name | |
553 | starting from an abbreviation for it. Completion works by comparing the | |
554 | user's input against a list of valid names and determining how much of | |
555 | the name is determined uniquely by what the user has typed. For | |
556 | example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then | |
557 | type the first few letters of the name of the buffer to which you wish | |
558 | to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs | |
559 | extends the name as far as it can. | |
560 | ||
561 | Standard Emacs commands offer completion for names of symbols, files, | |
562 | buffers, and processes; with the functions in this section, you can | |
563 | implement completion for other kinds of names. | |
564 | ||
565 | The @code{try-completion} function is the basic primitive for | |
566 | completion: it returns the longest determined completion of a given | |
567 | initial string, with a given set of strings to match against. | |
568 | ||
569 | The function @code{completing-read} provides a higher-level interface | |
570 | for completion. A call to @code{completing-read} specifies how to | |
571 | determine the list of valid names. The function then activates the | |
572 | minibuffer with a local keymap that binds a few keys to commands useful | |
573 | for completion. Other functions provide convenient simple interfaces | |
574 | for reading certain kinds of names with completion. | |
575 | ||
576 | @menu | |
577 | * Basic Completion:: Low-level functions for completing strings. | |
578 | (These are too low level to use the minibuffer.) | |
579 | * Minibuffer Completion:: Invoking the minibuffer with completion. | |
580 | * Completion Commands:: Minibuffer commands that do completion. | |
581 | * High-Level Completion:: Convenient special cases of completion | |
582 | (reading buffer name, file name, etc.) | |
583 | * Reading File Names:: Using completion to read file names. | |
4ff1926e | 584 | * Programmed Completion:: Writing your own completion-function. |
3e01fd9d RS |
585 | @end menu |
586 | ||
587 | @node Basic Completion | |
588 | @subsection Basic Completion Functions | |
589 | ||
7370e0a8 RS |
590 | The functions @code{try-completion}, @code{all-completions} and |
591 | @code{test-completion} have nothing in themselves to do with | |
592 | minibuffers. We describe them in this chapter so as to keep them near | |
593 | the higher-level completion features that do use the minibuffer. | |
793da230 | 594 | |
3e01fd9d RS |
595 | @defun try-completion string collection &optional predicate |
596 | This function returns the longest common substring of all possible | |
597 | completions of @var{string} in @var{collection}. The value of | |
a41c174f KS |
598 | @var{collection} must be a list of strings or symbols, an alist, an |
599 | obarray, a hash table, or a function that implements a virtual set of | |
600 | strings (see below). | |
3e01fd9d RS |
601 | |
602 | Completion compares @var{string} against each of the permissible | |
603 | completions specified by @var{collection}; if the beginning of the | |
604 | permissible completion equals @var{string}, it matches. If no permissible | |
605 | completions match, @code{try-completion} returns @code{nil}. If only | |
606 | one permissible completion matches, and the match is exact, then | |
607 | @code{try-completion} returns @code{t}. Otherwise, the value is the | |
608 | longest initial sequence common to all the permissible completions that | |
609 | match. | |
610 | ||
611 | If @var{collection} is an alist (@pxref{Association Lists}), the | |
4b574f3d | 612 | permissible completions are the elements of the alist that are either |
a41c174f KS |
613 | strings, symbols, or conses whose @sc{car} is a string or symbol. |
614 | Symbols are converted to strings using @code{symbol-name}. | |
615 | Other elements of the alist are ignored. (Remember that in Emacs Lisp, | |
616 | the elements of alists do not @emph{have} to be conses.) As all | |
617 | elements of the alist can be strings, this case actually includes | |
618 | lists of strings or symbols, even though we usually do not think of | |
619 | such lists as alists. | |
3e01fd9d RS |
620 | |
621 | @cindex obarray in completion | |
622 | If @var{collection} is an obarray (@pxref{Creating Symbols}), the names | |
623 | of all symbols in the obarray form the set of permissible completions. The | |
624 | global variable @code{obarray} holds an obarray containing the names of | |
625 | all interned Lisp symbols. | |
626 | ||
627 | Note that the only valid way to make a new obarray is to create it | |
628 | empty and then add symbols to it one by one using @code{intern}. | |
629 | Also, you cannot intern a given symbol in more than one obarray. | |
630 | ||
4b574f3d LT |
631 | If @var{collection} is a hash table, then the keys that are strings |
632 | are the possible completions. Other keys are ignored. | |
633 | ||
793da230 RS |
634 | You can also use a symbol that is a function as @var{collection}. Then |
635 | the function is solely responsible for performing completion; | |
3e01fd9d RS |
636 | @code{try-completion} returns whatever this function returns. The |
637 | function is called with three arguments: @var{string}, @var{predicate} | |
638 | and @code{nil}. (The reason for the third argument is so that the same | |
639 | function can be used in @code{all-completions} and do the appropriate | |
640 | thing in either case.) @xref{Programmed Completion}. | |
641 | ||
7370e0a8 | 642 | If the argument @var{predicate} is non-@code{nil}, then it must be a |
4b574f3d LT |
643 | function of one argument, unless @var{collection} is a hash table, in |
644 | which case it should be a function of two arguments. It is used to | |
645 | test each possible match, and the match is accepted only if | |
646 | @var{predicate} returns non-@code{nil}. The argument given to | |
647 | @var{predicate} is either a string or a cons cell (the @sc{car} of | |
648 | which is a string) from the alist, or a symbol (@emph{not} a symbol | |
649 | name) from the obarray. If @var{collection} is a hash table, | |
650 | @var{predicate} is called with two arguments, the string key and the | |
651 | associated value. | |
652 | ||
653 | In addition, to be acceptable, a completion must also match all the | |
654 | regular expressions in @code{completion-regexp-list}. (Unless | |
655 | @var{collection} is a function, in which case that function has to | |
656 | handle @code{completion-regexp-list} itself.) | |
7370e0a8 | 657 | |
3e01fd9d RS |
658 | In the first of the following examples, the string @samp{foo} is |
659 | matched by three of the alist @sc{car}s. All of the matches begin with | |
660 | the characters @samp{fooba}, so that is the result. In the second | |
661 | example, there is only one possible match, and it is exact, so the value | |
662 | is @code{t}. | |
663 | ||
664 | @smallexample | |
665 | @group | |
177c0ea7 | 666 | (try-completion |
3e01fd9d RS |
667 | "foo" |
668 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))) | |
669 | @result{} "fooba" | |
670 | @end group | |
671 | ||
672 | @group | |
673 | (try-completion "foo" '(("barfoo" 2) ("foo" 3))) | |
674 | @result{} t | |
675 | @end group | |
676 | @end smallexample | |
677 | ||
678 | In the following example, numerous symbols begin with the characters | |
679 | @samp{forw}, and all of them begin with the word @samp{forward}. In | |
680 | most of the symbols, this is followed with a @samp{-}, but not in all, | |
681 | so no more than @samp{forward} can be completed. | |
682 | ||
683 | @smallexample | |
684 | @group | |
685 | (try-completion "forw" obarray) | |
686 | @result{} "forward" | |
687 | @end group | |
688 | @end smallexample | |
689 | ||
690 | Finally, in the following example, only two of the three possible | |
691 | matches pass the predicate @code{test} (the string @samp{foobaz} is | |
692 | too short). Both of those begin with the string @samp{foobar}. | |
693 | ||
694 | @smallexample | |
695 | @group | |
177c0ea7 | 696 | (defun test (s) |
3e01fd9d RS |
697 | (> (length (car s)) 6)) |
698 | @result{} test | |
699 | @end group | |
700 | @group | |
177c0ea7 | 701 | (try-completion |
3e01fd9d | 702 | "foo" |
177c0ea7 | 703 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) |
793da230 | 704 | 'test) |
3e01fd9d RS |
705 | @result{} "foobar" |
