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
15 read arguments more complicated than the single numeric prefix
16 argument. These arguments include file names, buffer names, and
17 command names (as in @kbd{M-x}). The minibuffer is displayed on the
18 bottom line of the frame, in the same place as the echo area
19 (@pxref{The Echo Area}), but only while it is in use for reading an
23 * Intro to Minibuffers:: Basic information about minibuffers.
24 * Text from Minibuffer:: How to read a straight text string.
25 * Object from Minibuffer:: How to read a Lisp object or expression.
26 * Minibuffer History:: Recording previous minibuffer inputs
27 so the user can reuse them.
28 * Initial Input:: Specifying initial contents for the minibuffer.
29 * Completion:: How to invoke and customize completion.
30 * Yes-or-No Queries:: Asking a question with a simple answer.
31 * Multiple Queries:: Asking a series of similar questions.
32 * Reading a Password:: Reading a password from the terminal.
33 * Minibuffer Commands:: Commands used as key bindings in minibuffers.
34 * Minibuffer Contents:: How such commands access the minibuffer text.
35 * Minibuffer Windows:: Operating on the special minibuffer windows.
36 * Recursive Mini:: Whether recursive entry to minibuffer is allowed.
37 * Minibuffer Misc:: Various customization hooks and variables.
40 @node Intro to Minibuffers
41 @section Introduction to Minibuffers
43 In most ways, a minibuffer is a normal Emacs buffer. Most operations
44 @emph{within} a buffer, such as editing commands, work normally in a
45 minibuffer. However, many operations for managing buffers do not apply
46 to minibuffers. The name of a minibuffer always has the form @w{@samp{
47 *Minibuf-@var{number}*}}, and it cannot be changed. Minibuffers are
48 displayed only in special windows used only for minibuffers; these
49 windows always appear at the bottom of a frame. (Sometimes frames have
50 no minibuffer window, and sometimes a special kind of frame contains
51 nothing but a minibuffer window; see @ref{Minibuffers and Frames}.)
53 The text in the minibuffer always starts with the @dfn{prompt string},
54 the text that was specified by the program that is using the minibuffer
55 to tell the user what sort of input to type. This text is marked
56 read-only so you won't accidentally delete or change it. It is also
57 marked as a field (@pxref{Fields}), so that certain motion functions,
58 including @code{beginning-of-line}, @code{forward-word},
59 @code{forward-sentence}, and @code{forward-paragraph}, stop at the
60 boundary between the prompt and the actual text. (In older Emacs
61 versions, the prompt was displayed using a special mechanism and was not
62 part of the buffer contents.)
64 The minibuffer's window is normally a single line; it grows
65 automatically if necessary if the contents require more space. You can
66 explicitly resize it temporarily with the window sizing commands; it
67 reverts to its normal size when the minibuffer is exited. You can
68 resize it permanently by using the window sizing commands in the frame's
69 other window, when the minibuffer is not active. If the frame contains
70 just a minibuffer, you can change the minibuffer's size by changing the
73 Use of the minibuffer reads input events, and that alters the values
74 of variables such as @code{this-command} and @code{last-command}
75 (@pxref{Command Loop Info}). Your program should bind them around the
76 code that uses the minibuffer, if you do not want that to change them.
78 If a command uses a minibuffer while there is an active minibuffer,
79 this is called a @dfn{recursive minibuffer}. The first minibuffer is
80 named @w{@samp{ *Minibuf-0*}}. Recursive minibuffers are named by
81 incrementing the number at the end of the name. (The names begin with a
82 space so that they won't show up in normal buffer lists.) Of several
83 recursive minibuffers, the innermost (or most recently entered) is the
84 active minibuffer. We usually call this ``the'' minibuffer. You can
85 permit or forbid recursive minibuffers by setting the variable
86 @code{enable-recursive-minibuffers} or by putting properties of that
87 name on command symbols (@pxref{Minibuffer Misc}).
89 Like other buffers, a minibuffer may use any of several local keymaps
90 (@pxref{Keymaps}); these contain various exit commands and in some cases
91 completion commands (@pxref{Completion}).
95 @code{minibuffer-local-map} is for ordinary input (no completion).
98 @code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
102 @code{minibuffer-local-completion-map} is for permissive completion.
105 @code{minibuffer-local-must-match-map} is for strict completion and
106 for cautious completion.
109 When Emacs is running in batch mode, any request to read from the
110 minibuffer actually reads a line from the standard input descriptor that
111 was supplied when Emacs was started.
113 @node Text from Minibuffer
114 @section Reading Text Strings with the Minibuffer
116 Most often, the minibuffer is used to read text as a string. It can
117 also be used to read a Lisp object in textual form. The most basic
118 primitive for minibuffer input is @code{read-from-minibuffer}; it can do
119 either one. There are also specialized commands for reading
120 commands, variables, file names, etc. (@pxref{Completion}).
122 In most cases, you should not call minibuffer input functions in the
123 middle of a Lisp function. Instead, do all minibuffer input as part of
124 reading the arguments for a command, in the @code{interactive}
125 specification. @xref{Defining Commands}.
127 @defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method keep-all
128 This function is the most general way to get input through the
129 minibuffer. By default, it accepts arbitrary text and returns it as a
130 string; however, if @var{read} is non-@code{nil}, then it uses
131 @code{read} to convert the text into a Lisp object (@pxref{Input
134 The first thing this function does is to activate a minibuffer and
135 display it with @var{prompt-string} as the prompt. This value must be a
136 string. Then the user can edit text in the minibuffer.
138 When the user types a command to exit the minibuffer,
139 @code{read-from-minibuffer} constructs the return value from the text in
140 the minibuffer. Normally it returns a string containing that text.
141 However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer}
142 reads the text and returns the resulting Lisp object, unevaluated.
143 (@xref{Input Functions}, for information about reading.)
145 The argument @var{default} specifies a default value to make available
146 through the history commands. It should be a string, or @code{nil}.
147 If non-@code{nil}, the user can access it using
148 @code{next-history-element}, usually bound in the minibuffer to
149 @kbd{M-n}. If @var{read} is non-@code{nil}, then @var{default} is
150 also used as the input to @code{read}, if the user enters empty input.
151 (If @var{read} is non-@code{nil} and @var{default} is @code{nil}, empty
152 input results in an @code{end-of-file} error.) However, in the usual
153 case (where @var{read} is @code{nil}), @code{read-from-minibuffer}
154 ignores @var{default} when the user enters empty input and returns an
155 empty string, @code{""}. In this respect, it is different from all
156 the other minibuffer input functions in this chapter.
158 If @var{keymap} is non-@code{nil}, that keymap is the local keymap to
159 use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the
160 value of @code{minibuffer-local-map} is used as the keymap. Specifying
161 a keymap is the most important way to customize the minibuffer for
162 various applications such as completion.
164 The argument @var{hist} specifies which history list variable to use
165 for saving the input and for history commands used in the minibuffer.
166 It defaults to @code{minibuffer-history}. @xref{Minibuffer History}.
168 If the variable @code{minibuffer-allow-text-properties} is
169 non-@code{nil}, then the string which is returned includes whatever text
170 properties were present in the minibuffer. Otherwise all the text
171 properties are stripped when the value is returned.
173 If the argument @var{inherit-input-method} is non-@code{nil}, then the
174 minibuffer inherits the current input method (@pxref{Input Methods}) and
175 the setting of @code{enable-multibyte-characters} (@pxref{Text
176 Representations}) from whichever buffer was current before entering the
179 If @var{keep-all} is non-@code{nil}, even empty and duplicate inputs
180 are added to the history list.
182 Use of @var{initial-contents} is mostly deprecated; we recommend using
183 a non-@code{nil} value only in conjunction with specifying a cons cell
184 for @var{hist}. @xref{Initial Input}.
187 @defun read-string prompt &optional initial history default inherit-input-method
188 This function reads a string from the minibuffer and returns it. The
189 arguments @var{prompt}, @var{initial}, @var{history} and
190 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
191 The keymap used is @code{minibuffer-local-map}.
193 The optional argument @var{default} is used as in
194 @code{read-from-minibuffer}, except that, if non-@code{nil}, it also
195 specifies a default value to return if the user enters null input. As
196 in @code{read-from-minibuffer} it should be a string, or @code{nil},
197 which is equivalent to an empty string.
