2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001
4 @c Free Software Foundation, Inc.
5 @c See the file elisp.texi for copying conditions.
6 @setfilename ../info/minibuf
7 @node Minibuffers, Command Loop, Read and Print, Top
9 @cindex arguments, reading
10 @cindex complex arguments
13 A @dfn{minibuffer} is a special buffer that Emacs commands use to read
14 arguments more complicated than the single numeric prefix argument.
15 These arguments include file names, buffer names, and command names (as
16 in @kbd{M-x}). The minibuffer is displayed on the bottom line of the
17 frame, in the same place as the echo area, but only while it is in use
18 for reading an argument.
21 * Intro to Minibuffers:: Basic information about minibuffers.
22 * Text from Minibuffer:: How to read a straight text string.
23 * Object from Minibuffer:: How to read a Lisp object or expression.
24 * Minibuffer History:: Recording previous minibuffer inputs
25 so the user can reuse them.
26 * Completion:: How to invoke and customize completion.
27 * Yes-or-No Queries:: Asking a question with a simple answer.
28 * Multiple Queries:: Asking a series of similar questions.
29 * Reading a Password:: Reading a password from the terminal.
30 * Minibuffer Misc:: Various customization hooks and variables.
33 @node Intro to Minibuffers
34 @section Introduction to Minibuffers
36 In most ways, a minibuffer is a normal Emacs buffer. Most operations
37 @emph{within} a buffer, such as editing commands, work normally in a
38 minibuffer. However, many operations for managing buffers do not apply
39 to minibuffers. The name of a minibuffer always has the form @w{@samp{
40 *Minibuf-@var{number}*}}, and it cannot be changed. Minibuffers are
41 displayed only in special windows used only for minibuffers; these
42 windows always appear at the bottom of a frame. (Sometimes frames have
43 no minibuffer window, and sometimes a special kind of frame contains
44 nothing but a minibuffer window; see @ref{Minibuffers and Frames}.)
46 The text in the minibuffer always starts with the @dfn{prompt string},
47 the text that was specified by the program that is using the minibuffer
48 to tell the user what sort of input to type. This text is marked
49 read-only so you won't accidentally delete or change it. It is also
50 marked as a field (@pxref{Fields}), so that certain motion functions,
51 including @code{beginning-of-line}, @code{forward-word},
52 @code{forward-sentence}, and @code{forward-paragraph}, stop at the
53 boundary between the prompt and the actual text. (In older Emacs
54 versions, the prompt was displayed using a special mechanism and was not
55 part of the buffer contents.)
57 The minibuffer's window is normally a single line; it grows
58 automatically if necessary if the contents require more space. You can
59 explicitly resize it temporarily with the window sizing commands; it
60 reverts to its normal size when the minibuffer is exited. You can
61 resize it permanently by using the window sizing commands in the frame's
62 other window, when the minibuffer is not active. If the frame contains
63 just a minibuffer, you can change the minibuffer's size by changing the
66 Use of the minibuffer reads input events, and that alters the values
67 of variables such as @code{this-command} and @code{last-command}
68 (@pxref{Command Loop Info}). Your program should bind them around the
69 code that uses the minibuffer, if you do not want that to change them.
71 If a command uses a minibuffer while there is an active minibuffer,
72 this is called a @dfn{recursive minibuffer}. The first minibuffer is
73 named @w{@samp{ *Minibuf-0*}}. Recursive minibuffers are named by
74 incrementing the number at the end of the name. (The names begin with a
75 space so that they won't show up in normal buffer lists.) Of several
76 recursive minibuffers, the innermost (or most recently entered) is the
77 active minibuffer. We usually call this ``the'' minibuffer. You can
78 permit or forbid recursive minibuffers by setting the variable
79 @code{enable-recursive-minibuffers} or by putting properties of that
80 name on command symbols (@pxref{Minibuffer Misc}).
82 Like other buffers, a minibuffer may use any of several local keymaps
83 (@pxref{Keymaps}); these contain various exit commands and in some cases
84 completion commands (@pxref{Completion}).
88 @code{minibuffer-local-map} is for ordinary input (no completion).
91 @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
95 @code{minibuffer-local-completion-map} is for permissive completion.
98 @code{minibuffer-local-must-match-map} is for strict completion and
99 for cautious completion.
102 When Emacs is running in batch mode, any request to read from the
103 minibuffer actually reads a line from the standard input descriptor that
104 was supplied when Emacs was started.
106 @node Text from Minibuffer
107 @section Reading Text Strings with the Minibuffer
109 Most often, the minibuffer is used to read text as a string. It can
110 also be used to read a Lisp object in textual form. The most basic
111 primitive for minibuffer input is @code{read-from-minibuffer}; it can do
114 In most cases, you should not call minibuffer input functions in the
115 middle of a Lisp function. Instead, do all minibuffer input as part of
116 reading the arguments for a command, in the @code{interactive}
117 specification. @xref{Defining Commands}.
119 @defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method
120 This function is the most general way to get input through the
121 minibuffer. By default, it accepts arbitrary text and returns it as a
122 string; however, if @var{read} is non-@code{nil}, then it uses
123 @code{read} to convert the text into a Lisp object (@pxref{Input
126 The first thing this function does is to activate a minibuffer and
127 display it with @var{prompt-string} as the prompt. This value must be a
128 string. Then the user can edit text in the minibuffer.
130 When the user types a command to exit the minibuffer,
131 @code{read-from-minibuffer} constructs the return value from the text in
132 the minibuffer. Normally it returns a string containing that text.
133 However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer}
134 reads the text and returns the resulting Lisp object, unevaluated.
135 (@xref{Input Functions}, for information about reading.)
137 The argument @var{default} specifies a default value to make available
138 through the history commands. It should be a string, or @code{nil}.
139 If non-@code{nil}, the user can access it using
140 @code{next-history-element}, usually bound in the minibuffer to
141 @kbd{M-n}. If @var{read} is non-@code{nil}, then @var{default} is
142 also used as the input to @code{read}, if the user enters empty input.
143 (If @var{read} is non-@code{nil} and @var{default} is @code{nil}, empty
144 input results in an @code{end-of-file} error.) However, in the usual
145 case (where @var{read} is @code{nil}), @code{read-from-minibuffer}
146 ignores @var{default} when the user enters empty input and returns an
147 empty string, @code{""}. In this respect, it is different from all
148 the other minibuffer input functions in this chapter.
150 If @var{keymap} is non-@code{nil}, that keymap is the local keymap to
151 use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the
152 value of @code{minibuffer-local-map} is used as the keymap. Specifying
153 a keymap is the most important way to customize the minibuffer for
154 various applications such as completion.
156 The argument @var{hist} specifies which history list variable to use
157 for saving the input and for history commands used in the minibuffer.
158 It defaults to @code{minibuffer-history}. @xref{Minibuffer History}.
160 If the variable @code{minibuffer-allow-text-properties} is
161 non-@code{nil}, then the string which is returned includes whatever text
162 properties were present in the minibuffer. Otherwise all the text
163 properties are stripped when the value is returned.
165 If the argument @var{inherit-input-method} is non-@code{nil}, then the
166 minibuffer inherits the current input method (@pxref{Input Methods}) and
167 the setting of @code{enable-multibyte-characters} (@pxref{Text
168 Representations}) from whichever buffer was current before entering the
171 If @var{initial-contents} is a string, @code{read-from-minibuffer}
172 inserts it into the minibuffer, leaving point at the end, before the
173 user starts to edit the text. The minibuffer appears with this text as
174 its initial contents.
176 Alternatively, @var{initial-contents} can be a cons cell of the form
177 @code{(@var{string} . @var{position})}. This means to insert
178 @var{string} in the minibuffer but put point at @emph{one-indexed}
179 @var{position} in the minibuffer, rather than at the end. Any integer
180 value less or equal to one puts point at the beginning of the string.