706 | @end group | |
707 | @end smallexample | |
708 | @end defun | |
709 | ||
22697dac | 710 | @defun all-completions string collection &optional predicate nospace |
3e01fd9d | 711 | This function returns a list of all possible completions of |
4b574f3d LT |
712 | @var{string}. The arguments to this function (aside from |
713 | @var{nospace}) are the same as those of @code{try-completion}. Also, | |
714 | this function uses @code{completion-regexp-list} in the same way that | |
715 | @code{try-completion} does. The optional argument @var{nospace} only | |
716 | matters if @var{string} is the empty string. In that case, if | |
717 | @var{nospace} is non-@code{nil}, completions that start with a space | |
718 | are ignored. | |
3e01fd9d RS |
719 | |
720 | If @var{collection} is a function, it is called with three arguments: | |
721 | @var{string}, @var{predicate} and @code{t}; then @code{all-completions} | |
722 | returns whatever the function returns. @xref{Programmed Completion}. | |
723 | ||
724 | Here is an example, using the function @code{test} shown in the | |
725 | example for @code{try-completion}: | |
726 | ||
727 | @smallexample | |
728 | @group | |
177c0ea7 | 729 | (defun test (s) |
3e01fd9d RS |
730 | (> (length (car s)) 6)) |
731 | @result{} test | |
732 | @end group | |
733 | ||
734 | @group | |
177c0ea7 | 735 | (all-completions |
3e01fd9d RS |
736 | "foo" |
737 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) | |
793da230 | 738 | 'test) |
3e01fd9d RS |
739 | @result{} ("foobar1" "foobar2") |
740 | @end group | |
741 | @end smallexample | |
742 | @end defun | |
743 | ||
7370e0a8 | 744 | @defun test-completion string collection &optional predicate |
facf1bca | 745 | @anchor{Definition of test-completion} |
7370e0a8 RS |
746 | This function returns non-@code{nil} if @var{string} is a valid |
747 | completion possibility specified by @var{collection} and | |
4b574f3d LT |
748 | @var{predicate}. The arguments are the same as in |
749 | @code{try-completion}. For instance, if @var{collection} is a list of | |
750 | strings, this is true if @var{string} appears in the list and | |
751 | @var{predicate} is satisfied. | |
752 | ||
753 | @code{test-completion} uses @code{completion-regexp-list} in the same | |
754 | way that @code{try-completion} does. | |
755 | ||
756 | If @var{predicate} is non-@code{nil} and if @var{collection} contains | |
757 | several strings that are equal to each other, as determined by | |
758 | @code{compare-strings} according to @code{completion-ignore-case}, | |
759 | then @var{predicate} should accept either all or none of them. | |
760 | Otherwise, the return value of @code{test-completion} is essentially | |
761 | unpredictable. | |
7370e0a8 RS |
762 | |
763 | If @var{collection} is a function, it is called with three arguments, | |
764 | the values @var{string}, @var{predicate} and @code{lambda}; whatever | |
765 | it returns, @code{test-completion} returns in turn. | |
766 | @end defun | |
767 | ||
3e01fd9d | 768 | @defvar completion-ignore-case |
7370e0a8 RS |
769 | If the value of this variable is non-@code{nil}, Emacs does not |
770 | consider case significant in completion. | |
3e01fd9d RS |
771 | @end defvar |
772 | ||
4b574f3d LT |
773 | @defvar completion-regexp-list |
774 | This is a list of regular expressions. The completion functions only | |
775 | consider a completion acceptable if it matches all regular expressions | |
776 | in this list, with @code{case-fold-search} (@pxref{Searching and Case}) | |
777 | bound to the value of @code{completion-ignore-case}. | |
778 | @end defvar | |
779 | ||
4ff1926e RS |
780 | @defmac lazy-completion-table var fun &rest args |
781 | This macro provides a way to initialize the variable @var{var} as a | |
7370e0a8 RS |
782 | collection for completion in a lazy way, not computing its actual |
783 | contents until they are first needed. You use this macro to produce a | |
784 | value that you store in @var{var}. The actual computation of the | |
785 | proper value is done the first time you do completion using @var{var}. | |
786 | It is done by calling @var{fun} with the arguments @var{args}. The | |
787 | value @var{fun} returns becomes the permanent value of @var{var}. | |
788 | ||
789 | Here are two examples of use: | |
4ff1926e RS |
790 | |
791 | @example | |
792 | (defvar foo (lazy-completion-table foo make-my-alist 'global)) | |
7370e0a8 | 793 | |
4ff1926e RS |
794 | (make-local-variable 'bar) |
795 | (setq bar (lazy-completion-table foo make-my-alist 'local) | |
796 | @end example | |
797 | @end defmac | |
798 | ||
3e01fd9d RS |
799 | @node Minibuffer Completion |
800 | @subsection Completion and the Minibuffer | |
801 | ||
802 | This section describes the basic interface for reading from the | |
803 | minibuffer with completion. | |
804 | ||
f9f59935 | 805 | @defun completing-read prompt collection &optional predicate require-match initial hist default inherit-input-method |
3e01fd9d RS |
806 | This function reads a string in the minibuffer, assisting the user by |
807 | providing completion. It activates the minibuffer with prompt | |
969fe9b5 | 808 | @var{prompt}, which must be a string. |
3e01fd9d RS |
809 | |
810 | The actual completion is done by passing @var{collection} and | |
4b574f3d LT |
811 | @var{predicate} to the function @code{try-completion}. This happens |
812 | in certain commands bound in the local keymaps used for completion. | |
813 | Some of these commands also call @code{test-completion}. Thus, if | |
814 | @var{predicate} is non-@code{nil}, it should be compatible with | |
815 | @var{collection} and @code{completion-ignore-case}. @xref{Definition | |
816 | of test-completion}. | |
3e01fd9d | 817 | |
f9f59935 RS |
818 | If @var{require-match} is @code{nil}, the exit commands work regardless |
819 | of the input in the minibuffer. If @var{require-match} is @code{t}, the | |
820 | usual minibuffer exit commands won't exit unless the input completes to | |
821 | an element of @var{collection}. If @var{require-match} is neither | |
822 | @code{nil} nor @code{t}, then the exit commands won't exit unless the | |
823 | input already in the buffer matches an element of @var{collection}. | |
824 | ||
825 | However, empty input is always permitted, regardless of the value of | |
826 | @var{require-match}; in that case, @code{completing-read} returns | |
4b574f3d LT |
827 | @var{default}, or @code{""}, if @var{default} is @code{nil}. The |
828 | value of @var{default} (if non-@code{nil}) is also available to the | |
829 | user through the history commands. | |
830 | ||
831 | The function @code{completing-read} uses | |
832 | @code{minibuffer-local-completion-map} as the keymap if | |
833 | @var{require-match} is @code{nil}, and uses | |
3e01fd9d | 834 | @code{minibuffer-local-must-match-map} if @var{require-match} is |
793da230 | 835 | non-@code{nil}. @xref{Completion Commands}. |
3e01fd9d RS |
836 | |
837 | The argument @var{hist} specifies which history list variable to use for | |
838 | saving the input and for minibuffer history commands. It defaults to | |
839 | @code{minibuffer-history}. @xref{Minibuffer History}. | |
840 | ||
79467ffe RS |
841 | The argument @var{initial} is mostly deprecated; we recommend using a |
842 | non-@code{nil} value only in conjunction with specifying a cons cell | |
843 | for @var{hist}. @xref{Initial Input}. For default input, use | |
844 | @var{default} instead. | |
70c750c0 | 845 | |
f9f59935 | 846 | If the argument @var{inherit-input-method} is non-@code{nil}, then the |
1911e6e5 | 847 | minibuffer inherits the current input method (@pxref{Input |
a9f0a989 RS |
848 | Methods}) and the setting of @code{enable-multibyte-characters} |
849 | (@pxref{Text Representations}) from whichever buffer was current before | |
850 | entering the minibuffer. | |
f9f59935 | 851 | |
5d645852 RS |
852 | If the built-in variable @code{completion-ignore-case} is |
853 | non-@code{nil}, completion ignores case when comparing the input | |
854 | against the possible matches. @xref{Basic Completion}. In this mode | |
855 | of operation, @var{predicate} must also ignore case, or you will get | |
856 | surprising results. | |
3e01fd9d RS |
857 | |
858 | Here's an example of using @code{completing-read}: | |
859 | ||
860 | @smallexample | |
861 | @group | |
862 | (completing-read | |
863 | "Complete a foo: " | |
