2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
4 @c See the file elisp.texi for copying conditions.
5 @setfilename ../info/minibuf
6 @node Minibuffers, Command Loop, Streams, Top
8 @cindex arguments, reading
9 @cindex complex arguments
12 A @dfn{minibuffer} is a special buffer that Emacs commands use to read
13 arguments more complicated than the single numeric prefix argument.
14 These arguments include file names, buffer names, and command names (as
15 in @kbd{M-x}). The minibuffer is displayed on the bottom line of the
16 screen, in the same place as the echo area, but only while it is in
17 use for reading an argument.
20 * Intro to Minibuffers:: Basic information about minibuffers.
21 * Text from Minibuffer:: How to read a straight text string.
22 * Object from Minibuffer:: How to read a Lisp object or expression.
23 * Minibuffer History:: Recording previous minibuffer inputs
24 so the user can reuse them.
25 * Completion:: How to invoke and customize completion.
26 * Yes-or-No Queries:: Asking a question with a simple answer.
27 * Multiple Queries:: Asking a series of similar questions.
28 * Minibuffer Misc:: Various customization hooks and variables.
31 @node Intro to Minibuffers
32 @section Introduction to Minibuffers
34 In most ways, a minibuffer is a normal Emacs buffer. Most operations
35 @emph{within} a buffer, such as editing commands, work normally in a
36 minibuffer. However, many operations for managing buffers do not apply
37 to minibuffers. The name of a minibuffer always has the form @w{@samp{
38 *Minibuf-@var{number}}}, and it cannot be changed. Minibuffers are
39 displayed only in special windows used only for minibuffers; these
40 windows always appear at the bottom of a frame. (Sometime frames have
41 no minibuffer window, and sometimes a special kind of frame contains
42 nothing but a minibuffer window; see @ref{Minibuffers and Frames}.)
44 The minibuffers window is normally a single line. You can resize it
45 temporarily with the window sizing commands; it reverts to its normal
46 size when the minibuffer is exited. You can resize it permanently by
47 using the window sizing commands in the frame's other window, when the
48 minibuffer is not active. If the frame contains just a minibuffer, you
49 can change the minibuffer's size by changing the frame's size.
51 If a command uses a minibuffer while there is an active minibuffer,
52 this is called a @dfn{recursive minibuffer}. The first minibuffer is
53 named @w{@samp{ *Minibuf-0*}}. Recursive minibuffers are named by
54 incrementing the number at the end of the name. (The names begin with a
55 space so that they won't show up in normal buffer lists.) Of several
56 recursive minibuffers, the innermost (or most recently entered) is the
57 active minibuffer. We usually call this ``the'' minibuffer. You can
58 permit or forbid recursive minibuffers by setting the variable
59 @code{enable-recursive-minibuffers} or by putting properties of that
60 name on command symbols (@pxref{Minibuffer Misc}).
62 Like other buffers, a minibuffer may use any of several local keymaps
63 (@pxref{Keymaps}); these contain various exit commands and in some cases
64 completion commands. @xref{Completion}.
68 @code{minibuffer-local-map} is for ordinary input (no completion).
71 @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
72 just like @key{RET}. This is used mainly for Mocklisp compatibility.
75 @code{minibuffer-local-completion-map} is for permissive completion.
78 @code{minibuffer-local-must-match-map} is for strict completion and
79 for cautious completion.
82 @node Text from Minibuffer
83 @section Reading Text Strings with the Minibuffer
85 Most often, the minibuffer is used to read text which is returned as a
86 string. It can also be used to read a Lisp object in textual form. The
87 most basic primitive for minibuffer input is
88 @code{read-from-minibuffer}; it can do either one.
90 @defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist
91 This function is the most general way to get input through the
92 minibuffer. By default, it accepts arbitrary text and returns it as a
93 string; however, if @var{read} is non-@code{nil}, then it uses
94 @code{read} to convert the text into a Lisp object (@pxref{Input
97 The first thing this function does is to activate a minibuffer and
98 display it with @var{prompt-string} as the prompt. This value must be a
101 Then, if @var{initial-contents} is a string, @code{read-from-minibuffer}
102 inserts it into the minibuffer, leaving point at the end. The
103 minibuffer appears with this text as its contents.
106 The value of @var{initial-contents} may also be a cons cell of the form
107 @code{(@var{string} . @var{position})}. This means to insert
108 @var{string} in the minibuffer but put point @var{position} characters
109 from the beginning, rather than at the end.
111 If @var{keymap} is non-@code{nil}, that keymap is the local keymap to
112 use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the
113 value of @code{minibuffer-local-map} is used as the keymap. Specifying
114 a keymap is the most important way to customize the minibuffer for
115 various applications such as completion.
117 The argument @var{hist} specifies which history list variable to use
118 for saving the input and for history commands used in the minibuffer.
119 It defaults to @code{minibuffer-history}. @xref{Minibuffer History}.
121 When the user types a command to exit the minibuffer,
122 @code{read-from-minibuffer} uses the text in the minibuffer to produce
123 its return value. Normally it simply makes a string containing that
124 text. However, if @var{read} is non-@code{nil},
125 @code{read-from-minibuffer} reads the text and returns the resulting
126 Lisp object, unevaluated. (@xref{Input Functions}, for information
130 @defun read-string prompt &optional initial
131 This function reads a string from the minibuffer and returns it. The
132 arguments @var{prompt} and @var{initial} are used as in
133 @code{read-from-minibuffer}. The keymap used is
134 @code{minibuffer-local-map}.
