2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999,
5 @c Free Software Foundation, Inc.
6 @c See the file elisp.texi for copying conditions.
7 @setfilename ../info/minibuf
8 @node Minibuffers, Command Loop, Read and Print, Top
10 @cindex arguments, reading
11 @cindex complex arguments
14 A @dfn{minibuffer} is a special buffer that Emacs commands use to read
15 arguments more complicated than the single numeric prefix argument.
16 These arguments include file names, buffer names, and command names (as
17 in @kbd{M-x}). The minibuffer is displayed on the bottom line of the
18 frame, in the same place as the echo area, but only while it is in use
19 for reading an argument.
22 * Intro to Minibuffers:: Basic information about minibuffers.
23 * Text from Minibuffer:: How to read a straight text string.
24 * Object from Minibuffer:: How to read a Lisp object or expression.
25 * Minibuffer History:: Recording previous minibuffer inputs
26 so the user can reuse them.
27 * Initial Input:: Specifying initial contents for the minibuffer.
28 * Completion:: How to invoke and customize completion.
29 * Yes-or-No Queries:: Asking a question with a simple answer.
30 * Multiple Queries:: Asking a series of similar questions.
31 * Reading a Password:: Reading a password from the terminal.
32 * Minibuffer Misc:: Various customization hooks and variables.
35 @node Intro to Minibuffers
36 @section Introduction to Minibuffers
38 In most ways, a minibuffer is a normal Emacs buffer. Most operations
39 @emph{within} a buffer, such as editing commands, work normally in a
40 minibuffer. However, many operations for managing buffers do not apply
41 to minibuffers. The name of a minibuffer always has the form @w{@samp{
42 *Minibuf-@var{number}*}}, and it cannot be changed. Minibuffers are
43 displayed only in special windows used only for minibuffers; these
44 windows always appear at the bottom of a frame. (Sometimes frames have
45 no minibuffer window, and sometimes a special kind of frame contains
46 nothing but a minibuffer window; see @ref{Minibuffers and Frames}.)
48 The text in the minibuffer always starts with the @dfn{prompt string},
49 the text that was specified by the program that is using the minibuffer
50 to tell the user what sort of input to type. This text is marked
51 read-only so you won't accidentally delete or change it. It is also
52 marked as a field (@pxref{Fields}), so that certain motion functions,
53 including @code{beginning-of-line}, @code{forward-word},
54 @code{forward-sentence}, and @code{forward-paragraph}, stop at the
55 boundary between the prompt and the actual text. (In older Emacs
56 versions, the prompt was displayed using a special mechanism and was not
57 part of the buffer contents.)
59 The minibuffer's window is normally a single line; it grows
60 automatically if necessary if the contents require more space. You can
61 explicitly resize it temporarily with the window sizing commands; it
62 reverts to its normal size when the minibuffer is exited. You can
63 resize it permanently by using the window sizing commands in the frame's
64 other window, when the minibuffer is not active. If the frame contains
65 just a minibuffer, you can change the minibuffer's size by changing the
68 Use of the minibuffer reads input events, and that alters the values
69 of variables such as @code{this-command} and @code{last-command}
70 (@pxref{Command Loop Info}). Your program should bind them around the
71 code that uses the minibuffer, if you do not want that to change them.
73 If a command uses a minibuffer while there is an active minibuffer,
74 this is called a @dfn{recursive minibuffer}. The first minibuffer is
75 named @w{@samp{ *Minibuf-0*}}. Recursive minibuffers are named by
76 incrementing the number at the end of the name. (The names begin with a
77 space so that they won't show up in normal buffer lists.) Of several
78 recursive minibuffers, the innermost (or most recently entered) is the
79 active minibuffer. We usually call this ``the'' minibuffer. You can
80 permit or forbid recursive minibuffers by setting the variable
81 @code{enable-recursive-minibuffers} or by putting properties of that
82 name on command symbols (@pxref{Minibuffer Misc}).
84 Like other buffers, a minibuffer may use any of several local keymaps
85 (@pxref{Keymaps}); these contain various exit commands and in some cases
86 completion commands (@pxref{Completion}).
90 @code{minibuffer-local-map} is for ordinary input (no completion).
93 @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
97 @code{minibuffer-local-completion-map} is for permissive completion.
100 @code{minibuffer-local-must-match-map} is for strict completion and
101 for cautious completion.
104 When Emacs is running in batch mode, any request to read from the
105 minibuffer actually reads a line from the standard input descriptor that
106 was supplied when Emacs was started.
108 @node Text from Minibuffer
109 @section Reading Text Strings with the Minibuffer
111 Most often, the minibuffer is used to read text as a string. It can
112 also be used to read a Lisp object in textual form. The most basic
113 primitive for minibuffer input is @code{read-from-minibuffer}; it can do
114 either one. There are also specialized commands for reading
115 commands, variables, file names, etc. (@pxref{Completion}).
117 In most cases, you should not call minibuffer input functions in the
118 middle of a Lisp function. Instead, do all minibuffer input as part of
119 reading the arguments for a command, in the @code{interactive}
120 specification. @xref{Defining Commands}.
122 @defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method keep-all
123 This function is the most general way to get input through the
124 minibuffer. By default, it accepts arbitrary text and returns it as a
125 string; however, if @var{read} is non-@code{nil}, then it uses
126 @code{read} to convert the text into a Lisp object (@pxref{Input
129 The first thing this function does is to activate a minibuffer and
130 display it with @var{prompt-string} as the prompt. This value must be a
131 string. Then the user can edit text in the minibuffer.
133 When the user types a command to exit the minibuffer,
134 @code{read-from-minibuffer} constructs the return value from the text in
135 the minibuffer. Normally it returns a string containing that text.
136 However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer}
137 reads the text and returns the resulting Lisp object, unevaluated.
138 (@xref{Input Functions}, for information about reading.)
140 The argument @var{default} specifies a default value to make available
141 through the history commands. It should be a string, or @code{nil}.
142 If non-@code{nil}, the user can access it using
143 @code{next-history-element}, usually bound in the minibuffer to
144 @kbd{M-n}. If @var{read} is non-@code{nil}, then @var{default} is
145 also used as the input to @code{read}, if the user enters empty input.
146 (If @var{read} is non-@code{nil} and @var{default} is @code{nil}, empty
147 input results in an @code{end-of-file} error.) However, in the usual
148 case (where @var{read} is @code{nil}), @code{read-from-minibuffer}
149 ignores @var{default} when the user enters empty input and returns an
150 empty string, @code{""}. In this respect, it is different from all
151 the other minibuffer input functions in this chapter.
153 If @var{keymap} is non-@code{nil}, that keymap is the local keymap to
154 use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the
155 value of @code{minibuffer-local-map} is used as the keymap. Specifying
156 a keymap is the most important way to customize the minibuffer for
157 various applications such as completion.
159 The argument @var{hist} specifies which history list variable to use
160 for saving the input and for history commands used in the minibuffer.
161 It defaults to @code{minibuffer-history}. @xref{Minibuffer History}.
163 If the variable @code{minibuffer-allow-text-properties} is
164 non-@code{nil}, then the string which is returned includes whatever text
165 properties were present in the minibuffer. Otherwise all the text
166 properties are stripped when the value is returned.
168 If the argument @var{inherit-input-method} is non-@code{nil}, then the
169 minibuffer inherits the current input method (@pxref{Input Methods}) and
170 the setting of @code{enable-multibyte-characters} (@pxref{Text
171 Representations}) from whichever buffer was current before entering the
174 If @var{keep-all} is non-@code{nil}, even empty and duplicate inputs
175 are added to the history list.
177 Use of @var{initial-contents} is mostly deprecated; we recommend using
178 a non-@code{nil} value only in conjunction with specifying a cons cell
179 for @var{hist}. @xref{Initial Input}.