864 | '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)) | |
865 | nil t "fo") | |
866 | @end group | |
867 | ||
868 | @group | |
177c0ea7 | 869 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
870 | ;; @r{the following appears in the minibuffer:} |
871 | ||
872 | ---------- Buffer: Minibuffer ---------- | |
873 | Complete a foo: fo@point{} | |
874 | ---------- Buffer: Minibuffer ---------- | |
875 | @end group | |
876 | @end smallexample | |
877 | ||
878 | @noindent | |
879 | If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}}, | |
880 | @code{completing-read} returns @code{barfoo}. | |
881 | ||
882 | The @code{completing-read} function binds three variables to pass | |
793da230 RS |
883 | information to the commands that actually do completion. These |
884 | variables are @code{minibuffer-completion-table}, | |
885 | @code{minibuffer-completion-predicate} and | |
886 | @code{minibuffer-completion-confirm}. For more information about them, | |
887 | see @ref{Completion Commands}. | |
3e01fd9d RS |
888 | @end defun |
889 | ||
890 | @node Completion Commands | |
8241495d | 891 | @subsection Minibuffer Commands that Do Completion |
3e01fd9d | 892 | |
4b574f3d LT |
893 | This section describes the keymaps, commands and user options used |
894 | in the minibuffer to do completion. The description refers to the | |
6f6b0433 | 895 | situation when Partial Completion mode is disabled (as it is by |
4b574f3d | 896 | default). When enabled, this minor mode uses its own alternatives to |
1b91d47f LT |
897 | some of the commands described below. @xref{Completion Options,,, |
898 | emacs, The GNU Emacs Manual}, for a short description of Partial | |
899 | Completion mode. | |
3e01fd9d RS |
900 | |
901 | @defvar minibuffer-local-completion-map | |
793da230 | 902 | @code{completing-read} uses this value as the local keymap when an |
3e01fd9d RS |
903 | exact match of one of the completions is not required. By default, this |
904 | keymap makes the following bindings: | |
905 | ||
906 | @table @asis | |
907 | @item @kbd{?} | |
908 | @code{minibuffer-completion-help} | |
909 | ||
910 | @item @key{SPC} | |
911 | @code{minibuffer-complete-word} | |
912 | ||
913 | @item @key{TAB} | |
914 | @code{minibuffer-complete} | |
915 | @end table | |
916 | ||
917 | @noindent | |
793da230 | 918 | with other characters bound as in @code{minibuffer-local-map} |
4b574f3d | 919 | (@pxref{Definition of minibuffer-local-map}). |
3e01fd9d RS |
920 | @end defvar |
921 | ||
922 | @defvar minibuffer-local-must-match-map | |
923 | @code{completing-read} uses this value as the local keymap when an | |
924 | exact match of one of the completions is required. Therefore, no keys | |
793da230 | 925 | are bound to @code{exit-minibuffer}, the command that exits the |
3e01fd9d RS |
926 | minibuffer unconditionally. By default, this keymap makes the following |
927 | bindings: | |
928 | ||
929 | @table @asis | |
930 | @item @kbd{?} | |
931 | @code{minibuffer-completion-help} | |
932 | ||
933 | @item @key{SPC} | |
934 | @code{minibuffer-complete-word} | |
935 | ||
936 | @item @key{TAB} | |
937 | @code{minibuffer-complete} | |
938 | ||
969fe9b5 | 939 | @item @kbd{C-j} |
3e01fd9d RS |
940 | @code{minibuffer-complete-and-exit} |
941 | ||
942 | @item @key{RET} | |
943 | @code{minibuffer-complete-and-exit} | |
944 | @end table | |
945 | ||
946 | @noindent | |
947 | with other characters bound as in @code{minibuffer-local-map}. | |
948 | @end defvar | |
949 | ||
950 | @defvar minibuffer-completion-table | |
4b574f3d LT |
951 | The value of this variable is the collection used for completion in |
952 | the minibuffer. This is the global variable that contains what | |
3e01fd9d RS |
953 | @code{completing-read} passes to @code{try-completion}. It is used by |
954 | minibuffer completion commands such as @code{minibuffer-complete-word}. | |
955 | @end defvar | |
956 | ||
957 | @defvar minibuffer-completion-predicate | |
958 | This variable's value is the predicate that @code{completing-read} | |
959 | passes to @code{try-completion}. The variable is also used by the other | |
960 | minibuffer completion functions. | |
961 | @end defvar | |
962 | ||
963 | @deffn Command minibuffer-complete-word | |
964 | This function completes the minibuffer contents by at most a single | |
965 | word. Even if the minibuffer contents have only one completion, | |
966 | @code{minibuffer-complete-word} does not add any characters beyond the | |
967 | first character that is not a word constituent. @xref{Syntax Tables}. | |
968 | @end deffn | |
969 | ||
970 | @deffn Command minibuffer-complete | |
971 | This function completes the minibuffer contents as far as possible. | |
972 | @end deffn | |
973 | ||
974 | @deffn Command minibuffer-complete-and-exit | |
975 | This function completes the minibuffer contents, and exits if | |
976 | confirmation is not required, i.e., if | |
2770e862 | 977 | @code{minibuffer-completion-confirm} is @code{nil}. If confirmation |
793da230 RS |
978 | @emph{is} required, it is given by repeating this command |
979 | immediately---the command is programmed to work without confirmation | |
980 | when run twice in succession. | |
3e01fd9d RS |
981 | @end deffn |
982 | ||
983 | @defvar minibuffer-completion-confirm | |
984 | When the value of this variable is non-@code{nil}, Emacs asks for | |
985 | confirmation of a completion before exiting the minibuffer. The | |
986 | function @code{minibuffer-complete-and-exit} checks the value of this | |
987 | variable before it exits. | |
988 | @end defvar | |
989 | ||
990 | @deffn Command minibuffer-completion-help | |
991 | This function creates a list of the possible completions of the | |
992 | current minibuffer contents. It works by calling @code{all-completions} | |
993 | using the value of the variable @code{minibuffer-completion-table} as | |
994 | the @var{collection} argument, and the value of | |
995 | @code{minibuffer-completion-predicate} as the @var{predicate} argument. | |
996 | The list of completions is displayed as text in a buffer named | |
997 | @samp{*Completions*}. | |
998 | @end deffn | |
999 | ||
1000 | @defun display-completion-list completions | |
1001 | This function displays @var{completions} to the stream in | |
3e099569 | 1002 | @code{standard-output}, usually a buffer. (@xref{Read and Print}, for more |
3e01fd9d RS |
1003 | information about streams.) The argument @var{completions} is normally |
1004 | a list of completions just returned by @code{all-completions}, but it | |
1005 | does not have to be. Each element may be a symbol or a string, either | |
4b574f3d LT |
1006 | of which is simply printed. It can also be a list of two strings, |
1007 | which is printed as if the strings were concatenated. The first of | |
1008 | the two strings is the actual completion, the second string serves as | |
1009 | annotation. | |
3e01fd9d RS |
1010 | |
1011 | This function is called by @code{minibuffer-completion-help}. The | |
1012 | most common way to use it is together with | |
1013 | @code{with-output-to-temp-buffer}, like this: | |
1014 | ||
1015 | @example | |
1016 | (with-output-to-temp-buffer "*Completions*" | |
1017 | (display-completion-list | |
1018 | (all-completions (buffer-string) my-alist))) | |
1019 | @end example | |
1020 | @end defun | |
1021 | ||
1022 | @defopt completion-auto-help | |
1023 | If this variable is non-@code{nil}, the completion commands | |
1024 | automatically display a list of possible completions whenever nothing | |
1025 | can be completed because the next character is not uniquely determined. | |
1026 | @end defopt | |
1027 | ||
1028 | @node High-Level Completion | |
1029 | @subsection High-Level Completion Functions | |
1030 | ||
1031 | This section describes the higher-level convenient functions for | |
1032 | reading certain sorts of names with completion. | |
1033 | ||
bfe721d1 KH |
1034 | In most cases, you should not call these functions in the middle of a |
1035 | Lisp function. When possible, do all minibuffer input as part of | |
a9f0a989 RS |
1036 | reading the arguments for a command, in the @code{interactive} |
1037 | specification. @xref{Defining Commands}. | |
bfe721d1 | 1038 | |
3e01fd9d RS |
1039 | @defun read-buffer prompt &optional default existing |
1040 | This function reads the name of a buffer and returns it as a string. | |