182 @strong{Usage note:} The @var{initial-contents} argument and the
183 @var{default} argument are two alternative features for more or less the
184 same job. It does not make sense to use both features in a single call
185 to @code{read-from-minibuffer}. In general, we recommend using
186 @var{default}, since this permits the user to insert the default value
187 when it is wanted, but does not burden the user with deleting it from
188 the minibuffer on other occasions. For an exception to this rule,
189 see @ref{Minibuffer History}.
192 @defun read-string prompt &optional initial history default inherit-input-method
193 This function reads a string from the minibuffer and returns it. The
194 arguments @var{prompt}, @var{initial}, @var{history} and
195 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
196 The keymap used is @code{minibuffer-local-map}.
198 The optional argument @var{default} is used as in
199 @code{read-from-minibuffer}, except that, if non-@code{nil}, it also
200 specifies a default value to return if the user enters null input. As
201 in @code{read-from-minibuffer} it should be a string, or @code{nil},
202 which is equivalent to an empty string.
204 This function is a simplified interface to the
205 @code{read-from-minibuffer} function:
209 (read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit})
212 (read-from-minibuffer @var{prompt} @var{initial} nil nil
213 @var{history} @var{default} @var{inherit})))
214 (if (and (equal value "") @var{default})
221 @defvar minibuffer-allow-text-properties
222 If this variable is @code{nil}, then @code{read-from-minibuffer} strips
223 all text properties from the minibuffer input before returning it.
224 This variable also affects @code{read-string}. However,
225 @code{read-no-blanks-input} (see below), as well as
226 @code{read-minibuffer} and related functions (@pxref{Object from
227 Minibuffer,, Reading Lisp Objects With the Minibuffer}), and all
228 functions that do minibuffer input with completion, discard text
229 properties unconditionally, regardless of the value of this variable.
232 @anchor{Definition of minibuffer-local-map}
233 @defvar minibuffer-local-map
234 This is the default local keymap for reading from the minibuffer. By
235 default, it makes the following bindings:
239 @code{exit-minibuffer}
242 @code{exit-minibuffer}
245 @code{abort-recursive-edit}
248 @code{next-history-element}
251 @code{previous-history-element}
254 @code{next-matching-history-element}
257 @code{previous-matching-history-element}
261 @c In version 18, initial is required
263 @defun read-no-blanks-input prompt &optional initial inherit-input-method
264 This function reads a string from the minibuffer, but does not allow
265 whitespace characters as part of the input: instead, those characters
266 terminate the input. The arguments @var{prompt}, @var{initial}, and
267 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
269 This is a simplified interface to the @code{read-from-minibuffer}
270 function, and passes the value of the @code{minibuffer-local-ns-map}
271 keymap as the @var{keymap} argument for that function. Since the keymap
272 @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is}
273 possible to put a space into the string, by quoting it.
275 This function discards text properties, regardless of the value of
276 @code{minibuffer-allow-text-properties}.
280 (read-no-blanks-input @var{prompt} @var{initial})
282 (let (minibuffer-allow-text-properties)
283 (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map))
288 @defvar minibuffer-local-ns-map
289 This built-in variable is the keymap used as the minibuffer local keymap
290 in the function @code{read-no-blanks-input}. By default, it makes the
291 following bindings, in addition to those of @code{minibuffer-local-map}:
295 @cindex @key{SPC} in minibuffer
296 @code{exit-minibuffer}
299 @cindex @key{TAB} in minibuffer
300 @code{exit-minibuffer}
303 @cindex @kbd{?} in minibuffer
304 @code{self-insert-and-exit}
308 @node Object from Minibuffer
309 @section Reading Lisp Objects with the Minibuffer
311 This section describes functions for reading Lisp objects with the
314 @defun read-minibuffer prompt &optional initial
315 This function reads a Lisp object using the minibuffer, and returns it
316 without evaluating it. The arguments @var{prompt} and @var{initial} are
317 used as in @code{read-from-minibuffer}.
319 This is a simplified interface to the
320 @code{read-from-minibuffer} function:
324 (read-minibuffer @var{prompt} @var{initial})
326 (let (minibuffer-allow-text-properties)
327 (read-from-minibuffer @var{prompt} @var{initial} nil t))
331 Here is an example in which we supply the string @code{"(testing)"} as
337 "Enter an expression: " (format "%s" '(testing)))
339 ;; @r{Here is how the minibuffer is displayed:}
343 ---------- Buffer: Minibuffer ----------
344 Enter an expression: (testing)@point{}
345 ---------- Buffer: Minibuffer ----------
350 The user can type @key{RET} immediately to use the initial input as a
351 default, or can edit the input.
354 @defun eval-minibuffer prompt &optional initial
355 This function reads a Lisp expression using the minibuffer, evaluates
356 it, then returns the result. The arguments @var{prompt} and
357 @var{initial} are used as in @code{read-from-minibuffer}.
359 This function simply evaluates the result of a call to
360 @code{read-minibuffer}:
364 (eval-minibuffer @var{prompt} @var{initial})
366 (eval (read-minibuffer @var{prompt} @var{initial}))
371 @defun edit-and-eval-command prompt form
372 This function reads a Lisp expression in the minibuffer, and then
373 evaluates it. The difference between this command and
374 @code{eval-minibuffer} is that here the initial @var{form} is not
375 optional and it is treated as a Lisp object to be converted to printed
376 representation rather than as a string of text. It is printed with
377 @code{prin1}, so if it is a string, double-quote characters (@samp{"})
378 appear in the initial text. @xref{Output Functions}.
380 The first thing @code{edit-and-eval-command} does is to activate the
381 minibuffer with @var{prompt} as the prompt. Then it inserts the printed
382 representation of @var{form} in the minibuffer, and lets the user edit it.
383 When the user exits the minibuffer, the edited text is read with
384 @code{read} and then evaluated. The resulting value becomes the value
385 of @code{edit-and-eval-command}.
387 In the following example, we offer the user an expression with initial
388 text which is a valid form already:
392 (edit-and-eval-command "Please edit: " '(forward-word 1))
394 ;; @r{After evaluation of the preceding expression,}
395 ;; @r{the following appears in the minibuffer:}
399 ---------- Buffer: Minibuffer ----------
400 Please edit: (forward-word 1)@point{}
401 ---------- Buffer: Minibuffer ----------
406 Typing @key{RET} right away would exit the minibuffer and evaluate the
407 expression, thus moving point forward one word.
408 @code{edit-and-eval-command} returns @code{nil} in this example.
411 @node Minibuffer History
412 @section Minibuffer History
413 @cindex minibuffer history
416 A @dfn{minibuffer history list} records previous minibuffer inputs so
417 the user can reuse them conveniently. A history list is actually a
418 symbol, not a list; it is a variable whose value is a list of strings
419 (previous inputs), most recent first.
421 There are many separate history lists, used for different kinds of
422 inputs. It's the Lisp programmer's job to specify the right history
423 list for each use of the minibuffer.
425 The basic minibuffer input functions @code{read-from-minibuffer} and
426 @code{completing-read} both accept an optional argument named @var{hist}
427 which is how you specify the history list. Here are the possible
432 Use @var{variable} (a symbol) as the history list.
434 @item (@var{variable} . @var{startpos})
435 Use @var{variable} (a symbol) as the history list, and assume that the
436 initial history position is @var{startpos} (a nonnegative integer).
438 Specifying 0 for @var{startpos} is equivalent to just specifying the
439 symbol @var{variable}. @code{previous-history-element} will display
440 the most recent element of the history list in the minibuffer. If you
441 specify a positive @var{startpos}, the minibuffer history functions
442 behave as if @code{(elt @var{variable} (1- @var{STARTPOS}))} were the
443 history element currently shown in the minibuffer. For consistency,
444 you should also specify that element of the history as the initial
448 If you don't specify @var{hist}, then the default history list
449 @code{minibuffer-history} is used. For other standard history lists,
450 see below. You can also create your own history list variable; just
451 initialize it to @code{nil} before the first use.