199 This function is a simplified interface to the
200 @code{read-from-minibuffer} function:
204 (read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit})
207 (read-from-minibuffer @var{prompt} @var{initial} nil nil
208 @var{history} @var{default} @var{inherit})))
209 (if (and (equal value "") @var{default})
216 @defvar minibuffer-allow-text-properties
217 If this variable is @code{nil}, then @code{read-from-minibuffer} strips
218 all text properties from the minibuffer input before returning it.
219 This variable also affects @code{read-string}. However,
220 @code{read-no-blanks-input} (see below), as well as
221 @code{read-minibuffer} and related functions (@pxref{Object from
222 Minibuffer,, Reading Lisp Objects With the Minibuffer}), and all
223 functions that do minibuffer input with completion, discard text
224 properties unconditionally, regardless of the value of this variable.
227 @defvar minibuffer-local-map
228 @anchor{Definition of minibuffer-local-map}
229 This is the default local keymap for reading from the minibuffer. By
230 default, it makes the following bindings:
234 @code{exit-minibuffer}
237 @code{exit-minibuffer}
240 @code{abort-recursive-edit}
244 @code{next-history-element}
248 @code{previous-history-element}
251 @code{next-matching-history-element}
254 @code{previous-matching-history-element}
258 @c In version 18, initial is required
260 @defun read-no-blanks-input prompt &optional initial inherit-input-method
261 This function reads a string from the minibuffer, but does not allow
262 whitespace characters as part of the input: instead, those characters
263 terminate the input. The arguments @var{prompt}, @var{initial}, and
264 @var{inherit-input-method} are used as in @code{read-from-minibuffer}.
266 This is a simplified interface to the @code{read-from-minibuffer}
267 function, and passes the value of the @code{minibuffer-local-ns-map}
268 keymap as the @var{keymap} argument for that function. Since the keymap
269 @code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is}
270 possible to put a space into the string, by quoting it.
272 This function discards text properties, regardless of the value of
273 @code{minibuffer-allow-text-properties}.
277 (read-no-blanks-input @var{prompt} @var{initial})
279 (let (minibuffer-allow-text-properties)
280 (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map))
285 @defvar minibuffer-local-ns-map
286 This built-in variable is the keymap used as the minibuffer local keymap
287 in the function @code{read-no-blanks-input}. By default, it makes the
288 following bindings, in addition to those of @code{minibuffer-local-map}:
292 @cindex @key{SPC} in minibuffer
293 @code{exit-minibuffer}
296 @cindex @key{TAB} in minibuffer
297 @code{exit-minibuffer}
300 @cindex @kbd{?} in minibuffer
301 @code{self-insert-and-exit}
305 @node Object from Minibuffer
306 @section Reading Lisp Objects with the Minibuffer
308 This section describes functions for reading Lisp objects with the
311 @defun read-minibuffer prompt &optional initial
312 This function reads a Lisp object using the minibuffer, and returns it
313 without evaluating it. The arguments @var{prompt} and @var{initial} are
314 used as in @code{read-from-minibuffer}.
316 This is a simplified interface to the
317 @code{read-from-minibuffer} function:
321 (read-minibuffer @var{prompt} @var{initial})
323 (let (minibuffer-allow-text-properties)
324 (read-from-minibuffer @var{prompt} @var{initial} nil t))
328 Here is an example in which we supply the string @code{"(testing)"} as
334 "Enter an expression: " (format "%s" '(testing)))
336 ;; @r{Here is how the minibuffer is displayed:}
340 ---------- Buffer: Minibuffer ----------
341 Enter an expression: (testing)@point{}
342 ---------- Buffer: Minibuffer ----------
347 The user can type @key{RET} immediately to use the initial input as a
348 default, or can edit the input.
351 @defun eval-minibuffer prompt &optional initial
352 This function reads a Lisp expression using the minibuffer, evaluates
353 it, then returns the result. The arguments @var{prompt} and
354 @var{initial} are used as in @code{read-from-minibuffer}.
356 This function simply evaluates the result of a call to
357 @code{read-minibuffer}:
361 (eval-minibuffer @var{prompt} @var{initial})
363 (eval (read-minibuffer @var{prompt} @var{initial}))
368 @defun edit-and-eval-command prompt form
369 This function reads a Lisp expression in the minibuffer, and then
370 evaluates it. The difference between this command and
371 @code{eval-minibuffer} is that here the initial @var{form} is not
372 optional and it is treated as a Lisp object to be converted to printed
373 representation rather than as a string of text. It is printed with
374 @code{prin1}, so if it is a string, double-quote characters (@samp{"})
375 appear in the initial text. @xref{Output Functions}.
377 The first thing @code{edit-and-eval-command} does is to activate the
378 minibuffer with @var{prompt} as the prompt. Then it inserts the printed
379 representation of @var{form} in the minibuffer, and lets the user edit it.
380 When the user exits the minibuffer, the edited text is read with
381 @code{read} and then evaluated. The resulting value becomes the value
382 of @code{edit-and-eval-command}.
384 In the following example, we offer the user an expression with initial
385 text which is a valid form already:
389 (edit-and-eval-command "Please edit: " '(forward-word 1))
391 ;; @r{After evaluation of the preceding expression,}
392 ;; @r{the following appears in the minibuffer:}
396 ---------- Buffer: Minibuffer ----------
397 Please edit: (forward-word 1)@point{}
398 ---------- Buffer: Minibuffer ----------
403 Typing @key{RET} right away would exit the minibuffer and evaluate the
404 expression, thus moving point forward one word.
405 @code{edit-and-eval-command} returns @code{nil} in this example.
408 @node Minibuffer History
409 @section Minibuffer History
410 @cindex minibuffer history
413 A @dfn{minibuffer history list} records previous minibuffer inputs so
414 the user can reuse them conveniently. A history list is actually a
415 symbol, not a list; it is a variable whose value is a list of strings
416 (previous inputs), most recent first.
418 There are many separate history lists, used for different kinds of
419 inputs. It's the Lisp programmer's job to specify the right history
420 list for each use of the minibuffer.
422 You specify the history list with the optional @var{hist} argument
423 to either @code{read-from-minibuffer} or @code{completing-read}. Here
424 are the possible values for it:
428 Use @var{variable} (a symbol) as the history list.
430 @item (@var{variable} . @var{startpos})
431 Use @var{variable} (a symbol) as the history list, and assume that the
432 initial history position is @var{startpos} (a nonnegative integer).
434 Specifying 0 for @var{startpos} is equivalent to just specifying the
435 symbol @var{variable}. @code{previous-history-element} will display
436 the most recent element of the history list in the minibuffer. If you
437 specify a positive @var{startpos}, the minibuffer history functions
438 behave as if @code{(elt @var{variable} (1- @var{STARTPOS}))} were the
439 history element currently shown in the minibuffer.
441 For consistency, you should also specify that element of the history
442 as the initial minibuffer contents, using the @var{initial} argument
443 to the minibuffer input function (@pxref{Initial Input}).
446 If you don't specify @var{hist}, then the default history list
447 @code{minibuffer-history} is used. For other standard history lists,
448 see below. You can also create your own history list variable; just
449 initialize it to @code{nil} before the first use.
451 Both @code{read-from-minibuffer} and @code{completing-read} add new
452 elements to the history list automatically, and provide commands to
453 allow the user to reuse items on the list. The only thing your program
454 needs to do to use a history list is to initialize it and to pass its
455 name to the input functions when you wish. But it is safe to modify the
456 list by hand when the minibuffer input functions are not using it.
458 Emacs functions that add a new element to a history list can also
459 delete old elements if the list gets too long. The variable
460 @code{history-length} specifies the maximum length for most history
461 lists. To specify a different maximum length for a particular history
462 list, put the length in the @code{history-length} property of the
463 history list symbol. The variable @code{history-delete-duplicates}
464 specifies whether to delete duplicates in history.
