@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001, 2002,
+@c 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/minibuf
@node Minibuffers, Command Loop, Read and Print, Top
@cindex complex arguments
@cindex minibuffer
- A @dfn{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 @kbd{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.
+ A @dfn{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 @kbd{M-x}). The minibuffer is displayed on the
+bottom line of the frame, in the same place as the echo area
+(@pxref{The Echo Area}), but only while it is in use for reading an
+argument.
@menu
* Intro to Minibuffers:: Basic information about minibuffers.
* Object from Minibuffer:: How to read a Lisp object or expression.
* Minibuffer History:: Recording previous minibuffer inputs
so the user can reuse them.
+* Initial Input:: Specifying initial contents for the minibuffer.
* Completion:: How to invoke and customize completion.
* Yes-or-No Queries:: Asking a question with a simple answer.
* Multiple Queries:: Asking a series of similar questions.
+* Reading a Password:: Reading a password from the terminal.
+* Minibuffer Commands:: Commands used as key bindings in minibuffers.
+* Minibuffer Contents:: How such commands access the minibuffer text.
+* Minibuffer Windows:: Operating on the special minibuffer windows.
+* Recursive Mini:: Whether recursive entry to minibuffer is allowed.
* Minibuffer Misc:: Various customization hooks and variables.
@end menu
@emph{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 @w{@samp{
-*Minibuf-@var{number}}}, and it cannot be changed. Minibuffers are
+*Minibuf-@var{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
+windows always appear at the bottom of a frame. (Sometimes frames have
no minibuffer window, and sometimes a special kind of frame contains
nothing but a minibuffer window; see @ref{Minibuffers and Frames}.)
- The minibuffer's window is normally a single line. You can resize it
-temporarily with the window sizing commands; it reverts to its normal
-size when the minibuffer is exited. You can resize it permanently by
-using the window sizing commands in the frame's other window, when the
-minibuffer is not active. If the frame contains just a minibuffer, you
-can change the minibuffer's size by changing the frame's size.
+ The text in the minibuffer always starts with the @dfn{prompt string},
+the text that was specified by the program that is using the minibuffer
+to tell the user what sort of input to type. This text is marked
+read-only so you won't accidentally delete or change it. It is also
+marked as a field (@pxref{Fields}), so that certain motion functions,
+including @code{beginning-of-line}, @code{forward-word},
+@code{forward-sentence}, and @code{forward-paragraph}, stop at the
+boundary between the prompt and the actual text. (In older Emacs
+versions, the prompt was displayed using a special mechanism and was not
+part of the buffer contents.)
+
+ The minibuffer's window is normally a single line; it grows
+automatically if necessary if the contents require more space. You can
+explicitly resize it temporarily with the window sizing commands; it
+reverts to its normal size when the minibuffer is exited. You can
+resize it permanently by using the window sizing commands in the frame's
+other window, when the minibuffer is not active. If the frame contains
+just a minibuffer, you can change the minibuffer's size by changing the
+frame's size.
+
+ Use of the minibuffer reads input events, and that alters the values
+of variables such as @code{this-command} and @code{last-command}
+(@pxref{Command Loop Info}). Your program should bind them around the
+code that uses the minibuffer, if you do not want that to change them.
If a command uses a minibuffer while there is an active minibuffer,
this is called a @dfn{recursive minibuffer}. The first minibuffer is
active minibuffer. We usually call this ``the'' minibuffer. You can
permit or forbid recursive minibuffers by setting the variable
@code{enable-recursive-minibuffers} or by putting properties of that
-name on command symbols (@pxref{Minibuffer Misc}).
+name on command symbols (@pxref{Recursive Mini}).
- 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. @xref{Completion}.
+ Like other buffers, a minibuffer uses a local keymap
+(@pxref{Keymaps}) to specify special key bindings. The function that
+invokes the minibuffer also sets up its local map according to the job
+to be done. @xref{Text from Minibuffer}, for the non-completion
+minibuffer local maps. @xref{Completion Commands}, for the minibuffer
+local maps for completion.
-@itemize @bullet
-@item
-@code{minibuffer-local-map} is for ordinary input (no completion).
-
-@item
-@code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
-just like @key{RET}. This is used mainly for Mocklisp compatibility.
-
-@item
-@code{minibuffer-local-completion-map} is for permissive completion.
-
-@item
-@code{minibuffer-local-must-match-map} is for strict completion and
-for cautious completion.
-@end itemize
+ When Emacs is running in batch mode, any request to read from the
+minibuffer actually reads a line from the standard input descriptor that
+was supplied when Emacs was started.
@node Text from Minibuffer
@section Reading Text Strings with the Minibuffer
Most often, the minibuffer is used to read text as a string. It can
also be used to read a Lisp object in textual form. The most basic
primitive for minibuffer input is @code{read-from-minibuffer}; it can do
-either one.
+either one. There are also specialized commands for reading
+commands, variables, file names, etc. (@pxref{Completion}).
+
+ In most cases, you should not call minibuffer input functions in the
+middle of a Lisp function. Instead, do all minibuffer input as part of
+reading the arguments for a command, in the @code{interactive}
+specification. @xref{Defining Commands}.
-@defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist
+@defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method keep-all
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 @var{read} is non-@code{nil}, then it uses
@code{read} to convert the text into a Lisp object (@pxref{Input
Functions}).
-The first thing this function does is to activate a minibuffer and
+The first thing this function does is to activate a minibuffer and
display it with @var{prompt-string} as the prompt. This value must be a
-string.
-
-Then, if @var{initial-contents} is a string, @code{read-from-minibuffer}
-inserts it into the minibuffer, leaving point at the end. The
-minibuffer appears with this text as its contents.
+string. Then the user can edit text in the minibuffer.
-@c Emacs 19 feature
-The value of @var{initial-contents} may also be a cons cell of the form
-@code{(@var{string} . @var{position})}. This means to insert
-@var{string} in the minibuffer but put point @var{position} characters
-from the beginning, rather than at the end.
+When the user types a command to exit the minibuffer,
+@code{read-from-minibuffer} constructs the return value from the text in
+the minibuffer. Normally it returns a string containing that text.
+However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer}
+reads the text and returns the resulting Lisp object, unevaluated.
+(@xref{Input Functions}, for information about reading.)
+
+The argument @var{default} specifies a default value to make available
+through the history commands. It should be a string, or @code{nil}.
+If non-@code{nil}, the user can access it using
+@code{next-history-element}, usually bound in the minibuffer to
+@kbd{M-n}. If @var{read} is non-@code{nil}, then @var{default} is
+also used as the input to @code{read}, if the user enters empty input.
+(If @var{read} is non-@code{nil} and @var{default} is @code{nil}, empty
+input results in an @code{end-of-file} error.) However, in the usual
+case (where @var{read} is @code{nil}), @code{read-from-minibuffer}
+ignores @var{default} when the user enters empty input and returns an
+empty string, @code{""}. In this respect, it is different from all
+the other minibuffer input functions in this chapter.
If @var{keymap} is non-@code{nil}, that keymap is the local keymap to
use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the
for saving the input and for history commands used in the minibuffer.