136 This is a simplified interface to the
137 @code{read-from-minibuffer} function:
141 (read-string @var{prompt} @var{initial})
143 (read-from-minibuffer @var{prompt} @var{initial} nil nil)
148 @defvar minibuffer-local-map
149 This is the default local keymap for reading from the minibuffer. By
150 default, it makes the following bindings:
154 @code{exit-minibuffer}
157 @code{exit-minibuffer}
160 @code{abort-recursive-edit}
163 @code{next-history-element}
166 @code{previous-history-element}
169 @code{next-matching-history-element}
172 @code{previous-matching-history-element}
176 @c In version 18, initial is required
178 @defun read-no-blanks-input prompt &optional initial
179 This function reads a string from the minibuffer, but does not allow
180 whitespace characters as part of the input: instead, those characters
181 terminate the input. The arguments @var{prompt} and @var{initial} are
182 used as in @code{read-from-minibuffer}.
184 This is a simplified interface to the @code{read-from-minibuffer}
185 function, and passes the value of the @code{minibuffer-local-ns-map}
186 keymap as the @var{keymap} argument for that function. Since the keymap
187 @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is}
188 possible to put a space into the string, by quoting it.
192 (read-no-blanks-input @var{prompt} @var{initial})
194 (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map)
199 @defvar minibuffer-local-ns-map
200 This built-in variable is the keymap used as the minibuffer local keymap
201 in the function @code{read-no-blanks-input}. By default, it makes the
206 @code{exit-minibuffer}
209 @cindex @key{SPC} in minibuffer
210 @code{exit-minibuffer}
213 @cindex @key{TAB} in minibuffer
214 @code{exit-minibuffer}
217 @code{exit-minibuffer}
220 @code{abort-recursive-edit}
223 @cindex @kbd{?} in minibuffer
224 @code{self-insert-and-exit}
226 @item @kbd{M-n} and @kbd{M-p}
227 @code{next-history-element} and @code{previous-history-element}
230 @code{next-matching-history-element}
233 @code{previous-matching-history-element}
237 @node Object from Minibuffer
238 @section Reading Lisp Objects with the Minibuffer
240 This section describes functions for reading Lisp objects with the
243 @defun read-minibuffer prompt &optional initial
244 This function reads a Lisp object in the minibuffer and returns it,
245 without evaluating it. The arguments @var{prompt} and @var{initial} are
246 used as in @code{read-from-minibuffer}; in particular, @var{initial}
247 must be a string or @code{nil}.
249 This is a simplified interface to the
250 @code{read-from-minibuffer} function:
254 (read-minibuffer @var{prompt} @var{initial})
256 (read-from-minibuffer @var{prompt} @var{initial} nil t)
260 Here is an example in which we supply the string @code{"(testing)"} as
266 "Enter an expression: " (format "%s" '(testing)))
268 ;; @r{Here is how the minibuffer is displayed:}
272 ---------- Buffer: Minibuffer ----------
273 Enter an expression: (testing)@point{}
274 ---------- Buffer: Minibuffer ----------
279 The user can type @key{RET} immediately to use the initial input as a
280 default, or can edit the input.
283 @defun eval-minibuffer prompt &optional initial
284 This function reads a Lisp expression in the minibuffer, evaluates it,
285 then returns the result. The arguments @var{prompt} and @var{initial}
286 are used as in @code{read-from-minibuffer}.
288 This function simply evaluates the result of a call to
289 @code{read-minibuffer}:
293 (eval-minibuffer @var{prompt} @var{initial})
295 (eval (read-minibuffer @var{prompt} @var{initial}))
300 @defun edit-and-eval-command prompt form
301 This function reads a Lisp expression in the minibuffer, and then
302 evaluates it. The difference between this command and
303 @code{eval-minibuffer} is that here the initial @var{form} is not
304 optional and it is treated as a Lisp object to be converted to printed
305 representation rather than as a string of text. It is printed with
306 @code{prin1}, so if it is a string, double-quote characters (@samp{"})
307 appear in the initial text. @xref{Output Functions}.
309 The first thing @code{edit-and-eval-command} does is to activate the
310 minibuffer with @var{prompt} as the prompt. Then it inserts the printed
311 representation of @var{form} in the minibuffer, and lets the user edit.
312 When the user exits the minibuffer, the edited text is read with
313 @code{read} and then evaluated. The resulting value becomes the value
314 of @code{edit-and-eval-command}.
316 In the following example, we offer the user an expression with initial
317 text which is a valid form already:
321 (edit-and-eval-command "Please edit: " '(forward-word 1))
323 ;; @r{After evaluating the preceding expression,}
324 ;; @r{the following appears in the minibuffer:}
328 ---------- Buffer: Minibuffer ----------
329 Please edit: (forward-word 1)@point{}
330 ---------- Buffer: Minibuffer ----------
335 Typing @key{RET} right away would exit the minibuffer and evaluate the
336 expression, thus moving point forward one word.
337 @code{edit-and-eval-command} returns @code{nil} in this example.
340 @node Minibuffer History
341 @section Minibuffer History
342 @cindex minibuffer history
345 A @dfn{minibuffer history list} records previous minibuffer inputs so
346 the user can reuse them conveniently. A history list is a symbol, a
347 variable whose value is a list of strings (previous inputs), most recent
350 There are many separate history lists, used for different kinds of
351 inputs. It's the Lisp programmer's job to specify the right history
352 list for each use of the minibuffer.
