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
116 In most cases, you should not call minibuffer input functions in the
117 middle of a Lisp function. Instead, do all minibuffer input as part of
118 reading the arguments for a command, in the @code{interactive}
119 specification. @xref{Defining Commands}.
121 @defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method
122 This function is the most general way to get input through the
123 minibuffer. By default, it accepts arbitrary text and returns it as a
124 string; however, if @var{read} is non-@code{nil}, then it uses
125 @code{read} to convert the text into a Lisp object (@pxref{Input
128 The first thing this function does is to activate a minibuffer and
129 display it with @var{prompt-string} as the prompt. This value must be a
130 string. Then the user can edit text in the minibuffer.
132 When the user types a command to exit the minibuffer,
133 @code{read-from-minibuffer} constructs the return value from the text in
134 the minibuffer. Normally it returns a string containing that text.
135 However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer}
136 reads the text and returns the resulting Lisp object, unevaluated.
137 (@xref{Input Functions}, for information about reading.)
139 The argument @var{default} specifies a default value to make available
140 through the history commands. It should be a string, or @code{nil}.
141 If non-@code{nil}, the user can access it using
142 @code{next-history-element}, usually bound in the minibuffer to
143 @kbd{M-n}. If @var{read} is non-@code{nil}, then @var{default} is
144 also used as the input to @code{read}, if the user enters empty input.
145 (If @var{read} is non-@code{nil} and @var{default} is @code{nil}, empty
146 input results in an @code{end-of-file} error.) However, in the usual
147 case (where @var{read} is @code{nil}), @code{read-from-minibuffer}
148 ignores @var{default} when the user enters empty input and returns an
149 empty string, @code{""}. In this respect, it is different from all
150 the other minibuffer input functions in this chapter.
152 If @var{keymap} is non-@code{nil}, that keymap is the local keymap to
153 use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the
154 value of @code{minibuffer-local-map} is used as the keymap. Specifying
155 a keymap is the most important way to customize the minibuffer for
156 various applications such as completion.
158 The argument @var{hist} specifies which history list variable to use
159 for saving the input and for history commands used in the minibuffer.
160 It defaults to @code{minibuffer-history}. @xref{Minibuffer History}.
162 If the variable @code{minibuffer-allow-text-properties} is
163 non-@code{nil}, then the string which is returned includes whatever text
164 properties were present in the minibuffer. Otherwise all the text
165 properties are stripped when the value is returned.
167 If the argument @var{inherit-input-method} is non-@code{nil}, then the
168 minibuffer inherits the current input method (@pxref{Input Methods}) and
169 the setting of @code{enable-multibyte-characters} (@pxref{Text
170 Representations}) from whichever buffer was current before entering the
173 Use of @var{initial-contents} is mostly deprecated; we recommend using
174 a non-@code{nil} value only in conjunction with specifying a cons cell
175 for @var{hist}. @xref{Initial Input}.
178 @defun read-string prompt &optional initial history default inherit-input-method
179 This function reads a string from the minibuffer and returns it. The
180 arguments @var{prompt}, @var{initial}, @var{history} and
181 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
182 The keymap used is @code{minibuffer-local-map}.
184 The optional argument @var{default} is used as in
185 @code{read-from-minibuffer}, except that, if non-@code{nil}, it also
186 specifies a default value to return if the user enters null input. As
187 in @code{read-from-minibuffer} it should be a string, or @code{nil},
188 which is equivalent to an empty string.
190 This function is a simplified interface to the
191 @code{read-from-minibuffer} function:
195 (read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit})
198 (read-from-minibuffer @var{prompt} @var{initial} nil nil
199 @var{history} @var{default} @var{inherit})))
200 (if (and (equal value "") @var{default})
207 @defvar minibuffer-allow-text-properties
208 If this variable is @code{nil}, then @code{read-from-minibuffer} strips
209 all text properties from the minibuffer input before returning it.
210 This variable also affects @code{read-string}. However,
211 @code{read-no-blanks-input} (see below), as well as
212 @code{read-minibuffer} and related functions (@pxref{Object from
213 Minibuffer,, Reading Lisp Objects With the Minibuffer}), and all
214 functions that do minibuffer input with completion, discard text
215 properties unconditionally, regardless of the value of this variable.
218 @defvar minibuffer-local-map
219 @anchor{Definition of minibuffer-local-map}
220 This is the default local keymap for reading from the minibuffer. By
221 default, it makes the following bindings:
225 @code{exit-minibuffer}
228 @code{exit-minibuffer}
231 @code{abort-recursive-edit}
234 @code{next-history-element}
237 @code{previous-history-element}
240 @code{next-matching-history-element}
243 @code{previous-matching-history-element}
247 @c In version 18, initial is required
249 @defun read-no-blanks-input prompt &optional initial inherit-input-method
250 This function reads a string from the minibuffer, but does not allow
251 whitespace characters as part of the input: instead, those characters
252 terminate the input. The arguments @var{prompt}, @var{initial}, and
253 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
255 This is a simplified interface to the @code{read-from-minibuffer}
256 function, and passes the value of the @code{minibuffer-local-ns-map}
257 keymap as the @var{keymap} argument for that function. Since the keymap
258 @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is}
259 possible to put a space into the string, by quoting it.
261 This function discards text properties, regardless of the value of
262 @code{minibuffer-allow-text-properties}.
266 (read-no-blanks-input @var{prompt} @var{initial})
268 (let (minibuffer-allow-text-properties)
269 (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map))
274 @defvar minibuffer-local-ns-map
275 This built-in variable is the keymap used as the minibuffer local keymap
276 in the function @code{read-no-blanks-input}. By default, it makes the
277 following bindings, in addition to those of @code{minibuffer-local-map}:
281 @cindex @key{SPC} in minibuffer
282 @code{exit-minibuffer}
285 @cindex @key{TAB} in minibuffer
286 @code{exit-minibuffer}
289 @cindex @kbd{?} in minibuffer
290 @code{self-insert-and-exit}
294 @node Object from Minibuffer
295 @section Reading Lisp Objects with the Minibuffer
297 This section describes functions for reading Lisp objects with the
300 @defun read-minibuffer prompt &optional initial
301 This function reads a Lisp object using the minibuffer, and returns it
302 without evaluating it. The arguments @var{prompt} and @var{initial} are
303 used as in @code{read-from-minibuffer}.
305 This is a simplified interface to the
306 @code{read-from-minibuffer} function:
310 (read-minibuffer @var{prompt} @var{initial})
312 (let (minibuffer-allow-text-properties)
313 (read-from-minibuffer @var{prompt} @var{initial} nil t))
317 Here is an example in which we supply the string @code{"(testing)"} as
323 "Enter an expression: " (format "%s" '(testing)))
325 ;; @r{Here is how the minibuffer is displayed:}
329 ---------- Buffer: Minibuffer ----------
330 Enter an expression: (testing)@point{}
331 ---------- Buffer: Minibuffer ----------
336 The user can type @key{RET} immediately to use the initial input as a
337 default, or can edit the input.
340 @defun eval-minibuffer prompt &optional initial
341 This function reads a Lisp expression using the minibuffer, evaluates
342 it, then returns the result. The arguments @var{prompt} and
343 @var{initial} are used as in @code{read-from-minibuffer}.