453 Both @code{read-from-minibuffer} and @code{completing-read} add new
454 elements to the history list automatically, and provide commands to
455 allow the user to reuse items on the list. The only thing your program
456 needs to do to use a history list is to initialize it and to pass its
457 name to the input functions when you wish. But it is safe to modify the
458 list by hand when the minibuffer input functions are not using it.
460 Emacs functions that add a new element to a history list can also
461 delete old elements if the list gets too long. The variable
462 @code{history-length} specifies the maximum length for most history
463 lists. To specify a different maximum length for a particular history
464 list, put the length in the @code{history-length} property of the
467 @defvar history-length
468 The value of this variable specifies the maximum length for all
469 history lists that don't specify their own maximum lengths. If the
470 value is @code{t}, that means there no maximum (don't delete old
474 Here are some of the standard minibuffer history list variables:
476 @defvar minibuffer-history
477 The default history list for minibuffer history input.
480 @defvar query-replace-history
481 A history list for arguments to @code{query-replace} (and similar
482 arguments to other commands).
485 @defvar file-name-history
486 A history list for file-name arguments.
489 @defvar buffer-name-history
490 A history list for buffer-name arguments.
493 @defvar regexp-history
494 A history list for regular expression arguments.
497 @defvar extended-command-history
498 A history list for arguments that are names of extended commands.
501 @defvar shell-command-history
502 A history list for arguments that are shell commands.
505 @defvar read-expression-history
506 A history list for arguments that are Lisp expressions to evaluate.
513 @dfn{Completion} is a feature that fills in the rest of a name
514 starting from an abbreviation for it. Completion works by comparing the
515 user's input against a list of valid names and determining how much of
516 the name is determined uniquely by what the user has typed. For
517 example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then
518 type the first few letters of the name of the buffer to which you wish
519 to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs
520 extends the name as far as it can.
522 Standard Emacs commands offer completion for names of symbols, files,
523 buffers, and processes; with the functions in this section, you can
524 implement completion for other kinds of names.
526 The @code{try-completion} function is the basic primitive for
527 completion: it returns the longest determined completion of a given
528 initial string, with a given set of strings to match against.
530 The function @code{completing-read} provides a higher-level interface
531 for completion. A call to @code{completing-read} specifies how to
532 determine the list of valid names. The function then activates the
533 minibuffer with a local keymap that binds a few keys to commands useful
534 for completion. Other functions provide convenient simple interfaces
535 for reading certain kinds of names with completion.
538 * Basic Completion:: Low-level functions for completing strings.
539 (These are too low level to use the minibuffer.)
540 * Minibuffer Completion:: Invoking the minibuffer with completion.
541 * Completion Commands:: Minibuffer commands that do completion.
542 * High-Level Completion:: Convenient special cases of completion
543 (reading buffer name, file name, etc.)
544 * Reading File Names:: Using completion to read file names.
545 * Programmed Completion:: Writing your own completion-function.
548 @node Basic Completion
549 @subsection Basic Completion Functions
551 The functions @code{try-completion}, @code{all-completions} and
552 @code{test-completion} have nothing in themselves to do with
553 minibuffers. We describe them in this chapter so as to keep them near
554 the higher-level completion features that do use the minibuffer.
556 @defun try-completion string collection &optional predicate
557 This function returns the longest common substring of all possible
558 completions of @var{string} in @var{collection}. The value of
559 @var{collection} must be a list of strings, an alist, an obarray, a
560 hash table, or a function that implements a virtual set of strings
563 Completion compares @var{string} against each of the permissible
564 completions specified by @var{collection}; if the beginning of the
565 permissible completion equals @var{string}, it matches. If no permissible
566 completions match, @code{try-completion} returns @code{nil}. If only
567 one permissible completion matches, and the match is exact, then
568 @code{try-completion} returns @code{t}. Otherwise, the value is the
569 longest initial sequence common to all the permissible completions that
572 If @var{collection} is an alist (@pxref{Association Lists}), the
573 permissible completions are the elements of the alist that are either
574 strings or conses whose @sc{car} is a string. Other elements of the
575 alist are ignored. (Remember that in Emacs Lisp, the elements of
576 alists do not @emph{have} to be conses.) As all elements of the alist
577 can be strings, this case actually includes lists of strings, even
578 though we usually do not think of such lists as alists.
580 @cindex obarray in completion
581 If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
582 of all symbols in the obarray form the set of permissible completions. The
583 global variable @code{obarray} holds an obarray containing the names of
584 all interned Lisp symbols.
586 Note that the only valid way to make a new obarray is to create it
587 empty and then add symbols to it one by one using @code{intern}.
588 Also, you cannot intern a given symbol in more than one obarray.
590 If @var{collection} is a hash table, then the keys that are strings
591 are the possible completions. Other keys are ignored.
593 You can also use a symbol that is a function as @var{collection}. Then
594 the function is solely responsible for performing completion;
595 @code{try-completion} returns whatever this function returns. The
596 function is called with three arguments: @var{string}, @var{predicate}
597 and @code{nil}. (The reason for the third argument is so that the same
598 function can be used in @code{all-completions} and do the appropriate
599 thing in either case.) @xref{Programmed Completion}.
601 If the argument @var{predicate} is non-@code{nil}, then it must be a
602 function of one argument, unless @var{collection} is a hash table, in
603 which case it should be a function of two arguments. It is used to
604 test each possible match, and the match is accepted only if
605 @var{predicate} returns non-@code{nil}. The argument given to
606 @var{predicate} is either a string or a cons cell (the @sc{car} of
607 which is a string) from the alist, or a symbol (@emph{not} a symbol
608 name) from the obarray. If @var{collection} is a hash table,
609 @var{predicate} is called with two arguments, the string key and the
612 In addition, to be acceptable, a completion must also match all the
613 regular expressions in @code{completion-regexp-list}. (Unless
614 @var{collection} is a function, in which case that function has to
615 handle @code{completion-regexp-list} itself.)
617 In the first of the following examples, the string @samp{foo} is
618 matched by three of the alist @sc{car}s. All of the matches begin with
619 the characters @samp{fooba}, so that is the result. In the second
620 example, there is only one possible match, and it is exact, so the value
627 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
632 (try-completion "foo" '(("barfoo" 2) ("foo" 3)))
637 In the following example, numerous symbols begin with the characters
638 @samp{forw}, and all of them begin with the word @samp{forward}. In
639 most of the symbols, this is followed with a @samp{-}, but not in all,
640 so no more than @samp{forward} can be completed.
644 (try-completion "forw" obarray)
649 Finally, in the following example, only two of the three possible
650 matches pass the predicate @code{test} (the string @samp{foobaz} is
651 too short). Both of those begin with the string @samp{foobar}.
656 (> (length (car s)) 6))
662 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
669 @defun all-completions string collection &optional predicate nospace
670 This function returns a list of all possible completions of
671 @var{string}. The arguments to this function (aside from
672 @var{nospace}) are the same as those of @code{try-completion}. Also,
673 this function uses @code{completion-regexp-list} in the same way that
674 @code{try-completion} does. The optional argument @var{nospace} only
675 matters if @var{string} is the empty string. In that case, if
676 @var{nospace} is non-@code{nil}, completions that start with a space
679 If @var{collection} is a function, it is called with three arguments:
680 @var{string}, @var{predicate} and @code{t}; then @code{all-completions}
681 returns whatever the function returns. @xref{Programmed Completion}.
683 Here is an example, using the function @code{test} shown in the
684 example for @code{try-completion}:
689 (> (length (car s)) 6))
696 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
698 @result{} ("foobar1" "foobar2")
703 @anchor{Definition of test-completion}
704 @defun test-completion string collection &optional predicate
705 This function returns non-@code{nil} if @var{string} is a valid
706 completion possibility specified by @var{collection} and
707 @var{predicate}. The arguments are the same as in
708 @code{try-completion}. For instance, if @var{collection} is a list of
709 strings, this is true if @var{string} appears in the list and
710 @var{predicate} is satisfied.