354 The basic minibuffer input functions @code{read-from-minibuffer} and
355 @code{completing-read} both accept an optional argument named @var{hist}
356 which is how you specify the history list. Here are the possible
361 Use @var{variable} (a symbol) as the history list.
363 @item (@var{variable} . @var{startpos})
364 Use @var{variable} (a symbol) as the history list, and assume that the
365 initial history position is @var{startpos} (an integer, counting from
366 zero which specifies the most recent element of the history).
368 If you specify @var{startpos}, then you should also specify that element
369 of the history as the initial minibuffer contents, for consistency.
372 If you don't specify @var{hist}, then the default history list
373 @code{minibuffer-history} is used. For other standard history lists,
374 see below. You can also create your own history list variable; just
375 initialize it to @code{nil} before the first use.
377 Both @code{read-from-minibuffer} and @code{completing-read} add new
378 elements to the history list automatically, and provide commands to
379 allow the user to reuse items on the list. The only thing your program
380 needs to do to use a history list is to initialize it and to pass its
381 name to the input functions when you wish. But it is safe to modify the
382 list by hand when the minibuffer input functions are not using it.
384 @defvar minibuffer-history
385 The default history list for minibuffer history input.
388 @defvar query-replace-history
389 A history list for arguments to @code{query-replace} (and similar
390 arguments to other commands).
393 @defvar file-name-history
394 A history list for file name arguments.
397 @defvar regexp-history
398 A history list for regular expression arguments.
401 @defvar extended-command-history
402 A history list for arguments that are names of extended commands.
405 @defvar shell-command-history
406 A history list for arguments that are shell commands.
409 @defvar read-expression-history
410 A history list for arguments that are Lisp expressions to evaluate.
417 @dfn{Completion} is a feature that fills in the rest of a name
418 starting from an abbreviation for it. Completion works by comparing the
419 user's input against a list of valid names and determining how much of
420 the name is determined uniquely by what the user has typed. For
421 example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then
422 type the first few letters of the name of the buffer to which you wish
423 to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs
424 extends the name as far as it can.
426 Standard Emacs commands offer completion for names of symbols, files,
427 buffers, and processes; with the functions in this section, you can
428 implement completion for other kinds of names.
430 The @code{try-completion} function is the basic primitive for
431 completion: it returns the longest determined completion of a given
432 initial string, with a given set of strings to match against.
434 The function @code{completing-read} provides a higher-level interface
435 for completion. A call to @code{completing-read} specifies how to
436 determine the list of valid names. The function then activates the
437 minibuffer with a local keymap that binds a few keys to commands useful
438 for completion. Other functions provide convenient simple interfaces
439 for reading certain kinds of names with completion.
442 * Basic Completion:: Low-level functions for completing strings.
443 (These are too low level to use the minibuffer.)
444 * Minibuffer Completion:: Invoking the minibuffer with completion.
445 * Completion Commands:: Minibuffer commands that do completion.
446 * High-Level Completion:: Convenient special cases of completion
447 (reading buffer name, file name, etc.)
448 * Reading File Names:: Using completion to read file names.
449 * Programmed Completion:: Finding the completions for a given file name.
452 @node Basic Completion
453 @subsection Basic Completion Functions
455 @defun try-completion string collection &optional predicate
456 This function returns the longest common substring of all possible
457 completions of @var{string} in @var{collection}. The value of
458 @var{collection} must be an alist, an obarray, or a function which
459 implements a virtual set of strings (see below).
461 Completion compares @var{string} against each of the permissible
462 completions specified by @var{collection}; if the beginning of the
463 permissible completion equals @var{string}, it matches. If no permissible
464 completions match, @code{try-completion} returns @code{nil}. If only
465 one permissible completion matches, and the match is exact, then
466 @code{try-completion} returns @code{t}. Otherwise, the value is the
467 longest initial sequence common to all the permissible completions that
470 If @var{collection} is an alist (@pxref{Association Lists}), the
471 @sc{car}s of the alist elements form the set of permissible completions.
473 @cindex obarray in completion
474 If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
475 of all symbols in the obarray form the set of permissible completions. The
476 global variable @code{obarray} holds an obarray containing the names of
477 all interned Lisp symbols.
479 Note that the only valid way to make a new obarray is to create it
480 empty and then add symbols to it one by one using @code{intern}.
481 Also, you cannot intern a given symbol in more than one obarray.
483 If the argument @var{predicate} is non-@code{nil}, then it must be a
484 function of one argument. It is used to test each possible match, and
485 the match is accepted only if @var{predicate} returns non-@code{nil}.
486 The argument given to @var{predicate} is either a cons cell from the alist
487 (the @sc{car} of which is a string) or else it is a symbol (@emph{not} a
488 symbol name) from the obarray.
490 You can also use a function symbol as @var{collection}. Then the
491 function is solely responsible for performing completion;
492 @code{try-completion} returns whatever this function returns. The
493 function is called with three arguments: @var{string}, @var{predicate}
494 and @code{nil}. (The reason for the third argument is so that the same
495 function can be used in @code{all-completions} and do the appropriate
496 thing in either case.) @xref{Programmed Completion}.
