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A minibuffer is a special buffer that Emacs commands use to read arguments more complicated than the single numeric prefix argument. These arguments include file names, buffer names, and command names (as in M-x). The minibuffer is displayed on the bottom line of the screen, in the same place as the echo area, but only while it is in use for reading an argument.
| 1.1 Introduction to Minibuffers | Basic information about minibuffers. | |
| 1.2 Reading Text Strings with the Minibuffer | How to read a straight text string. | |
| 1.3 Reading Lisp Objects with the Minibuffer | How to read a Lisp object or expression. | |
| 1.4 Minibuffer History | Recording previous minibuffer inputs so the user can reuse them. | |
| 1.5 Completion | How to invoke and customize completion. | |
| 1.6 Yes-or-No Queries | Asking a question with a simple answer. | |
| 1.7 Asking Multiple Y-or-N Queries | Asking a series of similar questions. | |
| 1.8 Minibuffer Miscellany | Various customization hooks and variables. |
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In most ways, a minibuffer is a normal Emacs buffer. Most operations within a buffer, such as editing commands, work normally in a minibuffer. However, many operations for managing buffers do not apply to minibuffers. The name of a minibuffer always has the form ‘ *Minibuf-number’, and it cannot be changed. Minibuffers are displayed only in special windows used only for minibuffers; these windows always appear at the bottom of a frame. (Sometime frames have no minibuffer window, and sometimes a special kind of frame contains nothing but a minibuffer window; see @ref{Minibuffers and Frames}.)
The minibuffers window is normally a single line; you can resize it temporarily with the window sizing commands, but reverts to its normal size when the minibuffer is exited.
A recursive minibuffer may be created when there is an active
minibuffer and a command is invoked that requires input from a
minibuffer. The first minibuffer is named ‘ *Minibuf-0*’.
Recursive minibuffers are named by incrementing the number at the end of
the name. (The names begin with a space so that they won’t show up in
normal buffer lists.) Of several recursive minibuffers, the innermost
(or most recently entered) is the active minibuffer. We usually call
this “the” minibuffer. You can permit or forbid recursive minibuffers
by setting the variable enable-recursive-minibuffers or by
putting properties of that name on command symbols (see section Minibuffer Miscellany).
Like other buffers, a minibuffer may use any of several local keymaps (@pxref{Keymaps}); these contain various exit commands and in some cases completion commands. See section Completion.
minibuffer-local-map is for ordinary input (no completion).
minibuffer-local-ns-map is similar, except that <SPC> exits
just like <RET>. This is used mainly for Mocklisp compatibility.
minibuffer-local-completion-map is for permissive completion.
minibuffer-local-must-match-map is for strict completion and
for cautious completion.
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The minibuffer is usually used to read text which is returned as a
string, but can also be used to read a Lisp object in textual form. The
most basic primitive for minibuffer input is
read-from-minibuffer.
This function is the most general way to get input through the
minibuffer. By default, it accepts arbitrary text and returns it as a
string; however, if read is non-nil, then it uses
read to convert the text into a Lisp object (@pxref{Input
Functions}).
The first thing this function does is to activate a minibuffer and display it with prompt-string as the prompt. This value must be a string.
Then, if initial is a string; its contents are inserted into the minibuffer as initial contents. The text thus inserted is treated as if the user had inserted it; the user can alter it with Emacs editing commands.
The value of initial may also be a cons cell of the form
(string . position). This means to insert
string in the minibuffer but put the cursor position
characters from the beginning, rather than at the end.
If keymap is non-nil, that keymap is the local keymap to
use while reading. If keymap is omitted or nil, the value
of minibuffer-local-map is used as the keymap. Specifying a
keymap is the most important way to customize minibuffer input for
various applications including completion.
The argument hist specifies which history list variable to use
for saving the input and for history commands used in the minibuffer.
It defaults to minibuffer-history. See section Minibuffer History.
When the user types a command to exit the minibuffer, the current
minibuffer contents are usually made into a string which becomes the
value of read-from-minibuffer. However, if read is
non-nil, read-from-minibuffer converts the result to a
Lisp object, and returns that object, unevaluated.