182 @defun read-string prompt &optional initial history default inherit-input-method
183 This function reads a string from the minibuffer and returns it. The
184 arguments @var{prompt}, @var{initial}, @var{history} and
185 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
186 The keymap used is @code{minibuffer-local-map}.
188 The optional argument @var{default} is used as in
189 @code{read-from-minibuffer}, except that, if non-@code{nil}, it also
190 specifies a default value to return if the user enters null input. As
191 in @code{read-from-minibuffer} it should be a string, or @code{nil},
192 which is equivalent to an empty string.
194 This function is a simplified interface to the
195 @code{read-from-minibuffer} function:
199 (read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit})
202 (read-from-minibuffer @var{prompt} @var{initial} nil nil
203 @var{history} @var{default} @var{inherit})))
204 (if (and (equal value "") @var{default})
211 @defvar minibuffer-allow-text-properties
212 If this variable is @code{nil}, then @code{read-from-minibuffer} strips
213 all text properties from the minibuffer input before returning it.
214 This variable also affects @code{read-string}. However,
215 @code{read-no-blanks-input} (see below), as well as
216 @code{read-minibuffer} and related functions (@pxref{Object from
217 Minibuffer,, Reading Lisp Objects With the Minibuffer}), and all
218 functions that do minibuffer input with completion, discard text
219 properties unconditionally, regardless of the value of this variable.
222 @defvar minibuffer-local-map
223 @anchor{Definition of minibuffer-local-map}
224 This is the default local keymap for reading from the minibuffer. By
225 default, it makes the following bindings:
229 @code{exit-minibuffer}
232 @code{exit-minibuffer}
235 @code{abort-recursive-edit}
239 @code{next-history-element}
243 @code{previous-history-element}
246 @code{next-matching-history-element}
249 @code{previous-matching-history-element}
253 @c In version 18, initial is required
255 @defun read-no-blanks-input prompt &optional initial inherit-input-method
256 This function reads a string from the minibuffer, but does not allow
257 whitespace characters as part of the input: instead, those characters
258 terminate the input. The arguments @var{prompt}, @var{initial}, and
259 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
261 This is a simplified interface to the @code{read-from-minibuffer}
262 function, and passes the value of the @code{minibuffer-local-ns-map}
263 keymap as the @var{keymap} argument for that function. Since the keymap
264 @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is}
265 possible to put a space into the string, by quoting it.
267 This function discards text properties, regardless of the value of
268 @code{minibuffer-allow-text-properties}.
272 (read-no-blanks-input @var{prompt} @var{initial})
274 (let (minibuffer-allow-text-properties)
275 (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map))
280 @defvar minibuffer-local-ns-map
281 This built-in variable is the keymap used as the minibuffer local keymap
282 in the function @code{read-no-blanks-input}. By default, it makes the
283 following bindings, in addition to those of @code{minibuffer-local-map}:
287 @cindex @key{SPC} in minibuffer
288 @code{exit-minibuffer}
291 @cindex @key{TAB} in minibuffer
292 @code{exit-minibuffer}
295 @cindex @kbd{?} in minibuffer
296 @code{self-insert-and-exit}
300 @node Object from Minibuffer
301 @section Reading Lisp Objects with the Minibuffer
303 This section describes functions for reading Lisp objects with the
306 @defun read-minibuffer prompt &optional initial
307 This function reads a Lisp object using the minibuffer, and returns it
308 without evaluating it. The arguments @var{prompt} and @var{initial} are
309 used as in @code{read-from-minibuffer}.
311 This is a simplified interface to the
312 @code{read-from-minibuffer} function:
316 (read-minibuffer @var{prompt} @var{initial})
318 (let (minibuffer-allow-text-properties)
319 (read-from-minibuffer @var{prompt} @var{initial} nil t))
323 Here is an example in which we supply the string @code{"(testing)"} as
329 "Enter an expression: " (format "%s" '(testing)))
331 ;; @r{Here is how the minibuffer is displayed:}
335 ---------- Buffer: Minibuffer ----------
336 Enter an expression: (testing)@point{}
337 ---------- Buffer: Minibuffer ----------
342 The user can type @key{RET} immediately to use the initial input as a
343 default, or can edit the input.
346 @defun eval-minibuffer prompt &optional initial
347 This function reads a Lisp expression using the minibuffer, evaluates
348 it, then returns the result. The arguments @var{prompt} and
349 @var{initial} are used as in @code{read-from-minibuffer}.
351 This function simply evaluates the result of a call to
352 @code{read-minibuffer}:
356 (eval-minibuffer @var{prompt} @var{initial})
358 (eval (read-minibuffer @var{prompt} @var{initial}))
363 @defun edit-and-eval-command prompt form
364 This function reads a Lisp expression in the minibuffer, and then
365 evaluates it. The difference between this command and
366 @code{eval-minibuffer} is that here the initial @var{form} is not
367 optional and it is treated as a Lisp object to be converted to printed
368 representation rather than as a string of text. It is printed with
369 @code{prin1}, so if it is a string, double-quote characters (@samp{"})
370 appear in the initial text. @xref{Output Functions}.
372 The first thing @code{edit-and-eval-command} does is to activate the
373 minibuffer with @var{prompt} as the prompt. Then it inserts the printed
374 representation of @var{form} in the minibuffer, and lets the user edit it.
375 When the user exits the minibuffer, the edited text is read with
376 @code{read} and then evaluated. The resulting value becomes the value
377 of @code{edit-and-eval-command}.
379 In the following example, we offer the user an expression with initial
380 text which is a valid form already:
384 (edit-and-eval-command "Please edit: " '(forward-word 1))
386 ;; @r{After evaluation of the preceding expression,}
387 ;; @r{the following appears in the minibuffer:}
391 ---------- Buffer: Minibuffer ----------
392 Please edit: (forward-word 1)@point{}
393 ---------- Buffer: Minibuffer ----------
398 Typing @key{RET} right away would exit the minibuffer and evaluate the
399 expression, thus moving point forward one word.
400 @code{edit-and-eval-command} returns @code{nil} in this example.
403 @node Minibuffer History
404 @section Minibuffer History
405 @cindex minibuffer history
408 A @dfn{minibuffer history list} records previous minibuffer inputs so
409 the user can reuse them conveniently. A history list is actually a
410 symbol, not a list; it is a variable whose value is a list of strings
411 (previous inputs), most recent first.
413 There are many separate history lists, used for different kinds of
414 inputs. It's the Lisp programmer's job to specify the right history
415 list for each use of the minibuffer.
417 The basic minibuffer input functions @code{read-from-minibuffer} and
418 @code{completing-read} both accept an optional argument named @var{hist}
419 which is how you specify the history list. Here are the possible
424 Use @var{variable} (a symbol) as the history list.
426 @item (@var{variable} . @var{startpos})
427 Use @var{variable} (a symbol) as the history list, and assume that the
428 initial history position is @var{startpos} (a nonnegative integer).
430 Specifying 0 for @var{startpos} is equivalent to just specifying the
431 symbol @var{variable}. @code{previous-history-element} will display
432 the most recent element of the history list in the minibuffer. If you
433 specify a positive @var{startpos}, the minibuffer history functions
434 behave as if @code{(elt @var{variable} (1- @var{STARTPOS}))} were the
435 history element currently shown in the minibuffer.
437 For consistency, you should also specify that element of the history
438 as the initial minibuffer contents, using the @var{initial} argument
439 to the minibuffer input function (@pxref{Initial Input}).
442 If you don't specify @var{hist}, then the default history list
443 @code{minibuffer-history} is used. For other standard history lists,
444 see below. You can also create your own history list variable; just
445 initialize it to @code{nil} before the first use.
447 Both @code{read-from-minibuffer} and @code{completing-read} add new
448 elements to the history list automatically, and provide commands to
449 allow the user to reuse items on the list. The only thing your program
450 needs to do to use a history list is to initialize it and to pass its
451 name to the input functions when you wish. But it is safe to modify the
452 list by hand when the minibuffer input functions are not using it.