345 This function simply evaluates the result of a call to
346 @code{read-minibuffer}:
350 (eval-minibuffer @var{prompt} @var{initial})
352 (eval (read-minibuffer @var{prompt} @var{initial}))
357 @defun edit-and-eval-command prompt form
358 This function reads a Lisp expression in the minibuffer, and then
359 evaluates it. The difference between this command and
360 @code{eval-minibuffer} is that here the initial @var{form} is not
361 optional and it is treated as a Lisp object to be converted to printed
362 representation rather than as a string of text. It is printed with
363 @code{prin1}, so if it is a string, double-quote characters (@samp{"})
364 appear in the initial text. @xref{Output Functions}.
366 The first thing @code{edit-and-eval-command} does is to activate the
367 minibuffer with @var{prompt} as the prompt. Then it inserts the printed
368 representation of @var{form} in the minibuffer, and lets the user edit it.
369 When the user exits the minibuffer, the edited text is read with
370 @code{read} and then evaluated. The resulting value becomes the value
371 of @code{edit-and-eval-command}.
373 In the following example, we offer the user an expression with initial
374 text which is a valid form already:
378 (edit-and-eval-command "Please edit: " '(forward-word 1))
380 ;; @r{After evaluation of the preceding expression,}
381 ;; @r{the following appears in the minibuffer:}
385 ---------- Buffer: Minibuffer ----------
386 Please edit: (forward-word 1)@point{}
387 ---------- Buffer: Minibuffer ----------
392 Typing @key{RET} right away would exit the minibuffer and evaluate the
393 expression, thus moving point forward one word.
394 @code{edit-and-eval-command} returns @code{nil} in this example.
397 @node Minibuffer History
398 @section Minibuffer History
399 @cindex minibuffer history
402 A @dfn{minibuffer history list} records previous minibuffer inputs so
403 the user can reuse them conveniently. A history list is actually a
404 symbol, not a list; it is a variable whose value is a list of strings
405 (previous inputs), most recent first.
407 There are many separate history lists, used for different kinds of
408 inputs. It's the Lisp programmer's job to specify the right history
409 list for each use of the minibuffer.
411 The basic minibuffer input functions @code{read-from-minibuffer} and
412 @code{completing-read} both accept an optional argument named @var{hist}
413 which is how you specify the history list. Here are the possible
418 Use @var{variable} (a symbol) as the history list.
420 @item (@var{variable} . @var{startpos})
421 Use @var{variable} (a symbol) as the history list, and assume that the
422 initial history position is @var{startpos} (a nonnegative integer).
424 Specifying 0 for @var{startpos} is equivalent to just specifying the
425 symbol @var{variable}. @code{previous-history-element} will display
426 the most recent element of the history list in the minibuffer. If you
427 specify a positive @var{startpos}, the minibuffer history functions
428 behave as if @code{(elt @var{variable} (1- @var{STARTPOS}))} were the
429 history element currently shown in the minibuffer.
431 For consistency, you should also specify that element of the history
432 as the initial minibuffer contents, using the @var{initial} argument
433 to the minibuffer input function (@pxref{Initial Input}).
436 If you don't specify @var{hist}, then the default history list
437 @code{minibuffer-history} is used. For other standard history lists,
438 see below. You can also create your own history list variable; just
439 initialize it to @code{nil} before the first use.
441 Both @code{read-from-minibuffer} and @code{completing-read} add new
442 elements to the history list automatically, and provide commands to
443 allow the user to reuse items on the list. The only thing your program
444 needs to do to use a history list is to initialize it and to pass its
445 name to the input functions when you wish. But it is safe to modify the
446 list by hand when the minibuffer input functions are not using it.
448 Emacs functions that add a new element to a history list can also
449 delete old elements if the list gets too long. The variable
450 @code{history-length} specifies the maximum length for most history
451 lists. To specify a different maximum length for a particular history
452 list, put the length in the @code{history-length} property of the
455 @defvar history-length
456 The value of this variable specifies the maximum length for all
457 history lists that don't specify their own maximum lengths. If the
458 value is @code{t}, that means there no maximum (don't delete old
462 Here are some of the standard minibuffer history list variables:
464 @defvar minibuffer-history
465 The default history list for minibuffer history input.
468 @defvar query-replace-history
469 A history list for arguments to @code{query-replace} (and similar
470 arguments to other commands).
473 @defvar file-name-history
474 A history list for file-name arguments.
477 @defvar buffer-name-history
478 A history list for buffer-name arguments.
481 @defvar regexp-history
482 A history list for regular expression arguments.
485 @defvar extended-command-history
486 A history list for arguments that are names of extended commands.
489 @defvar shell-command-history
490 A history list for arguments that are shell commands.
493 @defvar read-expression-history
494 A history list for arguments that are Lisp expressions to evaluate.
498 @section Initial Input
500 Several of the functions for minibuffer input have an argument called
501 @var{initial} or @var{initial-contents}. This is a mostly-deprecated
502 feature for specifiying that the minibuffer should start out with
503 certain text, instead of empty as usual.
505 If @var{initial} is a string, the minibuffer starts out containing the
506 text of the string, with point at the end, when the user starts to
507 edit the text. If the user simply types @key{RET} to exit the
508 minibuffer, it will use the initial input string to determine the
511 @strong{We discourage use of a non-@code{nil} value for
512 @var{initial}}, because initial input is an intrusive interface.
513 History lists and default values provide a much more convenient method
514 to offer useful default inputs to the user.
516 There is just one situation where you should specify a string for an
517 @var{initial} argument. This is when you specify a cons cell for the
518 @var{hist} or @var{history} argument. @xref{Minibuffer History}.
520 @var{initial} can also be a cons cell of the form @code{(@var{string}
521 . @var{position})}. This means to insert @var{string} in the
522 minibuffer but put point at @var{position} within the string's text.
524 As a historical accident, @var{position} was implemented
525 inconsistently in different functions. In @code{completing-read},
526 @var{position}'s value is interpreted as origin-zero; that is, a value
527 of 0 means the beginning of the string, 1 means after the first
528 character, etc. In @code{read-minibuffer}, and the other
529 non-completion minibuffer input functions that support this argument,
530 1 means the beginning of the string 2 means after the first character,
533 Use of a cons cell as the value for @var{initial} arguments is
534 deprecated in user code.
540 @dfn{Completion} is a feature that fills in the rest of a name
541 starting from an abbreviation for it. Completion works by comparing the
542 user's input against a list of valid names and determining how much of
543 the name is determined uniquely by what the user has typed. For
544 example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then
545 type the first few letters of the name of the buffer to which you wish
546 to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs
547 extends the name as far as it can.
549 Standard Emacs commands offer completion for names of symbols, files,
550 buffers, and processes; with the functions in this section, you can
551 implement completion for other kinds of names.
553 The @code{try-completion} function is the basic primitive for
554 completion: it returns the longest determined completion of a given
555 initial string, with a given set of strings to match against.
557 The function @code{completing-read} provides a higher-level interface
558 for completion. A call to @code{completing-read} specifies how to
559 determine the list of valid names. The function then activates the
560 minibuffer with a local keymap that binds a few keys to commands useful
561 for completion. Other functions provide convenient simple interfaces
562 for reading certain kinds of names with completion.
565 * Basic Completion:: Low-level functions for completing strings.
566 (These are too low level to use the minibuffer.)
567 * Minibuffer Completion:: Invoking the minibuffer with completion.
568 * Completion Commands:: Minibuffer commands that do completion.