Suppose, for example, you are writing a search command and want to
record the last search string and provide it as a default for the next
search. Suppose that the previous search string is stored in the
variable last-search-string. Here is how you can read a search
string while providing the previous string as initial input to be
edited:
(read-from-minibuffer "Find string: " last-search-string)
Assuming the value of last-search-string is ‘No’, and
the user wants to search for ‘Nope’, the interaction looks
like this:
(setq last-search-string "No")
(read-from-minibuffer "Find string: " last-search-string)
---------- Buffer: Minibuffer ----------
Find string: No∗
---------- Buffer: Minibuffer ----------
;; The user now types pe <RET>:
⇒ "Nope"
This technique is no longer preferred for most applications; it is usually better to use a history list.
This function reads a string from the minibuffer and returns it. The
arguments prompt and initial are used as in
read-from-minibuffer.
This is a simplified interface to the
read-from-minibuffer function:
(read-string prompt initial) ≡ (read-from-minibuffer prompt initial nil nil)
This is the default local keymap for reading from the minibuffer. It is
the keymap used by the minibuffer for local bindings in the function
read-string. By default, it makes the following bindings:
exit-minibuffer
exit-minibuffer
abort-recursive-edit
next-history-element and previous-history-element
next-matching-history-element
previous-matching-history-element
This function reads a string from the minibuffer, but does not allow
whitespace characters as part of the input: instead, those characters
terminate the input. The arguments prompt and initial are
used as in read-from-minibuffer.
This is a simplified interface to the read-from-minibuffer
function, and passes the value of the minibuffer-local-ns-map
keymap as the keymap argument for that function. Since the keymap
minibuffer-local-ns-map does not rebind C-q, it is
possible to put a space into the string, by quoting it.
(read-no-blanks-input prompt initial) ≡ (read-from-minibuffer prompt initial minibuffer-local-ns-map)
This built-in variable is the keymap used as the minibuffer local keymap
in the function read-no-blanks-input. By default, it makes the
following bindings:
exit-minibuffer
exit-minibuffer
exit-minibuffer
exit-minibuffer
abort-recursive-edit
self-insert-and-exit
next-history-element and previous-history-element
next-matching-history-element
previous-matching-history-element
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This section describes functions for reading Lisp objects with the minibuffer.
This function reads a Lisp object in the minibuffer and returns it,
without evaluating it. The arguments prompt and initial are
used as in read-from-minibuffer; in particular, initial
must be a string or nil.
This is a simplified interface to the
read-from-minibuffer function:
(read-minibuffer prompt initial) ≡ (read-from-minibuffer prompt initial nil t)
Here is an example in which we supply the string "(testing)" as
initial input:
(read-minibuffer
"Enter an expression: " (format "%s" '(testing)))
;; Here is how the minibuffer is displayed:
---------- Buffer: Minibuffer ---------- Enter an expression: (testing)∗ ---------- Buffer: Minibuffer ----------
The user can type <RET> immediately to use the initial input as a default, or can edit the input.
This function reads a Lisp expression in the minibuffer, evaluates it,
then returns the result. The arguments prompt and initial
are used as in read-from-minibuffer.
This function simply evaluates the result of a call to
read-minibuffer:
(eval-minibuffer prompt initial) ≡ (eval (read-minibuffer prompt initial))
This function reads a Lisp expression in the minibuffer, and then
evaluates it. The difference between this command and
eval-minibuffer is that here the initial form is not
optional and it is treated as a Lisp object to be converted to printed
representation rather than as a string of text. It is printed with
prin1, so if it is a string, double-quote characters (‘"’)
appear in the initial text. @xref{Output Functions}.
The first thing edit-and-eval-command does is to activate the
minibuffer with prompt as the prompt. Then it inserts the printed
representation of form in the minibuffer, and lets the user edit.
When the user exits the minibuffer, the edited text is read with
read and then evaluated. The resulting value becomes the value
of edit-and-eval-command.
In the following example, we offer the user an expression with initial text which is a valid form already:
(edit-and-eval-command "Please edit: " '(forward-word 1)) ;; After evaluating the preceding expression, ;; the following appears in the minibuffer:
---------- Buffer: Minibuffer ---------- Please edit: (forward-word 1)∗ ---------- Buffer: Minibuffer ----------
Typing <RET> right away would exit the minibuffer and evaluate the
expression, thus moving point forward one word.
edit-and-eval-command returns nil in this example.