It defaults to @code{minibuffer-history}. @xref{Minibuffer History}.
-When the user types a command to exit the minibuffer,
-@code{read-from-minibuffer} uses the text in the minibuffer to produce
-its return value. Normally it simply makes a string containing that
-text. However, if @var{read} is non-@code{nil},
-@code{read-from-minibuffer} reads the text and returns the resulting
-Lisp object, unevaluated. (@xref{Input Functions}, for information
-about reading.)
+If the variable @code{minibuffer-allow-text-properties} is
+non-@code{nil}, then the string which is returned includes whatever text
+properties were present in the minibuffer. Otherwise all the text
+properties are stripped when the value is returned.
+
+If the argument @var{inherit-input-method} is non-@code{nil}, then the
+minibuffer inherits the current input method (@pxref{Input Methods}) and
+the setting of @code{enable-multibyte-characters} (@pxref{Text
+Representations}) from whichever buffer was current before entering the
+minibuffer.
+
+If @var{keep-all} is non-@code{nil}, even empty and duplicate inputs
+are added to the history list.
+
+Use of @var{initial-contents} is mostly deprecated; we recommend using
+a non-@code{nil} value only in conjunction with specifying a cons cell
+for @var{hist}. @xref{Initial Input}.
@end defun
-@defun read-string prompt &optional initial
+@defun read-string prompt &optional initial history default inherit-input-method
This function reads a string from the minibuffer and returns it. The
-arguments @var{prompt} and @var{initial} are used as in
-@code{read-from-minibuffer}. The keymap used is
-@code{minibuffer-local-map}.
+arguments @var{prompt}, @var{initial}, @var{history} and
+@var{inherit-input-method} are used as in @code{read-from-minibuffer}.
+The keymap used is @code{minibuffer-local-map}.
-This is a simplified interface to the
+The optional argument @var{default} is used as in
+@code{read-from-minibuffer}, except that, if non-@code{nil}, it also
+specifies a default value to return if the user enters null input. As
+in @code{read-from-minibuffer} it should be a string, or @code{nil},
+which is equivalent to an empty string.
+
+This function is a simplified interface to the
@code{read-from-minibuffer} function:
@smallexample
@group
-(read-string @var{prompt} @var{initial})
+(read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit})
@equiv{}
-(read-from-minibuffer @var{prompt} @var{initial} nil nil nil)
+(let ((value
+ (read-from-minibuffer @var{prompt} @var{initial} nil nil
+ @var{history} @var{default} @var{inherit})))
+ (if (and (equal value "") @var{default})
+ @var{default}
+ value))
@end group
@end smallexample
@end defun
+@defvar minibuffer-allow-text-properties
+If this variable is @code{nil}, then @code{read-from-minibuffer} strips
+all text properties from the minibuffer input before returning it.
+This variable also affects @code{read-string}. However,
+@code{read-no-blanks-input} (see below), as well as
+@code{read-minibuffer} and related functions (@pxref{Object from
+Minibuffer,, Reading Lisp Objects With the Minibuffer}), and all
+functions that do minibuffer input with completion, discard text
+properties unconditionally, regardless of the value of this variable.
+@end defvar
+
@defvar minibuffer-local-map
+@anchor{Definition of minibuffer-local-map}
This is the default local keymap for reading from the minibuffer. By
default, it makes the following bindings:
@table @asis
-@item @key{LFD}
+@item @kbd{C-j}
@code{exit-minibuffer}
@item @key{RET}
@code{abort-recursive-edit}
@item @kbd{M-n}
+@itemx @key{DOWN}
@code{next-history-element}
@item @kbd{M-p}
+@itemx @key{UP}
@code{previous-history-element}
-@item @kbd{M-r}
+@item @kbd{M-s}
@code{next-matching-history-element}
-@item @kbd{M-s}
+@item @kbd{M-r}
@code{previous-matching-history-element}
@end table
@end defvar
@c In version 18, initial is required
@c Emacs 19 feature
-@defun read-no-blanks-input prompt &optional initial
+@defun read-no-blanks-input prompt &optional initial inherit-input-method
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 @var{prompt} and @var{initial} are
-used as in @code{read-from-minibuffer}.
+terminate the input. The arguments @var{prompt}, @var{initial}, and
+@var{inherit-input-method} are used as in @code{read-from-minibuffer}.
This is a simplified interface to the @code{read-from-minibuffer}
function, and passes the value of the @code{minibuffer-local-ns-map}
@code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is}
possible to put a space into the string, by quoting it.
+This function discards text properties, regardless of the value of
+@code{minibuffer-allow-text-properties}.
+
@smallexample
@group
(read-no-blanks-input @var{prompt} @var{initial})
@equiv{}
-(read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map)
+(let (minibuffer-allow-text-properties)
+ (read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map))
@end group
@end smallexample
@end defun
@defvar minibuffer-local-ns-map
This built-in variable is the keymap used as the minibuffer local keymap
in the function @code{read-no-blanks-input}. By default, it makes the
-following bindings:
+following bindings, in addition to those of @code{minibuffer-local-map}:
@table @asis
-@item @key{LFD}
-@code{exit-minibuffer}
-
@item @key{SPC}
@cindex @key{SPC} in minibuffer
@code{exit-minibuffer}
@cindex @key{TAB} in minibuffer
@code{exit-minibuffer}
-@item @key{RET}
-@code{exit-minibuffer}
-
-@item @kbd{C-g}
-@code{abort-recursive-edit}
-
@item @kbd{?}
@cindex @kbd{?} in minibuffer
@code{self-insert-and-exit}
-
-@item @kbd{M-n}
-@code{next-history-element}
-
-@item @kbd{M-p}
-@code{previous-history-element}
-
-@item @kbd{M-r}
-@code{next-matching-history-element}
-
-@item @kbd{M-s}
-@code{previous-matching-history-element}
@end table
@end defvar
minibuffer.
@defun read-minibuffer prompt &optional initial
-This function reads a Lisp object in the minibuffer and returns it,
+This function reads a Lisp object using the minibuffer, and returns it
without evaluating it. The arguments @var{prompt} and @var{initial} are
used as in @code{read-from-minibuffer}.
@group
(read-minibuffer @var{prompt} @var{initial})
@equiv{}
-(read-from-minibuffer @var{prompt} @var{initial} nil t)
+(let (minibuffer-allow-text-properties)
+ (read-from-minibuffer @var{prompt} @var{initial} nil t))
@end group
@end smallexample
@end defun
@defun eval-minibuffer prompt &optional initial
-This function reads a Lisp expression in the minibuffer, evaluates it,
-then returns the result. The arguments @var{prompt} and @var{initial}
-are used as in @code{read-from-minibuffer}.
+This function reads a Lisp expression using the minibuffer, evaluates
+it, then returns the result. The arguments @var{prompt} and
+@var{initial} are used as in @code{read-from-minibuffer}.
This function simply evaluates the result of a call to
@code{read-minibuffer}:
The first thing @code{edit-and-eval-command} does is to activate the
minibuffer with @var{prompt} as the prompt. Then it inserts the printed
-representation of @var{form} in the minibuffer, and lets the user edit.