712 @code{test-completion} uses @code{completion-regexp-list} in the same
713 way that @code{try-completion} does.
715 If @var{predicate} is non-@code{nil} and if @var{collection} contains
716 several strings that are equal to each other, as determined by
717 @code{compare-strings} according to @code{completion-ignore-case},
718 then @var{predicate} should accept either all or none of them.
719 Otherwise, the return value of @code{test-completion} is essentially
722 If @var{collection} is a function, it is called with three arguments,
723 the values @var{string}, @var{predicate} and @code{lambda}; whatever
724 it returns, @code{test-completion} returns in turn.
727 @defvar completion-ignore-case
728 If the value of this variable is non-@code{nil}, Emacs does not
729 consider case significant in completion.
732 @defvar completion-regexp-list
733 This is a list of regular expressions. The completion functions only
734 consider a completion acceptable if it matches all regular expressions
735 in this list, with @code{case-fold-search} (@pxref{Searching and Case})
736 bound to the value of @code{completion-ignore-case}.
739 @defmac lazy-completion-table var fun &rest args
740 This macro provides a way to initialize the variable @var{var} as a
741 collection for completion in a lazy way, not computing its actual
742 contents until they are first needed. You use this macro to produce a
743 value that you store in @var{var}. The actual computation of the
744 proper value is done the first time you do completion using @var{var}.
745 It is done by calling @var{fun} with the arguments @var{args}. The
746 value @var{fun} returns becomes the permanent value of @var{var}.
748 Here are two examples of use:
751 (defvar foo (lazy-completion-table foo make-my-alist 'global))
753 (make-local-variable 'bar)
754 (setq bar (lazy-completion-table foo make-my-alist 'local)
758 @node Minibuffer Completion
759 @subsection Completion and the Minibuffer
761 This section describes the basic interface for reading from the
762 minibuffer with completion.
764 @defun completing-read prompt collection &optional predicate require-match initial hist default inherit-input-method
765 This function reads a string in the minibuffer, assisting the user by
766 providing completion. It activates the minibuffer with prompt
767 @var{prompt}, which must be a string.
769 The actual completion is done by passing @var{collection} and
770 @var{predicate} to the function @code{try-completion}. This happens
771 in certain commands bound in the local keymaps used for completion.
772 Some of these commands also call @code{test-completion}. Thus, if
773 @var{predicate} is non-@code{nil}, it should be compatible with
774 @var{collection} and @code{completion-ignore-case}. @xref{Definition
777 If @var{require-match} is @code{nil}, the exit commands work regardless
778 of the input in the minibuffer. If @var{require-match} is @code{t}, the
779 usual minibuffer exit commands won't exit unless the input completes to
780 an element of @var{collection}. If @var{require-match} is neither
781 @code{nil} nor @code{t}, then the exit commands won't exit unless the
782 input already in the buffer matches an element of @var{collection}.
784 However, empty input is always permitted, regardless of the value of
785 @var{require-match}; in that case, @code{completing-read} returns
786 @var{default}, or @code{""}, if @var{default} is @code{nil}. The
787 value of @var{default} (if non-@code{nil}) is also available to the
788 user through the history commands.
790 The function @code{completing-read} uses
791 @code{minibuffer-local-completion-map} as the keymap if
792 @var{require-match} is @code{nil}, and uses
793 @code{minibuffer-local-must-match-map} if @var{require-match} is
794 non-@code{nil}. @xref{Completion Commands}.
796 The argument @var{hist} specifies which history list variable to use for
797 saving the input and for minibuffer history commands. It defaults to
798 @code{minibuffer-history}. @xref{Minibuffer History}.
800 If @var{initial} is non-@code{nil}, @code{completing-read} inserts it
801 into the minibuffer as part of the input, with point at the end. Then
802 it allows the user to edit the input, providing several commands to
803 attempt completion. @var{initial} can also be a cons cell of the form
804 @code{(@var{string} . @var{position})}. In that case, point is put at
805 @emph{zero-indexed} position @var{position} in @var{string}. Note
806 that this is different from @code{read-from-minibuffer} and related
807 functions, which use a one-indexed position. In most cases, we
808 recommend using @var{default}, and not @var{initial}.
810 @strong{We discourage use of a non-@code{nil} value for
811 @var{initial}}, because it is an intrusive interface. The history
812 list feature (which did not exist when we introduced @var{initial})
813 offers a far more convenient and general way for the user to get the
814 default and edit it, and it is always available. For an exception to
815 this rule, see @ref{Minibuffer History}.
817 If the argument @var{inherit-input-method} is non-@code{nil}, then the
818 minibuffer inherits the current input method (@pxref{Input
819 Methods}) and the setting of @code{enable-multibyte-characters}
820 (@pxref{Text Representations}) from whichever buffer was current before
821 entering the minibuffer.
823 Completion ignores case when comparing the input against the possible
824 matches, if the built-in variable @code{completion-ignore-case} is
825 non-@code{nil}. @xref{Basic Completion}.
827 Here's an example of using @code{completing-read}:
833 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
838 ;; @r{After evaluation of the preceding expression,}
839 ;; @r{the following appears in the minibuffer:}
841 ---------- Buffer: Minibuffer ----------
842 Complete a foo: fo@point{}
843 ---------- Buffer: Minibuffer ----------
848 If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}},
849 @code{completing-read} returns @code{barfoo}.
851 The @code{completing-read} function binds three variables to pass
852 information to the commands that actually do completion. These
853 variables are @code{minibuffer-completion-table},
854 @code{minibuffer-completion-predicate} and
855 @code{minibuffer-completion-confirm}. For more information about them,
856 see @ref{Completion Commands}.
859 @node Completion Commands
860 @subsection Minibuffer Commands that Do Completion
862 This section describes the keymaps, commands and user options used
863 in the minibuffer to do completion. The description refers to the
864 situation when @code{partial-completion-mode} is disabled (as it is by
865 default). When enabled, this minor mode uses its own alternatives to
866 some of the commands described below.
868 @defvar minibuffer-local-completion-map
869 @code{completing-read} uses this value as the local keymap when an
870 exact match of one of the completions is not required. By default, this
871 keymap makes the following bindings:
875 @code{minibuffer-completion-help}
878 @code{minibuffer-complete-word}
881 @code{minibuffer-complete}
885 with other characters bound as in @code{minibuffer-local-map}
886 (@pxref{Definition of minibuffer-local-map}).
889 @defvar minibuffer-local-must-match-map
890 @code{completing-read} uses this value as the local keymap when an
891 exact match of one of the completions is required. Therefore, no keys
892 are bound to @code{exit-minibuffer}, the command that exits the
893 minibuffer unconditionally. By default, this keymap makes the following
898 @code{minibuffer-completion-help}
901 @code{minibuffer-complete-word}
904 @code{minibuffer-complete}
907 @code{minibuffer-complete-and-exit}
910 @code{minibuffer-complete-and-exit}
914 with other characters bound as in @code{minibuffer-local-map}.
917 @defvar minibuffer-completion-table
918 The value of this variable is the collection used for completion in
919 the minibuffer. This is the global variable that contains what
920 @code{completing-read} passes to @code{try-completion}. It is used by
921 minibuffer completion commands such as @code{minibuffer-complete-word}.
924 @defvar minibuffer-completion-predicate
925 This variable's value is the predicate that @code{completing-read}
926 passes to @code{try-completion}. The variable is also used by the other
927 minibuffer completion functions.
930 @deffn Command minibuffer-complete-word
931 This function completes the minibuffer contents by at most a single
932 word. Even if the minibuffer contents have only one completion,
933 @code{minibuffer-complete-word} does not add any characters beyond the
934 first character that is not a word constituent. @xref{Syntax Tables}.