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A minibuffer history list records previous minibuffer inputs so the user can reuse them conveniently. There are many separate history lists which contain different kinds of inputs. The Lisp programmer’s job is to specify the right history list for each use of the minibuffer.
The basic minibuffer input functions read-from-minibuffer and
completing-read both accept an optional argument named hist
which is how you specify the history list. Here are the possible
values:
If you specify a variable (a symbol), that variable is the history list.
If you specify a cons cell of this form, then variable is the history list variable, and startpos specifies the initial history position (an integer, counting from zero which specifies the most recent element of the history).
If you specify startpos, then you should also specify that element of the history as initial, for consistency.
If you don’t specify hist, then the default history list
minibuffer-history is used. For other standard history lists,
see below. You can also create your own history list variable; just
initialize it to nil before the first use. The value of the
history list variable is a list of strings, most recent first.
Both read-from-minibuffer and completing-read add new
elements to the history list automatically, and provide commands to
allow the user to reuse items on the list. The only thing your program
needs to do to use a history list is to initialize it and to pass its
name to the input functions when you wish. But it is safe to modify the
list by hand when the minibuffer input functions are not using it.
The default history list for minibuffer history input.
A history list for arguments to query-replace (and similar
arguments to other commands).
A history list for file name arguments.
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Completion is a feature that fills in the rest of a name starting from an abbreviation for it. Completion works by comparing the user’s input against a list of valid names and determining how much of the name is determined uniquely by what the user has typed.
For example, when you type C-x b (switch-to-buffer) and
then type the first few letters of the name of the buffer to which you
wish to switch, and then type <TAB> (minibuffer-complete),
Emacs extends the name as far as it can. Standard Emacs commands offer
completion for names of symbols, files, buffers, and processes; with the
functions in this section, you can implement completion for other kinds
of names.
The try-completion function is the basic primitive for
completion: it returns the longest determined completion of a given
initial string, with a given set of strings to match against.
The function completing-read provides a higher-level interface
for completion. A call to completing-read specifies how to
determine the list of valid names. The function then activates the
minibuffer with a local keymap that binds a few keys to commands useful
for completion. Other functions provide convenient simple interfaces
for reading certain kinds of names with completion.
| 1.5.1 Basic Completion Functions | Low-level functions for completing strings. (These are too low level to use the minibuffer.) | |
| 1.5.2 Programmed Completion | Finding the completions for a given file name. | |
| 1.5.3 Completion and the Minibuffer | Invoking the minibuffer with completion. | |
| 1.5.4 Minibuffer Commands That Do Completion | Minibuffer commands that do completion. | |
| 1.5.5 High-Level Completion Functions | Convenient special cases of completion (reading buffer name, file name, etc.) | |
| 1.5.6 Reading File Names | Using completion to read file names. | |
| 1.5.7 Lisp Symbol Completion | Completing the name of a symbol. |
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This function returns the longest common substring of all possible completions of string in collection. The value of collection must be an alist, an obarray, or a function which implements a virtual set of strings.
If collection is an alist (@pxref{Association Lists}),
completion compares the CAR of each cons cell in it against
string; if the beginning of the CAR equals string, the
cons cell matches. If no cons cells match, try-completion
returns nil. If only one cons cell matches, and the match is
exact, then try-completion returns t. Otherwise, the
value is the longest initial sequence common to all the matching strings
in the alist.
If collection is an obarray (@pxref{Creating Symbols}), the
names of all symbols in the obarray form the space of possible
completions. They are tested and used just like the CARs of the
elements of an association list. (The global variable obarray
holds an obarray containing the names of all interned Lisp symbols.)
Note that the only valid way to make a new obarray is to create it
empty and then add symbols to it one by one using intern.
Also, you cannot intern a given symbol in more than one obarray.
If the argument predicate is non-nil, then it must be a
function of one argument. It is used to test each possible match, and
the match is accepted only if predicate returns non-nil.
The argument given to predicate is either a cons cell from the alist
(the CAR of which is a string) or else it is a symbol (not a
symbol name) from the obarray.