+representation of @var{form} in the minibuffer, and lets the user edit it.
When the user exits the minibuffer, the edited text is read with
@code{read} and then evaluated. The resulting value becomes the value
of @code{edit-and-eval-command}.
@group
(edit-and-eval-command "Please edit: " '(forward-word 1))
-;; @r{After evaluation of the preceding expression,}
+;; @r{After evaluation of the preceding expression,}
;; @r{the following appears in the minibuffer:}
@end group
@cindex minibuffer history
@cindex history list
-A @dfn{minibuffer history list} records previous minibuffer inputs so
+ A @dfn{minibuffer history list} records previous minibuffer inputs so
the user can reuse them conveniently. A history list is actually a
symbol, not a list; it is a variable whose value is a list of strings
(previous inputs), most recent first.
-There are many separate history lists, used for different kinds of
+ There are many separate history lists, used for different kinds of
inputs. It's the Lisp programmer's job to specify the right history
list for each use of the minibuffer.
-The basic minibuffer input functions @code{read-from-minibuffer} and
-@code{completing-read} both accept an optional argument named @var{hist}
-which is how you specify the history list. Here are the possible
-values:
+ You specify the history list with the optional @var{hist} argument
+to either @code{read-from-minibuffer} or @code{completing-read}. Here
+are the possible values for it:
@table @asis
@item @var{variable}
@item (@var{variable} . @var{startpos})
Use @var{variable} (a symbol) as the history list, and assume that the
-initial history position is @var{startpos} (an integer, counting from
-zero which specifies the most recent element of the history).
-
-If you specify @var{startpos}, then you should also specify that element
-of the history as the initial minibuffer contents, for consistency.
+initial history position is @var{startpos} (a nonnegative integer).
+
+Specifying 0 for @var{startpos} is equivalent to just specifying the
+symbol @var{variable}. @code{previous-history-element} will display
+the most recent element of the history list in the minibuffer. If you
+specify a positive @var{startpos}, the minibuffer history functions
+behave as if @code{(elt @var{variable} (1- @var{STARTPOS}))} were the
+history element currently shown in the minibuffer.
+
+For consistency, you should also specify that element of the history
+as the initial minibuffer contents, using the @var{initial} argument
+to the minibuffer input function (@pxref{Initial Input}).
@end table
-If you don't specify @var{hist}, then the default history list
+ If you don't specify @var{hist}, then the default history list
@code{minibuffer-history} is used. For other standard history lists,
see below. You can also create your own history list variable; just
initialize it to @code{nil} before the first use.
-Both @code{read-from-minibuffer} and @code{completing-read} add new
+ Both @code{read-from-minibuffer} and @code{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.
+ Emacs functions that add a new element to a history list can also
+delete old elements if the list gets too long. The variable
+@code{history-length} specifies the maximum length for most history
+lists. To specify a different maximum length for a particular history
+list, put the length in the @code{history-length} property of the
+history list symbol. The variable @code{history-delete-duplicates}
+specifies whether to delete duplicates in history.
+
+@defvar history-length
+The value of this variable specifies the maximum length for all
+history lists that don't specify their own maximum lengths. If the
+value is @code{t}, that means there no maximum (don't delete old
+elements).
+@end defvar
+
+@defvar history-delete-duplicates
+If the value of this variable is @code{t}, that means when adding a
+new history element, all previous identical elements are deleted.
+@end defvar
+
+ Here are some of the standard minibuffer history list variables:
+
@defvar minibuffer-history
The default history list for minibuffer history input.
@end defvar
@end defvar
@defvar file-name-history
-A history list for file name arguments.
+A history list for file-name arguments.
+@end defvar
+
+@defvar buffer-name-history
+A history list for buffer-name arguments.
@end defvar
@defvar regexp-history
A history list for arguments that are Lisp expressions to evaluate.
@end defvar
+@node Initial Input
+@section Initial Input
+
+Several of the functions for minibuffer input have an argument called
+@var{initial} or @var{initial-contents}. This is a mostly-deprecated
+feature for specifiying that the minibuffer should start out with
+certain text, instead of empty as usual.
+
+If @var{initial} is a string, the minibuffer starts out containing the
+text of the string, with point at the end, when the user starts to
+edit the text. If the user simply types @key{RET} to exit the
+minibuffer, it will use the initial input string to determine the
+value to return.
+
+@strong{We discourage use of a non-@code{nil} value for
+@var{initial}}, because initial input is an intrusive interface.
+History lists and default values provide a much more convenient method
+to offer useful default inputs to the user.
+
+There is just one situation where you should specify a string for an
+@var{initial} argument. This is when you specify a cons cell for the
+@var{hist} or @var{history} argument. @xref{Minibuffer History}.
+
+@var{initial} can also be a cons cell of the form @code{(@var{string}
+. @var{position})}. This means to insert @var{string} in the
+minibuffer but put point at @var{position} within the string's text.
+
+As a historical accident, @var{position} was implemented
+inconsistently in different functions. In @code{completing-read},
+@var{position}'s value is interpreted as origin-zero; that is, a value
+of 0 means the beginning of the string, 1 means after the first
+character, etc. In @code{read-minibuffer}, and the other
+non-completion minibuffer input functions that support this argument,
+1 means the beginning of the string 2 means after the first character,
+etc.
+
+Use of a cons cell as the value for @var{initial} arguments is
+deprecated in user code.
+
@node Completion
@section Completion
@cindex completion
* High-Level Completion:: Convenient special cases of completion
(reading buffer name, file name, etc.)
* Reading File Names:: Using completion to read file names.
-* Programmed Completion:: Finding the completions for a given file name.
+* Programmed Completion:: Writing your own completion-function.
@end menu
@node Basic Completion
@subsection Basic Completion Functions
- The two functions @code{try-completion} and @code{all-completions}
-have nothing in themselves to do with minibuffers. We describe them in
-this chapter so as to keep them near the higher-level completion
-features that do use the minibuffer.
+ The completion functions @code{try-completion},
+@code{all-completions} and @code{test-completion} have nothing in
+themselves to do with minibuffers. We describe them in this chapter
+so as to keep them near the higher-level completion features that do
+use the minibuffer.
+
+ If you store a completion alist in a variable, you should mark the
+variable as ``risky'' with a non-@code{nil}
+@code{risky-local-variable} property.
@defun try-completion string collection &optional predicate
This function returns the longest common substring of all possible
completions of @var{string} in @var{collection}. The value of
-@var{collection} must be an alist, an obarray, or a function that
-implements a virtual set of strings (see below).
+@var{collection} must be a list of strings or symbols, an alist, an
+obarray, a hash table, or a function that implements a virtual set of
+strings (see below).
Completion compares @var{string} against each of the permissible
completions specified by @var{collection}; if the beginning of the
match.
If @var{collection} is an alist (@pxref{Association Lists}), the
-@sc{car}s of the alist elements form the set of permissible completions.
+permissible completions are the elements of the alist that are either
+strings, symbols, or conses whose @sc{car} is a string or symbol.
+Symbols are converted to strings using @code{symbol-name}.