466 @defvar history-length
467 The value of this variable specifies the maximum length for all
468 history lists that don't specify their own maximum lengths. If the
469 value is @code{t}, that means there no maximum (don't delete old
473 @defvar history-delete-duplicates
474 If the value of this variable is @code{t}, that means when adding a
475 new history element, all previous identical elements are deleted.
478 Here are some of the standard minibuffer history list variables:
480 @defvar minibuffer-history
481 The default history list for minibuffer history input.
484 @defvar query-replace-history
485 A history list for arguments to @code{query-replace} (and similar
486 arguments to other commands).
489 @defvar file-name-history
490 A history list for file-name arguments.
493 @defvar buffer-name-history
494 A history list for buffer-name arguments.
497 @defvar regexp-history
498 A history list for regular expression arguments.
501 @defvar extended-command-history
502 A history list for arguments that are names of extended commands.
505 @defvar shell-command-history
506 A history list for arguments that are shell commands.
509 @defvar read-expression-history
510 A history list for arguments that are Lisp expressions to evaluate.
514 @section Initial Input
516 Several of the functions for minibuffer input have an argument called
517 @var{initial} or @var{initial-contents}. This is a mostly-deprecated
518 feature for specifiying that the minibuffer should start out with
519 certain text, instead of empty as usual.
521 If @var{initial} is a string, the minibuffer starts out containing the
522 text of the string, with point at the end, when the user starts to
523 edit the text. If the user simply types @key{RET} to exit the
524 minibuffer, it will use the initial input string to determine the
527 @strong{We discourage use of a non-@code{nil} value for
528 @var{initial}}, because initial input is an intrusive interface.
529 History lists and default values provide a much more convenient method
530 to offer useful default inputs to the user.
532 There is just one situation where you should specify a string for an
533 @var{initial} argument. This is when you specify a cons cell for the
534 @var{hist} or @var{history} argument. @xref{Minibuffer History}.
536 @var{initial} can also be a cons cell of the form @code{(@var{string}
537 . @var{position})}. This means to insert @var{string} in the
538 minibuffer but put point at @var{position} within the string's text.
540 As a historical accident, @var{position} was implemented
541 inconsistently in different functions. In @code{completing-read},
542 @var{position}'s value is interpreted as origin-zero; that is, a value
543 of 0 means the beginning of the string, 1 means after the first
544 character, etc. In @code{read-minibuffer}, and the other
545 non-completion minibuffer input functions that support this argument,
546 1 means the beginning of the string 2 means after the first character,
549 Use of a cons cell as the value for @var{initial} arguments is
550 deprecated in user code.
556 @dfn{Completion} is a feature that fills in the rest of a name
557 starting from an abbreviation for it. Completion works by comparing the
558 user's input against a list of valid names and determining how much of
559 the name is determined uniquely by what the user has typed. For
560 example, when you type @kbd{C-x b} (@code{switch-to-buffer}) and then
561 type the first few letters of the name of the buffer to which you wish
562 to switch, and then type @key{TAB} (@code{minibuffer-complete}), Emacs
563 extends the name as far as it can.
565 Standard Emacs commands offer completion for names of symbols, files,
566 buffers, and processes; with the functions in this section, you can
567 implement completion for other kinds of names.
569 The @code{try-completion} function is the basic primitive for
570 completion: it returns the longest determined completion of a given
571 initial string, with a given set of strings to match against.
573 The function @code{completing-read} provides a higher-level interface
574 for completion. A call to @code{completing-read} specifies how to
575 determine the list of valid names. The function then activates the
576 minibuffer with a local keymap that binds a few keys to commands useful
577 for completion. Other functions provide convenient simple interfaces
578 for reading certain kinds of names with completion.
581 * Basic Completion:: Low-level functions for completing strings.
582 (These are too low level to use the minibuffer.)
583 * Minibuffer Completion:: Invoking the minibuffer with completion.
584 * Completion Commands:: Minibuffer commands that do completion.
585 * High-Level Completion:: Convenient special cases of completion
586 (reading buffer name, file name, etc.)
587 * Reading File Names:: Using completion to read file names.
588 * Programmed Completion:: Writing your own completion-function.
591 @node Basic Completion
592 @subsection Basic Completion Functions
594 The completion functions @code{try-completion},
595 @code{all-completions} and @code{test-completion} have nothing in
596 themselves to do with minibuffers. We describe them in this chapter
597 so as to keep them near the higher-level completion features that do
600 @defun try-completion string collection &optional predicate
601 This function returns the longest common substring of all possible
602 completions of @var{string} in @var{collection}. The value of
603 @var{collection} must be a list of strings or symbols, an alist, an
604 obarray, a hash table, or a function that implements a virtual set of
607 Completion compares @var{string} against each of the permissible
608 completions specified by @var{collection}; if the beginning of the
609 permissible completion equals @var{string}, it matches. If no permissible
610 completions match, @code{try-completion} returns @code{nil}. If only
611 one permissible completion matches, and the match is exact, then
612 @code{try-completion} returns @code{t}. Otherwise, the value is the
613 longest initial sequence common to all the permissible completions that
616 If @var{collection} is an alist (@pxref{Association Lists}), the
617 permissible completions are the elements of the alist that are either
618 strings, symbols, or conses whose @sc{car} is a string or symbol.
619 Symbols are converted to strings using @code{symbol-name}.
620 Other elements of the alist are ignored. (Remember that in Emacs Lisp,
621 the elements of alists do not @emph{have} to be conses.) As all
622 elements of the alist can be strings, this case actually includes
623 lists of strings or symbols, even though we usually do not think of
624 such lists as alists.
626 @cindex obarray in completion
627 If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
628 of all symbols in the obarray form the set of permissible completions. The
629 global variable @code{obarray} holds an obarray containing the names of
630 all interned Lisp symbols.
632 Note that the only valid way to make a new obarray is to create it
633 empty and then add symbols to it one by one using @code{intern}.
634 Also, you cannot intern a given symbol in more than one obarray.
636 If @var{collection} is a hash table, then the keys that are strings
637 are the possible completions. Other keys are ignored.
639 You can also use a symbol that is a function as @var{collection}. Then
640 the function is solely responsible for performing completion;
641 @code{try-completion} returns whatever this function returns. The
642 function is called with three arguments: @var{string}, @var{predicate}
643 and @code{nil}. (The reason for the third argument is so that the same
644 function can be used in @code{all-completions} and do the appropriate
645 thing in either case.) @xref{Programmed Completion}.
647 If the argument @var{predicate} is non-@code{nil}, then it must be a
648 function of one argument, unless @var{collection} is a hash table, in
649 which case it should be a function of two arguments. It is used to
650 test each possible match, and the match is accepted only if
651 @var{predicate} returns non-@code{nil}. The argument given to
652 @var{predicate} is either a string or a cons cell (the @sc{car} of
653 which is a string) from the alist, or a symbol (@emph{not} a symbol
654 name) from the obarray. If @var{collection} is a hash table,
655 @var{predicate} is called with two arguments, the string key and the
658 In addition, to be acceptable, a completion must also match all the
659 regular expressions in @code{completion-regexp-list}. (Unless
660 @var{collection} is a function, in which case that function has to
661 handle @code{completion-regexp-list} itself.)
663 In the first of the following examples, the string @samp{foo} is
664 matched by three of the alist @sc{car}s. All of the matches begin with
665 the characters @samp{fooba}, so that is the result. In the second
666 example, there is only one possible match, and it is exact, so the value
673 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
678 (try-completion "foo" '(("barfoo" 2) ("foo" 3)))
683 In the following example, numerous symbols begin with the characters
684 @samp{forw}, and all of them begin with the word @samp{forward}. In
685 most of the symbols, this is followed with a @samp{-}, but not in all,
686 so no more than @samp{forward} can be completed.
690 (try-completion "forw" obarray)
695 Finally, in the following example, only two of the three possible
696 matches pass the predicate @code{test} (the string @samp{foobaz} is
697 too short). Both of those begin with the string @samp{foobar}.