It is also possible to use a function symbol as collection.
Then the function is solely responsible for performing completion;
try-completion returns whatever this function returns. The
function is called with three arguments: string, predicate
and nil. (The reason for the third argument is so that the same
function can be used in all-completions and do the appropriate
thing in either case.) See section Programmed Completion.
In the first of the following examples, the string ‘foo’ is
matched by three of the alist CARs. All of the matches begin with
the characters ‘fooba’, so that is the result. In the second
example, there is only one possible match, and it is exact, so the value
is t.
(try-completion
"foo"
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
⇒ "fooba"
(try-completion "foo" '(("barfoo" 2) ("foo" 3)))
⇒ t
In the following example, numerous symbols begin with the characters ‘forw’, and all of them begin with the word ‘forward’. In most of the symbols, this is followed with a ‘-’, but not in all, so no more than ‘forward’ can be completed.
(try-completion "forw" obarray)
⇒ "forward"
Finally, in the following example, only two of the three possible
matches pass the predicate test (the string ‘foobaz’ is
too short). Both of those begin with the string ‘foobar’.
(defun test (s)
(> (length (car s)) 6))
⇒ test
(try-completion
"foo"
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
'test)
⇒ "foobar"
This function returns a list of all possible completions, instead of
the longest substring they share. The parameters to this function are
the same as to try-completion.
If collection is a function, it is called with three
arguments: string, predicate and t, and
all-completions returns whatever the function returns.
See section Programmed Completion.
Here is an example, using the function test shown in the
example for try-completion:
(defun test (s)
(> (length (car s)) 6))
⇒ test
(all-completions
"foo"
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
(function test))
⇒ ("foobar1" "foobar2")
If the value of this variable is
non-nil, Emacs does not consider case significant in completion.
The two functions try-completion and all-completions
have nothing in themselves to do with minibuffers. However,
completion is most often used there, which is why it is described in
this chapter.
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Sometimes it is not possible to create an alist or an obarray containing all the intended possible completions. In such a case, you can supply your own function to compute the completion of a given string. This is called programmed completion.
To use this feature, pass a symbol with a function definition as the
collection argument to completing-read. This command
arranges to pass the function along to try-completion and
all-completions, which will then let your function do all the
work.
The completion function should accept three arguments:
nil if none.
Your function should call the predicate for each possible match and ignore
the possible match if the predicate returns nil.
There are three flag values for three operations:
nil specifies try-completion. The completion function
should return the completion of the specified string, or t if the
string is an exact match already, or nil if the string matches no
possibility.
t specifies all-completions. The completion function
should return a list of all possible completions of the specified
string.
lambda specifies a test for an exact match. The completion
function should return t if the specified string is an exact
match for some possibility; nil otherwise.
It would be consistent and clean for completion functions to allow lambda expressions (lists which are functions) as well as function symbols as collection, but this is impossible. Lists as completion tables are already assigned another meaning—as alists. It would be unreliable to fail to handle an alist normally because it is also a possible function. So you must arrange for any function you wish to use for completion to be encapsulated in a symbol.
Emacs uses programmed completion when completing file names. @xref{File Name Completion}.
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This section describes the basic interface for reading from the minibuffer with completion.
This function reads a string in the minibuffer, assisting the user by
providing completion. It activates the minibuffer with prompt
prompt, which must be a string. If initial is
non-nil, completing-read inserts it into the minibuffer as
part of the input. Then it allows the user to edit the input, providing
several commands to attempt completion.
The actual completion is done by passing collection and
predicate to the function try-completion. This happens in
certain commands bound in the local keymaps used for completion.
If require-match is t, the user is not allowed to exit
unless the input completes to an element of collection. If
require-match is neither nil nor t, then
completing-read does not exit unless the input typed is itself an
element of collection. To accomplish this, completing-read
calls read-minibuffer. It uses the value of
minibuffer-local-completion-map as the keymap if
require-match is nil, and uses
minibuffer-local-must-match-map if require-match is
non-nil.
The argument hist specifies which history list variable to use for
saving the input and for minibuffer history commands. It defaults to
minibuffer-history. See section Minibuffer History.