+Other elements of the alist are ignored. (Remember that in Emacs Lisp,
+the elements of alists do not @emph{have} to be conses.) As all
+elements of the alist can be strings, this case actually includes
+lists of strings or symbols, even though we usually do not think of
+such lists as alists.
@cindex obarray in completion
If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
empty and then add symbols to it one by one using @code{intern}.
Also, you cannot intern a given symbol in more than one obarray.
-If the argument @var{predicate} is non-@code{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 @var{predicate} returns non-@code{nil}.
-The argument given to @var{predicate} is either a cons cell from the alist
-(the @sc{car} of which is a string) or else it is a symbol (@emph{not} a
-symbol name) from the obarray.
+If @var{collection} is a hash table, then the keys that are strings
+are the possible completions. Other keys are ignored.
You can also use a symbol that is a function as @var{collection}. Then
the function is solely responsible for performing completion;
function can be used in @code{all-completions} and do the appropriate
thing in either case.) @xref{Programmed Completion}.
+If the argument @var{predicate} is non-@code{nil}, then it must be a
+function of one argument, unless @var{collection} is a hash table, in
+which case it should be a function of two arguments. It is used to
+test each possible match, and the match is accepted only if
+@var{predicate} returns non-@code{nil}. The argument given to
+@var{predicate} is either a string or a cons cell (the @sc{car} of
+which is a string) from the alist, or a symbol (@emph{not} a symbol
+name) from the obarray. If @var{collection} is a hash table,
+@var{predicate} is called with two arguments, the string key and the
+associated value.
+
+In addition, to be acceptable, a completion must also match all the
+regular expressions in @code{completion-regexp-list}. (Unless
+@var{collection} is a function, in which case that function has to
+handle @code{completion-regexp-list} itself.)
+
In the first of the following examples, the string @samp{foo} is
matched by three of the alist @sc{car}s. All of the matches begin with
the characters @samp{fooba}, so that is the result. In the second
@smallexample
@group
-(try-completion
+(try-completion
"foo"
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
@result{} "fooba"
@smallexample
@group
-(defun test (s)
+(defun test (s)
(> (length (car s)) 6))
@result{} test
@end group
@group
-(try-completion
+(try-completion
"foo"
- '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
+ '(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
'test)
@result{} "foobar"
@end group
@end smallexample
@end defun
-@defun all-completions string collection &optional predicate
+@defun all-completions string collection &optional predicate nospace
This function returns a list of all possible completions of
-@var{string}. The parameters to this function are the same as to
-@code{try-completion}.
+@var{string}. The arguments to this function (aside from
+@var{nospace}) are the same as those of @code{try-completion}. Also,
+this function uses @code{completion-regexp-list} in the same way that
+@code{try-completion} does. The optional argument @var{nospace} only
+matters if @var{string} is the empty string. In that case, if
+@var{nospace} is non-@code{nil}, completions that start with a space
+are ignored.
If @var{collection} is a function, it is called with three arguments:
@var{string}, @var{predicate} and @code{t}; then @code{all-completions}
@smallexample
@group
-(defun test (s)
+(defun test (s)
(> (length (car s)) 6))
@result{} test
@end group
@group
-(all-completions
+(all-completions
"foo"
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
'test)
@end smallexample
@end defun
+@defun test-completion string collection &optional predicate
+@anchor{Definition of test-completion}
+This function returns non-@code{nil} if @var{string} is a valid
+completion possibility specified by @var{collection} and
+@var{predicate}. The arguments are the same as in
+@code{try-completion}. For instance, if @var{collection} is a list of
+strings, this is true if @var{string} appears in the list and
+@var{predicate} is satisfied.
+
+@code{test-completion} uses @code{completion-regexp-list} in the same
+way that @code{try-completion} does.
+
+If @var{predicate} is non-@code{nil} and if @var{collection} contains
+several strings that are equal to each other, as determined by
+@code{compare-strings} according to @code{completion-ignore-case},
+then @var{predicate} should accept either all or none of them.
+Otherwise, the return value of @code{test-completion} is essentially
+unpredictable.
+
+If @var{collection} is a function, it is called with three arguments,
+the values @var{string}, @var{predicate} and @code{lambda}; whatever
+it returns, @code{test-completion} returns in turn.
+@end defun
+
@defvar completion-ignore-case
-If the value of this variable is
-non-@code{nil}, Emacs does not consider case significant in completion.
+If the value of this variable is non-@code{nil}, Emacs does not
+consider case significant in completion.
@end defvar
+@defvar completion-regexp-list
+This is a list of regular expressions. The completion functions only
+consider a completion acceptable if it matches all regular expressions
+in this list, with @code{case-fold-search} (@pxref{Searching and Case})
+bound to the value of @code{completion-ignore-case}.
+@end defvar
+
+@defmac lazy-completion-table var fun
+This macro provides a way to initialize the variable @var{var} as a
+collection for completion in a lazy way, not computing its actual
+contents until they are first needed. You use this macro to produce a
+value that you store in @var{var}. The actual computation of the
+proper value is done the first time you do completion using @var{var}.
+It is done by calling @var{fun} with no arguments. The
+value @var{fun} returns becomes the permanent value of @var{var}.
+
+Here is an example of use:
+
+@smallexample
+(defvar foo (lazy-completion-table foo make-my-alist))
+@end smallexample
+@end defmac
+
@node Minibuffer Completion
@subsection Completion and the Minibuffer
This section describes the basic interface for reading from the
minibuffer with completion.
-@defun completing-read prompt collection &optional predicate require-match initial hist
+@defun completing-read prompt collection &optional predicate require-match initial hist default inherit-input-method
This function reads a string in the minibuffer, assisting the user by
providing completion. It activates the minibuffer with prompt
-@var{prompt}, which must be a string. If @var{initial} is
-non-@code{nil}, @code{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.
+@var{prompt}, which must be a string.
The actual completion is done by passing @var{collection} and
-@var{predicate} to the function @code{try-completion}. This happens in
-certain commands bound in the local keymaps used for completion.
-
-If @var{require-match} is @code{t}, the usual minibuffer exit commands
-won't exit unless the input completes to an element of @var{collection}.
-If @var{require-match} is neither @code{nil} nor @code{t}, then the exit
-commands won't exit unless the input typed is itself an element of
-@var{collection}. If @var{require-match} is @code{nil}, the exit
-commands work regardless of the input in the minibuffer.
-
-The function @code{completing-read} works by calling
-@code{read-minibuffer}. It uses @code{minibuffer-local-completion-map}
-as the keymap if @var{require-match} is @code{nil}, and uses
+@var{predicate} to the function @code{try-completion}. This happens
+in certain commands bound in the local keymaps used for completion.
+Some of these commands also call @code{test-completion}. Thus, if
+@var{predicate} is non-@code{nil}, it should be compatible with
+@var{collection} and @code{completion-ignore-case}. @xref{Definition
+of test-completion}.
+
+If @var{require-match} is @code{nil}, the exit commands work regardless
+of the input in the minibuffer. If @var{require-match} is @code{t}, the
+usual minibuffer exit commands won't exit unless the input completes to
+an element of @var{collection}. If @var{require-match} is neither
+@code{nil} nor @code{t}, then the exit commands won't exit unless the
+input already in the buffer matches an element of @var{collection}.