702 (> (length (car s)) 6))
708 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
715 @defun all-completions string collection &optional predicate nospace
716 This function returns a list of all possible completions of
717 @var{string}. The arguments to this function (aside from
718 @var{nospace}) are the same as those of @code{try-completion}. Also,
719 this function uses @code{completion-regexp-list} in the same way that
720 @code{try-completion} does. The optional argument @var{nospace} only
721 matters if @var{string} is the empty string. In that case, if
722 @var{nospace} is non-@code{nil}, completions that start with a space
725 If @var{collection} is a function, it is called with three arguments:
726 @var{string}, @var{predicate} and @code{t}; then @code{all-completions}
727 returns whatever the function returns. @xref{Programmed Completion}.
729 Here is an example, using the function @code{test} shown in the
730 example for @code{try-completion}:
735 (> (length (car s)) 6))
742 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
744 @result{} ("foobar1" "foobar2")
749 @defun test-completion string collection &optional predicate
750 @anchor{Definition of test-completion}
751 This function returns non-@code{nil} if @var{string} is a valid
752 completion possibility specified by @var{collection} and
753 @var{predicate}. The arguments are the same as in
754 @code{try-completion}. For instance, if @var{collection} is a list of
755 strings, this is true if @var{string} appears in the list and
756 @var{predicate} is satisfied.
758 @code{test-completion} uses @code{completion-regexp-list} in the same
759 way that @code{try-completion} does.
761 If @var{predicate} is non-@code{nil} and if @var{collection} contains
762 several strings that are equal to each other, as determined by
763 @code{compare-strings} according to @code{completion-ignore-case},
764 then @var{predicate} should accept either all or none of them.
765 Otherwise, the return value of @code{test-completion} is essentially
768 If @var{collection} is a function, it is called with three arguments,
769 the values @var{string}, @var{predicate} and @code{lambda}; whatever
770 it returns, @code{test-completion} returns in turn.
773 @defvar completion-ignore-case
774 If the value of this variable is non-@code{nil}, Emacs does not
775 consider case significant in completion.
778 @defvar completion-regexp-list
779 This is a list of regular expressions. The completion functions only
780 consider a completion acceptable if it matches all regular expressions
781 in this list, with @code{case-fold-search} (@pxref{Searching and Case})
782 bound to the value of @code{completion-ignore-case}.
785 @defmac lazy-completion-table var fun &rest args
786 This macro provides a way to initialize the variable @var{var} as a
787 collection for completion in a lazy way, not computing its actual
788 contents until they are first needed. You use this macro to produce a
789 value that you store in @var{var}. The actual computation of the
790 proper value is done the first time you do completion using @var{var}.
791 It is done by calling @var{fun} with the arguments @var{args}. The
792 value @var{fun} returns becomes the permanent value of @var{var}.
794 Here are two examples of use:
797 (defvar foo (lazy-completion-table foo make-my-alist 'global))
799 (make-local-variable 'bar)
800 (setq bar (lazy-completion-table foo make-my-alist 'local)
804 @node Minibuffer Completion
805 @subsection Completion and the Minibuffer
807 This section describes the basic interface for reading from the
808 minibuffer with completion.
810 @defun completing-read prompt collection &optional predicate require-match initial hist default inherit-input-method
811 This function reads a string in the minibuffer, assisting the user by
812 providing completion. It activates the minibuffer with prompt
813 @var{prompt}, which must be a string.
815 The actual completion is done by passing @var{collection} and
816 @var{predicate} to the function @code{try-completion}. This happens
817 in certain commands bound in the local keymaps used for completion.
818 Some of these commands also call @code{test-completion}. Thus, if
819 @var{predicate} is non-@code{nil}, it should be compatible with
820 @var{collection} and @code{completion-ignore-case}. @xref{Definition
823 If @var{require-match} is @code{nil}, the exit commands work regardless
824 of the input in the minibuffer. If @var{require-match} is @code{t}, the
825 usual minibuffer exit commands won't exit unless the input completes to
826 an element of @var{collection}. If @var{require-match} is neither
827 @code{nil} nor @code{t}, then the exit commands won't exit unless the
828 input already in the buffer matches an element of @var{collection}.
830 However, empty input is always permitted, regardless of the value of
831 @var{require-match}; in that case, @code{completing-read} returns
832 @var{default}, or @code{""}, if @var{default} is @code{nil}. The
833 value of @var{default} (if non-@code{nil}) is also available to the
834 user through the history commands.
836 The function @code{completing-read} uses
837 @code{minibuffer-local-completion-map} as the keymap if
838 @var{require-match} is @code{nil}, and uses
839 @code{minibuffer-local-must-match-map} if @var{require-match} is
840 non-@code{nil}. @xref{Completion Commands}.
842 The argument @var{hist} specifies which history list variable to use for
843 saving the input and for minibuffer history commands. It defaults to
844 @code{minibuffer-history}. @xref{Minibuffer History}.
846 The argument @var{initial} is mostly deprecated; we recommend using a
847 non-@code{nil} value only in conjunction with specifying a cons cell
848 for @var{hist}. @xref{Initial Input}. For default input, use
849 @var{default} instead.
851 If the argument @var{inherit-input-method} is non-@code{nil}, then the
852 minibuffer inherits the current input method (@pxref{Input
853 Methods}) and the setting of @code{enable-multibyte-characters}
854 (@pxref{Text Representations}) from whichever buffer was current before
855 entering the minibuffer.
857 If the built-in variable @code{completion-ignore-case} is
858 non-@code{nil}, completion ignores case when comparing the input
859 against the possible matches. @xref{Basic Completion}. In this mode
860 of operation, @var{predicate} must also ignore case, or you will get
863 Here's an example of using @code{completing-read}:
869 '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
874 ;; @r{After evaluation of the preceding expression,}
875 ;; @r{the following appears in the minibuffer:}
877 ---------- Buffer: Minibuffer ----------
878 Complete a foo: fo@point{}
879 ---------- Buffer: Minibuffer ----------
884 If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}},
885 @code{completing-read} returns @code{barfoo}.
887 The @code{completing-read} function binds variables to pass
888 information to the commands that actually do completion.
889 They are described in the following section.
892 @node Completion Commands
893 @subsection Minibuffer Commands that Do Completion
895 This section describes the keymaps, commands and user options used
896 in the minibuffer to do completion. The description refers to the
897 situation when Partial Completion mode is disabled (as it is by
898 default). When enabled, this minor mode uses its own alternatives to
899 some of the commands described below. @xref{Completion Options,,,
900 emacs, The GNU Emacs Manual}, for a short description of Partial
903 @defvar minibuffer-completion-table
904 The value of this variable is the collection used for completion in
905 the minibuffer. This is the global variable that contains what
906 @code{completing-read} passes to @code{try-completion}. It is used by
907 minibuffer completion commands such as @code{minibuffer-complete-word}.
910 @defvar minibuffer-completion-predicate
911 This variable's value is the predicate that @code{completing-read}
912 passes to @code{try-completion}. The variable is also used by the other
913 minibuffer completion functions.
916 @defvar minibuffer-completion-confirm
917 When the value of this variable is non-@code{nil}, Emacs asks for
918 confirmation of a completion before exiting the minibuffer.
919 @code{completing-read} binds this variable, and the function
920 @code{minibuffer-complete-and-exit} checks the value before exiting.
923 @deffn Command minibuffer-complete-word
924 This function completes the minibuffer contents by at most a single
925 word. Even if the minibuffer contents have only one completion,
926 @code{minibuffer-complete-word} does not add any characters beyond the
927 first character that is not a word constituent. @xref{Syntax Tables}.
930 @deffn Command minibuffer-complete
931 This function completes the minibuffer contents as far as possible.
934 @deffn Command minibuffer-complete-and-exit
935 This function completes the minibuffer contents, and exits if
936 confirmation is not required, i.e., if
937 @code{minibuffer-completion-confirm} is @code{nil}. If confirmation
938 @emph{is} required, it is given by repeating this command
939 immediately---the command is programmed to work without confirmation
940 when run twice in succession.
943 @deffn Command minibuffer-completion-help
944 This function creates a list of the possible completions of the
945 current minibuffer contents. It works by calling @code{all-completions}
946 using the value of the variable @code{minibuffer-completion-table} as
947 the @var{collection} argument, and the value of
948 @code{minibuffer-completion-predicate} as the @var{predicate} argument.
949 The list of completions is displayed as text in a buffer named
950 @samp{*Completions*}.