Case is ignored when comparing the input against the possible matches
if the built-in variable completion-ignore-case is
non-nil. See section Basic Completion Functions.
For example:
(completing-read
"Complete a foo: "
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
nil t "fo")
;; After evaluating the preceding expression, ;; the following appears in the minibuffer: ---------- Buffer: Minibuffer ---------- Complete a foo: fo∗ ---------- Buffer: Minibuffer ----------
If the user then types <DEL> <DEL> b <RET>,
completing-read returns barfoo.
The completing-read function binds three variables to pass
information to the commands which actually do completion. Here they
are:
minibuffer-completion-tableThis variable is bound to the collection argument. It is passed
to the try-completion function.
minibuffer-completion-predicateThis variable is bound to the predicate argument. It is passed to
the try-completion function.
minibuffer-completion-confirmThis variable is bound to the require-match argument. It is used
in the minibuffer-complete-and-exit function.
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This section describes the keymaps, commands and user options used in the minibuffer to do completion.
completing-read uses this value as the local keymap when an
exact match of one of the completions is not required. By default, this
keymap makes the following bindings:
minibuffer-completion-help
minibuffer-complete-word
minibuffer-complete
with other characters bound as in minibuffer-local-map.
completing-read uses this value as the local keymap when an
exact match of one of the completions is required. Therefore, no keys
are bound to exit-minibuffer, the command which exits the
minibuffer unconditionally. By default, this keymap makes the following
bindings:
minibuffer-completion-help
minibuffer-complete-word
minibuffer-complete
minibuffer-complete-and-exit
minibuffer-complete-and-exit
with other characters bound as in minibuffer-local-map.
The value of this variable is the alist or obarray used for completion
in the minibuffer. This is the global variable that contains what
completing-read passes to try-completion. It is used by
all the minibuffer completion functions, such as
minibuffer-complete-word.
This variable’s value is the predicate that completing-read
passes to try-completion. The variable is also used by the other
minibuffer completion functions.
This function completes the minibuffer contents by at most a single
word. Even if the minibuffer contents have only one completion,
minibuffer-complete-word does not add any characters beyond the
first character that is not a word constituent. @xref{Syntax Tables}.
This function completes the minibuffer contents as far as possible.
This function completes the minibuffer contents, and exits if
confirmation is not required, i.e., if
minibuffer-completion-confirm is non-nil. If confirmation
is required, it is given by repeating this command immediately.
When the value of this variable is non-nil, Emacs asks for
confirmation of a completion before exiting the minibuffer. The
function minibuffer-complete-and-exit checks the value of this
variable before it exits.
This function creates a list of the possible completions of the
current minibuffer contents. It works by calling all-completions
using the value of the variable minibuffer-completion-table as
the collection argument, and the value of
minibuffer-completion-predicate as the predicate argument.
The list of completions is displayed as text in a buffer named
‘*Completions*’.
This function displays completions to the stream in
standard-output, usually a buffer. (@xref{Streams}, for more
information about streams.) The argument completions is normally
a list of completions just returned by all-completions, but it
does not have to be. Each element may be a symbol or a string, either
of which is simply printed, or a list of two strings, which is printed
as if the strings were concatenated.
This function is called by minibuffer-completion-help. The
most common way to use it is together with
with-output-to-temp-buffer, like this:
(with-output-to-temp-buffer " *Completions*"
(display-completion-list
(all-completions (buffer-string) my-alist)))
If this variable is non-nil, the completion commands
automatically display a list of possible completions whenever nothing
can be completed because the next character is not uniquely determined.
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This section describes the higher-level convenient functions for reading certain sorts of names with completion.
This function reads the name of a buffer and returns it as a string.
The argument default is the default name to use, the value to
return if the user exits with an empty minibuffer. If non-nil,
it should be a string. It is mentioned in the prompt, but is not
inserted in the minibuffer as initial input.
If existing is non-nil, then the name specified must be
that of an existing buffer. The usual commands to exit the
minibuffer do not exit if the text is not valid, and <RET> does
completion to attempt to find a valid name. (However, default is
not checked for this; it is returned, whatever it is, if the user exits
with the minibuffer empty.)
In the following example, the user enters ‘minibuffer.t’, and
then types <RET>. The argument existing is t, and the
only buffer name starting with the given input is
‘minibuffer.texi’, so that name is the value.