1041 | The argument @var{default} is the default name to use, the value to | |
1042 | return if the user exits with an empty minibuffer. If non-@code{nil}, | |
1043 | it should be a string or a buffer. It is mentioned in the prompt, but | |
1044 | is not inserted in the minibuffer as initial input. | |
1045 | ||
1046 | If @var{existing} is non-@code{nil}, then the name specified must be | |
793da230 RS |
1047 | that of an existing buffer. The usual commands to exit the minibuffer |
1048 | do not exit if the text is not valid, and @key{RET} does completion to | |
4b574f3d LT |
1049 | attempt to find a valid name. If @var{existing} is neither @code{nil} |
1050 | nor @code{t}, confirmation is required after completion. (However, | |
1051 | @var{default} is not checked for validity; it is returned, whatever it | |
1052 | is, if the user exits with the minibuffer empty.) | |
3e01fd9d RS |
1053 | |
1054 | In the following example, the user enters @samp{minibuffer.t}, and | |
1055 | then types @key{RET}. The argument @var{existing} is @code{t}, and the | |
1056 | only buffer name starting with the given input is | |
1057 | @samp{minibuffer.texi}, so that name is the value. | |
1058 | ||
1059 | @example | |
1060 | (read-buffer "Buffer name? " "foo" t) | |
1061 | @group | |
177c0ea7 | 1062 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
1063 | ;; @r{the following prompt appears,} |
1064 | ;; @r{with an empty minibuffer:} | |
1065 | @end group | |
1066 | ||
1067 | @group | |
1068 | ---------- Buffer: Minibuffer ---------- | |
1069 | Buffer name? (default foo) @point{} | |
1070 | ---------- Buffer: Minibuffer ---------- | |
1071 | @end group | |
1072 | ||
1073 | @group | |
1074 | ;; @r{The user types @kbd{minibuffer.t @key{RET}}.} | |
1075 | @result{} "minibuffer.texi" | |
1076 | @end group | |
1077 | @end example | |
1078 | @end defun | |
1079 | ||
f9f59935 RS |
1080 | @defvar read-buffer-function |
1081 | This variable specifies how to read buffer names. For example, if you | |
1082 | set this variable to @code{iswitchb-read-buffer}, all Emacs commands | |
1083 | that call @code{read-buffer} to read a buffer name will actually use the | |
1084 | @code{iswitchb} package to read it. | |
1085 | @end defvar | |
1086 | ||
1087 | @defun read-command prompt &optional default | |
3e01fd9d RS |
1088 | This function reads the name of a command and returns it as a Lisp |
1089 | symbol. The argument @var{prompt} is used as in | |
1090 | @code{read-from-minibuffer}. Recall that a command is anything for | |
1091 | which @code{commandp} returns @code{t}, and a command name is a symbol | |
1092 | for which @code{commandp} returns @code{t}. @xref{Interactive Call}. | |
1093 | ||
f9f59935 | 1094 | The argument @var{default} specifies what to return if the user enters |
969fe9b5 RS |
1095 | null input. It can be a symbol or a string; if it is a string, |
1096 | @code{read-command} interns it before returning it. If @var{default} is | |
1097 | @code{nil}, that means no default has been specified; then if the user | |
4b574f3d LT |
1098 | enters null input, the return value is @code{(intern "")}, that is, a |
1099 | symbol whose name is an empty string. | |
f9f59935 | 1100 | |
3e01fd9d RS |
1101 | @example |
1102 | (read-command "Command name? ") | |
1103 | ||
1104 | @group | |
177c0ea7 | 1105 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
1106 | ;; @r{the following prompt appears with an empty minibuffer:} |
1107 | @end group | |
1108 | ||
1109 | @group | |
177c0ea7 JB |
1110 | ---------- Buffer: Minibuffer ---------- |
1111 | Command name? | |
3e01fd9d RS |
1112 | ---------- Buffer: Minibuffer ---------- |
1113 | @end group | |
1114 | @end example | |
1115 | ||
1116 | @noindent | |
1117 | If the user types @kbd{forward-c @key{RET}}, then this function returns | |
1118 | @code{forward-char}. | |
1119 | ||
9e2b495b RS |
1120 | The @code{read-command} function is a simplified interface to |
1121 | @code{completing-read}. It uses the variable @code{obarray} so as to | |
1122 | complete in the set of extant Lisp symbols, and it uses the | |
3e01fd9d RS |
1123 | @code{commandp} predicate so as to accept only command names: |
1124 | ||
1125 | @cindex @code{commandp} example | |
1126 | @example | |
1127 | @group | |
1128 | (read-command @var{prompt}) | |
1129 | @equiv{} | |
177c0ea7 | 1130 | (intern (completing-read @var{prompt} obarray |
3e01fd9d RS |
1131 | 'commandp t nil)) |
1132 | @end group | |
1133 | @end example | |
1134 | @end defun | |
1135 | ||
f9f59935 | 1136 | @defun read-variable prompt &optional default |
bdb3097a | 1137 | @anchor{Definition of read-variable} |
3e01fd9d RS |
1138 | This function reads the name of a user variable and returns it as a |
1139 | symbol. | |
1140 | ||
f9f59935 | 1141 | The argument @var{default} specifies what to return if the user enters |
969fe9b5 RS |
1142 | null input. It can be a symbol or a string; if it is a string, |
1143 | @code{read-variable} interns it before returning it. If @var{default} | |
1144 | is @code{nil}, that means no default has been specified; then if the | |
4b574f3d | 1145 | user enters null input, the return value is @code{(intern "")}. |
f9f59935 | 1146 | |
3e01fd9d RS |
1147 | @example |
1148 | @group | |
1149 | (read-variable "Variable name? ") | |
1150 | ||
177c0ea7 JB |
1151 | ;; @r{After evaluation of the preceding expression,} |
1152 | ;; @r{the following prompt appears,} | |
3e01fd9d RS |
1153 | ;; @r{with an empty minibuffer:} |
1154 | @end group | |
1155 | ||
1156 | @group | |
1157 | ---------- Buffer: Minibuffer ---------- | |
1158 | Variable name? @point{} | |
1159 | ---------- Buffer: Minibuffer ---------- | |
1160 | @end group | |
1161 | @end example | |
1162 | ||
1163 | @noindent | |
1164 | If the user then types @kbd{fill-p @key{RET}}, @code{read-variable} | |
1165 | returns @code{fill-prefix}. | |
1166 | ||
1167 | This function is similar to @code{read-command}, but uses the | |
1168 | predicate @code{user-variable-p} instead of @code{commandp}: | |
1169 | ||
1170 | @cindex @code{user-variable-p} example | |
1171 | @example | |
1172 | @group | |
1173 | (read-variable @var{prompt}) | |
1174 | @equiv{} | |
1175 | (intern | |
1176 | (completing-read @var{prompt} obarray | |
1177 | 'user-variable-p t nil)) | |
1178 | @end group | |
1179 | @end example | |
1180 | @end defun | |
1181 | ||
969fe9b5 | 1182 | See also the functions @code{read-coding-system} and |
1911e6e5 | 1183 | @code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems}. |
f9f59935 | 1184 | |
3e01fd9d RS |
1185 | @node Reading File Names |
1186 | @subsection Reading File Names | |
1187 | ||
1188 | Here is another high-level completion function, designed for reading a | |
1189 | file name. It provides special features including automatic insertion | |
1190 | of the default directory. | |
1191 | ||
1c7cdff5 | 1192 | @defun read-file-name prompt &optional directory default existing initial predicate |
3e01fd9d | 1193 | This function reads a file name in the minibuffer, prompting with |
4b574f3d | 1194 | @var{prompt} and providing completion. |
3e01fd9d | 1195 | |
793da230 RS |
1196 | If @var{existing} is non-@code{nil}, then the user must specify the name |
1197 | of an existing file; @key{RET} performs completion to make the name | |
1198 | valid if possible, and then refuses to exit if it is not valid. If the | |
1199 | value of @var{existing} is neither @code{nil} nor @code{t}, then | |
1200 | @key{RET} also requires confirmation after completion. If | |
1201 | @var{existing} is @code{nil}, then the name of a nonexistent file is | |
1202 | acceptable. | |
3e01fd9d RS |
1203 | |
1204 | The argument @var{directory} specifies the directory to use for | |
4b574f3d LT |
1205 | completion of relative file names. It should be an absolute directory |
1206 | name. If @code{insert-default-directory} is non-@code{nil}, | |
1207 | @var{directory} is also inserted in the minibuffer as initial input. | |
1208 | It defaults to the current buffer's value of @code{default-directory}. | |
3e01fd9d RS |
1209 | |
1210 | @c Emacs 19 feature | |
6142d1d0 RS |
1211 | If you specify @var{initial}, that is an initial file name to insert |
1212 | in the buffer (after @var{directory}, if that is inserted). In this | |
793da230 RS |
1213 | case, point goes at the beginning of @var{initial}. The default for |