953 @defun display-completion-list completions
954 This function displays @var{completions} to the stream in
955 @code{standard-output}, usually a buffer. (@xref{Read and Print}, for more
956 information about streams.) The argument @var{completions} is normally
957 a list of completions just returned by @code{all-completions}, but it
958 does not have to be. Each element may be a symbol or a string, either
959 of which is simply printed. It can also be a list of two strings,
960 which is printed as if the strings were concatenated. The first of
961 the two strings is the actual completion, the second string serves as
964 This function is called by @code{minibuffer-completion-help}. The
965 most common way to use it is together with
966 @code{with-output-to-temp-buffer}, like this:
969 (with-output-to-temp-buffer "*Completions*"
970 (display-completion-list
971 (all-completions (buffer-string) my-alist)))
975 @defopt completion-auto-help
976 If this variable is non-@code{nil}, the completion commands
977 automatically display a list of possible completions whenever nothing
978 can be completed because the next character is not uniquely determined.
981 @defvar minibuffer-local-completion-map
982 @code{completing-read} uses this value as the local keymap when an
983 exact match of one of the completions is not required. By default, this
984 keymap makes the following bindings:
988 @code{minibuffer-completion-help}
991 @code{minibuffer-complete-word}
994 @code{minibuffer-complete}
998 with other characters bound as in @code{minibuffer-local-map}
999 (@pxref{Definition of minibuffer-local-map}).
1002 @defvar minibuffer-local-must-match-map
1003 @code{completing-read} uses this value as the local keymap when an
1004 exact match of one of the completions is required. Therefore, no keys
1005 are bound to @code{exit-minibuffer}, the command that exits the
1006 minibuffer unconditionally. By default, this keymap makes the following
1011 @code{minibuffer-completion-help}
1014 @code{minibuffer-complete-word}
1017 @code{minibuffer-complete}
1020 @code{minibuffer-complete-and-exit}
1023 @code{minibuffer-complete-and-exit}
1027 with other characters bound as in @code{minibuffer-local-map}.
1030 @node High-Level Completion
1031 @subsection High-Level Completion Functions
1033 This section describes the higher-level convenient functions for
1034 reading certain sorts of names with completion.
1036 In most cases, you should not call these functions in the middle of a
1037 Lisp function. When possible, do all minibuffer input as part of
1038 reading the arguments for a command, in the @code{interactive}
1039 specification. @xref{Defining Commands}.
1041 @defun read-buffer prompt &optional default existing
1042 This function reads the name of a buffer and returns it as a string.
1043 The argument @var{default} is the default name to use, the value to
1044 return if the user exits with an empty minibuffer. If non-@code{nil},
1045 it should be a string or a buffer. It is mentioned in the prompt, but
1046 is not inserted in the minibuffer as initial input.
1048 If @var{existing} is non-@code{nil}, then the name specified must be
1049 that of an existing buffer. The usual commands to exit the minibuffer
1050 do not exit if the text is not valid, and @key{RET} does completion to
1051 attempt to find a valid name. If @var{existing} is neither @code{nil}
1052 nor @code{t}, confirmation is required after completion. (However,
1053 @var{default} is not checked for validity; it is returned, whatever it
1054 is, if the user exits with the minibuffer empty.)
1056 In the following example, the user enters @samp{minibuffer.t}, and
1057 then types @key{RET}. The argument @var{existing} is @code{t}, and the
1058 only buffer name starting with the given input is
1059 @samp{minibuffer.texi}, so that name is the value.
1062 (read-buffer "Buffer name? " "foo" t)
1064 ;; @r{After evaluation of the preceding expression,}
1065 ;; @r{the following prompt appears,}
1066 ;; @r{with an empty minibuffer:}
1070 ---------- Buffer: Minibuffer ----------
1071 Buffer name? (default foo) @point{}
1072 ---------- Buffer: Minibuffer ----------
1076 ;; @r{The user types @kbd{minibuffer.t @key{RET}}.}
1077 @result{} "minibuffer.texi"
1082 @defvar read-buffer-function
1083 This variable specifies how to read buffer names. For example, if you
1084 set this variable to @code{iswitchb-read-buffer}, all Emacs commands
1085 that call @code{read-buffer} to read a buffer name will actually use the
1086 @code{iswitchb} package to read it.
1089 @defun read-command prompt &optional default
1090 This function reads the name of a command and returns it as a Lisp
1091 symbol. The argument @var{prompt} is used as in
1092 @code{read-from-minibuffer}. Recall that a command is anything for
1093 which @code{commandp} returns @code{t}, and a command name is a symbol
1094 for which @code{commandp} returns @code{t}. @xref{Interactive Call}.
1096 The argument @var{default} specifies what to return if the user enters
1097 null input. It can be a symbol or a string; if it is a string,
1098 @code{read-command} interns it before returning it. If @var{default} is
1099 @code{nil}, that means no default has been specified; then if the user
1100 enters null input, the return value is @code{(intern "")}, that is, a
1101 symbol whose name is an empty string.
1104 (read-command "Command name? ")
1107 ;; @r{After evaluation of the preceding expression,}
1108 ;; @r{the following prompt appears with an empty minibuffer:}
1112 ---------- Buffer: Minibuffer ----------
1114 ---------- Buffer: Minibuffer ----------
1119 If the user types @kbd{forward-c @key{RET}}, then this function returns
1120 @code{forward-char}.
1122 The @code{read-command} function is a simplified interface to
1123 @code{completing-read}. It uses the variable @code{obarray} so as to
1124 complete in the set of extant Lisp symbols, and it uses the
1125 @code{commandp} predicate so as to accept only command names:
1127 @cindex @code{commandp} example
1130 (read-command @var{prompt})
1132 (intern (completing-read @var{prompt} obarray
1138 @defun read-variable prompt &optional default
1139 @anchor{Definition of read-variable}
1140 This function reads the name of a user variable and returns it as a
1143 The argument @var{default} specifies what to return if the user enters
1144 null input. It can be a symbol or a string; if it is a string,
1145 @code{read-variable} interns it before returning it. If @var{default}
1146 is @code{nil}, that means no default has been specified; then if the
1147 user enters null input, the return value is @code{(intern "")}.
1151 (read-variable "Variable name? ")
1153 ;; @r{After evaluation of the preceding expression,}
1154 ;; @r{the following prompt appears,}
1155 ;; @r{with an empty minibuffer:}
1159 ---------- Buffer: Minibuffer ----------
1160 Variable name? @point{}
1161 ---------- Buffer: Minibuffer ----------
1166 If the user then types @kbd{fill-p @key{RET}}, @code{read-variable}
1167 returns @code{fill-prefix}.
1169 This function is similar to @code{read-command}, but uses the
1170 predicate @code{user-variable-p} instead of @code{commandp}:
1172 @cindex @code{user-variable-p} example
1175 (read-variable @var{prompt})
1178 (completing-read @var{prompt} obarray
1179 'user-variable-p t nil))
1184 See also the functions @code{read-coding-system} and
1185 @code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems}.
1187 @node Reading File Names
1188 @subsection Reading File Names
1190 Here is another high-level completion function, designed for reading a
1191 file name. It provides special features including automatic insertion
1192 of the default directory.
1194 @defun read-file-name prompt &optional directory default existing initial predicate
1195 This function reads a file name in the minibuffer, prompting with
1196 @var{prompt} and providing completion.
1198 If @var{existing} is non-@code{nil}, then the user must specify the name
1199 of an existing file; @key{RET} performs completion to make the name
1200 valid if possible, and then refuses to exit if it is not valid. If the
1201 value of @var{existing} is neither @code{nil} nor @code{t}, then
1202 @key{RET} also requires confirmation after completion. If
1203 @var{existing} is @code{nil}, then the name of a nonexistent file is
1206 The argument @var{directory} specifies the directory to use for
1207 completion of relative file names. It should be an absolute directory
1208 name. If @code{insert-default-directory} is non-@code{nil},
1209 @var{directory} is also inserted in the minibuffer as initial input.