(read-buffer "Buffer name? " "foo" t)
;; After evaluating the preceding expression, ;; the following prompt appears, ;; with an empty minibuffer:
---------- Buffer: Minibuffer ---------- Buffer name? (default foo) ∗ ---------- Buffer: Minibuffer ----------
;; The user types minibuffer.t <RET>.
⇒ "minibuffer.texi"
This function reads the name of a command and returns it as a Lisp
symbol. The argument prompt is used as in
read-from-minibuffer. Recall that a command is anything for
which commandp returns t, and a command name is a symbol
for which commandp returns t. @xref{Interactive Call}.
(read-command "Command name? ")
;; After evaluating the preceding expression, ;; the following appears in the minibuffer:
---------- Buffer: Minibuffer ---------- Command name? ---------- Buffer: Minibuffer ----------
If the user types forward-c <RET>, then this function returns
forward-char.
The read-command function is a simplified interface to the
completing-read function. It uses the commandp
predicate to allow only commands to be entered, and it uses the
variable obarray so as to be able to complete all extant Lisp
symbols:
(read-command prompt) ≡ (intern (completing-read prompt obarray 'commandp t nil))
This function reads the name of a user variable and returns it as a symbol.
(read-variable "Variable name? ") ;; After evaluating the preceding expression, ;; the following prompt appears, ;; with an empty minibuffer:
---------- Buffer: Minibuffer ---------- Variable name? ∗ ---------- Buffer: Minibuffer ----------
If the user then types fill-p <RET>, read-variable will
return fill-prefix.
This function is similar to read-command, but uses the
predicate user-variable-p instead of commandp:
(read-variable prompt) ≡ (intern (completing-read prompt obarray 'user-variable-p t nil))
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Here is another high-level completion function, designed for reading a file name. It provides special features including automatic insertion of the default directory.
This function reads a file name in the minibuffer, prompting with
prompt and providing completion. If default is
non-nil, then the function returns default if the user just
types <RET>.
If existing is non-nil, then the name must refer to an
existing file; then <RET> performs completion to make the name valid
if possible, and then refuses to exit if it is not valid. If the value
of existing is neither nil nor t, then <RET>
also requires confirmation after completion.
The argument directory specifies the directory to use for completion of relative file names. Usually it is inserted in the minibuffer as initial input as well. It defaults to the current buffer’s default directory.
If you specify initial, that is an initial file name to insert in
the buffer along with directory. In this case, point goes after
directory, before initial. The default for initial is
nil—don’t insert any file name. To see what initial
does, try the command C-x C-v.
Here is an example:
(read-file-name "The file is ") ;; After evaluating the preceding expression, ;; the following appears in the minibuffer:
---------- Buffer: Minibuffer ---------- The file is /gp/gnu/elisp/∗ ---------- Buffer: Minibuffer ----------
Typing manual <TAB> results in the following:
---------- Buffer: Minibuffer ---------- The file is /gp/gnu/elisp/manual.texi∗ ---------- Buffer: Minibuffer ----------
If the user types <RET>, read-file-name returns
"/gp/gnu/elisp/manual.texi".
This variable is used by read-file-name. Its value controls
whether read-file-name starts by placing the name of the default
directory in the minibuffer, plus the initial file name if any. If the
value of this variable is nil, then read-file-name does
not place any initial input in the minibuffer. In that case, the
default directory is still used for completion of relative file names,
but is not displayed.
For example:
;; Here the minibuffer starts out containing the default directory.
(let ((insert-default-directory t))
(read-file-name "The file is "))
---------- Buffer: Minibuffer ---------- The file is ~lewis/manual/∗ ---------- Buffer: Minibuffer ----------
;; Here the minibuffer is empty and only the prompt ;; appears on its line. (let ((insert-default-directory nil)) (read-file-name "The file is "))
---------- Buffer: Minibuffer ---------- The file is ∗ ---------- Buffer: Minibuffer ----------
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If you type a part of a symbol, and then type M-<TAB>
(lisp-complete-symbol), this command attempts to fill in as much
more of the symbol name as it can. Not only does this save typing, but
it can help you with the name of a symbol that you have partially
forgotten.