498 In the first of the following examples, the string @samp{foo} is
499 matched by three of the alist @sc{car}s. All of the matches begin with
500 the characters @samp{fooba}, so that is the result. In the second
501 example, there is only one possible match, and it is exact, so the value
508 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
513 (try-completion "foo" '(("barfoo" 2) ("foo" 3)))
518 In the following example, numerous symbols begin with the characters
519 @samp{forw}, and all of them begin with the word @samp{forward}. In
520 most of the symbols, this is followed with a @samp{-}, but not in all,
521 so no more than @samp{forward} can be completed.
525 (try-completion "forw" obarray)
530 Finally, in the following example, only two of the three possible
531 matches pass the predicate @code{test} (the string @samp{foobaz} is
532 too short). Both of those begin with the string @samp{foobar}.
537 (> (length (car s)) 6))
543 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
550 @defun all-completions string collection &optional predicate
551 This function returns a list of all possible completions of
552 @var{string}. The parameters to this function are the same as to
553 @code{try-completion}.
555 If @var{collection} is a function, it is called with three arguments:
556 @var{string}, @var{predicate} and @code{t}; then @code{all-completions}
557 returns whatever the function returns. @xref{Programmed Completion}.
559 Here is an example, using the function @code{test} shown in the
560 example for @code{try-completion}:
565 (> (length (car s)) 6))
572 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
574 @result{} ("foobar1" "foobar2")
579 @defvar completion-ignore-case
580 If the value of this variable is
581 non-@code{nil}, Emacs does not consider case significant in completion.
584 The two functions @code{try-completion} and @code{all-completions}
585 have nothing in themselves to do with minibuffers. We describe them in
586 this chapter so as to keep them near the higher-level completion
587 features that do use the minibuffer.
589 @node Minibuffer Completion
590 @subsection Completion and the Minibuffer
592 This section describes the basic interface for reading from the
593 minibuffer with completion.
595 @defun completing-read prompt collection &optional predicate require-match initial hist
596 This function reads a string in the minibuffer, assisting the user by
597 providing completion. It activates the minibuffer with prompt
598 @var{prompt}, which must be a string. If @var{initial} is
599 non-@code{nil}, @code{completing-read} inserts it into the minibuffer as
600 part of the input. Then it allows the user to edit the input, providing
601 several commands to attempt completion.
603 The actual completion is done by passing @var{collection} and
604 @var{predicate} to the function @code{try-completion}. This happens in
605 certain commands bound in the local keymaps used for completion.
607 If @var{require-match} is @code{t}, the usual minibuffer exit commands
608 won't exit unless the input completes to an element of @var{collection}.
609 If @var{require-match} is neither @code{nil} nor @code{t}, then the exit
610 commands won't exit unless the input typed is itself an element of
613 The function @code{completing-read} works by calling
614 @code{read-minibuffer}. It uses @code{minibuffer-local-completion-map}
615 as the keymap if @var{require-match} is @code{nil}, and uses
616 @code{minibuffer-local-must-match-map} if @var{require-match} is
619 The argument @var{hist} specifies which history list variable to use for
620 saving the input and for minibuffer history commands. It defaults to
621 @code{minibuffer-history}. @xref{Minibuffer History}.
623 Completion ignores case when comparing the input against the possible
624 matches, if the built-in variable @code{completion-ignore-case} is
625 non-@code{nil}. @xref{Basic Completion}.
627 Here's an example of using @code{completing-read}:
633 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
638 ;; @r{After evaluating the preceding expression,}
639 ;; @r{the following appears in the minibuffer:}
641 ---------- Buffer: Minibuffer ----------
642 Complete a foo: fo@point{}
643 ---------- Buffer: Minibuffer ----------
648 If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}},
649 @code{completing-read} returns @code{barfoo}.
651 The @code{completing-read} function binds three variables to pass
652 information to the commands which actually do completion. Here they
656 @item minibuffer-completion-table
657 This variable is bound to the @var{collection} argument. It is passed
658 to the @code{try-completion} function.
660 @item minibuffer-completion-predicate
661 This variable is bound to the @var{predicate} argument. It is passed to
662 the @code{try-completion} function.
664 @item minibuffer-completion-confirm
665 This variable is bound to the @var{require-match} argument. It is used
666 in the @code{minibuffer-complete-and-exit} function.
670 @node Completion Commands
671 @subsection Minibuffer Commands That Do Completion
673 This section describes the keymaps, commands and user options used in
674 the minibuffer to do completion.
676 @defvar minibuffer-local-completion-map
677 @code{completing-read} uses this value as the local keymap when an
678 exact match of one of the completions is not required. By default, this
679 keymap makes the following bindings:
683 @code{minibuffer-completion-help}
686 @code{minibuffer-complete-word}
689 @code{minibuffer-complete}
693 with other characters bound as in @code{minibuffer-local-map}.
696 @defvar minibuffer-local-must-match-map
697 @code{completing-read} uses this value as the local keymap when an
698 exact match of one of the completions is required. Therefore, no keys
699 are bound to @code{exit-minibuffer}, the command which exits the
700 minibuffer unconditionally. By default, this keymap makes the following
705 @code{minibuffer-completion-help}
708 @code{minibuffer-complete-word}
711 @code{minibuffer-complete}
714 @code{minibuffer-complete-and-exit}
717 @code{minibuffer-complete-and-exit}
721 with other characters bound as in @code{minibuffer-local-map}.
724 @defvar minibuffer-completion-table
725 The value of this variable is the alist or obarray used for completion
726 in the minibuffer. This is the global variable that contains what
727 @code{completing-read} passes to @code{try-completion}. It is used by
728 minibuffer completion commands such as @code{minibuffer-complete-word}.