1214 | @var{initial} is @code{nil}---don't insert any file name. To see what | |
6142d1d0 RS |
1215 | @var{initial} does, try the command @kbd{C-x C-v}. @strong{Please |
1216 | note:} we recommend using @var{default} rather than @var{initial} in | |
1217 | most cases. | |
3e01fd9d | 1218 | |
4b574f3d LT |
1219 | If @var{default} is non-@code{nil}, then the function returns |
1220 | @var{default} if the user exits the minibuffer with the same non-empty | |
1221 | contents that @code{read-file-name} inserted initially. The initial | |
1222 | minibuffer contents are always non-empty if | |
1223 | @code{insert-default-directory} is non-@code{nil}, as it is by | |
1224 | default. @var{default} is not checked for validity, regardless of the | |
1225 | value of @var{existing}. However, if @var{existing} is | |
1226 | non-@code{nil}, the initial minibuffer contents should be a valid file | |
1227 | (or directory) name. Otherwise @code{read-file-name} attempts | |
1228 | completion if the user exits without any editing, and does not return | |
1229 | @var{default}. @var{default} is also available through the history | |
1230 | commands. | |
1231 | ||
1232 | If @var{default} is @code{nil}, @code{read-file-name} tries to find a | |
1233 | substitute default to use in its place, which it treats in exactly the | |
1234 | same way as if it had been specified explicitly. If @var{default} is | |
1235 | @code{nil}, but @var{initial} is non-@code{nil}, then the default is | |
1236 | the absolute file name obtained from @var{directory} and | |
1237 | @var{initial}. If both @var{default} and @var{initial} are @code{nil} | |
1238 | and the buffer is visiting a file, @code{read-file-name} uses the | |
1239 | absolute file name of that file as default. If the buffer is not | |
1240 | visiting a file, then there is no default. In that case, if the user | |
1241 | types @key{RET} without any editing, @code{read-file-name} simply | |
1242 | returns the pre-inserted contents of the minibuffer. | |
1243 | ||
1244 | If the user types @key{RET} in an empty minibuffer, this function | |
1245 | returns an empty string, regardless of the value of @var{existing}. | |
1246 | This is, for instance, how the user can make the current buffer visit | |
1247 | no file using @code{M-x set-visited-file-name}. | |
1248 | ||
1c7cdff5 RS |
1249 | If @var{predicate} is non-@code{nil}, it specifies a function of one |
1250 | argument that decides which file names are acceptable completion | |
1251 | possibilities. A file name is an acceptable value if @var{predicate} | |
1252 | returns non-@code{nil} for it. | |
1253 | ||
4b574f3d LT |
1254 | @code{read-file-name} does not automatically expand file names. You |
1255 | must call @code{expand-file-name} yourself if an absolute file name is | |
1256 | required. | |
1257 | ||
177c0ea7 | 1258 | Here is an example: |
3e01fd9d RS |
1259 | |
1260 | @example | |
1261 | @group | |
1262 | (read-file-name "The file is ") | |
1263 | ||
177c0ea7 | 1264 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
1265 | ;; @r{the following appears in the minibuffer:} |
1266 | @end group | |
1267 | ||
1268 | @group | |
1269 | ---------- Buffer: Minibuffer ---------- | |
1270 | The file is /gp/gnu/elisp/@point{} | |
1271 | ---------- Buffer: Minibuffer ---------- | |
1272 | @end group | |
1273 | @end example | |
1274 | ||
1275 | @noindent | |
1276 | Typing @kbd{manual @key{TAB}} results in the following: | |
1277 | ||
1278 | @example | |
1279 | @group | |
1280 | ---------- Buffer: Minibuffer ---------- | |
1281 | The file is /gp/gnu/elisp/manual.texi@point{} | |
1282 | ---------- Buffer: Minibuffer ---------- | |
1283 | @end group | |
1284 | @end example | |
1285 | ||
1286 | @c Wordy to avoid overfull hbox in smallbook mode. | |
1287 | @noindent | |
1288 | If the user types @key{RET}, @code{read-file-name} returns the file name | |
1289 | as the string @code{"/gp/gnu/elisp/manual.texi"}. | |
1290 | @end defun | |
1291 | ||
1c7cdff5 RS |
1292 | @defun read-directory-name prompt &optional directory default existing initial |
1293 | This function is like @code{read-file-name} but allows only directory | |
1294 | names as completion possibilities. | |
4b574f3d LT |
1295 | |
1296 | If @var{default} is @code{nil} and @var{initial} is non-@code{nil}, | |
1297 | @code{read-directory-name} constructs a substitute default by | |
1298 | combining @var{directory} (or the current buffer's default directory | |
1299 | if @var{directory} is @code{nil}) and @var{initial}. If both | |
1300 | @var{default} and @var{initial} are @code{nil}, this function uses the | |
1301 | current buffer's default directory as substitute default, ignoring | |
1302 | @var{directory}. | |
1c7cdff5 RS |
1303 | @end defun |
1304 | ||
3e01fd9d | 1305 | @defopt insert-default-directory |
4b574f3d LT |
1306 | This variable is used by @code{read-file-name}, and thus, indirectly, |
1307 | by most commands reading file names. (This includes all commands that | |
1308 | use the code letters @samp{f} or @samp{F} in their interactive form. | |
1309 | @xref{Interactive Codes,, Code Characters for interactive}.) Its | |
1310 | value controls whether @code{read-file-name} starts by placing the | |
1311 | name of the default directory in the minibuffer, plus the initial file | |
1312 | name if any. If the value of this variable is @code{nil}, then | |
1313 | @code{read-file-name} does not place any initial input in the | |
1314 | minibuffer (unless you specify initial input with the @var{initial} | |
1315 | argument). In that case, the default directory is still used for | |
1316 | completion of relative file names, but is not displayed. | |
1317 | ||
1318 | If this variable is @code{nil} and the initial minibuffer contents are | |
1319 | empty, the user may have to explicitly fetch the next history element | |
1320 | to access a default value. If the variable is non-@code{nil}, the | |
1321 | initial minibuffer contents are always non-empty and the user can | |
1322 | always request a default value by immediately typing @key{RET} in an | |
1323 | unedited minibuffer. (See above.) | |
3e01fd9d RS |
1324 | |
1325 | For example: | |
1326 | ||
1327 | @example | |
1328 | @group | |
1329 | ;; @r{Here the minibuffer starts out with the default directory.} | |
1330 | (let ((insert-default-directory t)) | |
1331 | (read-file-name "The file is ")) | |
1332 | @end group | |
1333 | ||
1334 | @group | |
1335 | ---------- Buffer: Minibuffer ---------- | |
1336 | The file is ~lewis/manual/@point{} | |
1337 | ---------- Buffer: Minibuffer ---------- | |
1338 | @end group | |
1339 | ||
1340 | @group | |
1341 | ;; @r{Here the minibuffer is empty and only the prompt} | |
1342 | ;; @r{appears on its line.} | |
1343 | (let ((insert-default-directory nil)) | |
1344 | (read-file-name "The file is ")) | |
1345 | @end group | |
1346 | ||
1347 | @group | |
1348 | ---------- Buffer: Minibuffer ---------- | |
1349 | The file is @point{} | |
1350 | ---------- Buffer: Minibuffer ---------- | |
1351 | @end group | |
1352 | @end example | |
1353 | @end defopt | |
1354 | ||
1355 | @node Programmed Completion | |
1356 | @subsection Programmed Completion | |
1357 | @cindex programmed completion | |
1358 | ||
1359 | Sometimes it is not possible to create an alist or an obarray | |
1360 | containing all the intended possible completions. In such a case, you | |
1361 | can supply your own function to compute the completion of a given string. | |
1362 | This is called @dfn{programmed completion}. | |
1363 | ||
1364 | To use this feature, pass a symbol with a function definition as the | |
793da230 RS |
1365 | @var{collection} argument to @code{completing-read}. The function |
1366 | @code{completing-read} arranges to pass your completion function along | |
1367 | to @code{try-completion} and @code{all-completions}, which will then let | |
1368 | your function do all the work. | |
3e01fd9d RS |
1369 | |
1370 | The completion function should accept three arguments: | |
1371 | ||
1372 | @itemize @bullet | |
1373 | @item | |
1374 | The string to be completed. | |
1375 | ||
1376 | @item | |
1377 | The predicate function to filter possible matches, or @code{nil} if | |
1378 | none. Your function should call the predicate for each possible match, | |
1379 | and ignore the possible match if the predicate returns @code{nil}. | |
1380 | ||
1381 | @item | |