937 @deffn Command minibuffer-complete
938 This function completes the minibuffer contents as far as possible.
941 @deffn Command minibuffer-complete-and-exit
942 This function completes the minibuffer contents, and exits if
943 confirmation is not required, i.e., if
944 @code{minibuffer-completion-confirm} is @code{nil}. If confirmation
945 @emph{is} required, it is given by repeating this command
946 immediately---the command is programmed to work without confirmation
947 when run twice in succession.
950 @defvar minibuffer-completion-confirm
951 When the value of this variable is non-@code{nil}, Emacs asks for
952 confirmation of a completion before exiting the minibuffer. The
953 function @code{minibuffer-complete-and-exit} checks the value of this
954 variable before it exits.
957 @deffn Command minibuffer-completion-help
958 This function creates a list of the possible completions of the
959 current minibuffer contents. It works by calling @code{all-completions}
960 using the value of the variable @code{minibuffer-completion-table} as
961 the @var{collection} argument, and the value of
962 @code{minibuffer-completion-predicate} as the @var{predicate} argument.
963 The list of completions is displayed as text in a buffer named
964 @samp{*Completions*}.
967 @defun display-completion-list completions
968 This function displays @var{completions} to the stream in
969 @code{standard-output}, usually a buffer. (@xref{Read and Print}, for more
970 information about streams.) The argument @var{completions} is normally
971 a list of completions just returned by @code{all-completions}, but it
972 does not have to be. Each element may be a symbol or a string, either
973 of which is simply printed. It can also be a list of two strings,
974 which is printed as if the strings were concatenated. The first of
975 the two strings is the actual completion, the second string serves as
978 This function is called by @code{minibuffer-completion-help}. The
979 most common way to use it is together with
980 @code{with-output-to-temp-buffer}, like this:
983 (with-output-to-temp-buffer "*Completions*"
984 (display-completion-list
985 (all-completions (buffer-string) my-alist)))
989 @defopt completion-auto-help
990 If this variable is non-@code{nil}, the completion commands
991 automatically display a list of possible completions whenever nothing
992 can be completed because the next character is not uniquely determined.
995 @node High-Level Completion
996 @subsection High-Level Completion Functions
998 This section describes the higher-level convenient functions for
999 reading certain sorts of names with completion.
1001 In most cases, you should not call these functions in the middle of a
1002 Lisp function. When possible, do all minibuffer input as part of
1003 reading the arguments for a command, in the @code{interactive}
1004 specification. @xref{Defining Commands}.
1006 @defun read-buffer prompt &optional default existing
1007 This function reads the name of a buffer and returns it as a string.
1008 The argument @var{default} is the default name to use, the value to
1009 return if the user exits with an empty minibuffer. If non-@code{nil},
1010 it should be a string or a buffer. It is mentioned in the prompt, but
1011 is not inserted in the minibuffer as initial input.
1013 If @var{existing} is non-@code{nil}, then the name specified must be
1014 that of an existing buffer. The usual commands to exit the minibuffer
1015 do not exit if the text is not valid, and @key{RET} does completion to
1016 attempt to find a valid name. If @var{existing} is neither @code{nil}
1017 nor @code{t}, confirmation is required after completion. (However,
1018 @var{default} is not checked for validity; it is returned, whatever it
1019 is, if the user exits with the minibuffer empty.)
1021 In the following example, the user enters @samp{minibuffer.t}, and
1022 then types @key{RET}. The argument @var{existing} is @code{t}, and the
1023 only buffer name starting with the given input is
1024 @samp{minibuffer.texi}, so that name is the value.
1027 (read-buffer "Buffer name? " "foo" t)
1029 ;; @r{After evaluation of the preceding expression,}
1030 ;; @r{the following prompt appears,}
1031 ;; @r{with an empty minibuffer:}
1035 ---------- Buffer: Minibuffer ----------
1036 Buffer name? (default foo) @point{}
1037 ---------- Buffer: Minibuffer ----------
1041 ;; @r{The user types @kbd{minibuffer.t @key{RET}}.}
1042 @result{} "minibuffer.texi"
1047 @defvar read-buffer-function
1048 This variable specifies how to read buffer names. For example, if you
1049 set this variable to @code{iswitchb-read-buffer}, all Emacs commands
1050 that call @code{read-buffer} to read a buffer name will actually use the
1051 @code{iswitchb} package to read it.
1054 @defun read-command prompt &optional default
1055 This function reads the name of a command and returns it as a Lisp
1056 symbol. The argument @var{prompt} is used as in
1057 @code{read-from-minibuffer}. Recall that a command is anything for
1058 which @code{commandp} returns @code{t}, and a command name is a symbol
1059 for which @code{commandp} returns @code{t}. @xref{Interactive Call}.
1061 The argument @var{default} specifies what to return if the user enters
1062 null input. It can be a symbol or a string; if it is a string,
1063 @code{read-command} interns it before returning it. If @var{default} is
1064 @code{nil}, that means no default has been specified; then if the user
1065 enters null input, the return value is @code{(intern "")}, that is, a
1066 symbol whose name is an empty string.
1069 (read-command "Command name? ")
1072 ;; @r{After evaluation of the preceding expression,}
1073 ;; @r{the following prompt appears with an empty minibuffer:}
1077 ---------- Buffer: Minibuffer ----------
1079 ---------- Buffer: Minibuffer ----------
1084 If the user types @kbd{forward-c @key{RET}}, then this function returns
1085 @code{forward-char}.
1087 The @code{read-command} function is a simplified interface to
1088 @code{completing-read}. It uses the variable @code{obarray} so as to
1089 complete in the set of extant Lisp symbols, and it uses the
1090 @code{commandp} predicate so as to accept only command names:
1092 @cindex @code{commandp} example
1095 (read-command @var{prompt})
1097 (intern (completing-read @var{prompt} obarray
1103 @defun read-variable prompt &optional default
1104 This function reads the name of a user variable and returns it as a
1107 The argument @var{default} specifies what to return if the user enters
1108 null input. It can be a symbol or a string; if it is a string,
1109 @code{read-variable} interns it before returning it. If @var{default}
1110 is @code{nil}, that means no default has been specified; then if the
1111 user enters null input, the return value is @code{(intern "")}.
1115 (read-variable "Variable name? ")
1117 ;; @r{After evaluation of the preceding expression,}
1118 ;; @r{the following prompt appears,}
1119 ;; @r{with an empty minibuffer:}
1123 ---------- Buffer: Minibuffer ----------
1124 Variable name? @point{}
1125 ---------- Buffer: Minibuffer ----------
1130 If the user then types @kbd{fill-p @key{RET}}, @code{read-variable}
1131 returns @code{fill-prefix}.
1133 This function is similar to @code{read-command}, but uses the
1134 predicate @code{user-variable-p} instead of @code{commandp}:
1136 @cindex @code{user-variable-p} example
1139 (read-variable @var{prompt})
1142 (completing-read @var{prompt} obarray
1143 'user-variable-p t nil))
1148 See also the functions @code{read-coding-system} and
1149 @code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems}.
1151 @node Reading File Names
1152 @subsection Reading File Names
1154 Here is another high-level completion function, designed for reading a
1155 file name. It provides special features including automatic insertion
1156 of the default directory.
1158 @defun read-file-name prompt &optional directory default existing initial predicate
1159 This function reads a file name in the minibuffer, prompting with
1160 @var{prompt} and providing completion.
1162 If @var{existing} is non-@code{nil}, then the user must specify the name
1163 of an existing file; @key{RET} performs completion to make the name
1164 valid if possible, and then refuses to exit if it is not valid. If the
1165 value of @var{existing} is neither @code{nil} nor @code{t}, then
1166 @key{RET} also requires confirmation after completion. If
1167 @var{existing} is @code{nil}, then the name of a nonexistent file is
1170 The argument @var{directory} specifies the directory to use for
1171 completion of relative file names. It should be an absolute directory
1172 name. If @code{insert-default-directory} is non-@code{nil},
1173 @var{directory} is also inserted in the minibuffer as initial input.