731 @defvar minibuffer-completion-predicate
732 This variable's value is the predicate that @code{completing-read}
733 passes to @code{try-completion}. The variable is also used by the other
734 minibuffer completion functions.
737 @deffn Command minibuffer-complete-word
738 This function completes the minibuffer contents by at most a single
739 word. Even if the minibuffer contents have only one completion,
740 @code{minibuffer-complete-word} does not add any characters beyond the
741 first character that is not a word constituent. @xref{Syntax Tables}.
744 @deffn Command minibuffer-complete
745 This function completes the minibuffer contents as far as possible.
748 @deffn Command minibuffer-complete-and-exit
749 This function completes the minibuffer contents, and exits if
750 confirmation is not required, i.e., if
751 @code{minibuffer-completion-confirm} is non-@code{nil}. If confirmation
752 @emph{is} required, it is given by repeating this command immediately.
755 @defvar minibuffer-completion-confirm
756 When the value of this variable is non-@code{nil}, Emacs asks for
757 confirmation of a completion before exiting the minibuffer. The
758 function @code{minibuffer-complete-and-exit} checks the value of this
759 variable before it exits.
762 @deffn Command minibuffer-completion-help
763 This function creates a list of the possible completions of the
764 current minibuffer contents. It works by calling @code{all-completions}
765 using the value of the variable @code{minibuffer-completion-table} as
766 the @var{collection} argument, and the value of
767 @code{minibuffer-completion-predicate} as the @var{predicate} argument.
768 The list of completions is displayed as text in a buffer named
769 @samp{*Completions*}.
772 @defun display-completion-list completions
773 This function displays @var{completions} to the stream in
774 @code{standard-output}, usually a buffer. (@xref{Streams}, for more
775 information about streams.) The argument @var{completions} is normally
776 a list of completions just returned by @code{all-completions}, but it
777 does not have to be. Each element may be a symbol or a string, either
778 of which is simply printed, or a list of two strings, which is printed
779 as if the strings were concatenated.
781 This function is called by @code{minibuffer-completion-help}. The
782 most common way to use it is together with
783 @code{with-output-to-temp-buffer}, like this:
786 (with-output-to-temp-buffer "*Completions*"
787 (display-completion-list
788 (all-completions (buffer-string) my-alist)))
792 @defopt completion-auto-help
793 If this variable is non-@code{nil}, the completion commands
794 automatically display a list of possible completions whenever nothing
795 can be completed because the next character is not uniquely determined.
798 @node High-Level Completion
799 @subsection High-Level Completion Functions
801 This section describes the higher-level convenient functions for
802 reading certain sorts of names with completion.
804 @defun read-buffer prompt &optional default existing
805 This function reads the name of a buffer and returns it as a string.
806 The argument @var{default} is the default name to use, the value to
807 return if the user exits with an empty minibuffer. If non-@code{nil},
808 it should be a string or a buffer. It is mentioned in the prompt, but
809 is not inserted in the minibuffer as initial input.
811 If @var{existing} is non-@code{nil}, then the name specified must be
812 that of an existing buffer. The usual commands to exit the
813 minibuffer do not exit if the text is not valid, and @key{RET} does
814 completion to attempt to find a valid name. (However, @var{default} is
815 not checked for this; it is returned, whatever it is, if the user exits
816 with the minibuffer empty.)
818 In the following example, the user enters @samp{minibuffer.t}, and
819 then types @key{RET}. The argument @var{existing} is @code{t}, and the
820 only buffer name starting with the given input is
821 @samp{minibuffer.texi}, so that name is the value.
824 (read-buffer "Buffer name? " "foo" t)
826 ;; @r{After evaluating the preceding expression,}
827 ;; @r{the following prompt appears,}
828 ;; @r{with an empty minibuffer:}
832 ---------- Buffer: Minibuffer ----------
833 Buffer name? (default foo) @point{}
834 ---------- Buffer: Minibuffer ----------
838 ;; @r{The user types @kbd{minibuffer.t @key{RET}}.}
839 @result{} "minibuffer.texi"
844 @defun read-command prompt
845 This function reads the name of a command and returns it as a Lisp
846 symbol. The argument @var{prompt} is used as in
847 @code{read-from-minibuffer}. Recall that a command is anything for
848 which @code{commandp} returns @code{t}, and a command name is a symbol
849 for which @code{commandp} returns @code{t}. @xref{Interactive Call}.
852 (read-command "Command name? ")
855 ;; @r{After evaluating the preceding expression,}
856 ;; @r{the following prompt appears with an empty minibuffer:}
860 ---------- Buffer: Minibuffer ----------
862 ---------- Buffer: Minibuffer ----------
867 If the user types @kbd{forward-c @key{RET}}, then this function returns
870 The @code{read-command} function is a simplified interface to the
871 function @code{completing-read}. It uses the variable @code{obarray} so
872 as to complete in the set of extant Lisp symbols, and it uses the
873 @code{commandp} predicate so as to accept only command names:
875 @cindex @code{commandp} example
878 (read-command @var{prompt})
880 (intern (completing-read @var{prompt} obarray
886 @defun read-variable prompt
887 This function reads the name of a user variable and returns it as a
892 (read-variable "Variable name? ")
894 ;; @r{After evaluating the preceding expression,}
895 ;; @r{the following prompt appears,}
896 ;; @r{with an empty minibuffer:}
900 ---------- Buffer: Minibuffer ----------
901 Variable name? @point{}
902 ---------- Buffer: Minibuffer ----------
907 If the user then types @kbd{fill-p @key{RET}}, @code{read-variable}
908 returns @code{fill-prefix}.