This function performs completion on the symbol name preceding point.
The name is completed against the symbols in the global variable
obarray, and characters from the completion are inserted into the
buffer, making the name longer. If there is more than one completion, a
list of all possible completions is placed in the ‘*Help*’ buffer.
The bell rings if there is no possible completion in obarray.
If an open parenthesis immediately precedes the name, only symbols with function definitions are considered. (By reducing the number of alternatives, this may succeed in completing more characters.) Otherwise, symbols with either a function definition, a value, or at least one property are considered.
lisp-complete-symbol returns t if the symbol had an exact,
and unique, match; otherwise, it returns nil.
In the following example, the user has already inserted ‘(forwa’
into the buffer ‘foo.el’. The command lisp-complete-symbol
then completes the name to ‘(forward-’.
---------- Buffer: foo.el ---------- (forwa∗ ---------- Buffer: foo.el ----------
(lisp-complete-symbol)
⇒ nil
---------- Buffer: foo.el ---------- (forward-∗ ---------- Buffer: foo.el ----------
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This section describes functions used to ask the user a yes-or-no
question. The function y-or-n-p can be answered with a single
character; it is useful for questions where an inadvertent wrong answer
will not have serious consequences. yes-or-no-p is suitable for
more momentous questions, since it requires three or four characters to
answer.
Strictly speaking, yes-or-no-p uses the minibuffer and
y-or-n-p does not; but it seems best to describe them together.
This function asks the user a question, expecting input in the echo
area. It returns t if the user types y, nil if the
user types n. This function also accepts <SPC> to mean yes
and <DEL> to mean no. It accepts C-] to mean “quit”, like
C-g, because the question might look like a minibuffer and for
that reason the user might try to use C-] to get out. The answer
is a single character, with no <RET> needed to terminate it. Upper
and lower case are equivalent.
“Asking the question” means printing prompt in the echo area, followed by the string ‘(y or n) ’. If the input is not one of the expected answers (y, n, <SPC>, <DEL>, or something that quits), the function responds ‘Please answer y or n.’, and repeats the request.
This function does not actually use the minibuffer, since it does not allow editing of the answer. It actually uses the echo area (@pxref{The Echo Area}), which uses the same screen space as the minibuffer. The cursor moves to the echo area while the question is being asked.
The meanings of answers, even ‘y’ and ‘n’, are not
hardwired. They are controlled by the keymap query-replace-map.
@xref{Replacement}.
In the following example, the user first types q, which is invalid. At the next prompt the user types n.
(y-or-n-p "Do you need a lift? ") ;; After evaluating the preceding expression, ;; the following prompt appears in the echo area:
---------- Echo area ---------- Do you need a lift? (y or n) ---------- Echo area ----------
;; If the user then types q, the following appears:
---------- Echo area ---------- Please answer y or n. Do you need a lift? (y or n) ---------- Echo area ----------
;; When the user types a valid answer, ;; it is displayed after the question:
---------- Echo area ---------- Do you need a lift? (y or n) y ---------- Echo area ----------
Note that we show successive lines of echo area messages here. Only one actually appears on the screen at a time.
This function asks the user a question, expecting input in minibuffer.
It returns t if the user enters ‘yes’, nil if the
user types ‘no’. The user must type <RET> to finalize the
response. Upper and lower case are equivalent.
yes-or-no-p starts by displaying prompt in the echo area,
followed by ‘(yes or no) ’. The user must type one of the
expected responses; otherwise, the function responds ‘Please answer
yes or no.’, waits about two seconds and repeats the request.
yes-or-no-p requires more work from the user than
y-or-n-p and is appropriate for more crucial decisions.
Here is an example:
(yes-or-no-p "Do you really want to remove everything? ") ;; After evaluating the preceding expression, ;; the following prompt appears, ;; with an empty minibuffer:
---------- Buffer: minibuffer ---------- Do you really want to remove everything? (yes or no) ---------- Buffer: minibuffer ----------
If the user first types y <RET>, which is invalid because this function demands the entire word ‘yes’, it responds by displaying these prompts, with a brief pause between them:
---------- Buffer: minibuffer ---------- Please answer yes or no. Do you really want to remove everything? (yes or no) ---------- Buffer: minibuffer ----------
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This function, new in Emacs 19, asks the user a series of questions, reading a single-character answer in the echo area for each one.