1174 It defaults to the current buffer's value of @code{default-directory}.
1177 If you specify @var{initial}, that is an initial file name to insert
1178 in the buffer (after @var{directory}, if that is inserted). In this
1179 case, point goes at the beginning of @var{initial}. The default for
1180 @var{initial} is @code{nil}---don't insert any file name. To see what
1181 @var{initial} does, try the command @kbd{C-x C-v}. @strong{Please
1182 note:} we recommend using @var{default} rather than @var{initial} in
1185 If @var{default} is non-@code{nil}, then the function returns
1186 @var{default} if the user exits the minibuffer with the same non-empty
1187 contents that @code{read-file-name} inserted initially. The initial
1188 minibuffer contents are always non-empty if
1189 @code{insert-default-directory} is non-@code{nil}, as it is by
1190 default. @var{default} is not checked for validity, regardless of the
1191 value of @var{existing}. However, if @var{existing} is
1192 non-@code{nil}, the initial minibuffer contents should be a valid file
1193 (or directory) name. Otherwise @code{read-file-name} attempts
1194 completion if the user exits without any editing, and does not return
1195 @var{default}. @var{default} is also available through the history
1198 If @var{default} is @code{nil}, @code{read-file-name} tries to find a
1199 substitute default to use in its place, which it treats in exactly the
1200 same way as if it had been specified explicitly. If @var{default} is
1201 @code{nil}, but @var{initial} is non-@code{nil}, then the default is
1202 the absolute file name obtained from @var{directory} and
1203 @var{initial}. If both @var{default} and @var{initial} are @code{nil}
1204 and the buffer is visiting a file, @code{read-file-name} uses the
1205 absolute file name of that file as default. If the buffer is not
1206 visiting a file, then there is no default. In that case, if the user
1207 types @key{RET} without any editing, @code{read-file-name} simply
1208 returns the pre-inserted contents of the minibuffer.
1210 If the user types @key{RET} in an empty minibuffer, this function
1211 returns an empty string, regardless of the value of @var{existing}.
1212 This is, for instance, how the user can make the current buffer visit
1213 no file using @code{M-x set-visited-file-name}.
1215 If @var{predicate} is non-@code{nil}, it specifies a function of one
1216 argument that decides which file names are acceptable completion
1217 possibilities. A file name is an acceptable value if @var{predicate}
1218 returns non-@code{nil} for it.
1220 @code{read-file-name} does not automatically expand file names. You
1221 must call @code{expand-file-name} yourself if an absolute file name is
1228 (read-file-name "The file is ")
1230 ;; @r{After evaluation of the preceding expression,}
1231 ;; @r{the following appears in the minibuffer:}
1235 ---------- Buffer: Minibuffer ----------
1236 The file is /gp/gnu/elisp/@point{}
1237 ---------- Buffer: Minibuffer ----------
1242 Typing @kbd{manual @key{TAB}} results in the following:
1246 ---------- Buffer: Minibuffer ----------
1247 The file is /gp/gnu/elisp/manual.texi@point{}
1248 ---------- Buffer: Minibuffer ----------
1252 @c Wordy to avoid overfull hbox in smallbook mode.
1254 If the user types @key{RET}, @code{read-file-name} returns the file name
1255 as the string @code{"/gp/gnu/elisp/manual.texi"}.
1258 @defun read-directory-name prompt &optional directory default existing initial
1259 This function is like @code{read-file-name} but allows only directory
1260 names as completion possibilities.
1262 If @var{default} is @code{nil} and @var{initial} is non-@code{nil},
1263 @code{read-directory-name} constructs a substitute default by
1264 combining @var{directory} (or the current buffer's default directory
1265 if @var{directory} is @code{nil}) and @var{initial}. If both
1266 @var{default} and @var{initial} are @code{nil}, this function uses the
1267 current buffer's default directory as substitute default, ignoring
1271 @defopt insert-default-directory
1272 This variable is used by @code{read-file-name}, and thus, indirectly,
1273 by most commands reading file names. (This includes all commands that
1274 use the code letters @samp{f} or @samp{F} in their interactive form.
1275 @xref{Interactive Codes,, Code Characters for interactive}.) Its
1276 value controls whether @code{read-file-name} starts by placing the
1277 name of the default directory in the minibuffer, plus the initial file
1278 name if any. If the value of this variable is @code{nil}, then
1279 @code{read-file-name} does not place any initial input in the
1280 minibuffer (unless you specify initial input with the @var{initial}
1281 argument). In that case, the default directory is still used for
1282 completion of relative file names, but is not displayed.
1284 If this variable is @code{nil} and the initial minibuffer contents are
1285 empty, the user may have to explicitly fetch the next history element
1286 to access a default value. If the variable is non-@code{nil}, the
1287 initial minibuffer contents are always non-empty and the user can
1288 always request a default value by immediately typing @key{RET} in an
1289 unedited minibuffer. (See above.)
1295 ;; @r{Here the minibuffer starts out with the default directory.}
1296 (let ((insert-default-directory t))
1297 (read-file-name "The file is "))
1301 ---------- Buffer: Minibuffer ----------
1302 The file is ~lewis/manual/@point{}
1303 ---------- Buffer: Minibuffer ----------
1307 ;; @r{Here the minibuffer is empty and only the prompt}
1308 ;; @r{appears on its line.}
1309 (let ((insert-default-directory nil))
1310 (read-file-name "The file is "))
1314 ---------- Buffer: Minibuffer ----------
1315 The file is @point{}
1316 ---------- Buffer: Minibuffer ----------
1321 @node Programmed Completion
1322 @subsection Programmed Completion
1323 @cindex programmed completion
1325 Sometimes it is not possible to create an alist or an obarray
1326 containing all the intended possible completions. In such a case, you
1327 can supply your own function to compute the completion of a given string.
1328 This is called @dfn{programmed completion}.
1330 To use this feature, pass a symbol with a function definition as the
1331 @var{collection} argument to @code{completing-read}. The function
1332 @code{completing-read} arranges to pass your completion function along
1333 to @code{try-completion} and @code{all-completions}, which will then let
1334 your function do all the work.
1336 The completion function should accept three arguments:
1340 The string to be completed.
1343 The predicate function to filter possible matches, or @code{nil} if
1344 none. Your function should call the predicate for each possible match,
1345 and ignore the possible match if the predicate returns @code{nil}.
1348 A flag specifying the type of operation.
1351 There are three flag values for three operations:
1355 @code{nil} specifies @code{try-completion}. The completion function
1356 should return the completion of the specified string, or @code{t} if the
1357 string is a unique and exact match already, or @code{nil} if the string
1358 matches no possibility.
1360 If the string is an exact match for one possibility, but also matches
1361 other longer possibilities, the function should return the string, not
1365 @code{t} specifies @code{all-completions}. The completion function
1366 should return a list of all possible completions of the specified
1370 @code{lambda} specifies @code{test-completion}. The completion
1371 function should return @code{t} if the specified string is an exact
1372 match for some possibility; @code{nil} otherwise.
1375 It would be consistent and clean for completion functions to allow
1376 lambda expressions (lists that are functions) as well as function
1377 symbols as @var{collection}, but this is impossible. Lists as
1378 completion tables already have other meanings, and it would be
1379 unreliable to treat one differently just because it is also a possible
1380 function. So you must arrange for any function you wish to use for
1381 completion to be encapsulated in a symbol.
1383 Emacs uses programmed completion when completing file names.
1384 @xref{File Name Completion}.
1386 @defmac dynamic-completion-table function
1387 This macro is a convenient way to write a function that can act as
1388 programmed completion function. The argument @var{function} should be
1389 a function that takes one argument, a string, and returns an alist of
1390 possible completions of it. You can think of
1391 @code{dynamic-completion-table} as a transducer between that interface
1392 and the interface for programmed completion functions.