+
+However, empty input is always permitted, regardless of the value of
+@var{require-match}; in that case, @code{completing-read} returns
+@var{default}, or @code{""}, if @var{default} is @code{nil}. The
+value of @var{default} (if non-@code{nil}) is also available to the
+user through the history commands.
+
+The function @code{completing-read} uses
+@code{minibuffer-local-completion-map} as the keymap if
+@var{require-match} is @code{nil}, and uses
@code{minibuffer-local-must-match-map} if @var{require-match} is
non-@code{nil}. @xref{Completion Commands}.
saving the input and for minibuffer history commands. It defaults to
@code{minibuffer-history}. @xref{Minibuffer History}.
-Completion ignores case when comparing the input against the possible
-matches, if the built-in variable @code{completion-ignore-case} is
-non-@code{nil}. @xref{Basic Completion}.
+The argument @var{initial} is mostly deprecated; we recommend using a
+non-@code{nil} value only in conjunction with specifying a cons cell
+for @var{hist}. @xref{Initial Input}. For default input, use
+@var{default} instead.
+
+If the argument @var{inherit-input-method} is non-@code{nil}, then the
+minibuffer inherits the current input method (@pxref{Input
+Methods}) and the setting of @code{enable-multibyte-characters}
+(@pxref{Text Representations}) from whichever buffer was current before
+entering the minibuffer.
+
+If the built-in variable @code{completion-ignore-case} is
+non-@code{nil}, completion ignores case when comparing the input
+against the possible matches. @xref{Basic Completion}. In this mode
+of operation, @var{predicate} must also ignore case, or you will get
+surprising results.
Here's an example of using @code{completing-read}:
@end group
@group
-;; @r{After evaluation of the preceding expression,}
+;; @r{After evaluation of the preceding expression,}
;; @r{the following appears in the minibuffer:}
---------- Buffer: Minibuffer ----------
If the user then types @kbd{@key{DEL} @key{DEL} b @key{RET}},
@code{completing-read} returns @code{barfoo}.
-The @code{completing-read} function binds three variables to pass
-information to the commands that actually do completion. These
-variables are @code{minibuffer-completion-table},
-@code{minibuffer-completion-predicate} and
-@code{minibuffer-completion-confirm}. For more information about them,
-see @ref{Completion Commands}.
+The @code{completing-read} function binds variables to pass
+information to the commands that actually do completion.
+They are described in the following section.
@end defun
@node Completion Commands
-@subsection Minibuffer Commands That Do Completion
+@subsection Minibuffer Commands that Do Completion
- This section describes the keymaps, commands and user options used in
-the minibuffer to do completion.
-
-@defvar minibuffer-local-completion-map
-@code{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:
-
-@table @asis
-@item @kbd{?}
-@code{minibuffer-completion-help}
-
-@item @key{SPC}
-@code{minibuffer-complete-word}
-
-@item @key{TAB}
-@code{minibuffer-complete}
-@end table
-
-@noindent
-with other characters bound as in @code{minibuffer-local-map}
-(@pxref{Text from Minibuffer}).
-@end defvar
-
-@defvar minibuffer-local-must-match-map
-@code{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 @code{exit-minibuffer}, the command that exits the
-minibuffer unconditionally. By default, this keymap makes the following
-bindings:
-
-@table @asis
-@item @kbd{?}
-@code{minibuffer-completion-help}
-
-@item @key{SPC}
-@code{minibuffer-complete-word}
-
-@item @key{TAB}
-@code{minibuffer-complete}
-
-@item @key{LFD}
-@code{minibuffer-complete-and-exit}
-
-@item @key{RET}
-@code{minibuffer-complete-and-exit}
-@end table
-
-@noindent
-with other characters bound as in @code{minibuffer-local-map}.
-@end defvar
+ This section describes the keymaps, commands and user options used
+in the minibuffer to do completion. The description refers to the
+situation when Partial Completion mode is disabled (as it is by
+default). When enabled, this minor mode uses its own alternatives to
+some of the commands described below. @xref{Completion Options,,,
+emacs, The GNU Emacs Manual}, for a short description of Partial
+Completion mode.
@defvar minibuffer-completion-table
-The value of this variable is the alist or obarray used for completion
-in the minibuffer. This is the global variable that contains what
+The value of this variable is the collection used for completion in
+the minibuffer. This is the global variable that contains what
@code{completing-read} passes to @code{try-completion}. It is used by
minibuffer completion commands such as @code{minibuffer-complete-word}.
@end defvar
minibuffer completion functions.
@end defvar
+@defvar minibuffer-completion-confirm
+When the value of this variable is non-@code{nil}, Emacs asks for
+confirmation of a completion before exiting the minibuffer.
+@code{completing-read} binds this variable, and the function
+@code{minibuffer-complete-and-exit} checks the value before exiting.
+@end defvar
+
@deffn Command minibuffer-complete-word
This function completes the minibuffer contents by at most a single
word. Even if the minibuffer contents have only one completion,
@deffn Command minibuffer-complete-and-exit
This function completes the minibuffer contents, and exits if
confirmation is not required, i.e., if
-@code{minibuffer-completion-confirm} is non-@code{nil}. If confirmation
+@code{minibuffer-completion-confirm} is @code{nil}. If confirmation
@emph{is} required, it is given by repeating this command
immediately---the command is programmed to work without confirmation
when run twice in succession.
@end deffn
-@defvar minibuffer-completion-confirm
-When the value of this variable is non-@code{nil}, Emacs asks for
-confirmation of a completion before exiting the minibuffer. The
-function @code{minibuffer-complete-and-exit} checks the value of this
-variable before it exits.
-@end defvar
-
@deffn Command minibuffer-completion-help
This function creates a list of the possible completions of the
current minibuffer contents. It works by calling @code{all-completions}
@samp{*Completions*}.
@end deffn
-@defun display-completion-list completions
+@defun display-completion-list completions &optional common-substring
This function displays @var{completions} to the stream in
@code{standard-output}, usually a buffer. (@xref{Read and Print}, for more
information about streams.) The argument @var{completions} is normally
a list of completions just returned by @code{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.
+of which is simply printed. It can also be a list of two strings,
+which is printed as if the strings were concatenated. The first of
+the two strings is the actual completion, the second string serves as
+annotation.
+
+The argument @var{common-substring} is the prefix that is common to
+all the completions. With normal Emacs completion, it is usually the
+same as the string that was completed. @code{display-completion-list}
+uses this to highlight text in the completion list for better visual
+feedback. This is not needed in the minibuffer; for minibuffer
+completion, you can pass @code{nil}.
This function is called by @code{minibuffer-completion-help}. The
most common way to use it is together with
@example
(with-output-to-temp-buffer "*Completions*"
(display-completion-list
- (all-completions (buffer-string) my-alist)))
+ (all-completions (buffer-string) my-alist)
+ (buffer-string)))
@end example
@end defun
can be completed because the next character is not uniquely determined.