The value of list specifies what varies from question to question
within the series. It should be either a list of objects or a generator
function. If it is a function, it should expect no arguments, and
should return either the next object or nil meaning there are no
more questions.
The argument prompter specifies how to ask each question. If prompter is a string, the question text is computed like this:
(format prompter object)
where object is the next object to ask about (as obtained from list).
If not a string, prompter should be a function of one argument (the next object to ask about) and should return the question text.
The argument actor says how to act on the answers that the user gives. It should be a function of one argument, and it is called with each object that the user says yes for. Its argument is always an object obtained from list.
If the argument help is given, it should be a list of this form:
(singular plural action)
where singular is a string containing a singular noun that describes the objects conceptually being acted on, plural is the corresponding plural noun, and action is a transitive verb describing what actor does.
If you don’t specify help, the default is ("object"
"objects" "act on").
Each time a question is asked, the user may enter y, Y, or
<SPC> to act on that object; n, N, or <DEL> to skip
that object; ! to act on all following objects; <ESC> or
q to exit (skip all following objects); . (period) to act on
the current object and then exit; or C-h to get help. These are
the same answers that query-replace accepts. The keymap
query-replace-map defines their meaning for map-y-or-n-p
as well as for query-replace; see @ref{Replacement}.
You can use action-alist to specify additional possible answers
and what they mean. It is an alist of elements of the form
(char function help), each of which defines one
additional answer. In this element, char is a character (the
answer); function is a function of one argument (an object from
list); help is a string.
When the user responds with char, map-y-or-n-p calls
function. If it returns non-nil, the object is considered
“acted upon”, and map-y-or-n-p advances to the next object in
list. If it returns nil, the prompt is repeated for the
same object.
The return value of map-y-or-n-p is the number of objects acted on.
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This section describes some basic functions and variables related to minibuffers.
This command exits the active minibuffer. It is normally bound to keys in minibuffer local keymaps.
This command exits the active minibuffer after inserting the last
character typed on the keyboard (found in last-command-char;
@pxref{Command Loop Info}).
This command replaces the minibuffer contents with the value of the nth previous (older) history element.
This command replaces the minibuffer contents with the value of the nth more recent history element.
This command replaces the minibuffer contents with the value of the previous (older) history element that matches pattern. At the time of printing, we have not made a final decision about how to get the pattern interactively or how to match it against history elements.
This command replaces the minibuffer contents with the value of the next (newer) history element that matches pattern.
The current value of this variable is used to rebind help-form
locally inside the minibuffer (@pxref{Help Functions}).
This function returns the window that is used for the minibuffer. In Emacs 18, there is one and only one minibuffer window; this window always exists and cannot be deleted. In Emacs 19, each frame can have its own minibuffer, and this function returns the minibuffer window used for frame frame (which defaults to the currently selected frame).
This function returns non-nil if window is a minibuffer window.
It is not correct to determine whether a given window is a minibuffer by
comparing it with the result of (minibuffer-window), because
there can be more than one minibuffer window there is more than one
frame.
If the value of this variable is non-nil, it should be a window
object. When the function scroll-other-window is called in the
minibuffer, it scrolls this window.
Finally, some functions and variables deal with recursive minibuffers (@pxref{Recursive Editing}):
This function returns the current depth of activations of the minibuffer, a nonnegative integer. If no minibuffers are active, it returns zero.
If this variable is non-nil, you can invoke commands (such as
find-file) which use minibuffers even while in the minibuffer
window. Such invocation produces a recursive editing level for a new
minibuffer. The outer-level minibuffer is invisible while you are
editing the inner one.
This variable only affects invoking the minibuffer while the minibuffer window is selected. If you switch windows while in the minibuffer, you can always invoke minibuffer commands while some other window is selected.
If a command name has a property enable-recursive-minibuffers
which is non-nil, then the command can use the minibuffer to read
arguments even if it is invoked from the minibuffer. The minibuffer
command next-matching-history-element (normally bound to
M-s in the minibuffer) uses this feature.
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