454 Emacs functions that add a new element to a history list can also
455 delete old elements if the list gets too long. The variable
456 @code{history-length} specifies the maximum length for most history
457 lists. To specify a different maximum length for a particular history
458 list, put the length in the @code{history-length} property of the
459 history list symbol. The variable @code{history-delete-duplicates}
460 specifies whether to delete duplicates in history.
462 @defvar history-length
463 The value of this variable specifies the maximum length for all
464 history lists that don't specify their own maximum lengths. If the
465 value is @code{t}, that means there no maximum (don't delete old
469 @defvar history-delete-duplicates
470 If the value of this variable is @code{t}, that means when adding a
471 new history element, all previous identical elements are deleted.
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.
510 @section Initial Input
512 Several of the functions for minibuffer input have an argument called
513 @var{initial} or @var{initial-contents}. This is a mostly-deprecated
514 feature for specifiying that the minibuffer should start out with
515 certain text, instead of empty as usual.
517 If @var{initial} is a string, the minibuffer starts out containing the
518 text of the string, with point at the end, when the user starts to
519 edit the text. If the user simply types @key{RET} to exit the
520 minibuffer, it will use the initial input string to determine the
523 @strong{We discourage use of a non-@code{nil} value for
524 @var{initial}}, because initial input is an intrusive interface.
525 History lists and default values provide a much more convenient method
526 to offer useful default inputs to the user.
528 There is just one situation where you should specify a string for an
529 @var{initial} argument. This is when you specify a cons cell for the
530 @var{hist} or @var{history} argument. @xref{Minibuffer History}.
532 @var{initial} can also be a cons cell of the form @code{(@var{string}
533 . @var{position})}. This means to insert @var{string} in the
534 minibuffer but put point at @var{position} within the string's text.
536 As a historical accident, @var{position} was implemented
537 inconsistently in different functions. In @code{completing-read},
538 @var{position}'s value is interpreted as origin-zero; that is, a value
539 of 0 means the beginning of the string, 1 means after the first
540 character, etc. In @code{read-minibuffer}, and the other
541 non-completion minibuffer input functions that support this argument,
542 1 means the beginning of the string 2 means after the first character,
545 Use of a cons cell as the value for @var{initial} arguments is
546 deprecated in user code.
552 @dfn{Completion} is a feature that fills in the rest of a name
553 starting from an abbreviation for it. Completion works by comparing the
554 user's input against a list of valid names and determining how much of
555 the name is determined uniquely by what the user has typed. For
556 example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then
557 type the first few letters of the name of the buffer to which you wish
558 to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs
559 extends the name as far as it can.
561 Standard Emacs commands offer completion for names of symbols, files,
562 buffers, and processes; with the functions in this section, you can
563 implement completion for other kinds of names.
565 The @code{try-completion} function is the basic primitive for
566 completion: it returns the longest determined completion of a given
567 initial string, with a given set of strings to match against.
569 The function @code{completing-read} provides a higher-level interface
570 for completion. A call to @code{completing-read} specifies how to
571 determine the list of valid names. The function then activates the
572 minibuffer with a local keymap that binds a few keys to commands useful
573 for completion. Other functions provide convenient simple interfaces
574 for reading certain kinds of names with completion.
577 * Basic Completion:: Low-level functions for completing strings.
578 (These are too low level to use the minibuffer.)
579 * Minibuffer Completion:: Invoking the minibuffer with completion.
580 * Completion Commands:: Minibuffer commands that do completion.
581 * High-Level Completion:: Convenient special cases of completion
582 (reading buffer name, file name, etc.)
583 * Reading File Names:: Using completion to read file names.
584 * Programmed Completion:: Writing your own completion-function.
587 @node Basic Completion
588 @subsection Basic Completion Functions
590 The functions @code{try-completion}, @code{all-completions} and
591 @code{test-completion} have nothing in themselves to do with
592 minibuffers. We describe them in this chapter so as to keep them near
593 the higher-level completion features that do use the minibuffer.
595 @defun try-completion string collection &optional predicate
596 This function returns the longest common substring of all possible
597 completions of @var{string} in @var{collection}. The value of
598 @var{collection} must be a list of strings, an alist, an obarray, a
599 hash table, or a function that implements a virtual set of strings
602 Completion compares @var{string} against each of the permissible
603 completions specified by @var{collection}; if the beginning of the
604 permissible completion equals @var{string}, it matches. If no permissible
605 completions match, @code{try-completion} returns @code{nil}. If only
606 one permissible completion matches, and the match is exact, then
607 @code{try-completion} returns @code{t}. Otherwise, the value is the
608 longest initial sequence common to all the permissible completions that
611 If @var{collection} is an alist (@pxref{Association Lists}), the
612 permissible completions are the elements of the alist that are either
613 strings or conses whose @sc{car} is a string. Other elements of the
614 alist are ignored. (Remember that in Emacs Lisp, the elements of
615 alists do not @emph{have} to be conses.) As all elements of the alist
616 can be strings, this case actually includes lists of strings, even
617 though we usually do not think of such lists as alists.
619 @cindex obarray in completion
620 If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
621 of all symbols in the obarray form the set of permissible completions. The
622 global variable @code{obarray} holds an obarray containing the names of
623 all interned Lisp symbols.
625 Note that the only valid way to make a new obarray is to create it
626 empty and then add symbols to it one by one using @code{intern}.
627 Also, you cannot intern a given symbol in more than one obarray.
629 If @var{collection} is a hash table, then the keys that are strings
630 are the possible completions. Other keys are ignored.
632 You can also use a symbol that is a function as @var{collection}. Then
633 the function is solely responsible for performing completion;
634 @code{try-completion} returns whatever this function returns. The
635 function is called with three arguments: @var{string}, @var{predicate}
636 and @code{nil}. (The reason for the third argument is so that the same
637 function can be used in @code{all-completions} and do the appropriate
638 thing in either case.) @xref{Programmed Completion}.
640 If the argument @var{predicate} is non-@code{nil}, then it must be a
641 function of one argument, unless @var{collection} is a hash table, in
642 which case it should be a function of two arguments. It is used to
643 test each possible match, and the match is accepted only if
644 @var{predicate} returns non-@code{nil}. The argument given to
645 @var{predicate} is either a string or a cons cell (the @sc{car} of
646 which is a string) from the alist, or a symbol (@emph{not} a symbol
647 name) from the obarray. If @var{collection} is a hash table,
648 @var{predicate} is called with two arguments, the string key and the
651 In addition, to be acceptable, a completion must also match all the
652 regular expressions in @code{completion-regexp-list}. (Unless
653 @var{collection} is a function, in which case that function has to
654 handle @code{completion-regexp-list} itself.)
656 In the first of the following examples, the string @samp{foo} is
657 matched by three of the alist @sc{car}s. All of the matches begin with
658 the characters @samp{fooba}, so that is the result. In the second
659 example, there is only one possible match, and it is exact, so the value
666 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
671 (try-completion "foo" '(("barfoo" 2) ("foo" 3)))
676 In the following example, numerous symbols begin with the characters
677 @samp{forw}, and all of them begin with the word @samp{forward}. In
678 most of the symbols, this is followed with a @samp{-}, but not in all,
679 so no more than @samp{forward} can be completed.
683 (try-completion "forw" obarray)
688 Finally, in the following example, only two of the three possible
689 matches pass the predicate @code{test} (the string @samp{foobaz} is
690 too short). Both of those begin with the string @samp{foobar}.
695 (> (length (car s)) 6))
701 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
708 @defun all-completions string collection &optional predicate nospace
709 This function returns a list of all possible completions of
710 @var{string}. The arguments to this function (aside from
711 @var{nospace}) are the same as those of @code{try-completion}. Also,
712 this function uses @code{completion-regexp-list} in the same way that
713 @code{try-completion} does. The optional argument @var{nospace} only
714 matters if @var{string} is the empty string. In that case, if
715 @var{nospace} is non-@code{nil}, completions that start with a space
718 If @var{collection} is a function, it is called with three arguments:
719 @var{string}, @var{predicate} and @code{t}; then @code{all-completions}
720 returns whatever the function returns. @xref{Programmed Completion}.