569 * High-Level Completion:: Convenient special cases of completion
570 (reading buffer name, file name, etc.)
571 * Reading File Names:: Using completion to read file names.
572 * Programmed Completion:: Writing your own completion-function.
575 @node Basic Completion
576 @subsection Basic Completion Functions
578 The functions @code{try-completion}, @code{all-completions} and
579 @code{test-completion} have nothing in themselves to do with
580 minibuffers. We describe them in this chapter so as to keep them near
581 the higher-level completion features that do use the minibuffer.
583 @defun try-completion string collection &optional predicate
584 This function returns the longest common substring of all possible
585 completions of @var{string} in @var{collection}. The value of
586 @var{collection} must be a list of strings, an alist, an obarray, a
587 hash table, or a function that implements a virtual set of strings
590 Completion compares @var{string} against each of the permissible
591 completions specified by @var{collection}; if the beginning of the
592 permissible completion equals @var{string}, it matches. If no permissible
593 completions match, @code{try-completion} returns @code{nil}. If only
594 one permissible completion matches, and the match is exact, then
595 @code{try-completion} returns @code{t}. Otherwise, the value is the
596 longest initial sequence common to all the permissible completions that
599 If @var{collection} is an alist (@pxref{Association Lists}), the
600 permissible completions are the elements of the alist that are either
601 strings or conses whose @sc{car} is a string. Other elements of the
602 alist are ignored. (Remember that in Emacs Lisp, the elements of
603 alists do not @emph{have} to be conses.) As all elements of the alist
604 can be strings, this case actually includes lists of strings, even
605 though we usually do not think of such lists as alists.
607 @cindex obarray in completion
608 If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
609 of all symbols in the obarray form the set of permissible completions. The
610 global variable @code{obarray} holds an obarray containing the names of
611 all interned Lisp symbols.
613 Note that the only valid way to make a new obarray is to create it
614 empty and then add symbols to it one by one using @code{intern}.
615 Also, you cannot intern a given symbol in more than one obarray.
617 If @var{collection} is a hash table, then the keys that are strings
618 are the possible completions. Other keys are ignored.
620 You can also use a symbol that is a function as @var{collection}. Then
621 the function is solely responsible for performing completion;
622 @code{try-completion} returns whatever this function returns. The
623 function is called with three arguments: @var{string}, @var{predicate}
624 and @code{nil}. (The reason for the third argument is so that the same
625 function can be used in @code{all-completions} and do the appropriate
626 thing in either case.) @xref{Programmed Completion}.
628 If the argument @var{predicate} is non-@code{nil}, then it must be a
629 function of one argument, unless @var{collection} is a hash table, in
630 which case it should be a function of two arguments. It is used to
631 test each possible match, and the match is accepted only if
632 @var{predicate} returns non-@code{nil}. The argument given to
633 @var{predicate} is either a string or a cons cell (the @sc{car} of
634 which is a string) from the alist, or a symbol (@emph{not} a symbol
635 name) from the obarray. If @var{collection} is a hash table,
636 @var{predicate} is called with two arguments, the string key and the
639 In addition, to be acceptable, a completion must also match all the
640 regular expressions in @code{completion-regexp-list}. (Unless
641 @var{collection} is a function, in which case that function has to
642 handle @code{completion-regexp-list} itself.)
644 In the first of the following examples, the string @samp{foo} is
645 matched by three of the alist @sc{car}s. All of the matches begin with
646 the characters @samp{fooba}, so that is the result. In the second
647 example, there is only one possible match, and it is exact, so the value
654 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
659 (try-completion "foo" '(("barfoo" 2) ("foo" 3)))
664 In the following example, numerous symbols begin with the characters
665 @samp{forw}, and all of them begin with the word @samp{forward}. In
666 most of the symbols, this is followed with a @samp{-}, but not in all,
667 so no more than @samp{forward} can be completed.
671 (try-completion "forw" obarray)
676 Finally, in the following example, only two of the three possible
677 matches pass the predicate @code{test} (the string @samp{foobaz} is
678 too short). Both of those begin with the string @samp{foobar}.
683 (> (length (car s)) 6))
689 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
696 @defun all-completions string collection &optional predicate nospace
697 This function returns a list of all possible completions of
698 @var{string}. The arguments to this function (aside from
699 @var{nospace}) are the same as those of @code{try-completion}. Also,
700 this function uses @code{completion-regexp-list} in the same way that
701 @code{try-completion} does. The optional argument @var{nospace} only
702 matters if @var{string} is the empty string. In that case, if
703 @var{nospace} is non-@code{nil}, completions that start with a space
706 If @var{collection} is a function, it is called with three arguments:
707 @var{string}, @var{predicate} and @code{t}; then @code{all-completions}
708 returns whatever the function returns. @xref{Programmed Completion}.
710 Here is an example, using the function @code{test} shown in the
711 example for @code{try-completion}:
716 (> (length (car s)) 6))
723 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
725 @result{} ("foobar1" "foobar2")
730 @defun test-completion string collection &optional predicate
731 @anchor{Definition of test-completion}
732 This function returns non-@code{nil} if @var{string} is a valid
733 completion possibility specified by @var{collection} and
734 @var{predicate}. The arguments are the same as in
735 @code{try-completion}. For instance, if @var{collection} is a list of
736 strings, this is true if @var{string} appears in the list and
737 @var{predicate} is satisfied.
739 @code{test-completion} uses @code{completion-regexp-list} in the same
740 way that @code{try-completion} does.
742 If @var{predicate} is non-@code{nil} and if @var{collection} contains
743 several strings that are equal to each other, as determined by
744 @code{compare-strings} according to @code{completion-ignore-case},
745 then @var{predicate} should accept either all or none of them.
746 Otherwise, the return value of @code{test-completion} is essentially
749 If @var{collection} is a function, it is called with three arguments,
750 the values @var{string}, @var{predicate} and @code{lambda}; whatever
751 it returns, @code{test-completion} returns in turn.
754 @defvar completion-ignore-case
755 If the value of this variable is non-@code{nil}, Emacs does not
756 consider case significant in completion.
759 @defvar completion-regexp-list
760 This is a list of regular expressions. The completion functions only
761 consider a completion acceptable if it matches all regular expressions
762 in this list, with @code{case-fold-search} (@pxref{Searching and Case})
763 bound to the value of @code{completion-ignore-case}.
766 @defmac lazy-completion-table var fun &rest args
767 This macro provides a way to initialize the variable @var{var} as a
768 collection for completion in a lazy way, not computing its actual
769 contents until they are first needed. You use this macro to produce a
770 value that you store in @var{var}. The actual computation of the
771 proper value is done the first time you do completion using @var{var}.
772 It is done by calling @var{fun} with the arguments @var{args}. The
773 value @var{fun} returns becomes the permanent value of @var{var}.
775 Here are two examples of use:
778 (defvar foo (lazy-completion-table foo make-my-alist 'global))
780 (make-local-variable 'bar)
781 (setq bar (lazy-completion-table foo make-my-alist 'local)
785 @node Minibuffer Completion
786 @subsection Completion and the Minibuffer
788 This section describes the basic interface for reading from the
789 minibuffer with completion.
791 @defun completing-read prompt collection &optional predicate require-match initial hist default inherit-input-method
792 This function reads a string in the minibuffer, assisting the user by
793 providing completion. It activates the minibuffer with prompt
794 @var{prompt}, which must be a string.