1210 It defaults to the current buffer's value of @code{default-directory}.
1213 If you specify @var{initial}, that is an initial file name to insert
1214 in the buffer (after @var{directory}, if that is inserted). In this
1215 case, point goes at the beginning of @var{initial}. The default for
1216 @var{initial} is @code{nil}---don't insert any file name. To see what
1217 @var{initial} does, try the command @kbd{C-x C-v}. @strong{Please
1218 note:} we recommend using @var{default} rather than @var{initial} in
1221 If @var{default} is non-@code{nil}, then the function returns
1222 @var{default} if the user exits the minibuffer with the same non-empty
1223 contents that @code{read-file-name} inserted initially. The initial
1224 minibuffer contents are always non-empty if
1225 @code{insert-default-directory} is non-@code{nil}, as it is by
1226 default. @var{default} is not checked for validity, regardless of the
1227 value of @var{existing}. However, if @var{existing} is
1228 non-@code{nil}, the initial minibuffer contents should be a valid file
1229 (or directory) name. Otherwise @code{read-file-name} attempts
1230 completion if the user exits without any editing, and does not return
1231 @var{default}. @var{default} is also available through the history
1234 If @var{default} is @code{nil}, @code{read-file-name} tries to find a
1235 substitute default to use in its place, which it treats in exactly the
1236 same way as if it had been specified explicitly. If @var{default} is
1237 @code{nil}, but @var{initial} is non-@code{nil}, then the default is
1238 the absolute file name obtained from @var{directory} and
1239 @var{initial}. If both @var{default} and @var{initial} are @code{nil}
1240 and the buffer is visiting a file, @code{read-file-name} uses the
1241 absolute file name of that file as default. If the buffer is not
1242 visiting a file, then there is no default. In that case, if the user
1243 types @key{RET} without any editing, @code{read-file-name} simply
1244 returns the pre-inserted contents of the minibuffer.
1246 If the user types @key{RET} in an empty minibuffer, this function
1247 returns an empty string, regardless of the value of @var{existing}.
1248 This is, for instance, how the user can make the current buffer visit
1249 no file using @code{M-x set-visited-file-name}.
1251 If @var{predicate} is non-@code{nil}, it specifies a function of one
1252 argument that decides which file names are acceptable completion
1253 possibilities. A file name is an acceptable value if @var{predicate}
1254 returns non-@code{nil} for it.
1256 @code{read-file-name} does not automatically expand file names. You
1257 must call @code{expand-file-name} yourself if an absolute file name is
1264 (read-file-name "The file is ")
1266 ;; @r{After evaluation of the preceding expression,}
1267 ;; @r{the following appears in the minibuffer:}
1271 ---------- Buffer: Minibuffer ----------
1272 The file is /gp/gnu/elisp/@point{}
1273 ---------- Buffer: Minibuffer ----------
1278 Typing @kbd{manual @key{TAB}} results in the following:
1282 ---------- Buffer: Minibuffer ----------
1283 The file is /gp/gnu/elisp/manual.texi@point{}
1284 ---------- Buffer: Minibuffer ----------
1288 @c Wordy to avoid overfull hbox in smallbook mode.
1290 If the user types @key{RET}, @code{read-file-name} returns the file name
1291 as the string @code{"/gp/gnu/elisp/manual.texi"}.
1294 @defvar read-file-name-function
1295 If non-@code{nil}, this should be a function that accepts the same
1296 arguments as @code{read-file-name}. When @code{read-file-name} is
1297 called, it calls this function with the supplied arguments instead of
1298 doing its usual work.
1301 @defvar read-file-name-completion-ignore-case
1302 If this variable is non-@code{nil}, @code{read-file-name} ignores case
1303 when performing completion.
1306 @defun read-directory-name prompt &optional directory default existing initial
1307 This function is like @code{read-file-name} but allows only directory
1308 names as completion possibilities.
1310 If @var{default} is @code{nil} and @var{initial} is non-@code{nil},
1311 @code{read-directory-name} constructs a substitute default by
1312 combining @var{directory} (or the current buffer's default directory
1313 if @var{directory} is @code{nil}) and @var{initial}. If both
1314 @var{default} and @var{initial} are @code{nil}, this function uses
1315 @var{directory} as substitute default, or the current buffer's default
1316 directory if @var{directory} is @code{nil}.
1319 @defopt insert-default-directory
1320 This variable is used by @code{read-file-name}, and thus, indirectly,
1321 by most commands reading file names. (This includes all commands that
1322 use the code letters @samp{f} or @samp{F} in their interactive form.
1323 @xref{Interactive Codes,, Code Characters for interactive}.) Its
1324 value controls whether @code{read-file-name} starts by placing the
1325 name of the default directory in the minibuffer, plus the initial file
1326 name if any. If the value of this variable is @code{nil}, then
1327 @code{read-file-name} does not place any initial input in the
1328 minibuffer (unless you specify initial input with the @var{initial}
1329 argument). In that case, the default directory is still used for
1330 completion of relative file names, but is not displayed.
1332 If this variable is @code{nil} and the initial minibuffer contents are
1333 empty, the user may have to explicitly fetch the next history element
1334 to access a default value. If the variable is non-@code{nil}, the
1335 initial minibuffer contents are always non-empty and the user can
1336 always request a default value by immediately typing @key{RET} in an
1337 unedited minibuffer. (See above.)
1343 ;; @r{Here the minibuffer starts out with the default directory.}
1344 (let ((insert-default-directory t))
1345 (read-file-name "The file is "))
1349 ---------- Buffer: Minibuffer ----------
1350 The file is ~lewis/manual/@point{}
1351 ---------- Buffer: Minibuffer ----------
1355 ;; @r{Here the minibuffer is empty and only the prompt}
1356 ;; @r{appears on its line.}
1357 (let ((insert-default-directory nil))
1358 (read-file-name "The file is "))
1362 ---------- Buffer: Minibuffer ----------
1363 The file is @point{}
1364 ---------- Buffer: Minibuffer ----------
1369 @node Programmed Completion
1370 @subsection Programmed Completion
1371 @cindex programmed completion
1373 Sometimes it is not possible to create an alist or an obarray
1374 containing all the intended possible completions. In such a case, you
1375 can supply your own function to compute the completion of a given string.
1376 This is called @dfn{programmed completion}.
1378 To use this feature, pass a symbol with a function definition as the
1379 @var{collection} argument to @code{completing-read}. The function
1380 @code{completing-read} arranges to pass your completion function along
1381 to @code{try-completion} and @code{all-completions}, which will then let
1382 your function do all the work.
1384 The completion function should accept three arguments:
1388 The string to be completed.
1391 The predicate function to filter possible matches, or @code{nil} if
1392 none. Your function should call the predicate for each possible match,
1393 and ignore the possible match if the predicate returns @code{nil}.
1396 A flag specifying the type of operation.
1399 There are three flag values for three operations:
1403 @code{nil} specifies @code{try-completion}. The completion function
1404 should return the completion of the specified string, or @code{t} if the
1405 string is a unique and exact match already, or @code{nil} if the string
1406 matches no possibility.
1408 If the string is an exact match for one possibility, but also matches
1409 other longer possibilities, the function should return the string, not
1413 @code{t} specifies @code{all-completions}. The completion function
1414 should return a list of all possible completions of the specified
1418 @code{lambda} specifies @code{test-completion}. The completion
1419 function should return @code{t} if the specified string is an exact
1420 match for some possibility; @code{nil} otherwise.
1423 It would be consistent and clean for completion functions to allow
1424 lambda expressions (lists that are functions) as well as function
1425 symbols as @var{collection}, but this is impossible. Lists as
1426 completion tables already have other meanings, and it would be
1427 unreliable to treat one differently just because it is also a possible
1428 function. So you must arrange for any function you wish to use for
1429 completion to be encapsulated in a symbol.
1431 Emacs uses programmed completion when completing file names.
1432 @xref{File Name Completion}.
1434 @defmac dynamic-completion-table function
1435 This macro is a convenient way to write a function that can act as
1436 programmed completion function. The argument @var{function} should be
1437 a function that takes one argument, a string, and returns an alist of
1438 possible completions of it. You can think of
1439 @code{dynamic-completion-table} as a transducer between that interface
1440 and the interface for programmed completion functions.