722 Here is an example, using the function @code{test} shown in the
723 example for @code{try-completion}:
728 (> (length (car s)) 6))
735 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
737 @result{} ("foobar1" "foobar2")
742 @defun test-completion string collection &optional predicate
743 @anchor{Definition of test-completion}
744 This function returns non-@code{nil} if @var{string} is a valid
745 completion possibility specified by @var{collection} and
746 @var{predicate}. The arguments are the same as in
747 @code{try-completion}. For instance, if @var{collection} is a list of
748 strings, this is true if @var{string} appears in the list and
749 @var{predicate} is satisfied.
751 @code{test-completion} uses @code{completion-regexp-list} in the same
752 way that @code{try-completion} does.
754 If @var{predicate} is non-@code{nil} and if @var{collection} contains
755 several strings that are equal to each other, as determined by
756 @code{compare-strings} according to @code{completion-ignore-case},
757 then @var{predicate} should accept either all or none of them.
758 Otherwise, the return value of @code{test-completion} is essentially
761 If @var{collection} is a function, it is called with three arguments,
762 the values @var{string}, @var{predicate} and @code{lambda}; whatever
763 it returns, @code{test-completion} returns in turn.
766 @defvar completion-ignore-case
767 If the value of this variable is non-@code{nil}, Emacs does not
768 consider case significant in completion.
771 @defvar completion-regexp-list
772 This is a list of regular expressions. The completion functions only
773 consider a completion acceptable if it matches all regular expressions
774 in this list, with @code{case-fold-search} (@pxref{Searching and Case})
775 bound to the value of @code{completion-ignore-case}.
778 @defmac lazy-completion-table var fun &rest args
779 This macro provides a way to initialize the variable @var{var} as a
780 collection for completion in a lazy way, not computing its actual
781 contents until they are first needed. You use this macro to produce a
782 value that you store in @var{var}. The actual computation of the
783 proper value is done the first time you do completion using @var{var}.
784 It is done by calling @var{fun} with the arguments @var{args}. The
785 value @var{fun} returns becomes the permanent value of @var{var}.
787 Here are two examples of use:
790 (defvar foo (lazy-completion-table foo make-my-alist 'global))
792 (make-local-variable 'bar)
793 (setq bar (lazy-completion-table foo make-my-alist 'local)
797 @node Minibuffer Completion
798 @subsection Completion and the Minibuffer
800 This section describes the basic interface for reading from the
801 minibuffer with completion.
803 @defun completing-read prompt collection &optional predicate require-match initial hist default inherit-input-method
804 This function reads a string in the minibuffer, assisting the user by
805 providing completion. It activates the minibuffer with prompt
806 @var{prompt}, which must be a string.
808 The actual completion is done by passing @var{collection} and
809 @var{predicate} to the function @code{try-completion}. This happens
810 in certain commands bound in the local keymaps used for completion.
811 Some of these commands also call @code{test-completion}. Thus, if
812 @var{predicate} is non-@code{nil}, it should be compatible with
813 @var{collection} and @code{completion-ignore-case}. @xref{Definition
816 If @var{require-match} is @code{nil}, the exit commands work regardless
817 of the input in the minibuffer. If @var{require-match} is @code{t}, the
818 usual minibuffer exit commands won't exit unless the input completes to
819 an element of @var{collection}. If @var{require-match} is neither
820 @code{nil} nor @code{t}, then the exit commands won't exit unless the
821 input already in the buffer matches an element of @var{collection}.
823 However, empty input is always permitted, regardless of the value of
824 @var{require-match}; in that case, @code{completing-read} returns
825 @var{default}, or @code{""}, if @var{default} is @code{nil}. The
826 value of @var{default} (if non-@code{nil}) is also available to the
827 user through the history commands.
829 The function @code{completing-read} uses
830 @code{minibuffer-local-completion-map} as the keymap if
831 @var{require-match} is @code{nil}, and uses
832 @code{minibuffer-local-must-match-map} if @var{require-match} is
833 non-@code{nil}. @xref{Completion Commands}.
835 The argument @var{hist} specifies which history list variable to use for
836 saving the input and for minibuffer history commands. It defaults to
837 @code{minibuffer-history}. @xref{Minibuffer History}.
839 The argument @var{initial} is mostly deprecated; we recommend using a
840 non-@code{nil} value only in conjunction with specifying a cons cell
841 for @var{hist}. @xref{Initial Input}. For default input, use
842 @var{default} instead.
844 If the argument @var{inherit-input-method} is non-@code{nil}, then the
845 minibuffer inherits the current input method (@pxref{Input
846 Methods}) and the setting of @code{enable-multibyte-characters}
847 (@pxref{Text Representations}) from whichever buffer was current before
848 entering the minibuffer.
850 If the built-in variable @code{completion-ignore-case} is
851 non-@code{nil}, completion ignores case when comparing the input
852 against the possible matches. @xref{Basic Completion}. In this mode
853 of operation, @var{predicate} must also ignore case, or you will get
856 Here's an example of using @code{completing-read}:
862 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
867 ;; @r{After evaluation of the preceding expression,}
868 ;; @r{the following appears in the minibuffer:}
870 ---------- Buffer: Minibuffer ----------
871 Complete a foo: fo@point{}
872 ---------- Buffer: Minibuffer ----------
877 If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}},
878 @code{completing-read} returns @code{barfoo}.
880 The @code{completing-read} function binds three variables to pass
881 information to the commands that actually do completion. These
882 variables are @code{minibuffer-completion-table},
883 @code{minibuffer-completion-predicate} and
884 @code{minibuffer-completion-confirm}. For more information about them,
885 see @ref{Completion Commands}.
888 @node Completion Commands
889 @subsection Minibuffer Commands that Do Completion
891 This section describes the keymaps, commands and user options used
892 in the minibuffer to do completion. The description refers to the
893 situation when Partial Completion mode is disabled (as it is by
894 default). When enabled, this minor mode uses its own alternatives to
895 some of the commands described below. @xref{Completion Options,,,
896 emacs, The GNU Emacs Manual}, for a short description of Partial
899 @defvar minibuffer-local-completion-map
900 @code{completing-read} uses this value as the local keymap when an
901 exact match of one of the completions is not required. By default, this
902 keymap makes the following bindings:
906 @code{minibuffer-completion-help}
909 @code{minibuffer-complete-word}
912 @code{minibuffer-complete}
916 with other characters bound as in @code{minibuffer-local-map}
917 (@pxref{Definition of minibuffer-local-map}).
920 @defvar minibuffer-local-must-match-map
921 @code{completing-read} uses this value as the local keymap when an
922 exact match of one of the completions is required. Therefore, no keys
923 are bound to @code{exit-minibuffer}, the command that exits the
924 minibuffer unconditionally. By default, this keymap makes the following
929 @code{minibuffer-completion-help}
932 @code{minibuffer-complete-word}
935 @code{minibuffer-complete}
938 @code{minibuffer-complete-and-exit}
941 @code{minibuffer-complete-and-exit}
945 with other characters bound as in @code{minibuffer-local-map}.
948 @defvar minibuffer-completion-table
949 The value of this variable is the collection used for completion in
950 the minibuffer. This is the global variable that contains what
951 @code{completing-read} passes to @code{try-completion}. It is used by
952 minibuffer completion commands such as @code{minibuffer-complete-word}.
955 @defvar minibuffer-completion-predicate
956 This variable's value is the predicate that @code{completing-read}
957 passes to @code{try-completion}. The variable is also used by the other
958 minibuffer completion functions.
961 @deffn Command minibuffer-complete-word
962 This function completes the minibuffer contents by at most a single
963 word. Even if the minibuffer contents have only one completion,
964 @code{minibuffer-complete-word} does not add any characters beyond the
965 first character that is not a word constituent. @xref{Syntax Tables}.