796 The actual completion is done by passing @var{collection} and
797 @var{predicate} to the function @code{try-completion}. This happens
798 in certain commands bound in the local keymaps used for completion.
799 Some of these commands also call @code{test-completion}. Thus, if
800 @var{predicate} is non-@code{nil}, it should be compatible with
801 @var{collection} and @code{completion-ignore-case}. @xref{Definition
804 If @var{require-match} is @code{nil}, the exit commands work regardless
805 of the input in the minibuffer. If @var{require-match} is @code{t}, the
806 usual minibuffer exit commands won't exit unless the input completes to
807 an element of @var{collection}. If @var{require-match} is neither
808 @code{nil} nor @code{t}, then the exit commands won't exit unless the
809 input already in the buffer matches an element of @var{collection}.
811 However, empty input is always permitted, regardless of the value of
812 @var{require-match}; in that case, @code{completing-read} returns
813 @var{default}, or @code{""}, if @var{default} is @code{nil}. The
814 value of @var{default} (if non-@code{nil}) is also available to the
815 user through the history commands.
817 The function @code{completing-read} uses
818 @code{minibuffer-local-completion-map} as the keymap if
819 @var{require-match} is @code{nil}, and uses
820 @code{minibuffer-local-must-match-map} if @var{require-match} is
821 non-@code{nil}. @xref{Completion Commands}.
823 The argument @var{hist} specifies which history list variable to use for
824 saving the input and for minibuffer history commands. It defaults to
825 @code{minibuffer-history}. @xref{Minibuffer History}.
827 The argument @var{initial} is mostly deprecated; we recommend using a
828 non-@code{nil} value only in conjunction with specifying a cons cell
829 for @var{hist}. @xref{Initial Input}. For default input, use
830 @var{default} instead.
832 If the argument @var{inherit-input-method} is non-@code{nil}, then the
833 minibuffer inherits the current input method (@pxref{Input
834 Methods}) and the setting of @code{enable-multibyte-characters}
835 (@pxref{Text Representations}) from whichever buffer was current before
836 entering the minibuffer.
838 Completion ignores case when comparing the input against the possible
839 matches, if the built-in variable @code{completion-ignore-case} is
840 non-@code{nil}. @xref{Basic Completion}.
842 Here's an example of using @code{completing-read}:
848 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
853 ;; @r{After evaluation of the preceding expression,}
854 ;; @r{the following appears in the minibuffer:}
856 ---------- Buffer: Minibuffer ----------
857 Complete a foo: fo@point{}
858 ---------- Buffer: Minibuffer ----------
863 If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}},
864 @code{completing-read} returns @code{barfoo}.
866 The @code{completing-read} function binds three variables to pass
867 information to the commands that actually do completion. These
868 variables are @code{minibuffer-completion-table},
869 @code{minibuffer-completion-predicate} and
870 @code{minibuffer-completion-confirm}. For more information about them,
871 see @ref{Completion Commands}.
874 @node Completion Commands
875 @subsection Minibuffer Commands that Do Completion
877 This section describes the keymaps, commands and user options used
878 in the minibuffer to do completion. The description refers to the
879 situation when Partial Completion mode is disabled (as it is by
880 default). When enabled, this minor mode uses its own alternatives to
881 some of the commands described below. @xref{Completion Options,,,
882 emacs, The GNU Emacs Manual}, for a short description of Partial
885 @defvar minibuffer-local-completion-map
886 @code{completing-read} uses this value as the local keymap when an
887 exact match of one of the completions is not required. By default, this
888 keymap makes the following bindings:
892 @code{minibuffer-completion-help}
895 @code{minibuffer-complete-word}
898 @code{minibuffer-complete}
902 with other characters bound as in @code{minibuffer-local-map}
903 (@pxref{Definition of minibuffer-local-map}).
906 @defvar minibuffer-local-must-match-map
907 @code{completing-read} uses this value as the local keymap when an
908 exact match of one of the completions is required. Therefore, no keys
909 are bound to @code{exit-minibuffer}, the command that exits the
910 minibuffer unconditionally. By default, this keymap makes the following
915 @code{minibuffer-completion-help}
918 @code{minibuffer-complete-word}
921 @code{minibuffer-complete}
924 @code{minibuffer-complete-and-exit}
927 @code{minibuffer-complete-and-exit}
931 with other characters bound as in @code{minibuffer-local-map}.
934 @defvar minibuffer-completion-table
935 The value of this variable is the collection used for completion in
936 the minibuffer. This is the global variable that contains what
937 @code{completing-read} passes to @code{try-completion}. It is used by
938 minibuffer completion commands such as @code{minibuffer-complete-word}.
941 @defvar minibuffer-completion-predicate
942 This variable's value is the predicate that @code{completing-read}
943 passes to @code{try-completion}. The variable is also used by the other
944 minibuffer completion functions.
947 @deffn Command minibuffer-complete-word
948 This function completes the minibuffer contents by at most a single
949 word. Even if the minibuffer contents have only one completion,
950 @code{minibuffer-complete-word} does not add any characters beyond the
951 first character that is not a word constituent. @xref{Syntax Tables}.
954 @deffn Command minibuffer-complete
955 This function completes the minibuffer contents as far as possible.
958 @deffn Command minibuffer-complete-and-exit
959 This function completes the minibuffer contents, and exits if
960 confirmation is not required, i.e., if
961 @code{minibuffer-completion-confirm} is @code{nil}. If confirmation
962 @emph{is} required, it is given by repeating this command
963 immediately---the command is programmed to work without confirmation
964 when run twice in succession.
967 @defvar minibuffer-completion-confirm
968 When the value of this variable is non-@code{nil}, Emacs asks for
969 confirmation of a completion before exiting the minibuffer. The
970 function @code{minibuffer-complete-and-exit} checks the value of this
971 variable before it exits.
974 @deffn Command minibuffer-completion-help
975 This function creates a list of the possible completions of the
976 current minibuffer contents. It works by calling @code{all-completions}
977 using the value of the variable @code{minibuffer-completion-table} as
978 the @var{collection} argument, and the value of
979 @code{minibuffer-completion-predicate} as the @var{predicate} argument.
980 The list of completions is displayed as text in a buffer named
981 @samp{*Completions*}.
984 @defun display-completion-list completions
985 This function displays @var{completions} to the stream in
986 @code{standard-output}, usually a buffer. (@xref{Read and Print}, for more
987 information about streams.) The argument @var{completions} is normally
988 a list of completions just returned by @code{all-completions}, but it
989 does not have to be. Each element may be a symbol or a string, either
990 of which is simply printed. It can also be a list of two strings,
991 which is printed as if the strings were concatenated. The first of
992 the two strings is the actual completion, the second string serves as
995 This function is called by @code{minibuffer-completion-help}. The
996 most common way to use it is together with
997 @code{with-output-to-temp-buffer}, like this:
1000 (with-output-to-temp-buffer "*Completions*"
1001 (display-completion-list
1002 (all-completions (buffer-string) my-alist)))
1006 @defopt completion-auto-help
1007 If this variable is non-@code{nil}, the completion commands
1008 automatically display a list of possible completions whenever nothing
1009 can be completed because the next character is not uniquely determined.
1012 @node High-Level Completion
1013 @subsection High-Level Completion Functions
1015 This section describes the higher-level convenient functions for
1016 reading certain sorts of names with completion.