1395 @node Yes-or-No Queries
1396 @section Yes-or-No Queries
1397 @cindex asking the user questions
1398 @cindex querying the user
1399 @cindex yes-or-no questions
1401 This section describes functions used to ask the user a yes-or-no
1402 question. The function @code{y-or-n-p} can be answered with a single
1403 character; it is useful for questions where an inadvertent wrong answer
1404 will not have serious consequences. @code{yes-or-no-p} is suitable for
1405 more momentous questions, since it requires three or four characters to
1408 If either of these functions is called in a command that was invoked
1409 using the mouse---more precisely, if @code{last-nonmenu-event}
1410 (@pxref{Command Loop Info}) is either @code{nil} or a list---then it
1411 uses a dialog box or pop-up menu to ask the question. Otherwise, it
1412 uses keyboard input. You can force use of the mouse or use of keyboard
1413 input by binding @code{last-nonmenu-event} to a suitable value around
1416 Strictly speaking, @code{yes-or-no-p} uses the minibuffer and
1417 @code{y-or-n-p} does not; but it seems best to describe them together.
1419 @defun y-or-n-p prompt
1420 This function asks the user a question, expecting input in the echo
1421 area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the
1422 user types @kbd{n}. This function also accepts @key{SPC} to mean yes
1423 and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like
1424 @kbd{C-g}, because the question might look like a minibuffer and for
1425 that reason the user might try to use @kbd{C-]} to get out. The answer
1426 is a single character, with no @key{RET} needed to terminate it. Upper
1427 and lower case are equivalent.
1429 ``Asking the question'' means printing @var{prompt} in the echo area,
1430 followed by the string @w{@samp{(y or n) }}. If the input is not one of
1431 the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}},
1432 @kbd{@key{DEL}}, or something that quits), the function responds
1433 @samp{Please answer y or n.}, and repeats the request.
1435 This function does not actually use the minibuffer, since it does not
1436 allow editing of the answer. It actually uses the echo area (@pxref{The
1437 Echo Area}), which uses the same screen space as the minibuffer. The
1438 cursor moves to the echo area while the question is being asked.
1440 The answers and their meanings, even @samp{y} and @samp{n}, are not
1441 hardwired. The keymap @code{query-replace-map} specifies them.
1442 @xref{Search and Replace}.
1444 In the following example, the user first types @kbd{q}, which is
1445 invalid. At the next prompt the user types @kbd{y}.
1449 (y-or-n-p "Do you need a lift? ")
1451 ;; @r{After evaluation of the preceding expression,}
1452 ;; @r{the following prompt appears in the echo area:}
1456 ---------- Echo area ----------
1457 Do you need a lift? (y or n)
1458 ---------- Echo area ----------
1461 ;; @r{If the user then types @kbd{q}, the following appears:}
1464 ---------- Echo area ----------
1465 Please answer y or n. Do you need a lift? (y or n)
1466 ---------- Echo area ----------
1469 ;; @r{When the user types a valid answer,}
1470 ;; @r{it is displayed after the question:}
1473 ---------- Echo area ----------
1474 Do you need a lift? (y or n) y
1475 ---------- Echo area ----------
1480 We show successive lines of echo area messages, but only one actually
1481 appears on the screen at a time.
1484 @defun y-or-n-p-with-timeout prompt seconds default-value
1485 Like @code{y-or-n-p}, except that if the user fails to answer within
1486 @var{seconds} seconds, this function stops waiting and returns
1487 @var{default-value}. It works by setting up a timer; see @ref{Timers}.
1488 The argument @var{seconds} may be an integer or a floating point number.
1491 @defun yes-or-no-p prompt
1492 This function asks the user a question, expecting input in the
1493 minibuffer. It returns @code{t} if the user enters @samp{yes},
1494 @code{nil} if the user types @samp{no}. The user must type @key{RET} to
1495 finalize the response. Upper and lower case are equivalent.
1497 @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area,
1498 followed by @w{@samp{(yes or no) }}. The user must type one of the
1499 expected responses; otherwise, the function responds @samp{Please answer
1500 yes or no.}, waits about two seconds and repeats the request.
1502 @code{yes-or-no-p} requires more work from the user than
1503 @code{y-or-n-p} and is appropriate for more crucial decisions.
1509 (yes-or-no-p "Do you really want to remove everything? ")
1511 ;; @r{After evaluation of the preceding expression,}
1512 ;; @r{the following prompt appears,}
1513 ;; @r{with an empty minibuffer:}
1517 ---------- Buffer: minibuffer ----------
1518 Do you really want to remove everything? (yes or no)
1519 ---------- Buffer: minibuffer ----------
1524 If the user first types @kbd{y @key{RET}}, which is invalid because this
1525 function demands the entire word @samp{yes}, it responds by displaying
1526 these prompts, with a brief pause between them:
1530 ---------- Buffer: minibuffer ----------
1531 Please answer yes or no.
1532 Do you really want to remove everything? (yes or no)
1533 ---------- Buffer: minibuffer ----------
1538 @node Multiple Queries
1539 @section Asking Multiple Y-or-N Questions
1541 When you have a series of similar questions to ask, such as ``Do you
1542 want to save this buffer'' for each buffer in turn, you should use
1543 @code{map-y-or-n-p} to ask the collection of questions, rather than
1544 asking each question individually. This gives the user certain
1545 convenient facilities such as the ability to answer the whole series at
1548 @defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area
1549 This function asks the user a series of questions, reading a
1550 single-character answer in the echo area for each one.
1552 The value of @var{list} specifies the objects to ask questions about.
1553 It should be either a list of objects or a generator function. If it is
1554 a function, it should expect no arguments, and should return either the
1555 next object to ask about, or @code{nil} meaning stop asking questions.
1557 The argument @var{prompter} specifies how to ask each question. If
1558 @var{prompter} is a string, the question text is computed like this:
1561 (format @var{prompter} @var{object})
1565 where @var{object} is the next object to ask about (as obtained from
1568 If not a string, @var{prompter} should be a function of one argument
1569 (the next object to ask about) and should return the question text. If
1570 the value is a string, that is the question to ask the user. The
1571 function can also return @code{t} meaning do act on this object (and
1572 don't ask the user), or @code{nil} meaning ignore this object (and don't
1575 The argument @var{actor} says how to act on the answers that the user
1576 gives. It should be a function of one argument, and it is called with
1577 each object that the user says yes for. Its argument is always an
1578 object obtained from @var{list}.
1580 If the argument @var{help} is given, it should be a list of this form:
1583 (@var{singular} @var{plural} @var{action})
1587 where @var{singular} is a string containing a singular noun that
1588 describes the objects conceptually being acted on, @var{plural} is the
1589 corresponding plural noun, and @var{action} is a transitive verb
1590 describing what @var{actor} does.
1592 If you don't specify @var{help}, the default is @code{("object"
1593 "objects" "act on")}.
1595 Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or
1596 @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip
1597 that object; @kbd{!} to act on all following objects; @key{ESC} or
1598 @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on
1599 the current object and then exit; or @kbd{C-h} to get help. These are
1600 the same answers that @code{query-replace} accepts. The keymap
1601 @code{query-replace-map} defines their meaning for @code{map-y-or-n-p}
1602 as well as for @code{query-replace}; see @ref{Search and Replace}.
1604 You can use @var{action-alist} to specify additional possible answers
1605 and what they mean. It is an alist of elements of the form
1606 @code{(@var{char} @var{function} @var{help})}, each of which defines one
1607 additional answer. In this element, @var{char} is a character (the
1608 answer); @var{function} is a function of one argument (an object from
1609 @var{list}); @var{help} is a string.