968 @deffn Command minibuffer-complete
969 This function completes the minibuffer contents as far as possible.
972 @deffn Command minibuffer-complete-and-exit
973 This function completes the minibuffer contents, and exits if
974 confirmation is not required, i.e., if
975 @code{minibuffer-completion-confirm} is @code{nil}. If confirmation
976 @emph{is} required, it is given by repeating this command
977 immediately---the command is programmed to work without confirmation
978 when run twice in succession.
981 @defvar minibuffer-completion-confirm
982 When the value of this variable is non-@code{nil}, Emacs asks for
983 confirmation of a completion before exiting the minibuffer. The
984 function @code{minibuffer-complete-and-exit} checks the value of this
985 variable before it exits.
988 @deffn Command minibuffer-completion-help
989 This function creates a list of the possible completions of the
990 current minibuffer contents. It works by calling @code{all-completions}
991 using the value of the variable @code{minibuffer-completion-table} as
992 the @var{collection} argument, and the value of
993 @code{minibuffer-completion-predicate} as the @var{predicate} argument.
994 The list of completions is displayed as text in a buffer named
995 @samp{*Completions*}.
998 @defun display-completion-list completions
999 This function displays @var{completions} to the stream in
1000 @code{standard-output}, usually a buffer. (@xref{Read and Print}, for more
1001 information about streams.) The argument @var{completions} is normally
1002 a list of completions just returned by @code{all-completions}, but it
1003 does not have to be. Each element may be a symbol or a string, either
1004 of which is simply printed. It can also be a list of two strings,
1005 which is printed as if the strings were concatenated. The first of
1006 the two strings is the actual completion, the second string serves as
1009 This function is called by @code{minibuffer-completion-help}. The
1010 most common way to use it is together with
1011 @code{with-output-to-temp-buffer}, like this:
1014 (with-output-to-temp-buffer "*Completions*"
1015 (display-completion-list
1016 (all-completions (buffer-string) my-alist)))
1020 @defopt completion-auto-help
1021 If this variable is non-@code{nil}, the completion commands
1022 automatically display a list of possible completions whenever nothing
1023 can be completed because the next character is not uniquely determined.
1026 @node High-Level Completion
1027 @subsection High-Level Completion Functions
1029 This section describes the higher-level convenient functions for
1030 reading certain sorts of names with completion.
1032 In most cases, you should not call these functions in the middle of a
1033 Lisp function. When possible, do all minibuffer input as part of
1034 reading the arguments for a command, in the @code{interactive}
1035 specification. @xref{Defining Commands}.
1037 @defun read-buffer prompt &optional default existing
1038 This function reads the name of a buffer and returns it as a string.
1039 The argument @var{default} is the default name to use, the value to
1040 return if the user exits with an empty minibuffer. If non-@code{nil},
1041 it should be a string or a buffer. It is mentioned in the prompt, but
1042 is not inserted in the minibuffer as initial input.
1044 If @var{existing} is non-@code{nil}, then the name specified must be
1045 that of an existing buffer. The usual commands to exit the minibuffer
1046 do not exit if the text is not valid, and @key{RET} does completion to
1047 attempt to find a valid name. If @var{existing} is neither @code{nil}
1048 nor @code{t}, confirmation is required after completion. (However,
1049 @var{default} is not checked for validity; it is returned, whatever it
1050 is, if the user exits with the minibuffer empty.)
1052 In the following example, the user enters @samp{minibuffer.t}, and
1053 then types @key{RET}. The argument @var{existing} is @code{t}, and the
1054 only buffer name starting with the given input is
1055 @samp{minibuffer.texi}, so that name is the value.
1058 (read-buffer "Buffer name? " "foo" t)
1060 ;; @r{After evaluation of the preceding expression,}
1061 ;; @r{the following prompt appears,}
1062 ;; @r{with an empty minibuffer:}
1066 ---------- Buffer: Minibuffer ----------
1067 Buffer name? (default foo) @point{}
1068 ---------- Buffer: Minibuffer ----------
1072 ;; @r{The user types @kbd{minibuffer.t @key{RET}}.}
1073 @result{} "minibuffer.texi"
1078 @defvar read-buffer-function
1079 This variable specifies how to read buffer names. For example, if you
1080 set this variable to @code{iswitchb-read-buffer}, all Emacs commands
1081 that call @code{read-buffer} to read a buffer name will actually use the
1082 @code{iswitchb} package to read it.
1085 @defun read-command prompt &optional default
1086 This function reads the name of a command and returns it as a Lisp
1087 symbol. The argument @var{prompt} is used as in
1088 @code{read-from-minibuffer}. Recall that a command is anything for
1089 which @code{commandp} returns @code{t}, and a command name is a symbol
1090 for which @code{commandp} returns @code{t}. @xref{Interactive Call}.
1092 The argument @var{default} specifies what to return if the user enters
1093 null input. It can be a symbol or a string; if it is a string,
1094 @code{read-command} interns it before returning it. If @var{default} is
1095 @code{nil}, that means no default has been specified; then if the user
1096 enters null input, the return value is @code{(intern "")}, that is, a
1097 symbol whose name is an empty string.
1100 (read-command "Command name? ")
1103 ;; @r{After evaluation of the preceding expression,}
1104 ;; @r{the following prompt appears with an empty minibuffer:}
1108 ---------- Buffer: Minibuffer ----------
1110 ---------- Buffer: Minibuffer ----------
1115 If the user types @kbd{forward-c @key{RET}}, then this function returns
1116 @code{forward-char}.
1118 The @code{read-command} function is a simplified interface to
1119 @code{completing-read}. It uses the variable @code{obarray} so as to
1120 complete in the set of extant Lisp symbols, and it uses the
1121 @code{commandp} predicate so as to accept only command names:
1123 @cindex @code{commandp} example
1126 (read-command @var{prompt})
1128 (intern (completing-read @var{prompt} obarray
1134 @defun read-variable prompt &optional default
1135 @anchor{Definition of read-variable}
1136 This function reads the name of a user variable and returns it as a
1139 The argument @var{default} specifies what to return if the user enters
1140 null input. It can be a symbol or a string; if it is a string,
1141 @code{read-variable} interns it before returning it. If @var{default}
1142 is @code{nil}, that means no default has been specified; then if the
1143 user enters null input, the return value is @code{(intern "")}.
1147 (read-variable "Variable name? ")
1149 ;; @r{After evaluation of the preceding expression,}
1150 ;; @r{the following prompt appears,}
1151 ;; @r{with an empty minibuffer:}
1155 ---------- Buffer: Minibuffer ----------
1156 Variable name? @point{}
1157 ---------- Buffer: Minibuffer ----------
1162 If the user then types @kbd{fill-p @key{RET}}, @code{read-variable}
1163 returns @code{fill-prefix}.
1165 This function is similar to @code{read-command}, but uses the
1166 predicate @code{user-variable-p} instead of @code{commandp}:
1168 @cindex @code{user-variable-p} example
1171 (read-variable @var{prompt})
1174 (completing-read @var{prompt} obarray
1175 'user-variable-p t nil))
1180 See also the functions @code{read-coding-system} and
1181 @code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems}.
1183 @node Reading File Names
1184 @subsection Reading File Names
1186 Here is another high-level completion function, designed for reading a
1187 file name. It provides special features including automatic insertion
1188 of the default directory.
1190 @defun read-file-name prompt &optional directory default existing initial predicate
1191 This function reads a file name in the minibuffer, prompting with
1192 @var{prompt} and providing completion.
1194 If @var{existing} is non-@code{nil}, then the user must specify the name
1195 of an existing file; @key{RET} performs completion to make the name
1196 valid if possible, and then refuses to exit if it is not valid. If the
1197 value of @var{existing} is neither @code{nil} nor @code{t}, then
1198 @key{RET} also requires confirmation after completion. If
1199 @var{existing} is @code{nil}, then the name of a nonexistent file is
1202 The argument @var{directory} specifies the directory to use for
1203 completion of relative file names. It should be an absolute directory
1204 name. If @code{insert-default-directory} is non-@code{nil},
1205 @var{directory} is also inserted in the minibuffer as initial input.