1018 In most cases, you should not call these functions in the middle of a
1019 Lisp function. When possible, do all minibuffer input as part of
1020 reading the arguments for a command, in the @code{interactive}
1021 specification. @xref{Defining Commands}.
1023 @defun read-buffer prompt &optional default existing
1024 This function reads the name of a buffer and returns it as a string.
1025 The argument @var{default} is the default name to use, the value to
1026 return if the user exits with an empty minibuffer. If non-@code{nil},
1027 it should be a string or a buffer. It is mentioned in the prompt, but
1028 is not inserted in the minibuffer as initial input.
1030 If @var{existing} is non-@code{nil}, then the name specified must be
1031 that of an existing buffer. The usual commands to exit the minibuffer
1032 do not exit if the text is not valid, and @key{RET} does completion to
1033 attempt to find a valid name. If @var{existing} is neither @code{nil}
1034 nor @code{t}, confirmation is required after completion. (However,
1035 @var{default} is not checked for validity; it is returned, whatever it
1036 is, if the user exits with the minibuffer empty.)
1038 In the following example, the user enters @samp{minibuffer.t}, and
1039 then types @key{RET}. The argument @var{existing} is @code{t}, and the
1040 only buffer name starting with the given input is
1041 @samp{minibuffer.texi}, so that name is the value.
1044 (read-buffer "Buffer name? " "foo" t)
1046 ;; @r{After evaluation of the preceding expression,}
1047 ;; @r{the following prompt appears,}
1048 ;; @r{with an empty minibuffer:}
1052 ---------- Buffer: Minibuffer ----------
1053 Buffer name? (default foo) @point{}
1054 ---------- Buffer: Minibuffer ----------
1058 ;; @r{The user types @kbd{minibuffer.t @key{RET}}.}
1059 @result{} "minibuffer.texi"
1064 @defvar read-buffer-function
1065 This variable specifies how to read buffer names. For example, if you
1066 set this variable to @code{iswitchb-read-buffer}, all Emacs commands
1067 that call @code{read-buffer} to read a buffer name will actually use the
1068 @code{iswitchb} package to read it.
1071 @defun read-command prompt &optional default
1072 This function reads the name of a command and returns it as a Lisp
1073 symbol. The argument @var{prompt} is used as in
1074 @code{read-from-minibuffer}. Recall that a command is anything for
1075 which @code{commandp} returns @code{t}, and a command name is a symbol
1076 for which @code{commandp} returns @code{t}. @xref{Interactive Call}.
1078 The argument @var{default} specifies what to return if the user enters
1079 null input. It can be a symbol or a string; if it is a string,
1080 @code{read-command} interns it before returning it. If @var{default} is
1081 @code{nil}, that means no default has been specified; then if the user
1082 enters null input, the return value is @code{(intern "")}, that is, a
1083 symbol whose name is an empty string.
1086 (read-command "Command name? ")
1089 ;; @r{After evaluation of the preceding expression,}
1090 ;; @r{the following prompt appears with an empty minibuffer:}
1094 ---------- Buffer: Minibuffer ----------
1096 ---------- Buffer: Minibuffer ----------
1101 If the user types @kbd{forward-c @key{RET}}, then this function returns
1102 @code{forward-char}.
1104 The @code{read-command} function is a simplified interface to
1105 @code{completing-read}. It uses the variable @code{obarray} so as to
1106 complete in the set of extant Lisp symbols, and it uses the
1107 @code{commandp} predicate so as to accept only command names:
1109 @cindex @code{commandp} example
1112 (read-command @var{prompt})
1114 (intern (completing-read @var{prompt} obarray
1120 @defun read-variable prompt &optional default
1121 @anchor{Definition of read-variable}
1122 This function reads the name of a user variable and returns it as a
1125 The argument @var{default} specifies what to return if the user enters
1126 null input. It can be a symbol or a string; if it is a string,
1127 @code{read-variable} interns it before returning it. If @var{default}
1128 is @code{nil}, that means no default has been specified; then if the
1129 user enters null input, the return value is @code{(intern "")}.
1133 (read-variable "Variable name? ")
1135 ;; @r{After evaluation of the preceding expression,}
1136 ;; @r{the following prompt appears,}
1137 ;; @r{with an empty minibuffer:}
1141 ---------- Buffer: Minibuffer ----------
1142 Variable name? @point{}
1143 ---------- Buffer: Minibuffer ----------
1148 If the user then types @kbd{fill-p @key{RET}}, @code{read-variable}
1149 returns @code{fill-prefix}.
1151 This function is similar to @code{read-command}, but uses the
1152 predicate @code{user-variable-p} instead of @code{commandp}:
1154 @cindex @code{user-variable-p} example
1157 (read-variable @var{prompt})
1160 (completing-read @var{prompt} obarray
1161 'user-variable-p t nil))
1166 See also the functions @code{read-coding-system} and
1167 @code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems}.
1169 @node Reading File Names
1170 @subsection Reading File Names
1172 Here is another high-level completion function, designed for reading a
1173 file name. It provides special features including automatic insertion
1174 of the default directory.
1176 @defun read-file-name prompt &optional directory default existing initial predicate
1177 This function reads a file name in the minibuffer, prompting with
1178 @var{prompt} and providing completion.
1180 If @var{existing} is non-@code{nil}, then the user must specify the name
1181 of an existing file; @key{RET} performs completion to make the name
1182 valid if possible, and then refuses to exit if it is not valid. If the
1183 value of @var{existing} is neither @code{nil} nor @code{t}, then
1184 @key{RET} also requires confirmation after completion. If
1185 @var{existing} is @code{nil}, then the name of a nonexistent file is
1188 The argument @var{directory} specifies the directory to use for
1189 completion of relative file names. It should be an absolute directory
1190 name. If @code{insert-default-directory} is non-@code{nil},
1191 @var{directory} is also inserted in the minibuffer as initial input.
1192 It defaults to the current buffer's value of @code{default-directory}.
1195 If you specify @var{initial}, that is an initial file name to insert
1196 in the buffer (after @var{directory}, if that is inserted). In this
1197 case, point goes at the beginning of @var{initial}. The default for
1198 @var{initial} is @code{nil}---don't insert any file name. To see what
1199 @var{initial} does, try the command @kbd{C-x C-v}. @strong{Please
1200 note:} we recommend using @var{default} rather than @var{initial} in
1203 If @var{default} is non-@code{nil}, then the function returns
1204 @var{default} if the user exits the minibuffer with the same non-empty
1205 contents that @code{read-file-name} inserted initially. The initial
1206 minibuffer contents are always non-empty if
1207 @code{insert-default-directory} is non-@code{nil}, as it is by
1208 default. @var{default} is not checked for validity, regardless of the
1209 value of @var{existing}. However, if @var{existing} is
1210 non-@code{nil}, the initial minibuffer contents should be a valid file
1211 (or directory) name. Otherwise @code{read-file-name} attempts
1212 completion if the user exits without any editing, and does not return
1213 @var{default}. @var{default} is also available through the history
1216 If @var{default} is @code{nil}, @code{read-file-name} tries to find a
1217 substitute default to use in its place, which it treats in exactly the
1218 same way as if it had been specified explicitly. If @var{default} is
1219 @code{nil}, but @var{initial} is non-@code{nil}, then the default is
1220 the absolute file name obtained from @var{directory} and
1221 @var{initial}. If both @var{default} and @var{initial} are @code{nil}
1222 and the buffer is visiting a file, @code{read-file-name} uses the
1223 absolute file name of that file as default. If the buffer is not
1224 visiting a file, then there is no default. In that case, if the user
1225 types @key{RET} without any editing, @code{read-file-name} simply
1226 returns the pre-inserted contents of the minibuffer.