@end defopt
+@defvar minibuffer-local-completion-map
+@code{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:
+
+@table @asis
+@item @kbd{?}
+@code{minibuffer-completion-help}
+
+@item @key{SPC}
+@code{minibuffer-complete-word}
+
+@item @key{TAB}
+@code{minibuffer-complete}
+@end table
+
+@noindent
+with other characters bound as in @code{minibuffer-local-map}
+(@pxref{Definition of minibuffer-local-map}).
+@end defvar
+
+@defvar minibuffer-local-must-match-map
+@code{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 @code{exit-minibuffer}, the command that exits the
+minibuffer unconditionally. By default, this keymap makes the following
+bindings:
+
+@table @asis
+@item @kbd{?}
+@code{minibuffer-completion-help}
+
+@item @key{SPC}
+@code{minibuffer-complete-word}
+
+@item @key{TAB}
+@code{minibuffer-complete}
+
+@item @kbd{C-j}
+@code{minibuffer-complete-and-exit}
+
+@item @key{RET}
+@code{minibuffer-complete-and-exit}
+@end table
+
+@noindent
+with other characters bound as in @code{minibuffer-local-map}.
+@end defvar
+
+@defvar minibuffer-local-filename-completion-map
+This is like @code{minibuffer-local-completion-map}
+except that it does not bind @key{SPC}. This keymap is used by the
+function @code{read-file-name}.
+@end defvar
+
+@defvar minibuffer-local-must-match-filename-map
+This is like @code{minibuffer-local-must-match-map}
+except that it does not bind @key{SPC}. This keymap is used by the
+function @code{read-file-name}.
+@end defvar
+
@node High-Level Completion
@subsection High-Level Completion Functions
This section describes the higher-level convenient functions for
reading certain sorts of names with completion.
+ In most cases, you should not call these functions in the middle of a
+Lisp function. When possible, do all minibuffer input as part of
+reading the arguments for a command, in the @code{interactive}
+specification. @xref{Defining Commands}.
+
@defun read-buffer prompt &optional default existing
This function reads the name of a buffer and returns it as a string.
The argument @var{default} is the default name to use, the value to
it should be a string or a buffer. It is mentioned in the prompt, but
is not inserted in the minibuffer as initial input.
+The argument @var{prompt} should be a string ending with a colon and a
+space. If @var{default} is non-@code{nil}, the function inserts it in
+@var{prompt} before the colon to follow the convention for reading from
+the minibuffer with a default value (@pxref{Programming Tips}).
+
If @var{existing} is non-@code{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 @key{RET} does completion to
-attempt to find a valid name. (However, @var{default} is not checked
-for validity; it is returned, whatever it is, if the user exits with the
-minibuffer empty.)
+attempt to find a valid name. If @var{existing} is neither @code{nil}
+nor @code{t}, confirmation is required after completion. (However,
+@var{default} is not checked for validity; it is returned, whatever it
+is, if the user exits with the minibuffer empty.)
In the following example, the user enters @samp{minibuffer.t}, and
then types @key{RET}. The argument @var{existing} is @code{t}, and the
@samp{minibuffer.texi}, so that name is the value.
@example
-(read-buffer "Buffer name? " "foo" t)
+(read-buffer "Buffer name: " "foo" t)
@group
-;; @r{After evaluation of the preceding expression,}
+;; @r{After evaluation of the preceding expression,}
;; @r{the following prompt appears,}
;; @r{with an empty minibuffer:}
@end group
@group
---------- Buffer: Minibuffer ----------
-Buffer name? (default foo) @point{}
+Buffer name (default foo): @point{}
---------- Buffer: Minibuffer ----------
@end group
@end example
@end defun
-@defun read-command prompt
+@defvar read-buffer-function
+This variable specifies how to read buffer names. For example, if you
+set this variable to @code{iswitchb-read-buffer}, all Emacs commands
+that call @code{read-buffer} to read a buffer name will actually use the
+@code{iswitchb} package to read it.
+@end defvar
+
+@defun read-command prompt &optional default
This function reads the name of a command and returns it as a Lisp
symbol. The argument @var{prompt} is used as in
@code{read-from-minibuffer}. Recall that a command is anything for
which @code{commandp} returns @code{t}, and a command name is a symbol
for which @code{commandp} returns @code{t}. @xref{Interactive Call}.
+The argument @var{default} specifies what to return if the user enters
+null input. It can be a symbol or a string; if it is a string,
+@code{read-command} interns it before returning it. If @var{default} is
+@code{nil}, that means no default has been specified; then if the user
+enters null input, the return value is @code{(intern "")}, that is, a
+symbol whose name is an empty string.
+
@example
(read-command "Command name? ")
@group
-;; @r{After evaluation of the preceding expression,}
+;; @r{After evaluation of the preceding expression,}
;; @r{the following prompt appears with an empty minibuffer:}
@end group
@group
----------- Buffer: Minibuffer ----------
-Command name?
+---------- Buffer: Minibuffer ----------
+Command name?
---------- Buffer: Minibuffer ----------
@end group
@end example
If the user types @kbd{forward-c @key{RET}}, then this function returns
@code{forward-char}.
-The @code{read-command} function is a simplified interface to the
-function @code{completing-read}. It uses the variable @code{obarray} so
-as to complete in the set of extant Lisp symbols, and it uses the
+The @code{read-command} function is a simplified interface to
+@code{completing-read}. It uses the variable @code{obarray} so as to
+complete in the set of extant Lisp symbols, and it uses the
@code{commandp} predicate so as to accept only command names:
@cindex @code{commandp} example
@group
(read-command @var{prompt})
@equiv{}
-(intern (completing-read @var{prompt} obarray
+(intern (completing-read @var{prompt} obarray
'commandp t nil))
@end group
@end example
@end defun
-@defun read-variable prompt
+@defun read-variable prompt &optional default
+@anchor{Definition of read-variable}
This function reads the name of a user variable and returns it as a
symbol.
+The argument @var{default} specifies what to return if the user enters
+null input. It can be a symbol or a string; if it is a string,
+@code{read-variable} interns it before returning it. If @var{default}
+is @code{nil}, that means no default has been specified; then if the
+user enters null input, the return value is @code{(intern "")}.
+
@example
@group
(read-variable "Variable name? ")
-;; @r{After evaluation of the preceding expression,}
-;; @r{the following prompt appears,}
+;; @r{After evaluation of the preceding expression,}
+;; @r{the following prompt appears,}
;; @r{with an empty minibuffer:}
@end group
@end example
@end defun
+ See also the functions @code{read-coding-system} and
+@code{read-non-nil-coding-system}, in @ref{User-Chosen Coding Systems},
+and @code{read-input-method-name}, in @ref{Input Methods}.
+
@node Reading File Names
@subsection Reading File Names
file name. It provides special features including automatic insertion
of the default directory.
-@defun read-file-name prompt &optional directory default existing initial
+@defun read-file-name prompt &optional directory default existing initial predicate
This function reads a file name in the minibuffer, prompting with
-@var{prompt} and providing completion. If @var{default} is
-non-@code{nil}, then the function returns @var{default} if the user just
-types @key{RET}. @var{default} is not checked for validity; it is
-returned, whatever it is, if the user exits with the minibuffer empty.