1206 It defaults to the current buffer's value of @code{default-directory}.
1209 If you specify @var{initial}, that is an initial file name to insert
1210 in the buffer (after @var{directory}, if that is inserted). In this
1211 case, point goes at the beginning of @var{initial}. The default for
1212 @var{initial} is @code{nil}---don't insert any file name. To see what
1213 @var{initial} does, try the command @kbd{C-x C-v}. @strong{Please
1214 note:} we recommend using @var{default} rather than @var{initial} in
1217 If @var{default} is non-@code{nil}, then the function returns
1218 @var{default} if the user exits the minibuffer with the same non-empty
1219 contents that @code{read-file-name} inserted initially. The initial
1220 minibuffer contents are always non-empty if
1221 @code{insert-default-directory} is non-@code{nil}, as it is by
1222 default. @var{default} is not checked for validity, regardless of the
1223 value of @var{existing}. However, if @var{existing} is
1224 non-@code{nil}, the initial minibuffer contents should be a valid file
1225 (or directory) name. Otherwise @code{read-file-name} attempts
1226 completion if the user exits without any editing, and does not return
1227 @var{default}. @var{default} is also available through the history
1230 If @var{default} is @code{nil}, @code{read-file-name} tries to find a
1231 substitute default to use in its place, which it treats in exactly the
1232 same way as if it had been specified explicitly. If @var{default} is
1233 @code{nil}, but @var{initial} is non-@code{nil}, then the default is
1234 the absolute file name obtained from @var{directory} and
1235 @var{initial}. If both @var{default} and @var{initial} are @code{nil}
1236 and the buffer is visiting a file, @code{read-file-name} uses the
1237 absolute file name of that file as default. If the buffer is not
1238 visiting a file, then there is no default. In that case, if the user
1239 types @key{RET} without any editing, @code{read-file-name} simply
1240 returns the pre-inserted contents of the minibuffer.
1242 If the user types @key{RET} in an empty minibuffer, this function
1243 returns an empty string, regardless of the value of @var{existing}.
1244 This is, for instance, how the user can make the current buffer visit
1245 no file using @code{M-x set-visited-file-name}.
1247 If @var{predicate} is non-@code{nil}, it specifies a function of one
1248 argument that decides which file names are acceptable completion
1249 possibilities. A file name is an acceptable value if @var{predicate}
1250 returns non-@code{nil} for it.
1252 @code{read-file-name} does not automatically expand file names. You
1253 must call @code{expand-file-name} yourself if an absolute file name is
1260 (read-file-name "The file is ")
1262 ;; @r{After evaluation of the preceding expression,}
1263 ;; @r{the following appears in the minibuffer:}
1267 ---------- Buffer: Minibuffer ----------
1268 The file is /gp/gnu/elisp/@point{}
1269 ---------- Buffer: Minibuffer ----------
1274 Typing @kbd{manual @key{TAB}} results in the following:
1278 ---------- Buffer: Minibuffer ----------
1279 The file is /gp/gnu/elisp/manual.texi@point{}
1280 ---------- Buffer: Minibuffer ----------
1284 @c Wordy to avoid overfull hbox in smallbook mode.
1286 If the user types @key{RET}, @code{read-file-name} returns the file name
1287 as the string @code{"/gp/gnu/elisp/manual.texi"}.
1290 @defun read-directory-name prompt &optional directory default existing initial
1291 This function is like @code{read-file-name} but allows only directory
1292 names as completion possibilities.
1294 If @var{default} is @code{nil} and @var{initial} is non-@code{nil},
1295 @code{read-directory-name} constructs a substitute default by
1296 combining @var{directory} (or the current buffer's default directory
1297 if @var{directory} is @code{nil}) and @var{initial}. If both
1298 @var{default} and @var{initial} are @code{nil}, this function uses the
1299 current buffer's default directory as substitute default, ignoring
1303 @defopt insert-default-directory
1304 This variable is used by @code{read-file-name}, and thus, indirectly,
1305 by most commands reading file names. (This includes all commands that
1306 use the code letters @samp{f} or @samp{F} in their interactive form.
1307 @xref{Interactive Codes,, Code Characters for interactive}.) Its
1308 value controls whether @code{read-file-name} starts by placing the
1309 name of the default directory in the minibuffer, plus the initial file
1310 name if any. If the value of this variable is @code{nil}, then
1311 @code{read-file-name} does not place any initial input in the
1312 minibuffer (unless you specify initial input with the @var{initial}
1313 argument). In that case, the default directory is still used for
1314 completion of relative file names, but is not displayed.
1316 If this variable is @code{nil} and the initial minibuffer contents are
1317 empty, the user may have to explicitly fetch the next history element
1318 to access a default value. If the variable is non-@code{nil}, the
1319 initial minibuffer contents are always non-empty and the user can
1320 always request a default value by immediately typing @key{RET} in an
1321 unedited minibuffer. (See above.)
1327 ;; @r{Here the minibuffer starts out with the default directory.}
1328 (let ((insert-default-directory t))
1329 (read-file-name "The file is "))
1333 ---------- Buffer: Minibuffer ----------
1334 The file is ~lewis/manual/@point{}
1335 ---------- Buffer: Minibuffer ----------
1339 ;; @r{Here the minibuffer is empty and only the prompt}
1340 ;; @r{appears on its line.}
1341 (let ((insert-default-directory nil))
1342 (read-file-name "The file is "))
1346 ---------- Buffer: Minibuffer ----------
1347 The file is @point{}
1348 ---------- Buffer: Minibuffer ----------
1353 @node Programmed Completion
1354 @subsection Programmed Completion
1355 @cindex programmed completion
1357 Sometimes it is not possible to create an alist or an obarray
1358 containing all the intended possible completions. In such a case, you
1359 can supply your own function to compute the completion of a given string.
1360 This is called @dfn{programmed completion}.
1362 To use this feature, pass a symbol with a function definition as the
1363 @var{collection} argument to @code{completing-read}. The function
1364 @code{completing-read} arranges to pass your completion function along
1365 to @code{try-completion} and @code{all-completions}, which will then let
1366 your function do all the work.
1368 The completion function should accept three arguments:
1372 The string to be completed.
1375 The predicate function to filter possible matches, or @code{nil} if
1376 none. Your function should call the predicate for each possible match,
1377 and ignore the possible match if the predicate returns @code{nil}.
1380 A flag specifying the type of operation.
1383 There are three flag values for three operations:
1387 @code{nil} specifies @code{try-completion}. The completion function
1388 should return the completion of the specified string, or @code{t} if the
1389 string is a unique and exact match already, or @code{nil} if the string
1390 matches no possibility.
1392 If the string is an exact match for one possibility, but also matches
1393 other longer possibilities, the function should return the string, not
1397 @code{t} specifies @code{all-completions}. The completion function
1398 should return a list of all possible completions of the specified
1402 @code{lambda} specifies @code{test-completion}. The completion
1403 function should return @code{t} if the specified string is an exact
1404 match for some possibility; @code{nil} otherwise.
1407 It would be consistent and clean for completion functions to allow
1408 lambda expressions (lists that are functions) as well as function
1409 symbols as @var{collection}, but this is impossible. Lists as
1410 completion tables already have other meanings, and it would be
1411 unreliable to treat one differently just because it is also a possible
1412 function. So you must arrange for any function you wish to use for
1413 completion to be encapsulated in a symbol.
1415 Emacs uses programmed completion when completing file names.
1416 @xref{File Name Completion}.
1418 @defmac dynamic-completion-table function
1419 This macro is a convenient way to write a function that can act as
1420 programmed completion function. The argument @var{function} should be
1421 a function that takes one argument, a string, and returns an alist of
1422 possible completions of it. You can think of
1423 @code{dynamic-completion-table} as a transducer between that interface
1424 and the interface for programmed completion functions.