1382 | A flag specifying the type of operation. | |
1383 | @end itemize | |
1384 | ||
1385 | There are three flag values for three operations: | |
1386 | ||
1387 | @itemize @bullet | |
1388 | @item | |
1389 | @code{nil} specifies @code{try-completion}. The completion function | |
1390 | should return the completion of the specified string, or @code{t} if the | |
d595eca0 RS |
1391 | string is a unique and exact match already, or @code{nil} if the string |
1392 | matches no possibility. | |
1393 | ||
1394 | If the string is an exact match for one possibility, but also matches | |
969fe9b5 | 1395 | other longer possibilities, the function should return the string, not |
d595eca0 | 1396 | @code{t}. |
3e01fd9d RS |
1397 | |
1398 | @item | |
1399 | @code{t} specifies @code{all-completions}. The completion function | |
1400 | should return a list of all possible completions of the specified | |
1401 | string. | |
1402 | ||
1403 | @item | |
7370e0a8 | 1404 | @code{lambda} specifies @code{test-completion}. The completion |
3e01fd9d RS |
1405 | function should return @code{t} if the specified string is an exact |
1406 | match for some possibility; @code{nil} otherwise. | |
1407 | @end itemize | |
1408 | ||
1409 | It would be consistent and clean for completion functions to allow | |
bfe721d1 | 1410 | lambda expressions (lists that are functions) as well as function |
3e01fd9d | 1411 | symbols as @var{collection}, but this is impossible. Lists as |
7370e0a8 RS |
1412 | completion tables already have other meanings, and it would be |
1413 | unreliable to treat one differently just because it is also a possible | |
1414 | function. So you must arrange for any function you wish to use for | |
1415 | completion to be encapsulated in a symbol. | |
3e01fd9d RS |
1416 | |
1417 | Emacs uses programmed completion when completing file names. | |
1418 | @xref{File Name Completion}. | |
1419 | ||
4ff1926e RS |
1420 | @defmac dynamic-completion-table function |
1421 | This macro is a convenient way to write a function that can act as | |
1422 | programmed completion function. The argument @var{function} should be | |
1423 | a function that takes one argument, a string, and returns an alist of | |
1424 | possible completions of it. You can think of | |
1425 | @code{dynamic-completion-table} as a transducer between that interface | |
1426 | and the interface for programmed completion functions. | |
1427 | @end defmac | |
1428 | ||
3e01fd9d RS |
1429 | @node Yes-or-No Queries |
1430 | @section Yes-or-No Queries | |
1431 | @cindex asking the user questions | |
1432 | @cindex querying the user | |
1433 | @cindex yes-or-no questions | |
1434 | ||
1435 | This section describes functions used to ask the user a yes-or-no | |
1436 | question. The function @code{y-or-n-p} can be answered with a single | |
1437 | character; it is useful for questions where an inadvertent wrong answer | |
1438 | will not have serious consequences. @code{yes-or-no-p} is suitable for | |
1439 | more momentous questions, since it requires three or four characters to | |
1440 | answer. | |
1441 | ||
3e099569 RS |
1442 | If either of these functions is called in a command that was invoked |
1443 | using the mouse---more precisely, if @code{last-nonmenu-event} | |
1444 | (@pxref{Command Loop Info}) is either @code{nil} or a list---then it | |
1445 | uses a dialog box or pop-up menu to ask the question. Otherwise, it | |
1446 | uses keyboard input. You can force use of the mouse or use of keyboard | |
1447 | input by binding @code{last-nonmenu-event} to a suitable value around | |
1448 | the call. | |
1449 | ||
3e01fd9d RS |
1450 | Strictly speaking, @code{yes-or-no-p} uses the minibuffer and |
1451 | @code{y-or-n-p} does not; but it seems best to describe them together. | |
1452 | ||
1453 | @defun y-or-n-p prompt | |
793da230 | 1454 | This function asks the user a question, expecting input in the echo |
3e01fd9d RS |
1455 | area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the |
1456 | user types @kbd{n}. This function also accepts @key{SPC} to mean yes | |
1457 | and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like | |
1458 | @kbd{C-g}, because the question might look like a minibuffer and for | |
1459 | that reason the user might try to use @kbd{C-]} to get out. The answer | |
1460 | is a single character, with no @key{RET} needed to terminate it. Upper | |
1461 | and lower case are equivalent. | |
1462 | ||
793da230 | 1463 | ``Asking the question'' means printing @var{prompt} in the echo area, |
3e01fd9d RS |
1464 | followed by the string @w{@samp{(y or n) }}. If the input is not one of |
1465 | the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}}, | |
1466 | @kbd{@key{DEL}}, or something that quits), the function responds | |
1467 | @samp{Please answer y or n.}, and repeats the request. | |
1468 | ||
793da230 | 1469 | This function does not actually use the minibuffer, since it does not |
3e01fd9d RS |
1470 | allow editing of the answer. It actually uses the echo area (@pxref{The |
1471 | Echo Area}), which uses the same screen space as the minibuffer. The | |
1472 | cursor moves to the echo area while the question is being asked. | |
1473 | ||
793da230 | 1474 | The answers and their meanings, even @samp{y} and @samp{n}, are not |
3e01fd9d RS |
1475 | hardwired. The keymap @code{query-replace-map} specifies them. |
1476 | @xref{Search and Replace}. | |
1477 | ||
793da230 | 1478 | In the following example, the user first types @kbd{q}, which is |
3e01fd9d RS |
1479 | invalid. At the next prompt the user types @kbd{y}. |
1480 | ||
1481 | @smallexample | |
1482 | @group | |
1483 | (y-or-n-p "Do you need a lift? ") | |
1484 | ||
177c0ea7 | 1485 | ;; @r{After evaluation of the preceding expression,} |
3e01fd9d RS |
1486 | ;; @r{the following prompt appears in the echo area:} |
1487 | @end group | |
1488 | ||
1489 | @group | |
1490 | ---------- Echo area ---------- | |
177c0ea7 | 1491 | Do you need a lift? (y or n) |
3e01fd9d RS |
1492 | ---------- Echo area ---------- |
1493 | @end group | |
1494 | ||
1495 | ;; @r{If the user then types @kbd{q}, the following appears:} | |
1496 | ||
1497 | @group | |
1498 | ---------- Echo area ---------- | |
177c0ea7 | 1499 | Please answer y or n. Do you need a lift? (y or n) |
3e01fd9d RS |
1500 | ---------- Echo area ---------- |
1501 | @end group | |
1502 | ||
1503 | ;; @r{When the user types a valid answer,} | |
1504 | ;; @r{it is displayed after the question:} | |
1505 | ||
1506 | @group | |
1507 | ---------- Echo area ---------- | |
1508 | Do you need a lift? (y or n) y | |
1509 | ---------- Echo area ---------- | |
1510 | @end group | |
1511 | @end smallexample | |
1512 | ||
1513 | @noindent | |
1514 | We show successive lines of echo area messages, but only one actually | |
1515 | appears on the screen at a time. | |
1516 | @end defun | |
1517 | ||
48a58303 RS |
1518 | @defun y-or-n-p-with-timeout prompt seconds default-value |
1519 | Like @code{y-or-n-p}, except that if the user fails to answer within | |
1520 | @var{seconds} seconds, this function stops waiting and returns | |
1521 | @var{default-value}. It works by setting up a timer; see @ref{Timers}. | |
1522 | The argument @var{seconds} may be an integer or a floating point number. | |
1523 | @end defun | |
1524 | ||
3e01fd9d | 1525 | @defun yes-or-no-p prompt |
793da230 RS |
1526 | This function asks the user a question, expecting input in the |
1527 | minibuffer. It returns @code{t} if the user enters @samp{yes}, | |
1528 | @code{nil} if the user types @samp{no}. The user must type @key{RET} to | |
1529 | finalize the response. Upper and lower case are equivalent. | |
3e01fd9d | 1530 | |
793da230 | 1531 | @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area, |
3e01fd9d RS |
1532 | followed by @w{@samp{(yes or no) }}. The user must type one of the |
1533 | expected responses; otherwise, the function responds @samp{Please answer | |
1534 | yes or no.}, waits about two seconds and repeats the request. | |
1535 | ||
793da230 | 1536 | @code{yes-or-no-p} requires more work from the user than |
3e01fd9d RS |
1537 | @code{y-or-n-p} and is appropriate for more crucial decisions. |
1538 | ||
3e01fd9d RS |
1539 | Here is an example: |
1540 | ||
1541 | @smallexample | |
1542 | @group | |
1543 | (yes-or-no-p "Do you really want to remove everything? ") | |
1544 | ||
177c0ea7 JB |