1228 If the user types @key{RET} in an empty minibuffer, this function
1229 returns an empty string, regardless of the value of @var{existing}.
1230 This is, for instance, how the user can make the current buffer visit
1231 no file using @code{M-x set-visited-file-name}.
1233 If @var{predicate} is non-@code{nil}, it specifies a function of one
1234 argument that decides which file names are acceptable completion
1235 possibilities. A file name is an acceptable value if @var{predicate}
1236 returns non-@code{nil} for it.
1238 @code{read-file-name} does not automatically expand file names. You
1239 must call @code{expand-file-name} yourself if an absolute file name is
1246 (read-file-name "The file is ")
1248 ;; @r{After evaluation of the preceding expression,}
1249 ;; @r{the following appears in the minibuffer:}
1253 ---------- Buffer: Minibuffer ----------
1254 The file is /gp/gnu/elisp/@point{}
1255 ---------- Buffer: Minibuffer ----------
1260 Typing @kbd{manual @key{TAB}} results in the following:
1264 ---------- Buffer: Minibuffer ----------
1265 The file is /gp/gnu/elisp/manual.texi@point{}
1266 ---------- Buffer: Minibuffer ----------
1270 @c Wordy to avoid overfull hbox in smallbook mode.
1272 If the user types @key{RET}, @code{read-file-name} returns the file name
1273 as the string @code{"/gp/gnu/elisp/manual.texi"}.
1276 @defun read-directory-name prompt &optional directory default existing initial
1277 This function is like @code{read-file-name} but allows only directory
1278 names as completion possibilities.
1280 If @var{default} is @code{nil} and @var{initial} is non-@code{nil},
1281 @code{read-directory-name} constructs a substitute default by
1282 combining @var{directory} (or the current buffer's default directory
1283 if @var{directory} is @code{nil}) and @var{initial}. If both
1284 @var{default} and @var{initial} are @code{nil}, this function uses the
1285 current buffer's default directory as substitute default, ignoring
1289 @defopt insert-default-directory
1290 This variable is used by @code{read-file-name}, and thus, indirectly,
1291 by most commands reading file names. (This includes all commands that
1292 use the code letters @samp{f} or @samp{F} in their interactive form.
1293 @xref{Interactive Codes,, Code Characters for interactive}.) Its
1294 value controls whether @code{read-file-name} starts by placing the
1295 name of the default directory in the minibuffer, plus the initial file
1296 name if any. If the value of this variable is @code{nil}, then
1297 @code{read-file-name} does not place any initial input in the
1298 minibuffer (unless you specify initial input with the @var{initial}
1299 argument). In that case, the default directory is still used for
1300 completion of relative file names, but is not displayed.
1302 If this variable is @code{nil} and the initial minibuffer contents are
1303 empty, the user may have to explicitly fetch the next history element
1304 to access a default value. If the variable is non-@code{nil}, the
1305 initial minibuffer contents are always non-empty and the user can
1306 always request a default value by immediately typing @key{RET} in an
1307 unedited minibuffer. (See above.)
1313 ;; @r{Here the minibuffer starts out with the default directory.}
1314 (let ((insert-default-directory t))
1315 (read-file-name "The file is "))
1319 ---------- Buffer: Minibuffer ----------
1320 The file is ~lewis/manual/@point{}
1321 ---------- Buffer: Minibuffer ----------
1325 ;; @r{Here the minibuffer is empty and only the prompt}
1326 ;; @r{appears on its line.}
1327 (let ((insert-default-directory nil))
1328 (read-file-name "The file is "))
1332 ---------- Buffer: Minibuffer ----------
1333 The file is @point{}
1334 ---------- Buffer: Minibuffer ----------
1339 @node Programmed Completion
1340 @subsection Programmed Completion
1341 @cindex programmed completion
1343 Sometimes it is not possible to create an alist or an obarray
1344 containing all the intended possible completions. In such a case, you
1345 can supply your own function to compute the completion of a given string.
1346 This is called @dfn{programmed completion}.
1348 To use this feature, pass a symbol with a function definition as the
1349 @var{collection} argument to @code{completing-read}. The function
1350 @code{completing-read} arranges to pass your completion function along
1351 to @code{try-completion} and @code{all-completions}, which will then let
1352 your function do all the work.
1354 The completion function should accept three arguments:
1358 The string to be completed.
1361 The predicate function to filter possible matches, or @code{nil} if
1362 none. Your function should call the predicate for each possible match,
1363 and ignore the possible match if the predicate returns @code{nil}.
1366 A flag specifying the type of operation.
1369 There are three flag values for three operations:
1373 @code{nil} specifies @code{try-completion}. The completion function
1374 should return the completion of the specified string, or @code{t} if the
1375 string is a unique and exact match already, or @code{nil} if the string
1376 matches no possibility.
1378 If the string is an exact match for one possibility, but also matches
1379 other longer possibilities, the function should return the string, not
1383 @code{t} specifies @code{all-completions}. The completion function
1384 should return a list of all possible completions of the specified
1388 @code{lambda} specifies @code{test-completion}. The completion
1389 function should return @code{t} if the specified string is an exact
1390 match for some possibility; @code{nil} otherwise.
1393 It would be consistent and clean for completion functions to allow
1394 lambda expressions (lists that are functions) as well as function
1395 symbols as @var{collection}, but this is impossible. Lists as
1396 completion tables already have other meanings, and it would be
1397 unreliable to treat one differently just because it is also a possible
1398 function. So you must arrange for any function you wish to use for
1399 completion to be encapsulated in a symbol.
1401 Emacs uses programmed completion when completing file names.
1402 @xref{File Name Completion}.
1404 @defmac dynamic-completion-table function
1405 This macro is a convenient way to write a function that can act as
1406 programmed completion function. The argument @var{function} should be
1407 a function that takes one argument, a string, and returns an alist of
1408 possible completions of it. You can think of
1409 @code{dynamic-completion-table} as a transducer between that interface
1410 and the interface for programmed completion functions.
1413 @node Yes-or-No Queries
1414 @section Yes-or-No Queries
1415 @cindex asking the user questions
1416 @cindex querying the user
1417 @cindex yes-or-no questions
1419 This section describes functions used to ask the user a yes-or-no
1420 question. The function @code{y-or-n-p} can be answered with a single
1421 character; it is useful for questions where an inadvertent wrong answer
1422 will not have serious consequences. @code{yes-or-no-p} is suitable for
1423 more momentous questions, since it requires three or four characters to
1426 If either of these functions is called in a command that was invoked
1427 using the mouse---more precisely, if @code{last-nonmenu-event}
1428 (@pxref{Command Loop Info}) is either @code{nil} or a list---then it
1429 uses a dialog box or pop-up menu to ask the question. Otherwise, it
1430 uses keyboard input. You can force use of the mouse or use of keyboard
1431 input by binding @code{last-nonmenu-event} to a suitable value around
1434 Strictly speaking, @code{yes-or-no-p} uses the minibuffer and
1435 @code{y-or-n-p} does not; but it seems best to describe them together.