1443 @node Yes-or-No Queries
1444 @section Yes-or-No Queries
1445 @cindex asking the user questions
1446 @cindex querying the user
1447 @cindex yes-or-no questions
1449 This section describes functions used to ask the user a yes-or-no
1450 question. The function @code{y-or-n-p} can be answered with a single
1451 character; it is useful for questions where an inadvertent wrong answer
1452 will not have serious consequences. @code{yes-or-no-p} is suitable for
1453 more momentous questions, since it requires three or four characters to
1456 If either of these functions is called in a command that was invoked
1457 using the mouse---more precisely, if @code{last-nonmenu-event}
1458 (@pxref{Command Loop Info}) is either @code{nil} or a list---then it
1459 uses a dialog box or pop-up menu to ask the question. Otherwise, it
1460 uses keyboard input. You can force use of the mouse or use of keyboard
1461 input by binding @code{last-nonmenu-event} to a suitable value around
1464 Strictly speaking, @code{yes-or-no-p} uses the minibuffer and
1465 @code{y-or-n-p} does not; but it seems best to describe them together.
1467 @defun y-or-n-p prompt
1468 This function asks the user a question, expecting input in the echo
1469 area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the
1470 user types @kbd{n}. This function also accepts @key{SPC} to mean yes
1471 and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like
1472 @kbd{C-g}, because the question might look like a minibuffer and for
1473 that reason the user might try to use @kbd{C-]} to get out. The answer
1474 is a single character, with no @key{RET} needed to terminate it. Upper
1475 and lower case are equivalent.
1477 ``Asking the question'' means printing @var{prompt} in the echo area,
1478 followed by the string @w{@samp{(y or n) }}. If the input is not one of
1479 the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}},
1480 @kbd{@key{DEL}}, or something that quits), the function responds
1481 @samp{Please answer y or n.}, and repeats the request.
1483 This function does not actually use the minibuffer, since it does not
1484 allow editing of the answer. It actually uses the echo area (@pxref{The
1485 Echo Area}), which uses the same screen space as the minibuffer. The
1486 cursor moves to the echo area while the question is being asked.
1488 The answers and their meanings, even @samp{y} and @samp{n}, are not
1489 hardwired. The keymap @code{query-replace-map} specifies them.
1490 @xref{Search and Replace}.
1492 In the following example, the user first types @kbd{q}, which is
1493 invalid. At the next prompt the user types @kbd{y}.
1497 (y-or-n-p "Do you need a lift? ")
1499 ;; @r{After evaluation of the preceding expression,}
1500 ;; @r{the following prompt appears in the echo area:}
1504 ---------- Echo area ----------
1505 Do you need a lift? (y or n)
1506 ---------- Echo area ----------
1509 ;; @r{If the user then types @kbd{q}, the following appears:}
1512 ---------- Echo area ----------
1513 Please answer y or n. Do you need a lift? (y or n)
1514 ---------- Echo area ----------
1517 ;; @r{When the user types a valid answer,}
1518 ;; @r{it is displayed after the question:}
1521 ---------- Echo area ----------
1522 Do you need a lift? (y or n) y
1523 ---------- Echo area ----------
1528 We show successive lines of echo area messages, but only one actually
1529 appears on the screen at a time.
1532 @defun y-or-n-p-with-timeout prompt seconds default-value
1533 Like @code{y-or-n-p}, except that if the user fails to answer within
1534 @var{seconds} seconds, this function stops waiting and returns
1535 @var{default-value}. It works by setting up a timer; see @ref{Timers}.
1536 The argument @var{seconds} may be an integer or a floating point number.
1539 @defun yes-or-no-p prompt
1540 This function asks the user a question, expecting input in the
1541 minibuffer. It returns @code{t} if the user enters @samp{yes},
1542 @code{nil} if the user types @samp{no}. The user must type @key{RET} to
1543 finalize the response. Upper and lower case are equivalent.
1545 @code{yes-or-no-p} starts by displaying @var{prompt} in the echo area,
1546 followed by @w{@samp{(yes or no) }}. The user must type one of the
1547 expected responses; otherwise, the function responds @samp{Please answer
1548 yes or no.}, waits about two seconds and repeats the request.
1550 @code{yes-or-no-p} requires more work from the user than
1551 @code{y-or-n-p} and is appropriate for more crucial decisions.
1557 (yes-or-no-p "Do you really want to remove everything? ")
1559 ;; @r{After evaluation of the preceding expression,}
1560 ;; @r{the following prompt appears,}
1561 ;; @r{with an empty minibuffer:}
1565 ---------- Buffer: minibuffer ----------
1566 Do you really want to remove everything? (yes or no)
1567 ---------- Buffer: minibuffer ----------
1572 If the user first types @kbd{y @key{RET}}, which is invalid because this
1573 function demands the entire word @samp{yes}, it responds by displaying
1574 these prompts, with a brief pause between them:
1578 ---------- Buffer: minibuffer ----------
1579 Please answer yes or no.
1580 Do you really want to remove everything? (yes or no)
1581 ---------- Buffer: minibuffer ----------
1586 @node Multiple Queries
1587 @section Asking Multiple Y-or-N Questions
1589 When you have a series of similar questions to ask, such as ``Do you
1590 want to save this buffer'' for each buffer in turn, you should use
1591 @code{map-y-or-n-p} to ask the collection of questions, rather than
1592 asking each question individually. This gives the user certain
1593 convenient facilities such as the ability to answer the whole series at
1596 @defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area
1597 This function asks the user a series of questions, reading a
1598 single-character answer in the echo area for each one.
1600 The value of @var{list} specifies the objects to ask questions about.
1601 It should be either a list of objects or a generator function. If it is
1602 a function, it should expect no arguments, and should return either the
1603 next object to ask about, or @code{nil} meaning stop asking questions.
1605 The argument @var{prompter} specifies how to ask each question. If
1606 @var{prompter} is a string, the question text is computed like this:
1609 (format @var{prompter} @var{object})
1613 where @var{object} is the next object to ask about (as obtained from
1616 If not a string, @var{prompter} should be a function of one argument
1617 (the next object to ask about) and should return the question text. If
1618 the value is a string, that is the question to ask the user. The
1619 function can also return @code{t} meaning do act on this object (and
1620 don't ask the user), or @code{nil} meaning ignore this object (and don't
1623 The argument @var{actor} says how to act on the answers that the user
1624 gives. It should be a function of one argument, and it is called with
1625 each object that the user says yes for. Its argument is always an
1626 object obtained from @var{list}.
1628 If the argument @var{help} is given, it should be a list of this form:
1631 (@var{singular} @var{plural} @var{action})
1635 where @var{singular} is a string containing a singular noun that
1636 describes the objects conceptually being acted on, @var{plural} is the
1637 corresponding plural noun, and @var{action} is a transitive verb
1638 describing what @var{actor} does.
1640 If you don't specify @var{help}, the default is @code{("object"
1641 "objects" "act on")}.
1643 Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or
1644 @key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip
1645 that object; @kbd{!} to act on all following objects; @key{ESC} or
1646 @kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on
1647 the current object and then exit; or @kbd{C-h} to get help. These are
1648 the same answers that @code{query-replace} accepts. The keymap
1649 @code{query-replace-map} defines their meaning for @code{map-y-or-n-p}
1650 as well as for @code{query-replace}; see @ref{Search and Replace}.
1652 You can use @var{action-alist} to specify additional possible answers
1653 and what they mean. It is an alist of elements of the form
1654 @code{(@var{char} @var{function} @var{help})}, each of which defines one
1655 additional answer. In this element, @var{char} is a character (the
1656 answer); @var{function} is a function of one argument (an object from
1657 @var{list}); @var{help} is a string.
1659 When the user responds with @var{char}, @code{map-y-or-n-p} calls
1660 @var{function}. If it returns non-@code{nil}, the object is considered
1661 ``acted upon'', and @code{map-y-or-n-p} advances to the next object in
1662 @var{list}. If it returns @code{nil}, the prompt is repeated for the
1665 Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while
1666 prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it
1669 If @code{map-y-or-n-p} is called in a command that was invoked using the
1670 mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command
1671 Loop Info}) is either @code{nil} or a list---then it uses a dialog box
1672 or pop-up menu to ask the question. In this case, it does not use
1673 keyboard input or the echo area. You can force use of the mouse or use
1674 of keyboard input by binding @code{last-nonmenu-event} to a suitable
1675 value around the call.