+@var{prompt} and providing completion.
If @var{existing} is non-@code{nil}, then the user must specify the name
of an existing file; @key{RET} performs completion to make the name
@var{existing} is @code{nil}, then the name of a nonexistent file is
acceptable.
+The function @code{read-file-name} uses
+@code{minibuffer-local-filename-completion-map} as the keymap if
+@var{existing} is @code{nil}, and uses
+@code{minibuffer-local-must-match-filename-map} if @var{existing} is
+non-@code{nil}. @xref{Completion Commands}.
+
The argument @var{directory} specifies the directory to use for
-completion of relative file names. If @code{insert-default-directory}
-is non-@code{nil}, @var{directory} is also inserted in the minibuffer as
-initial input. It defaults to the current buffer's value of
-@code{default-directory}.
+completion of relative file names. It should be an absolute directory
+name. If @code{insert-default-directory} is non-@code{nil},
+@var{directory} is also inserted in the minibuffer as initial input.
+It defaults to the current buffer's value of @code{default-directory}.
@c Emacs 19 feature
-If you specify @var{initial}, that is an initial file name to insert in
-the buffer (after with @var{directory}, if that is inserted). In this
+If you specify @var{initial}, that is an initial file name to insert
+in the buffer (after @var{directory}, if that is inserted). In this
case, point goes at the beginning of @var{initial}. The default for
@var{initial} is @code{nil}---don't insert any file name. To see what
-@var{initial} does, try the command @kbd{C-x C-v}.
+@var{initial} does, try the command @kbd{C-x C-v}. @strong{Please
+note:} we recommend using @var{default} rather than @var{initial} in
+most cases.
+
+If @var{default} is non-@code{nil}, then the function returns
+@var{default} if the user exits the minibuffer with the same non-empty
+contents that @code{read-file-name} inserted initially. The initial
+minibuffer contents are always non-empty if
+@code{insert-default-directory} is non-@code{nil}, as it is by
+default. @var{default} is not checked for validity, regardless of the
+value of @var{existing}. However, if @var{existing} is
+non-@code{nil}, the initial minibuffer contents should be a valid file
+(or directory) name. Otherwise @code{read-file-name} attempts
+completion if the user exits without any editing, and does not return
+@var{default}. @var{default} is also available through the history
+commands.
+
+If @var{default} is @code{nil}, @code{read-file-name} tries to find a
+substitute default to use in its place, which it treats in exactly the
+same way as if it had been specified explicitly. If @var{default} is
+@code{nil}, but @var{initial} is non-@code{nil}, then the default is
+the absolute file name obtained from @var{directory} and
+@var{initial}. If both @var{default} and @var{initial} are @code{nil}
+and the buffer is visiting a file, @code{read-file-name} uses the
+absolute file name of that file as default. If the buffer is not
+visiting a file, then there is no default. In that case, if the user
+types @key{RET} without any editing, @code{read-file-name} simply
+returns the pre-inserted contents of the minibuffer.
+
+If the user types @key{RET} in an empty minibuffer, this function
+returns an empty string, regardless of the value of @var{existing}.
+This is, for instance, how the user can make the current buffer visit
+no file using @code{M-x set-visited-file-name}.
+
+If @var{predicate} is non-@code{nil}, it specifies a function of one
+argument that decides which file names are acceptable completion
+possibilities. A file name is an acceptable value if @var{predicate}
+returns non-@code{nil} for it.
+
+@code{read-file-name} does not automatically expand file names. You
+must call @code{expand-file-name} yourself if an absolute file name is
+required.
-Here is an example:
+Here is an example:
@example
@group
(read-file-name "The file is ")
-;; @r{After evaluation of the preceding expression,}
+;; @r{After evaluation of the preceding expression,}
;; @r{the following appears in the minibuffer:}
@end group
as the string @code{"/gp/gnu/elisp/manual.texi"}.
@end defun
+@defvar read-file-name-function
+If non-@code{nil}, this should be a function that accepts the same
+arguments as @code{read-file-name}. When @code{read-file-name} is
+called, it calls this function with the supplied arguments instead of
+doing its usual work.
+@end defvar
+
+@defvar read-file-name-completion-ignore-case
+If this variable is non-@code{nil}, @code{read-file-name} ignores case
+when performing completion.
+@end defvar
+
+@defun read-directory-name prompt &optional directory default existing initial
+This function is like @code{read-file-name} but allows only directory
+names as completion possibilities.
+
+If @var{default} is @code{nil} and @var{initial} is non-@code{nil},
+@code{read-directory-name} constructs a substitute default by
+combining @var{directory} (or the current buffer's default directory
+if @var{directory} is @code{nil}) and @var{initial}. If both
+@var{default} and @var{initial} are @code{nil}, this function uses
+@var{directory} as substitute default, or the current buffer's default
+directory if @var{directory} is @code{nil}.
+@end defun
+
@defopt insert-default-directory
-This variable is used by @code{read-file-name}. Its value controls
-whether @code{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 @code{nil}, then @code{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.
+This variable is used by @code{read-file-name}, and thus, indirectly,
+by most commands reading file names. (This includes all commands that
+use the code letters @samp{f} or @samp{F} in their interactive form.
+@xref{Interactive Codes,, Code Characters for interactive}.) Its
+value controls whether @code{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 @code{nil}, then
+@code{read-file-name} does not place any initial input in the
+minibuffer (unless you specify initial input with the @var{initial}
+argument). In that case, the default directory is still used for
+completion of relative file names, but is not displayed.
+
+If this variable is @code{nil} and the initial minibuffer contents are
+empty, the user may have to explicitly fetch the next history element
+to access a default value. If the variable is non-@code{nil}, the
+initial minibuffer contents are always non-empty and the user can
+always request a default value by immediately typing @key{RET} in an
+unedited minibuffer. (See above.)
For example:
@item
@code{nil} specifies @code{try-completion}. The completion function
should return the completion of the specified string, or @code{t} if the
-string is an exact match already, or @code{nil} if the string matches no
-possibility.
+string is a unique and exact match already, or @code{nil} if the string
+matches no possibility.
+
+If the string is an exact match for one possibility, but also matches
+other longer possibilities, the function should return the string, not
+@code{t}.
@item
@code{t} specifies @code{all-completions}. The completion function
string.
@item
-@code{lambda} specifies a test for an exact match. The completion
+@code{lambda} specifies @code{test-completion}. The completion
function should return @code{t} if the specified string is an exact
match for some possibility; @code{nil} otherwise.
@end itemize
It would be consistent and clean for completion functions to allow
-lambda expressions (lists tha are functions) as well as function
+lambda expressions (lists that are functions) as well as function
symbols as @var{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.
+completion tables already have other meanings, and it would be
+unreliable to treat one differently just 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}.
+@defmac dynamic-completion-table function
+This macro is a convenient way to write a function that can act as
+programmed completion function. The argument @var{function} should be
+a function that takes one argument, a string, and returns an alist of
+possible completions of it. You can think of
+@code{dynamic-completion-table} as a transducer between that interface
+and the interface for programmed completion functions.