1427 @node Yes-or-No Queries
1428 @section Yes-or-No Queries
1429 @cindex asking the user questions
1430 @cindex querying the user
1431 @cindex yes-or-no questions
1433 This section describes functions used to ask the user a yes-or-no
1434 question. The function @code{y-or-n-p} can be answered with a single
1435 character; it is useful for questions where an inadvertent wrong answer
1436 will not have serious consequences. @code{yes-or-no-p} is suitable for
1437 more momentous questions, since it requires three or four characters to
1440 If either of these functions is called in a command that was invoked
1441 using the mouse---more precisely, if @code{last-nonmenu-event}
1442 (@pxref{Command Loop Info}) is either @code{nil} or a list---then it
1443 uses a dialog box or pop-up menu to ask the question. Otherwise, it
1444 uses keyboard input. You can force use of the mouse or use of keyboard
1445 input by binding @code{last-nonmenu-event} to a suitable value around
1448 Strictly speaking, @code{yes-or-no-p} uses the minibuffer and
1449 @code{y-or-n-p} does not; but it seems best to describe them together.
1451 @defun y-or-n-p prompt
1452 This function asks the user a question, expecting input in the echo
1453 area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the
1454 user types @kbd{n}. This function also accepts @key{SPC} to mean yes
1455 and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like
1456 @kbd{C-g}, because the question might look like a minibuffer and for
1457 that reason the user might try to use @kbd{C-]} to get out. The answer
1458 is a single character, with no @key{RET} needed to terminate it. Upper
1459 and lower case are equivalent.
1461 ``Asking the question'' means printing @var{prompt} in the echo area,
1462 followed by the string @w{@samp{(y or n) }}. If the input is not one of
1463 the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}},
1464 @kbd{@key{DEL}}, or something that quits), the function responds
1465 @samp{Please answer y or n.}, and repeats the request.
1467 This function does not actually use the minibuffer, since it does not
1468 allow editing of the answer. It actually uses the echo area (@pxref{The
1469 Echo Area}), which uses the same screen space as the minibuffer. The
1470 cursor moves to the echo area while the question is being asked.
1472 The answers and their meanings, even @samp{y} and @samp{n}, are not
1473 hardwired. The keymap @code{query-replace-map} specifies them.
1474 @xref{Search and Replace}.
1476 In the following example, the user first types @kbd{q}, which is
1477 invalid. At the next prompt the user types @kbd{y}.
1481 (y-or-n-p "Do you need a lift? ")
1483 ;; @r{After evaluation of the preceding expression,}
1484 ;; @r{the following prompt appears in the echo area:}
1488 ---------- Echo area ----------
1489 Do you need a lift? (y or n)
1490 ---------- Echo area ----------
1493 ;; @r{If the user then types @kbd{q}, the following appears:}
1496 ---------- Echo area ----------
1497 Please answer y or n. Do you need a lift? (y or n)
1498 ---------- Echo area ----------
1501 ;; @r{When the user types a valid answer,}
1502 ;; @r{it is displayed after the question:}
1505 ---------- Echo area ----------
1506 Do you need a lift? (y or n) y
1507 ---------- Echo area ----------
1512 We show successive lines of echo area messages, but only one actually
1513 appears on the screen at a time.
1516 @defun y-or-n-p-with-timeout prompt seconds default-value
1517 Like @code{y-or-n-p}, except that if the user fails to answer within
1518 @var{seconds} seconds, this function stops waiting and returns
1519 @var{default-value}. It works by setting up a timer; see @ref{Timers}.
1520 The argument @var{seconds} may be an integer or a floating point number.
1523 @defun yes-or-no-p prompt
1524 This function asks the user a question, expecting input in the
1525 minibuffer. It returns @code{t} if the user enters @samp{yes},
1526 @code{nil} if the user types @samp{no}. The user must type @key{RET} to
1527 finalize the response. Upper and lower case are equivalent.
1529 @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area,
1530 followed by @w{@samp{(yes or no) }}. The user must type one of the
1531 expected responses; otherwise, the function responds @samp{Please answer
1532 yes or no.}, waits about two seconds and repeats the request.
1534 @code{yes-or-no-p} requires more work from the user than
1535 @code{y-or-n-p} and is appropriate for more crucial decisions.
1541 (yes-or-no-p "Do you really want to remove everything? ")
1543 ;; @r{After evaluation of the preceding expression,}
1544 ;; @r{the following prompt appears,}
1545 ;; @r{with an empty minibuffer:}
1549 ---------- Buffer: minibuffer ----------
1550 Do you really want to remove everything? (yes or no)
1551 ---------- Buffer: minibuffer ----------
1556 If the user first types @kbd{y @key{RET}}, which is invalid because this
1557 function demands the entire word @samp{yes}, it responds by displaying
1558 these prompts, with a brief pause between them:
1562 ---------- Buffer: minibuffer ----------
1563 Please answer yes or no.
1564 Do you really want to remove everything? (yes or no)
1565 ---------- Buffer: minibuffer ----------
1570 @node Multiple Queries
1571 @section Asking Multiple Y-or-N Questions
1573 When you have a series of similar questions to ask, such as ``Do you
1574 want to save this buffer'' for each buffer in turn, you should use
1575 @code{map-y-or-n-p} to ask the collection of questions, rather than
1576 asking each question individually. This gives the user certain
1577 convenient facilities such as the ability to answer the whole series at
1580 @defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area
1581 This function asks the user a series of questions, reading a
1582 single-character answer in the echo area for each one.
1584 The value of @var{list} specifies the objects to ask questions about.
1585 It should be either a list of objects or a generator function. If it is
1586 a function, it should expect no arguments, and should return either the
1587 next object to ask about, or @code{nil} meaning stop asking questions.
1589 The argument @var{prompter} specifies how to ask each question. If
1590 @var{prompter} is a string, the question text is computed like this:
1593 (format @var{prompter} @var{object})
1597 where @var{object} is the next object to ask about (as obtained from
1600 If not a string, @var{prompter} should be a function of one argument
1601 (the next object to ask about) and should return the question text. If
1602 the value is a string, that is the question to ask the user. The
1603 function can also return @code{t} meaning do act on this object (and
1604 don't ask the user), or @code{nil} meaning ignore this object (and don't
1607 The argument @var{actor} says how to act on the answers that the user
1608 gives. It should be a function of one argument, and it is called with
1609 each object that the user says yes for. Its argument is always an
1610 object obtained from @var{list}.
1612 If the argument @var{help} is given, it should be a list of this form:
1615 (@var{singular} @var{plural} @var{action})
1619 where @var{singular} is a string containing a singular noun that
1620 describes the objects conceptually being acted on, @var{plural} is the
1621 corresponding plural noun, and @var{action} is a transitive verb
1622 describing what @var{actor} does.
1624 If you don't specify @var{help}, the default is @code{("object"
1625 "objects" "act on")}.
1627 Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or
1628 @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip
1629 that object; @kbd{!} to act on all following objects; @key{ESC} or
1630 @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on
1631 the current object and then exit; or @kbd{C-h} to get help. These are
1632 the same answers that @code{query-replace} accepts. The keymap
1633 @code{query-replace-map} defines their meaning for @code{map-y-or-n-p}
1634 as well as for @code{query-replace}; see @ref{Search and Replace}.
1636 You can use @var{action-alist} to specify additional possible answers
1637 and what they mean. It is an alist of elements of the form
1638 @code{(@var{char} @var{function} @var{help})}, each of which defines one
1639 additional answer. In this element, @var{char} is a character (the
1640 answer); @var{function} is a function of one argument (an object from
1641 @var{list}); @var{help} is a string.