910 This function is similar to @code{read-command}, but uses the
911 predicate @code{user-variable-p} instead of @code{commandp}:
913 @cindex @code{user-variable-p} example
916 (read-variable @var{prompt})
919 (completing-read @var{prompt} obarray
920 'user-variable-p t nil))
925 @node Reading File Names
926 @subsection Reading File Names
928 Here is another high-level completion function, designed for reading a
929 file name. It provides special features including automatic insertion
930 of the default directory.
932 @defun read-file-name prompt &optional directory default existing initial
933 This function reads a file name in the minibuffer, prompting with
934 @var{prompt} and providing completion. If @var{default} is
935 non-@code{nil}, then the function returns @var{default} if the user just
938 If @var{existing} is non-@code{nil}, then the name must refer to an
939 existing file; then @key{RET} performs completion to make the name valid
940 if possible, and then refuses to exit if it is not valid. If the value
941 of @var{existing} is neither @code{nil} nor @code{t}, then @key{RET}
942 also requires confirmation after completion.
944 The argument @var{directory} specifies the directory to use for
945 completion of relative file names. Usually it is inserted in the
946 minibuffer as initial input as well. It defaults to the current
947 buffer's value of @code{default-directory}.
950 If you specify @var{initial}, that is an initial file name to insert in
951 the buffer along with @var{directory}. In this case, point goes after
952 @var{directory}, before @var{initial}. The default for @var{initial} is
953 @code{nil}---don't insert any file name. To see what @var{initial}
954 does, try the command @kbd{C-x C-v}.
960 (read-file-name "The file is ")
962 ;; @r{After evaluating the preceding expression,}
963 ;; @r{the following appears in the minibuffer:}
967 ---------- Buffer: Minibuffer ----------
968 The file is /gp/gnu/elisp/@point{}
969 ---------- Buffer: Minibuffer ----------
974 Typing @kbd{manual @key{TAB}} results in the following:
978 ---------- Buffer: Minibuffer ----------
979 The file is /gp/gnu/elisp/manual.texi@point{}
980 ---------- Buffer: Minibuffer ----------
984 @c Wordy to avoid overfull hbox in smallbook mode.
986 If the user types @key{RET}, @code{read-file-name} returns the file name
987 as the string @code{"/gp/gnu/elisp/manual.texi"}.
990 @defopt insert-default-directory
991 This variable is used by @code{read-file-name}. Its value controls
992 whether @code{read-file-name} starts by placing the name of the default
993 directory in the minibuffer, plus the initial file name if any. If the
994 value of this variable is @code{nil}, then @code{read-file-name} does
995 not place any initial input in the minibuffer. In that case, the
996 default directory is still used for completion of relative file names,
997 but is not displayed.
1003 ;; @r{Here the minibuffer starts out with the default directory.}
1004 (let ((insert-default-directory t))
1005 (read-file-name "The file is "))
1009 ---------- Buffer: Minibuffer ----------
1010 The file is ~lewis/manual/@point{}
1011 ---------- Buffer: Minibuffer ----------
1015 ;; @r{Here the minibuffer is empty and only the prompt}
1016 ;; @r{appears on its line.}
1017 (let ((insert-default-directory nil))
1018 (read-file-name "The file is "))
1022 ---------- Buffer: Minibuffer ----------
1023 The file is @point{}
1024 ---------- Buffer: Minibuffer ----------
1029 @node Programmed Completion
1030 @subsection Programmed Completion
1031 @cindex programmed completion
1033 Sometimes it is not possible to create an alist or an obarray
1034 containing all the intended possible completions. In such a case, you
1035 can supply your own function to compute the completion of a given string.
1036 This is called @dfn{programmed completion}.
1038 To use this feature, pass a symbol with a function definition as the
1039 @var{collection} argument to @code{completing-read}. This function
1040 arranges to pass your completion function along to @code{try-completion}
1041 and @code{all-completions}, which will then let your function do all the
1044 The completion function should accept three arguments:
1048 The string to be completed.
1051 The predicate function to filter possible matches, or @code{nil} if
1052 none. Your function should call the predicate for each possible match,
1053 and ignore the possible match if the predicate returns @code{nil}.
1056 A flag specifying the type of operation.
1059 There are three flag values for three operations:
1063 @code{nil} specifies @code{try-completion}. The completion function
1064 should return the completion of the specified string, or @code{t} if the
1065 string is an exact match already, or @code{nil} if the string matches no
1069 @code{t} specifies @code{all-completions}. The completion function
1070 should return a list of all possible completions of the specified
1074 @code{lambda} specifies a test for an exact match. The completion
1075 function should return @code{t} if the specified string is an exact
1076 match for some possibility; @code{nil} otherwise.
1079 It would be consistent and clean for completion functions to allow
1080 lambda expressions (lists which are functions) as well as function
1081 symbols as @var{collection}, but this is impossible. Lists as
1082 completion tables are already assigned another meaning---as alists. It
1083 would be unreliable to fail to handle an alist normally because it is
1084 also a possible function. So you must arrange for any function you wish
1085 to use for completion to be encapsulated in a symbol.
1087 Emacs uses programmed completion when completing file names.
1088 @xref{File Name Completion}.