1611 When the user responds with @var{char}, @code{map-y-or-n-p} calls
1612 @var{function}. If it returns non-@code{nil}, the object is considered
1613 ``acted upon'', and @code{map-y-or-n-p} advances to the next object in
1614 @var{list}. If it returns @code{nil}, the prompt is repeated for the
1617 Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while
1618 prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it
1621 If @code{map-y-or-n-p} is called in a command that was invoked using the
1622 mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command
1623 Loop Info}) is either @code{nil} or a list---then it uses a dialog box
1624 or pop-up menu to ask the question. In this case, it does not use
1625 keyboard input or the echo area. You can force use of the mouse or use
1626 of keyboard input by binding @code{last-nonmenu-event} to a suitable
1627 value around the call.
1629 The return value of @code{map-y-or-n-p} is the number of objects acted on.
1632 @node Reading a Password
1633 @section Reading a Password
1634 @cindex passwords, reading
1636 To read a password to pass to another program, you can use the
1637 function @code{read-passwd}.
1639 @defun read-passwd prompt &optional confirm default
1640 This function reads a password, prompting with @var{prompt}. It does
1641 not echo the password as the user types it; instead, it echoes @samp{.}
1642 for each character in the password.
1644 The optional argument @var{confirm}, if non-@code{nil}, says to read the
1645 password twice and insist it must be the same both times. If it isn't
1646 the same, the user has to type it over and over until the last two
1649 The optional argument @var{default} specifies the default password to
1650 return if the user enters empty input. If @var{default} is @code{nil},
1651 then @code{read-passwd} returns the null string in that case.
1654 @node Minibuffer Misc
1655 @section Minibuffer Miscellany
1657 This section describes some basic functions and variables related to
1660 @deffn Command exit-minibuffer
1661 This command exits the active minibuffer. It is normally bound to
1662 keys in minibuffer local keymaps.
1665 @deffn Command self-insert-and-exit
1666 This command exits the active minibuffer after inserting the last
1667 character typed on the keyboard (found in @code{last-command-char};
1668 @pxref{Command Loop Info}).
1671 @deffn Command previous-history-element n
1672 This command replaces the minibuffer contents with the value of the
1673 @var{n}th previous (older) history element.
1676 @deffn Command next-history-element n
1677 This command replaces the minibuffer contents with the value of the
1678 @var{n}th more recent history element.
1681 @deffn Command previous-matching-history-element pattern n
1682 This command replaces the minibuffer contents with the value of the
1683 @var{n}th previous (older) history element that matches @var{pattern} (a
1684 regular expression).
1687 @deffn Command next-matching-history-element pattern n
1688 This command replaces the minibuffer contents with the value of the
1689 @var{n}th next (newer) history element that matches @var{pattern} (a
1690 regular expression).
1693 @defun minibuffer-prompt
1694 This function returns the prompt string of the currently active
1695 minibuffer. If no minibuffer is active, it returns @code{nil}.
1698 @defun minibuffer-prompt-end
1699 @tindex minibuffer-prompt-end
1700 This function, available starting in Emacs 21, returns the current
1701 position of the end of the minibuffer prompt, if a minibuffer is
1702 current. Otherwise, it returns the minimum valid buffer position.
1705 @defun minibuffer-contents
1706 @tindex minibuffer-contents
1707 This function, available starting in Emacs 21, returns the editable
1708 contents of the minibuffer (that is, everything except the prompt) as
1709 a string, if a minibuffer is current. Otherwise, it returns the
1710 entire contents of the current buffer.
1713 @defun minibuffer-contents-no-properties
1714 @tindex minibuffer-contents-no-properties
1715 This is like @code{minibuffer-contents}, except that it does not copy text
1716 properties, just the characters themselves. @xref{Text Properties}.
1719 @defun delete-minibuffer-contents
1720 @tindex delete-minibuffer-contents
1721 This function, available starting in Emacs 21, erases the editable
1722 contents of the minibuffer (that is, everything except the prompt), if
1723 a minibuffer is current. Otherwise, it erases the entire buffer.
1726 @defun minibuffer-prompt-width
1727 This function returns the current display-width of the minibuffer
1728 prompt, if a minibuffer is current. Otherwise, it returns zero.
1731 @defvar minibuffer-setup-hook
1732 This is a normal hook that is run whenever the minibuffer is entered.
1736 @defvar minibuffer-exit-hook
1737 This is a normal hook that is run whenever the minibuffer is exited.
1741 @defvar minibuffer-help-form
1742 The current value of this variable is used to rebind @code{help-form}
1743 locally inside the minibuffer (@pxref{Help Functions}).
1746 @defun minibufferp &optional buffer-or-name
1747 This function returns non-@code{nil} if @var{buffer-or-name} is a
1748 minibuffer. If @var{buffer-or-name} is omitted, it tests the current
1752 @defun active-minibuffer-window
1753 This function returns the currently active minibuffer window, or
1754 @code{nil} if none is currently active.
1757 @defun minibuffer-window &optional frame
1758 This function returns the minibuffer window used for frame @var{frame}.
1759 If @var{frame} is @code{nil}, that stands for the current frame. Note
1760 that the minibuffer window used by a frame need not be part of that
1761 frame---a frame that has no minibuffer of its own necessarily uses some
1762 other frame's minibuffer window.
1765 @defun set-minibuffer-window window
1766 This function specifies @var{window} as the minibuffer window to use.
1767 This affects where the minibuffer is displayed if you put text in it
1768 without invoking the usual minibuffer commands. It has no effect on
1769 the usual minibuffer input functions because they all start by
1770 choosing the minibuffer window according to the current frame.
1774 @defun window-minibuffer-p &optional window
1775 This function returns non-@code{nil} if @var{window} is a minibuffer
1777 @var{window} defaults to the selected window.
1780 It is not correct to determine whether a given window is a minibuffer by
1781 comparing it with the result of @code{(minibuffer-window)}, because
1782 there can be more than one minibuffer window if there is more than one
1785 @defun minibuffer-window-active-p window
1786 This function returns non-@code{nil} if @var{window}, assumed to be
1787 a minibuffer window, is currently active.
1790 @defvar minibuffer-scroll-window
1791 If the value of this variable is non-@code{nil}, it should be a window
1792 object. When the function @code{scroll-other-window} is called in the
1793 minibuffer, it scrolls this window.
1796 @defun minibuffer-selected-window
1797 This function returns the window which was selected when the
1798 minibuffer was entered. If selected window is not a minibuffer
1799 window, it returns @code{nil}.
1802 Finally, some functions and variables deal with recursive minibuffers
1803 (@pxref{Recursive Editing}):
1805 @defun minibuffer-depth
1806 This function returns the current depth of activations of the
1807 minibuffer, a nonnegative integer. If no minibuffers are active, it
1811 @defopt enable-recursive-minibuffers
1812 If this variable is non-@code{nil}, you can invoke commands (such as
1813 @code{find-file}) that use minibuffers even while the minibuffer window
1814 is active. Such invocation produces a recursive editing level for a new
1815 minibuffer. The outer-level minibuffer is invisible while you are
1816 editing the inner one.
1818 If this variable is @code{nil}, you cannot invoke minibuffer
1819 commands when the minibuffer window is active, not even if you switch to
1820 another window to do it.
1824 If a command name has a property @code{enable-recursive-minibuffers}
1825 that is non-@code{nil}, then the command can use the minibuffer to read
1826 arguments even if it is invoked from the minibuffer. A command can
1827 also achieve this by binding @code{enable-recursive-minibuffers}
1828 to @code{t} in the interactive declaration (@pxref{Using Interactive}).
1829 The minibuffer command @code{next-matching-history-element} (normally
1830 @kbd{M-s} in the minibuffer) does the latter.
1832 @defun minibuffer-message string
1833 This function displays @var{string} temporarily at the end of the
1834 minibuffer text, for two seconds, or until the next input event
1835 arrives, whichever comes first.
1839 arch-tag: bba7f945-9078-477f-a2ce-18818a6e1218