1437 @defun y-or-n-p prompt
1438 This function asks the user a question, expecting input in the echo
1439 area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the
1440 user types @kbd{n}. This function also accepts @key{SPC} to mean yes
1441 and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like
1442 @kbd{C-g}, because the question might look like a minibuffer and for
1443 that reason the user might try to use @kbd{C-]} to get out. The answer
1444 is a single character, with no @key{RET} needed to terminate it. Upper
1445 and lower case are equivalent.
1447 ``Asking the question'' means printing @var{prompt} in the echo area,
1448 followed by the string @w{@samp{(y or n) }}. If the input is not one of
1449 the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}},
1450 @kbd{@key{DEL}}, or something that quits), the function responds
1451 @samp{Please answer y or n.}, and repeats the request.
1453 This function does not actually use the minibuffer, since it does not
1454 allow editing of the answer. It actually uses the echo area (@pxref{The
1455 Echo Area}), which uses the same screen space as the minibuffer. The
1456 cursor moves to the echo area while the question is being asked.
1458 The answers and their meanings, even @samp{y} and @samp{n}, are not
1459 hardwired. The keymap @code{query-replace-map} specifies them.
1460 @xref{Search and Replace}.
1462 In the following example, the user first types @kbd{q}, which is
1463 invalid. At the next prompt the user types @kbd{y}.
1467 (y-or-n-p "Do you need a lift? ")
1469 ;; @r{After evaluation of the preceding expression,}
1470 ;; @r{the following prompt appears in the echo area:}
1474 ---------- Echo area ----------
1475 Do you need a lift? (y or n)
1476 ---------- Echo area ----------
1479 ;; @r{If the user then types @kbd{q}, the following appears:}
1482 ---------- Echo area ----------
1483 Please answer y or n. Do you need a lift? (y or n)
1484 ---------- Echo area ----------
1487 ;; @r{When the user types a valid answer,}
1488 ;; @r{it is displayed after the question:}
1491 ---------- Echo area ----------
1492 Do you need a lift? (y or n) y
1493 ---------- Echo area ----------
1498 We show successive lines of echo area messages, but only one actually
1499 appears on the screen at a time.
1502 @defun y-or-n-p-with-timeout prompt seconds default-value
1503 Like @code{y-or-n-p}, except that if the user fails to answer within
1504 @var{seconds} seconds, this function stops waiting and returns
1505 @var{default-value}. It works by setting up a timer; see @ref{Timers}.
1506 The argument @var{seconds} may be an integer or a floating point number.
1509 @defun yes-or-no-p prompt
1510 This function asks the user a question, expecting input in the
1511 minibuffer. It returns @code{t} if the user enters @samp{yes},
1512 @code{nil} if the user types @samp{no}. The user must type @key{RET} to
1513 finalize the response. Upper and lower case are equivalent.
1515 @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area,
1516 followed by @w{@samp{(yes or no) }}. The user must type one of the
1517 expected responses; otherwise, the function responds @samp{Please answer
1518 yes or no.}, waits about two seconds and repeats the request.
1520 @code{yes-or-no-p} requires more work from the user than
1521 @code{y-or-n-p} and is appropriate for more crucial decisions.
1527 (yes-or-no-p "Do you really want to remove everything? ")
1529 ;; @r{After evaluation of the preceding expression,}
1530 ;; @r{the following prompt appears,}
1531 ;; @r{with an empty minibuffer:}
1535 ---------- Buffer: minibuffer ----------
1536 Do you really want to remove everything? (yes or no)
1537 ---------- Buffer: minibuffer ----------
1542 If the user first types @kbd{y @key{RET}}, which is invalid because this
1543 function demands the entire word @samp{yes}, it responds by displaying
1544 these prompts, with a brief pause between them:
1548 ---------- Buffer: minibuffer ----------
1549 Please answer yes or no.
1550 Do you really want to remove everything? (yes or no)
1551 ---------- Buffer: minibuffer ----------
1556 @node Multiple Queries
1557 @section Asking Multiple Y-or-N Questions
1559 When you have a series of similar questions to ask, such as ``Do you
1560 want to save this buffer'' for each buffer in turn, you should use
1561 @code{map-y-or-n-p} to ask the collection of questions, rather than
1562 asking each question individually. This gives the user certain
1563 convenient facilities such as the ability to answer the whole series at
1566 @defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area
1567 This function asks the user a series of questions, reading a
1568 single-character answer in the echo area for each one.
1570 The value of @var{list} specifies the objects to ask questions about.
1571 It should be either a list of objects or a generator function. If it is
1572 a function, it should expect no arguments, and should return either the
1573 next object to ask about, or @code{nil} meaning stop asking questions.
1575 The argument @var{prompter} specifies how to ask each question. If
1576 @var{prompter} is a string, the question text is computed like this:
1579 (format @var{prompter} @var{object})
1583 where @var{object} is the next object to ask about (as obtained from
1586 If not a string, @var{prompter} should be a function of one argument
1587 (the next object to ask about) and should return the question text. If
1588 the value is a string, that is the question to ask the user. The
1589 function can also return @code{t} meaning do act on this object (and
1590 don't ask the user), or @code{nil} meaning ignore this object (and don't
1593 The argument @var{actor} says how to act on the answers that the user
1594 gives. It should be a function of one argument, and it is called with
1595 each object that the user says yes for. Its argument is always an
1596 object obtained from @var{list}.
1598 If the argument @var{help} is given, it should be a list of this form:
1601 (@var{singular} @var{plural} @var{action})
1605 where @var{singular} is a string containing a singular noun that
1606 describes the objects conceptually being acted on, @var{plural} is the
1607 corresponding plural noun, and @var{action} is a transitive verb
1608 describing what @var{actor} does.
1610 If you don't specify @var{help}, the default is @code{("object"
1611 "objects" "act on")}.
1613 Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or
1614 @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip
1615 that object; @kbd{!} to act on all following objects; @key{ESC} or
1616 @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on
1617 the current object and then exit; or @kbd{C-h} to get help. These are
1618 the same answers that @code{query-replace} accepts. The keymap
1619 @code{query-replace-map} defines their meaning for @code{map-y-or-n-p}
1620 as well as for @code{query-replace}; see @ref{Search and Replace}.
1622 You can use @var{action-alist} to specify additional possible answers
1623 and what they mean. It is an alist of elements of the form
1624 @code{(@var{char} @var{function} @var{help})}, each of which defines one
1625 additional answer. In this element, @var{char} is a character (the
1626 answer); @var{function} is a function of one argument (an object from
1627 @var{list}); @var{help} is a string.
1629 When the user responds with @var{char}, @code{map-y-or-n-p} calls
1630 @var{function}. If it returns non-@code{nil}, the object is considered
1631 ``acted upon'', and @code{map-y-or-n-p} advances to the next object in
1632 @var{list}. If it returns @code{nil}, the prompt is repeated for the
1635 Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while
1636 prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it
1639 If @code{map-y-or-n-p} is called in a command that was invoked using the
1640 mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command
1641 Loop Info}) is either @code{nil} or a list---then it uses a dialog box
1642 or pop-up menu to ask the question. In this case, it does not use
1643 keyboard input or the echo area. You can force use of the mouse or use
1644 of keyboard input by binding @code{last-nonmenu-event} to a suitable
1645 value around the call.