1090 @node Yes-or-No Queries
1091 @section Yes-or-No Queries
1092 @cindex asking the user questions
1093 @cindex querying the user
1094 @cindex yes-or-no questions
1096 This section describes functions used to ask the user a yes-or-no
1097 question. The function @code{y-or-n-p} can be answered with a single
1098 character; it is useful for questions where an inadvertent wrong answer
1099 will not have serious consequences. @code{yes-or-no-p} is suitable for
1100 more momentous questions, since it requires three or four characters to
1103 Strictly speaking, @code{yes-or-no-p} uses the minibuffer and
1104 @code{y-or-n-p} does not; but it seems best to describe them together.
1106 @defun y-or-n-p prompt
1107 This function asks the user a question, expecting input in the echo
1108 area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the
1109 user types @kbd{n}. This function also accepts @key{SPC} to mean yes
1110 and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like
1111 @kbd{C-g}, because the question might look like a minibuffer and for
1112 that reason the user might try to use @kbd{C-]} to get out. The answer
1113 is a single character, with no @key{RET} needed to terminate it. Upper
1114 and lower case are equivalent.
1116 ``Asking the question'' means printing @var{prompt} in the echo area,
1117 followed by the string @w{@samp{(y or n) }}. If the input is not one of
1118 the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}},
1119 @kbd{@key{DEL}}, or something that quits), the function responds
1120 @samp{Please answer y or n.}, and repeats the request.
1122 This function does not actually use the minibuffer, since it does not
1123 allow editing of the answer. It actually uses the echo area (@pxref{The
1124 Echo Area}), which uses the same screen space as the minibuffer. The
1125 cursor moves to the echo area while the question is being asked.
1127 The answers and their meanings, even @samp{y} and @samp{n}, are not
1128 hardwired. The keymap @code{query-replace-map} specifies them.
1129 @xref{Search and Replace}.
1131 If @code{y-or-n-p} is called in a command that was invoked using the
1132 mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command
1133 Loop Info}) is either @code{nil} or a mouse event---then it uses a
1134 dialog box or pop-up menu to ask the question. In this case, it does
1135 not use keyboard input or the echo area.
1137 In the following example, the user first types @kbd{q}, which is
1138 invalid. At the next prompt the user types @kbd{y}.
1142 (y-or-n-p "Do you need a lift? ")
1144 ;; @r{After evaluating the preceding expression,}
1145 ;; @r{the following prompt appears in the echo area:}
1149 ---------- Echo area ----------
1150 Do you need a lift? (y or n)
1151 ---------- Echo area ----------
1154 ;; @r{If the user then types @kbd{q}, the following appears:}
1157 ---------- Echo area ----------
1158 Please answer y or n. Do you need a lift? (y or n)
1159 ---------- Echo area ----------
1162 ;; @r{When the user types a valid answer,}
1163 ;; @r{it is displayed after the question:}
1166 ---------- Echo area ----------
1167 Do you need a lift? (y or n) y
1168 ---------- Echo area ----------
1173 We show successive lines of echo area messages, but only one actually
1174 appears on the screen at a time.
1177 @defun yes-or-no-p prompt
1178 This function asks the user a question, expecting input in minibuffer.
1179 It returns @code{t} if the user enters @samp{yes}, @code{nil} if the
1180 user types @samp{no}. The user must type @key{RET} to finalize the
1181 response. Upper and lower case are equivalent.
1183 @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area,
1184 followed by @w{@samp{(yes or no) }}. The user must type one of the
1185 expected responses; otherwise, the function responds @samp{Please answer
1186 yes or no.}, waits about two seconds and repeats the request.
1188 @code{yes-or-no-p} requires more work from the user than
1189 @code{y-or-n-p} and is appropriate for more crucial decisions.
1191 If @code{yes-or-no-p} is called in a command that was invoked using
1192 the mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command
1193 Loop Info}) is either @code{nil} or a mouse event---then it uses a
1194 dialog box or pop-up menu to ask the question. In this case, it does
1195 not use keyboard input or the echo area.
1201 (yes-or-no-p "Do you really want to remove everything? ")
1203 ;; @r{After evaluating the preceding expression,}
1204 ;; @r{the following prompt appears,}
1205 ;; @r{with an empty minibuffer:}
1209 ---------- Buffer: minibuffer ----------
1210 Do you really want to remove everything? (yes or no)
1211 ---------- Buffer: minibuffer ----------
1216 If the user first types @kbd{y @key{RET}}, which is invalid because this
1217 function demands the entire word @samp{yes}, it responds by displaying
1218 these prompts, with a brief pause between them:
1222 ---------- Buffer: minibuffer ----------
1223 Please answer yes or no.
1224 Do you really want to remove everything? (yes or no)
1225 ---------- Buffer: minibuffer ----------
1230 @node Multiple Queries
1231 @section Asking Multiple Y-or-N Questions
1233 @defun map-y-or-n-p prompter actor list &optional help action-alist
1234 This function, new in Emacs 19, asks the user a series of questions,
1235 reading a single-character answer in the echo area for each one.
1237 The value of @var{list} specifies the objects to ask questions about.
1238 It should be either a list of objects or a generator function. If it is
1239 a function, it should expect no arguments, and should return either the
1240 next object to ask about, or @code{nil} meaning stop asking questions.
1242 The argument @var{prompter} specifies how to ask each question. If
1243 @var{prompter} is a string, the question text is computed like this:
1246 (format @var{prompter} @var{object})
1250 where @var{object} is the next object to ask about (as obtained from
1253 If not a string, @var{prompter} should be a function of one argument
1254 (the next object to ask about) and should return the question text.