1643 When the user responds with @var{char}, @code{map-y-or-n-p} calls
1644 @var{function}. If it returns non-@code{nil}, the object is considered
1645 ``acted upon'', and @code{map-y-or-n-p} advances to the next object in
1646 @var{list}. If it returns @code{nil}, the prompt is repeated for the
1649 Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while
1650 prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it
1653 If @code{map-y-or-n-p} is called in a command that was invoked using the
1654 mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command
1655 Loop Info}) is either @code{nil} or a list---then it uses a dialog box
1656 or pop-up menu to ask the question. In this case, it does not use
1657 keyboard input or the echo area. You can force use of the mouse or use
1658 of keyboard input by binding @code{last-nonmenu-event} to a suitable
1659 value around the call.
1661 The return value of @code{map-y-or-n-p} is the number of objects acted on.
1664 @node Reading a Password
1665 @section Reading a Password
1666 @cindex passwords, reading
1668 To read a password to pass to another program, you can use the
1669 function @code{read-passwd}.
1671 @defun read-passwd prompt &optional confirm default
1672 This function reads a password, prompting with @var{prompt}. It does
1673 not echo the password as the user types it; instead, it echoes @samp{.}
1674 for each character in the password.
1676 The optional argument @var{confirm}, if non-@code{nil}, says to read the
1677 password twice and insist it must be the same both times. If it isn't
1678 the same, the user has to type it over and over until the last two
1681 The optional argument @var{default} specifies the default password to
1682 return if the user enters empty input. If @var{default} is @code{nil},
1683 then @code{read-passwd} returns the null string in that case.
1686 @node Minibuffer Misc
1687 @section Minibuffer Miscellany
1689 This section describes some basic functions and variables related to
1692 @deffn Command exit-minibuffer
1693 This command exits the active minibuffer. It is normally bound to
1694 keys in minibuffer local keymaps.
1697 @deffn Command self-insert-and-exit
1698 This command exits the active minibuffer after inserting the last
1699 character typed on the keyboard (found in @code{last-command-char};
1700 @pxref{Command Loop Info}).
1703 @deffn Command previous-history-element n
1704 This command replaces the minibuffer contents with the value of the
1705 @var{n}th previous (older) history element.
1708 @deffn Command next-history-element n
1709 This command replaces the minibuffer contents with the value of the
1710 @var{n}th more recent history element.
1713 @deffn Command previous-matching-history-element pattern n
1714 This command replaces the minibuffer contents with the value of the
1715 @var{n}th previous (older) history element that matches @var{pattern} (a
1716 regular expression).
1719 @deffn Command next-matching-history-element pattern n
1720 This command replaces the minibuffer contents with the value of the
1721 @var{n}th next (newer) history element that matches @var{pattern} (a
1722 regular expression).
1725 @defun minibuffer-prompt
1726 This function returns the prompt string of the currently active
1727 minibuffer. If no minibuffer is active, it returns @code{nil}.
1730 @defun minibuffer-prompt-end
1731 @tindex minibuffer-prompt-end
1732 This function, available starting in Emacs 21, returns the current
1733 position of the end of the minibuffer prompt, if a minibuffer is
1734 current. Otherwise, it returns the minimum valid buffer position.
1737 @defun minibuffer-contents
1738 @tindex minibuffer-contents
1739 This function, available starting in Emacs 21, returns the editable
1740 contents of the minibuffer (that is, everything except the prompt) as
1741 a string, if a minibuffer is current. Otherwise, it returns the
1742 entire contents of the current buffer.
1745 @defun minibuffer-contents-no-properties
1746 @tindex minibuffer-contents-no-properties
1747 This is like @code{minibuffer-contents}, except that it does not copy text
1748 properties, just the characters themselves. @xref{Text Properties}.
1751 @defun delete-minibuffer-contents
1752 @tindex delete-minibuffer-contents
1753 This function, available starting in Emacs 21, erases the editable
1754 contents of the minibuffer (that is, everything except the prompt), if
1755 a minibuffer is current. Otherwise, it erases the entire buffer.
1758 @defun minibuffer-prompt-width
1759 This function returns the current display-width of the minibuffer
1760 prompt, if a minibuffer is current. Otherwise, it returns zero.
1763 @defvar minibuffer-setup-hook
1764 This is a normal hook that is run whenever the minibuffer is entered.
1768 @defvar minibuffer-exit-hook
1769 This is a normal hook that is run whenever the minibuffer is exited.
1773 @defvar minibuffer-help-form
1774 @anchor{Definition of minibuffer-help-form}
1775 The current value of this variable is used to rebind @code{help-form}
1776 locally inside the minibuffer (@pxref{Help Functions}).
1779 @defun minibufferp &optional buffer-or-name
1780 This function returns non-@code{nil} if @var{buffer-or-name} is a
1781 minibuffer. If @var{buffer-or-name} is omitted, it tests the current
1785 @defun active-minibuffer-window
1786 This function returns the currently active minibuffer window, or
1787 @code{nil} if none is currently active.
1790 @defun minibuffer-window &optional frame
1791 @anchor{Definition of minibuffer-window}
1792 This function returns the minibuffer window used for frame @var{frame}.
1793 If @var{frame} is @code{nil}, that stands for the current frame. Note
1794 that the minibuffer window used by a frame need not be part of that
1795 frame---a frame that has no minibuffer of its own necessarily uses some
1796 other frame's minibuffer window.
1799 @defun set-minibuffer-window window
1800 This function specifies @var{window} as the minibuffer window to use.
1801 This affects where the minibuffer is displayed if you put text in it
1802 without invoking the usual minibuffer commands. It has no effect on
1803 the usual minibuffer input functions because they all start by
1804 choosing the minibuffer window according to the current frame.
1808 @defun window-minibuffer-p &optional window
1809 This function returns non-@code{nil} if @var{window} is a minibuffer
1811 @var{window} defaults to the selected window.
1814 It is not correct to determine whether a given window is a minibuffer by
1815 comparing it with the result of @code{(minibuffer-window)}, because
1816 there can be more than one minibuffer window if there is more than one
1819 @defun minibuffer-window-active-p window
1820 This function returns non-@code{nil} if @var{window}, assumed to be
1821 a minibuffer window, is currently active.
1824 @defvar minibuffer-scroll-window
1825 @anchor{Definition of minibuffer-scroll-window}
1826 If the value of this variable is non-@code{nil}, it should be a window
1827 object. When the function @code{scroll-other-window} is called in the
1828 minibuffer, it scrolls this window.
1831 @defun minibuffer-selected-window
1832 This function returns the window which was selected when the
1833 minibuffer was entered. If selected window is not a minibuffer
1834 window, it returns @code{nil}.
1837 Finally, some functions and variables deal with recursive minibuffers
1838 (@pxref{Recursive Editing}):
1840 @defun minibuffer-depth
1841 This function returns the current depth of activations of the
1842 minibuffer, a nonnegative integer. If no minibuffers are active, it
1846 @defopt enable-recursive-minibuffers
1847 If this variable is non-@code{nil}, you can invoke commands (such as
1848 @code{find-file}) that use minibuffers even while the minibuffer window
1849 is active. Such invocation produces a recursive editing level for a new
1850 minibuffer. The outer-level minibuffer is invisible while you are
1851 editing the inner one.
1853 If this variable is @code{nil}, you cannot invoke minibuffer
1854 commands when the minibuffer window is active, not even if you switch to
1855 another window to do it.
1859 If a command name has a property @code{enable-recursive-minibuffers}
1860 that is non-@code{nil}, then the command can use the minibuffer to read
1861 arguments even if it is invoked from the minibuffer. A command can
1862 also achieve this by binding @code{enable-recursive-minibuffers}
1863 to @code{t} in the interactive declaration (@pxref{Using Interactive}).
1864 The minibuffer command @code{next-matching-history-element} (normally
1865 @kbd{M-s} in the minibuffer) does the latter.
1867 @defun minibuffer-message string
1868 This function displays @var{string} temporarily at the end of the
1869 minibuffer text, for two seconds, or until the next input event
1870 arrives, whichever comes first.
1874 arch-tag: bba7f945-9078-477f-a2ce-18818a6e1218