1545 | ;; @r{After evaluation of the preceding expression,} |
1546 | ;; @r{the following prompt appears,} | |
3e01fd9d RS |
1547 | ;; @r{with an empty minibuffer:} |
1548 | @end group | |
1549 | ||
1550 | @group | |
1551 | ---------- Buffer: minibuffer ---------- | |
177c0ea7 | 1552 | Do you really want to remove everything? (yes or no) |
3e01fd9d RS |
1553 | ---------- Buffer: minibuffer ---------- |
1554 | @end group | |
1555 | @end smallexample | |
1556 | ||
1557 | @noindent | |
1558 | If the user first types @kbd{y @key{RET}}, which is invalid because this | |
1559 | function demands the entire word @samp{yes}, it responds by displaying | |
1560 | these prompts, with a brief pause between them: | |
1561 | ||
1562 | @smallexample | |
1563 | @group | |
1564 | ---------- Buffer: minibuffer ---------- | |
1565 | Please answer yes or no. | |
1566 | Do you really want to remove everything? (yes or no) | |
1567 | ---------- Buffer: minibuffer ---------- | |
1568 | @end group | |
1569 | @end smallexample | |
1570 | @end defun | |
1571 | ||
1572 | @node Multiple Queries | |
1573 | @section Asking Multiple Y-or-N Questions | |
1574 | ||
793da230 RS |
1575 | When you have a series of similar questions to ask, such as ``Do you |
1576 | want to save this buffer'' for each buffer in turn, you should use | |
1577 | @code{map-y-or-n-p} to ask the collection of questions, rather than | |
1578 | asking each question individually. This gives the user certain | |
1579 | convenient facilities such as the ability to answer the whole series at | |
1580 | once. | |
1581 | ||
2468d0c0 | 1582 | @defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area |
f9f59935 RS |
1583 | This function asks the user a series of questions, reading a |
1584 | single-character answer in the echo area for each one. | |
3e01fd9d RS |
1585 | |
1586 | The value of @var{list} specifies the objects to ask questions about. | |
1587 | It should be either a list of objects or a generator function. If it is | |
1588 | a function, it should expect no arguments, and should return either the | |
1589 | next object to ask about, or @code{nil} meaning stop asking questions. | |
1590 | ||
1591 | The argument @var{prompter} specifies how to ask each question. If | |
1592 | @var{prompter} is a string, the question text is computed like this: | |
1593 | ||
1594 | @example | |
1595 | (format @var{prompter} @var{object}) | |
1596 | @end example | |
1597 | ||
1598 | @noindent | |
1599 | where @var{object} is the next object to ask about (as obtained from | |
1600 | @var{list}). | |
1601 | ||
1602 | If not a string, @var{prompter} should be a function of one argument | |
63ff95ee MW |
1603 | (the next object to ask about) and should return the question text. If |
1604 | the value is a string, that is the question to ask the user. The | |
1605 | function can also return @code{t} meaning do act on this object (and | |
1606 | don't ask the user), or @code{nil} meaning ignore this object (and don't | |
1607 | ask the user). | |
3e01fd9d RS |
1608 | |
1609 | The argument @var{actor} says how to act on the answers that the user | |
1610 | gives. It should be a function of one argument, and it is called with | |
1611 | each object that the user says yes for. Its argument is always an | |
1612 | object obtained from @var{list}. | |
1613 | ||
1614 | If the argument @var{help} is given, it should be a list of this form: | |
1615 | ||
1616 | @example | |
1617 | (@var{singular} @var{plural} @var{action}) | |
1618 | @end example | |
1619 | ||
1620 | @noindent | |
1621 | where @var{singular} is a string containing a singular noun that | |
1622 | describes the objects conceptually being acted on, @var{plural} is the | |
1623 | corresponding plural noun, and @var{action} is a transitive verb | |
1624 | describing what @var{actor} does. | |
1625 | ||
1626 | If you don't specify @var{help}, the default is @code{("object" | |
1627 | "objects" "act on")}. | |
1628 | ||
1629 | Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or | |
1630 | @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip | |
1631 | that object; @kbd{!} to act on all following objects; @key{ESC} or | |
1632 | @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on | |
1633 | the current object and then exit; or @kbd{C-h} to get help. These are | |
1634 | the same answers that @code{query-replace} accepts. The keymap | |
1635 | @code{query-replace-map} defines their meaning for @code{map-y-or-n-p} | |
1636 | as well as for @code{query-replace}; see @ref{Search and Replace}. | |
1637 | ||
1638 | You can use @var{action-alist} to specify additional possible answers | |
1639 | and what they mean. It is an alist of elements of the form | |
1640 | @code{(@var{char} @var{function} @var{help})}, each of which defines one | |
1641 | additional answer. In this element, @var{char} is a character (the | |
1642 | answer); @var{function} is a function of one argument (an object from | |
1643 | @var{list}); @var{help} is a string. | |
1644 | ||
1645 | When the user responds with @var{char}, @code{map-y-or-n-p} calls | |
1646 | @var{function}. If it returns non-@code{nil}, the object is considered | |
1647 | ``acted upon'', and @code{map-y-or-n-p} advances to the next object in | |
1648 | @var{list}. If it returns @code{nil}, the prompt is repeated for the | |
1649 | same object. | |
1650 | ||
2468d0c0 DL |
1651 | Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while |
1652 | prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it | |
1653 | does not do that. | |
1654 | ||
3e099569 RS |
1655 | If @code{map-y-or-n-p} is called in a command that was invoked using the |
1656 | mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command | |
1657 | Loop Info}) is either @code{nil} or a list---then it uses a dialog box | |
1658 | or pop-up menu to ask the question. In this case, it does not use | |
1659 | keyboard input or the echo area. You can force use of the mouse or use | |
1660 | of keyboard input by binding @code{last-nonmenu-event} to a suitable | |
1661 | value around the call. | |
1662 | ||
3e01fd9d RS |
1663 | The return value of @code{map-y-or-n-p} is the number of objects acted on. |
1664 | @end defun | |
1665 | ||
e75ecfec KH |
1666 | @node Reading a Password |
1667 | @section Reading a Password | |
1668 | @cindex passwords, reading | |
1669 | ||
1670 | To read a password to pass to another program, you can use the | |
1671 | function @code{read-passwd}. | |
1672 | ||
e75ecfec KH |
1673 | @defun read-passwd prompt &optional confirm default |
1674 | This function reads a password, prompting with @var{prompt}. It does | |
1675 | not echo the password as the user types it; instead, it echoes @samp{.} | |
1676 | for each character in the password. | |
1677 | ||
1678 | The optional argument @var{confirm}, if non-@code{nil}, says to read the | |
1679 | password twice and insist it must be the same both times. If it isn't | |
1680 | the same, the user has to type it over and over until the last two | |
1681 | times match. | |
1682 | ||
1683 | The optional argument @var{default} specifies the default password to | |
1684 | return if the user enters empty input. If @var{default} is @code{nil}, | |
1685 | then @code{read-passwd} returns the null string in that case. | |
1686 | @end defun | |
1687 | ||
3e01fd9d | 1688 | @node Minibuffer Misc |
3e01fd9d RS |
1689 | @section Minibuffer Miscellany |
1690 | ||
1691 | This section describes some basic functions and variables related to | |
1692 | minibuffers. | |
1693 | ||
1694 | @deffn Command exit-minibuffer | |
1695 | This command exits the active minibuffer. It is normally bound to | |
1696 | keys in minibuffer local keymaps. | |
1697 | @end deffn | |
1698 | ||
1699 | @deffn Command self-insert-and-exit | |
1700 | This command exits the active minibuffer after inserting the last | |
1701 | character typed on the keyboard (found in @code{last-command-char}; | |
1702 | @pxref{Command Loop Info}). | |
1703 | @end deffn | |
1704 | ||
1705 | @deffn Command previous-history-element n | |
1706 | This command replaces the minibuffer contents with the value of the | |
1707 | @var{n}th previous (older) history element. | |
1708 | @end deffn | |
1709 | ||
1710 | @deffn Command next-history-element n | |
1711 | This command replaces the minibuffer contents with the value of the | |