1256 The argument @var{actor} says how to act on the answers that the user
1257 gives. It should be a function of one argument, and it is called with
1258 each object that the user says yes for. Its argument is always an
1259 object obtained from @var{list}.
1261 If the argument @var{help} is given, it should be a list of this form:
1264 (@var{singular} @var{plural} @var{action})
1268 where @var{singular} is a string containing a singular noun that
1269 describes the objects conceptually being acted on, @var{plural} is the
1270 corresponding plural noun, and @var{action} is a transitive verb
1271 describing what @var{actor} does.
1273 If you don't specify @var{help}, the default is @code{("object"
1274 "objects" "act on")}.
1276 Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or
1277 @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip
1278 that object; @kbd{!} to act on all following objects; @key{ESC} or
1279 @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on
1280 the current object and then exit; or @kbd{C-h} to get help. These are
1281 the same answers that @code{query-replace} accepts. The keymap
1282 @code{query-replace-map} defines their meaning for @code{map-y-or-n-p}
1283 as well as for @code{query-replace}; see @ref{Search and Replace}.
1285 You can use @var{action-alist} to specify additional possible answers
1286 and what they mean. It is an alist of elements of the form
1287 @code{(@var{char} @var{function} @var{help})}, each of which defines one
1288 additional answer. In this element, @var{char} is a character (the
1289 answer); @var{function} is a function of one argument (an object from
1290 @var{list}); @var{help} is a string.
1292 When the user responds with @var{char}, @code{map-y-or-n-p} calls
1293 @var{function}. If it returns non-@code{nil}, the object is considered
1294 ``acted upon'', and @code{map-y-or-n-p} advances to the next object in
1295 @var{list}. If it returns @code{nil}, the prompt is repeated for the
1298 The return value of @code{map-y-or-n-p} is the number of objects acted on.
1301 @node Minibuffer Misc
1302 @comment node-name, next, previous, up
1303 @section Minibuffer Miscellany
1305 This section describes some basic functions and variables related to
1308 @deffn Command exit-minibuffer
1309 This command exits the active minibuffer. It is normally bound to
1310 keys in minibuffer local keymaps.
1313 @deffn Command self-insert-and-exit
1314 This command exits the active minibuffer after inserting the last
1315 character typed on the keyboard (found in @code{last-command-char};
1316 @pxref{Command Loop Info}).
1319 @deffn Command previous-history-element n
1320 This command replaces the minibuffer contents with the value of the
1321 @var{n}th previous (older) history element.
1324 @deffn Command next-history-element n
1325 This command replaces the minibuffer contents with the value of the
1326 @var{n}th more recent history element.
1329 @deffn Command previous-matching-history-element pattern
1330 This command replaces the minibuffer contents with the value of the
1331 previous (older) history element that matches @var{pattern}.
1334 @deffn Command next-matching-history-element pattern
1335 This command replaces the minibuffer contents with the value of the
1336 next (newer) history element that matches @var{pattern}.
1339 @defvar minibuffer-setup-hook
1340 This is a normal hook that is run whenever the minibuffer is entered.
1343 @defvar minibuffer-help-form
1344 The current value of this variable is used to rebind @code{help-form}
1345 locally inside the minibuffer (@pxref{Help Functions}).
1348 @defun minibuffer-window &optional frame
1349 This function returns the window that is used for the minibuffer. In
1350 Emacs 18, there is one and only one minibuffer window; this window
1351 always exists and cannot be deleted. In Emacs 19, each frame can have
1352 its own minibuffer, and this function returns the minibuffer window used
1353 for frame @var{frame} (which defaults to the currently selected frame).
1357 @defun window-minibuffer-p window
1358 This function returns non-@code{nil} if @var{window} is a minibuffer window.
1361 It is not correct to determine whether a given window is a minibuffer by
1362 comparing it with the result of @code{(minibuffer-window)}, because
1363 there can be more than one minibuffer window if there is more than one
1366 @defun minibuffer-window-active-p window
1367 This function returns non-@code{nil} if @var{window}, assumed to be
1368 a minibuffer window, is currently active.
1371 @defvar minibuffer-scroll-window
1372 If the value of this variable is non-@code{nil}, it should be a window
1373 object. When the function @code{scroll-other-window} is called in the
1374 minibuffer, it scrolls this window.
1377 Finally, some functions and variables deal with recursive minibuffers
1378 (@pxref{Recursive Editing}):
1380 @defun minibuffer-depth
1381 This function returns the current depth of activations of the
1382 minibuffer, a nonnegative integer. If no minibuffers are active, it
1386 @defopt enable-recursive-minibuffers
1387 If this variable is non-@code{nil}, you can invoke commands (such as
1388 @code{find-file}) which use minibuffers even while in the minibuffer
1389 window. Such invocation produces a recursive editing level for a new
1390 minibuffer. The outer-level minibuffer is invisible while you are
1391 editing the inner one.
1393 This variable only affects invoking the minibuffer while the
1394 minibuffer window is selected. If you switch windows while in the
1395 minibuffer, you can always invoke minibuffer commands while some other
1400 If a command name has a property @code{enable-recursive-minibuffers}
1401 which is non-@code{nil}, then the command can use the minibuffer to read
1402 arguments even if it is invoked from the minibuffer. The minibuffer
1403 command @code{next-matching-history-element} (normally bound to
1404 @kbd{M-s} in the minibuffer) uses this feature.