1677 The return value of @code{map-y-or-n-p} is the number of objects acted on.
1680 @node Reading a Password
1681 @section Reading a Password
1682 @cindex passwords, reading
1684 To read a password to pass to another program, you can use the
1685 function @code{read-passwd}.
1687 @defun read-passwd prompt &optional confirm default
1688 This function reads a password, prompting with @var{prompt}. It does
1689 not echo the password as the user types it; instead, it echoes @samp{.}
1690 for each character in the password.
1692 The optional argument @var{confirm}, if non-@code{nil}, says to read the
1693 password twice and insist it must be the same both times. If it isn't
1694 the same, the user has to type it over and over until the last two
1697 The optional argument @var{default} specifies the default password to
1698 return if the user enters empty input. If @var{default} is @code{nil},
1699 then @code{read-passwd} returns the null string in that case.
1702 @node Minibuffer Commands
1703 @section Minibuffer Commands
1705 This section describes some commands meant for use in the
1708 @deffn Command exit-minibuffer
1709 This command exits the active minibuffer. It is normally bound to
1710 keys in minibuffer local keymaps.
1713 @deffn Command self-insert-and-exit
1714 This command exits the active minibuffer after inserting the last
1715 character typed on the keyboard (found in @code{last-command-char};
1716 @pxref{Command Loop Info}).
1719 @deffn Command previous-history-element n
1720 This command replaces the minibuffer contents with the value of the
1721 @var{n}th previous (older) history element.
1724 @deffn Command next-history-element n
1725 This command replaces the minibuffer contents with the value of the
1726 @var{n}th more recent history element.
1729 @deffn Command previous-matching-history-element pattern n
1730 This command replaces the minibuffer contents with the value of the
1731 @var{n}th previous (older) history element that matches @var{pattern} (a
1732 regular expression).
1735 @deffn Command next-matching-history-element pattern n
1736 This command replaces the minibuffer contents with the value of the
1737 @var{n}th next (newer) history element that matches @var{pattern} (a
1738 regular expression).
1741 @node Minibuffer Windows
1742 @section Minibuffer Windows
1744 These functions access and select minibuffer windows
1745 and test whether they are active.
1747 @defun active-minibuffer-window
1748 This function returns the currently active minibuffer window, or
1749 @code{nil} if none is currently active.
1752 @defun minibuffer-window &optional frame
1753 @anchor{Definition of minibuffer-window}
1754 This function returns the minibuffer window used for frame @var{frame}.
1755 If @var{frame} is @code{nil}, that stands for the current frame. Note
1756 that the minibuffer window used by a frame need not be part of that
1757 frame---a frame that has no minibuffer of its own necessarily uses some
1758 other frame's minibuffer window.
1761 @defun set-minibuffer-window window
1762 This function specifies @var{window} as the minibuffer window to use.
1763 This affects where the minibuffer is displayed if you put text in it
1764 without invoking the usual minibuffer commands. It has no effect on
1765 the usual minibuffer input functions because they all start by
1766 choosing the minibuffer window according to the current frame.
1770 @defun window-minibuffer-p &optional window
1771 This function returns non-@code{nil} if @var{window} is a minibuffer
1773 @var{window} defaults to the selected window.
1776 It is not correct to determine whether a given window is a minibuffer by
1777 comparing it with the result of @code{(minibuffer-window)}, because
1778 there can be more than one minibuffer window if there is more than one
1781 @defun minibuffer-window-active-p window
1782 This function returns non-@code{nil} if @var{window}, assumed to be
1783 a minibuffer window, is currently active.
1786 @node Minibuffer Contents
1787 @section Minibuffer Contents
1789 These functions access the minibuffer prompt and contents.
1791 @defun minibuffer-prompt
1792 This function returns the prompt string of the currently active
1793 minibuffer. If no minibuffer is active, it returns @code{nil}.
1796 @defun minibuffer-prompt-end
1797 @tindex minibuffer-prompt-end
1798 This function returns the current
1799 position of the end of the minibuffer prompt, if a minibuffer is
1800 current. Otherwise, it returns the minimum valid buffer position.
1803 @defun minibuffer-prompt-width
1804 This function returns the current display-width of the minibuffer
1805 prompt, if a minibuffer is current. Otherwise, it returns zero.
1808 @defun minibuffer-contents
1809 @tindex minibuffer-contents
1810 This function returns the editable
1811 contents of the minibuffer (that is, everything except the prompt) as
1812 a string, if a minibuffer is current. Otherwise, it returns the
1813 entire contents of the current buffer.
1816 @defun minibuffer-contents-no-properties
1817 @tindex minibuffer-contents-no-properties
1818 This is like @code{minibuffer-contents}, except that it does not copy text
1819 properties, just the characters themselves. @xref{Text Properties}.
1822 @defun delete-minibuffer-contents
1823 @tindex delete-minibuffer-contents
1824 This function erases the editable contents of the minibuffer (that is,
1825 everything except the prompt), if a minibuffer is current. Otherwise,
1826 it erases the entire current buffer.
1829 @node Recursive Mini
1830 @section Recursive Minibuffers
1832 These functions and variables deal with recursive minibuffers
1833 (@pxref{Recursive Editing}):
1835 @defun minibuffer-depth
1836 This function returns the current depth of activations of the
1837 minibuffer, a nonnegative integer. If no minibuffers are active, it
1841 @defopt enable-recursive-minibuffers
1842 If this variable is non-@code{nil}, you can invoke commands (such as
1843 @code{find-file}) that use minibuffers even while the minibuffer window
1844 is active. Such invocation produces a recursive editing level for a new
1845 minibuffer. The outer-level minibuffer is invisible while you are
1846 editing the inner one.
1848 If this variable is @code{nil}, you cannot invoke minibuffer
1849 commands when the minibuffer window is active, not even if you switch to
1850 another window to do it.
1854 If a command name has a property @code{enable-recursive-minibuffers}
1855 that is non-@code{nil}, then the command can use the minibuffer to read
1856 arguments even if it is invoked from the minibuffer. A command can
1857 also achieve this by binding @code{enable-recursive-minibuffers}
1858 to @code{t} in the interactive declaration (@pxref{Using Interactive}).
1859 The minibuffer command @code{next-matching-history-element} (normally
1860 @kbd{M-s} in the minibuffer) does the latter.
1862 @node Minibuffer Misc
1863 @section Minibuffer Miscellany
1865 @defun minibufferp &optional buffer-or-name
1866 This function returns non-@code{nil} if @var{buffer-or-name} is a
1867 minibuffer. If @var{buffer-or-name} is omitted, it tests the current
1871 @defvar minibuffer-setup-hook
1872 This is a normal hook that is run whenever the minibuffer is entered.
1876 @defvar minibuffer-exit-hook
1877 This is a normal hook that is run whenever the minibuffer is exited.
1881 @defvar minibuffer-help-form
1882 @anchor{Definition of minibuffer-help-form}
1883 The current value of this variable is used to rebind @code{help-form}
1884 locally inside the minibuffer (@pxref{Help Functions}).
1887 @defvar minibuffer-scroll-window
1888 @anchor{Definition of minibuffer-scroll-window}
1889 If the value of this variable is non-@code{nil}, it should be a window
1890 object. When the function @code{scroll-other-window} is called in the
1891 minibuffer, it scrolls this window.
1894 @defun minibuffer-selected-window
1895 This function returns the window which was selected when the
1896 minibuffer was entered. If selected window is not a minibuffer
1897 window, it returns @code{nil}.
1900 @defopt max-mini-window-height
1901 This variable specifies the maximum height for resizing minibuffer
1902 windows. If a float, it specifies a fraction of the height of the
1903 frame. If an integer, it specifies a number of lines.
1906 @defun minibuffer-message string
1907 This function displays @var{string} temporarily at the end of the
1908 minibuffer text, for two seconds, or until the next input event
1909 arrives, whichever comes first.
1913 arch-tag: bba7f945-9078-477f-a2ce-18818a6e1218