1712 | @var{n}th more recent history element. | |
1713 | @end deffn | |
1714 | ||
2468d0c0 | 1715 | @deffn Command previous-matching-history-element pattern n |
3e01fd9d | 1716 | This command replaces the minibuffer contents with the value of the |
2468d0c0 DL |
1717 | @var{n}th previous (older) history element that matches @var{pattern} (a |
1718 | regular expression). | |
3e01fd9d RS |
1719 | @end deffn |
1720 | ||
2468d0c0 DL |
1721 | @deffn Command next-matching-history-element pattern n |
1722 | This command replaces the minibuffer contents with the value of the | |
1723 | @var{n}th next (newer) history element that matches @var{pattern} (a | |
1724 | regular expression). | |
3e01fd9d RS |
1725 | @end deffn |
1726 | ||
bfe721d1 KH |
1727 | @defun minibuffer-prompt |
1728 | This function returns the prompt string of the currently active | |
1729 | minibuffer. If no minibuffer is active, it returns @code{nil}. | |
1730 | @end defun | |
1731 | ||
2468d0c0 | 1732 | @defun minibuffer-prompt-end |
b3b044f2 | 1733 | @tindex minibuffer-prompt-end |
2a1cf636 | 1734 | This function returns the current |
8241495d | 1735 | position of the end of the minibuffer prompt, if a minibuffer is |
b3b044f2 MB |
1736 | current. Otherwise, it returns the minimum valid buffer position. |
1737 | @end defun | |
1738 | ||
1739 | @defun minibuffer-contents | |
1740 | @tindex minibuffer-contents | |
2a1cf636 | 1741 | This function returns the editable |
b3b044f2 MB |
1742 | contents of the minibuffer (that is, everything except the prompt) as |
1743 | a string, if a minibuffer is current. Otherwise, it returns the | |
1744 | entire contents of the current buffer. | |
1745 | @end defun | |
1746 | ||
1747 | @defun minibuffer-contents-no-properties | |
1748 | @tindex minibuffer-contents-no-properties | |
1749 | This is like @code{minibuffer-contents}, except that it does not copy text | |
1750 | properties, just the characters themselves. @xref{Text Properties}. | |
1751 | @end defun | |
1752 | ||
1753 | @defun delete-minibuffer-contents | |
1754 | @tindex delete-minibuffer-contents | |
2a1cf636 | 1755 | This function erases the editable |
b3b044f2 MB |
1756 | contents of the minibuffer (that is, everything except the prompt), if |
1757 | a minibuffer is current. Otherwise, it erases the entire buffer. | |
8241495d RS |
1758 | @end defun |
1759 | ||
42d9d13a | 1760 | @defun minibuffer-prompt-width |
8241495d RS |
1761 | This function returns the current display-width of the minibuffer |
1762 | prompt, if a minibuffer is current. Otherwise, it returns zero. | |
bfe721d1 KH |
1763 | @end defun |
1764 | ||
3e01fd9d RS |
1765 | @defvar minibuffer-setup-hook |
1766 | This is a normal hook that is run whenever the minibuffer is entered. | |
793da230 RS |
1767 | @xref{Hooks}. |
1768 | @end defvar | |
1769 | ||
612b4d5c | 1770 | @defvar minibuffer-exit-hook |
793da230 RS |
1771 | This is a normal hook that is run whenever the minibuffer is exited. |
1772 | @xref{Hooks}. | |
3e01fd9d RS |
1773 | @end defvar |
1774 | ||
1775 | @defvar minibuffer-help-form | |
facf1bca | 1776 | @anchor{Definition of minibuffer-help-form} |
3e01fd9d RS |
1777 | The current value of this variable is used to rebind @code{help-form} |
1778 | locally inside the minibuffer (@pxref{Help Functions}). | |
1779 | @end defvar | |
1780 | ||
4b574f3d LT |
1781 | @defun minibufferp &optional buffer-or-name |
1782 | This function returns non-@code{nil} if @var{buffer-or-name} is a | |
1783 | minibuffer. If @var{buffer-or-name} is omitted, it tests the current | |
1784 | buffer. | |
7370e0a8 RS |
1785 | @end defun |
1786 | ||
22697dac KH |
1787 | @defun active-minibuffer-window |
1788 | This function returns the currently active minibuffer window, or | |
1789 | @code{nil} if none is currently active. | |
1790 | @end defun | |
1791 | ||
3e01fd9d | 1792 | @defun minibuffer-window &optional frame |
b1895e73 | 1793 | @anchor{Definition of minibuffer-window} |
22697dac KH |
1794 | This function returns the minibuffer window used for frame @var{frame}. |
1795 | If @var{frame} is @code{nil}, that stands for the current frame. Note | |
1796 | that the minibuffer window used by a frame need not be part of that | |
1797 | frame---a frame that has no minibuffer of its own necessarily uses some | |
1798 | other frame's minibuffer window. | |
3e01fd9d RS |
1799 | @end defun |
1800 | ||
41495ddd RS |
1801 | @defun set-minibuffer-window window |
1802 | This function specifies @var{window} as the minibuffer window to use. | |
1803 | This affects where the minibuffer is displayed if you put text in it | |
1804 | without invoking the usual minibuffer commands. It has no effect on | |
1805 | the usual minibuffer input functions because they all start by | |
1806 | choosing the minibuffer window according to the current frame. | |
1807 | @end defun | |
1808 | ||
3e01fd9d | 1809 | @c Emacs 19 feature |
4b574f3d LT |
1810 | @defun window-minibuffer-p &optional window |
1811 | This function returns non-@code{nil} if @var{window} is a minibuffer | |
1812 | window. | |
1813 | @var{window} defaults to the selected window. | |
3e01fd9d RS |
1814 | @end defun |
1815 | ||
1816 | It is not correct to determine whether a given window is a minibuffer by | |
1817 | comparing it with the result of @code{(minibuffer-window)}, because | |
1818 | there can be more than one minibuffer window if there is more than one | |
1819 | frame. | |
1820 | ||
1821 | @defun minibuffer-window-active-p window | |
1822 | This function returns non-@code{nil} if @var{window}, assumed to be | |
1823 | a minibuffer window, is currently active. | |
1824 | @end defun | |
1825 | ||
1826 | @defvar minibuffer-scroll-window | |
f96bad52 | 1827 | @anchor{Definition of minibuffer-scroll-window} |
3e01fd9d RS |
1828 | If the value of this variable is non-@code{nil}, it should be a window |
1829 | object. When the function @code{scroll-other-window} is called in the | |
1830 | minibuffer, it scrolls this window. | |
1831 | @end defvar | |
1832 | ||
f460db36 RS |
1833 | @defun minibuffer-selected-window |
1834 | This function returns the window which was selected when the | |
1835 | minibuffer was entered. If selected window is not a minibuffer | |
1836 | window, it returns @code{nil}. | |
1837 | @end defun | |
1838 | ||
3e01fd9d RS |
1839 | Finally, some functions and variables deal with recursive minibuffers |
1840 | (@pxref{Recursive Editing}): | |
1841 | ||
1842 | @defun minibuffer-depth | |
1843 | This function returns the current depth of activations of the | |
1844 | minibuffer, a nonnegative integer. If no minibuffers are active, it | |
1845 | returns zero. | |
1846 | @end defun | |
1847 | ||
1848 | @defopt enable-recursive-minibuffers | |
1849 | If this variable is non-@code{nil}, you can invoke commands (such as | |
969fe9b5 RS |
1850 | @code{find-file}) that use minibuffers even while the minibuffer window |
1851 | is active. Such invocation produces a recursive editing level for a new | |
3e01fd9d RS |
1852 | minibuffer. The outer-level minibuffer is invisible while you are |
1853 | editing the inner one. | |
1854 | ||
969fe9b5 RS |
1855 | If this variable is @code{nil}, you cannot invoke minibuffer |
1856 | commands when the minibuffer window is active, not even if you switch to | |
1857 | another window to do it. | |
3e01fd9d RS |
1858 | @end defopt |
1859 | ||
1860 | @c Emacs 19 feature | |
1861 | If a command name has a property @code{enable-recursive-minibuffers} | |
793da230 | 1862 | that is non-@code{nil}, then the command can use the minibuffer to read |
4b574f3d LT |
1863 | arguments even if it is invoked from the minibuffer. A command can |
1864 | also achieve this by binding @code{enable-recursive-minibuffers} | |
1865 | to @code{t} in the interactive declaration (@pxref{Using Interactive}). | |
1866 | The minibuffer command @code{next-matching-history-element} (normally | |
1867 | @kbd{M-s} in the minibuffer) does the latter. | |
9a191eba | 1868 | |
4b574f3d | 1869 | @defun minibuffer-message string |
9a191eba | 1870 | This function displays @var{string} temporarily at the end of the |
4b574f3d LT |
1871 | minibuffer text, for two seconds, or until the next input event |
1872 | arrives, whichever comes first. | |
9a191eba | 1873 | @end defun |
ab5796a9 MB |
1874 | |
1875 | @ignore | |
1876 | arch-tag: bba7f945-9078-477f-a2ce-18818a6e1218 | |
1877 | @end ignore |