1647 The return value of @code{map-y-or-n-p} is the number of objects acted on.
1650 @node Reading a Password
1651 @section Reading a Password
1652 @cindex passwords, reading
1654 To read a password to pass to another program, you can use the
1655 function @code{read-passwd}.
1657 @defun read-passwd prompt &optional confirm default
1658 This function reads a password, prompting with @var{prompt}. It does
1659 not echo the password as the user types it; instead, it echoes @samp{.}
1660 for each character in the password.
1662 The optional argument @var{confirm}, if non-@code{nil}, says to read the
1663 password twice and insist it must be the same both times. If it isn't
1664 the same, the user has to type it over and over until the last two
1667 The optional argument @var{default} specifies the default password to
1668 return if the user enters empty input. If @var{default} is @code{nil},
1669 then @code{read-passwd} returns the null string in that case.
1672 @node Minibuffer Misc
1673 @section Minibuffer Miscellany
1675 This section describes some basic functions and variables related to
1678 @deffn Command exit-minibuffer
1679 This command exits the active minibuffer. It is normally bound to
1680 keys in minibuffer local keymaps.
1683 @deffn Command self-insert-and-exit
1684 This command exits the active minibuffer after inserting the last
1685 character typed on the keyboard (found in @code{last-command-char};
1686 @pxref{Command Loop Info}).
1689 @deffn Command previous-history-element n
1690 This command replaces the minibuffer contents with the value of the
1691 @var{n}th previous (older) history element.
1694 @deffn Command next-history-element n
1695 This command replaces the minibuffer contents with the value of the
1696 @var{n}th more recent history element.
1699 @deffn Command previous-matching-history-element pattern n
1700 This command replaces the minibuffer contents with the value of the
1701 @var{n}th previous (older) history element that matches @var{pattern} (a
1702 regular expression).
1705 @deffn Command next-matching-history-element pattern n
1706 This command replaces the minibuffer contents with the value of the
1707 @var{n}th next (newer) history element that matches @var{pattern} (a
1708 regular expression).
1711 @defun minibuffer-prompt
1712 This function returns the prompt string of the currently active
1713 minibuffer. If no minibuffer is active, it returns @code{nil}.
1716 @defun minibuffer-prompt-end
1717 @tindex minibuffer-prompt-end
1718 This function, available starting in Emacs 21, returns the current
1719 position of the end of the minibuffer prompt, if a minibuffer is
1720 current. Otherwise, it returns the minimum valid buffer position.
1723 @defun minibuffer-contents
1724 @tindex minibuffer-contents
1725 This function, available starting in Emacs 21, returns the editable
1726 contents of the minibuffer (that is, everything except the prompt) as
1727 a string, if a minibuffer is current. Otherwise, it returns the
1728 entire contents of the current buffer.
1731 @defun minibuffer-contents-no-properties
1732 @tindex minibuffer-contents-no-properties
1733 This is like @code{minibuffer-contents}, except that it does not copy text
1734 properties, just the characters themselves. @xref{Text Properties}.
1737 @defun delete-minibuffer-contents
1738 @tindex delete-minibuffer-contents
1739 This function, available starting in Emacs 21, erases the editable
1740 contents of the minibuffer (that is, everything except the prompt), if
1741 a minibuffer is current. Otherwise, it erases the entire buffer.
1744 @defun minibuffer-prompt-width
1745 This function returns the current display-width of the minibuffer
1746 prompt, if a minibuffer is current. Otherwise, it returns zero.
1749 @defvar minibuffer-setup-hook
1750 This is a normal hook that is run whenever the minibuffer is entered.
1754 @defvar minibuffer-exit-hook
1755 This is a normal hook that is run whenever the minibuffer is exited.
1759 @defvar minibuffer-help-form
1760 @anchor{Definition of minibuffer-help-form}
1761 The current value of this variable is used to rebind @code{help-form}
1762 locally inside the minibuffer (@pxref{Help Functions}).
1765 @defun minibufferp &optional buffer-or-name
1766 This function returns non-@code{nil} if @var{buffer-or-name} is a
1767 minibuffer. If @var{buffer-or-name} is omitted, it tests the current
1771 @defun active-minibuffer-window
1772 This function returns the currently active minibuffer window, or
1773 @code{nil} if none is currently active.
1776 @defun minibuffer-window &optional frame
1777 @anchor{Definition of minibuffer-window}
1778 This function returns the minibuffer window used for frame @var{frame}.
1779 If @var{frame} is @code{nil}, that stands for the current frame. Note
1780 that the minibuffer window used by a frame need not be part of that
1781 frame---a frame that has no minibuffer of its own necessarily uses some
1782 other frame's minibuffer window.
1785 @defun set-minibuffer-window window
1786 This function specifies @var{window} as the minibuffer window to use.
1787 This affects where the minibuffer is displayed if you put text in it
1788 without invoking the usual minibuffer commands. It has no effect on
1789 the usual minibuffer input functions because they all start by
1790 choosing the minibuffer window according to the current frame.
1794 @defun window-minibuffer-p &optional window
1795 This function returns non-@code{nil} if @var{window} is a minibuffer
1797 @var{window} defaults to the selected window.
1800 It is not correct to determine whether a given window is a minibuffer by
1801 comparing it with the result of @code{(minibuffer-window)}, because
1802 there can be more than one minibuffer window if there is more than one
1805 @defun minibuffer-window-active-p window
1806 This function returns non-@code{nil} if @var{window}, assumed to be
1807 a minibuffer window, is currently active.
1810 @defvar minibuffer-scroll-window
1811 @anchor{Definition of minibuffer-scroll-window}
1812 If the value of this variable is non-@code{nil}, it should be a window
1813 object. When the function @code{scroll-other-window} is called in the
1814 minibuffer, it scrolls this window.
1817 @defun minibuffer-selected-window
1818 This function returns the window which was selected when the
1819 minibuffer was entered. If selected window is not a minibuffer
1820 window, it returns @code{nil}.
1823 Finally, some functions and variables deal with recursive minibuffers
1824 (@pxref{Recursive Editing}):
1826 @defun minibuffer-depth
1827 This function returns the current depth of activations of the
1828 minibuffer, a nonnegative integer. If no minibuffers are active, it
1832 @defopt enable-recursive-minibuffers
1833 If this variable is non-@code{nil}, you can invoke commands (such as
1834 @code{find-file}) that use minibuffers even while the minibuffer window
1835 is active. Such invocation produces a recursive editing level for a new
1836 minibuffer. The outer-level minibuffer is invisible while you are
1837 editing the inner one.
1839 If this variable is @code{nil}, you cannot invoke minibuffer
1840 commands when the minibuffer window is active, not even if you switch to
1841 another window to do it.
1845 If a command name has a property @code{enable-recursive-minibuffers}
1846 that is non-@code{nil}, then the command can use the minibuffer to read
1847 arguments even if it is invoked from the minibuffer. A command can
1848 also achieve this by binding @code{enable-recursive-minibuffers}
1849 to @code{t} in the interactive declaration (@pxref{Using Interactive}).
1850 The minibuffer command @code{next-matching-history-element} (normally
1851 @kbd{M-s} in the minibuffer) does the latter.
1853 @defun minibuffer-message string
1854 This function displays @var{string} temporarily at the end of the
1855 minibuffer text, for two seconds, or until the next input event
1856 arrives, whichever comes first.
1860 arch-tag: bba7f945-9078-477f-a2ce-18818a6e1218