+@end defmac
+
@node Yes-or-No Queries
@section Yes-or-No Queries
@cindex asking the user questions
@group
(y-or-n-p "Do you need a lift? ")
-;; @r{After evaluation of the preceding expression,}
+;; @r{After evaluation of the preceding expression,}
;; @r{the following prompt appears in the echo area:}
@end group
@group
---------- Echo area ----------
-Do you need a lift? (y or n)
+Do you need a lift? (y or n)
---------- Echo area ----------
@end group
@group
---------- Echo area ----------
-Please answer y or n. Do you need a lift? (y or n)
+Please answer y or n. Do you need a lift? (y or n)
---------- Echo area ----------
@end group
appears on the screen at a time.
@end defun
+@defun y-or-n-p-with-timeout prompt seconds default-value
+Like @code{y-or-n-p}, except that if the user fails to answer within
+@var{seconds} seconds, this function stops waiting and returns
+@var{default-value}. It works by setting up a timer; see @ref{Timers}.
+The argument @var{seconds} may be an integer or a floating point number.
+@end defun
+
@defun yes-or-no-p prompt
This function asks the user a question, expecting input in the
minibuffer. It returns @code{t} if the user enters @samp{yes},
@group
(yes-or-no-p "Do you really want to remove everything? ")
-;; @r{After evaluation of the preceding expression,}
-;; @r{the following prompt appears,}
+;; @r{After evaluation of the preceding expression,}
+;; @r{the following prompt appears,}
;; @r{with an empty minibuffer:}
@end group
@group
---------- Buffer: minibuffer ----------
-Do you really want to remove everything? (yes or no)
+Do you really want to remove everything? (yes or no)
---------- Buffer: minibuffer ----------
@end group
@end smallexample
convenient facilities such as the ability to answer the whole series at
once.
-@defun map-y-or-n-p prompter actor list &optional help action-alist
-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.
+@defun map-y-or-n-p prompter actor list &optional help action-alist no-cursor-in-echo-area
+This function asks the user a series of questions, reading a
+single-character answer in the echo area for each one.
The value of @var{list} specifies the objects to ask questions about.
It should be either a list of objects or a generator function. If it is
@var{list}).
If not a string, @var{prompter} should be a function of one argument
-(the next object to ask about) and should return the question text.
+(the next object to ask about) and should return the question text. If
+the value is a string, that is the question to ask the user. The
+function can also return @code{t} meaning do act on this object (and
+don't ask the user), or @code{nil} meaning ignore this object (and don't
+ask the user).
The argument @var{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
@var{list}. If it returns @code{nil}, the prompt is repeated for the
same object.
+Normally, @code{map-y-or-n-p} binds @code{cursor-in-echo-area} while
+prompting. But if @var{no-cursor-in-echo-area} is non-@code{nil}, it
+does not do that.
+
If @code{map-y-or-n-p} is called in a command that was invoked using the
mouse---more precisely, if @code{last-nonmenu-event} (@pxref{Command
Loop Info}) is either @code{nil} or a list---then it uses a dialog box
The return value of @code{map-y-or-n-p} is the number of objects acted on.
@end defun
-@node Minibuffer Misc
-@comment node-name, next, previous, up
-@section Minibuffer Miscellany
+@node Reading a Password
+@section Reading a Password
+@cindex passwords, reading
+
+ To read a password to pass to another program, you can use the
+function @code{read-passwd}.
+
+@defun read-passwd prompt &optional confirm default
+This function reads a password, prompting with @var{prompt}. It does
+not echo the password as the user types it; instead, it echoes @samp{.}
+for each character in the password.
+
+The optional argument @var{confirm}, if non-@code{nil}, says to read the
+password twice and insist it must be the same both times. If it isn't
+the same, the user has to type it over and over until the last two
+times match.
+
+The optional argument @var{default} specifies the default password to
+return if the user enters empty input. If @var{default} is @code{nil},
+then @code{read-passwd} returns the null string in that case.
+@end defun
+
+@node Minibuffer Commands
+@section Minibuffer Commands
- This section describes some basic functions and variables related to
-minibuffers.
+ This section describes some commands meant for use in the
+minibuffer.
@deffn Command exit-minibuffer
This command exits the active minibuffer. It is normally bound to
@var{n}th more recent history element.
@end deffn
-@deffn Command previous-matching-history-element pattern
+@deffn Command previous-matching-history-element pattern n
This command replaces the minibuffer contents with the value of the
-previous (older) history element that matches @var{pattern} (a regular
-expression).
+@var{n}th previous (older) history element that matches @var{pattern} (a
+regular expression).
@end deffn
-@deffn Command next-matching-history-element pattern
-This command replaces the minibuffer contents with the value of the next
-(newer) history element that matches @var{pattern} (a regular
-expression).
+@deffn Command next-matching-history-element pattern n
+This command replaces the minibuffer contents with the value of the
+@var{n}th next (newer) history element that matches @var{pattern} (a
+regular expression).
@end deffn
-@defvar minibuffer-setup-hook
-This is a normal hook that is run whenever the minibuffer is entered.
-@xref{Hooks}.
-@end defvar
+@node Minibuffer Windows
+@section Minibuffer Windows
-@defvar minibuffer-setup-hook
-This is a normal hook that is run whenever the minibuffer is exited.
-@xref{Hooks}.
-@end defvar
+ These functions access and select minibuffer windows
+and test whether they are active.
-@defvar minibuffer-help-form
-The current value of this variable is used to rebind @code{help-form}
-locally inside the minibuffer (@pxref{Help Functions}).
-@end defvar
+@defun active-minibuffer-window
+This function returns the currently active minibuffer window, or
+@code{nil} if none is currently active.
+@end defun
@defun minibuffer-window &optional frame
-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 @var{frame} (which defaults to the currently selected frame).
+@anchor{Definition of minibuffer-window}
+This function returns the minibuffer window used for frame @var{frame}.
+If @var{frame} is @code{nil}, that stands for the current frame. Note
+that the minibuffer window used by a frame need not be part of that
+frame---a frame that has no minibuffer of its own necessarily uses some
+other frame's minibuffer window.
+@end defun
+
+@defun set-minibuffer-window window
+This function specifies @var{window} as the minibuffer window to use.
+This affects where the minibuffer is displayed if you put text in it
+without invoking the usual minibuffer commands. It has no effect on
+the usual minibuffer input functions because they all start by
+choosing the minibuffer window according to the current frame.
@end defun
@c Emacs 19 feature
-@defun window-minibuffer-p window
-This function returns non-@code{nil} if @var{window} is a minibuffer window.
+@defun window-minibuffer-p &optional window
+This function returns non-@code{nil} if @var{window} is a minibuffer
+window.
+@var{window} defaults to the selected window.
@end defun
It is not correct to determine whether a given window is a minibuffer by
a minibuffer window, is currently active.
@end defun
-@defvar minibuffer-scroll-window
-If the value of this variable is non-@code{nil}, it should be a window
-object. When the function @code{scroll-other-window} is called in the
-minibuffer, it scrolls this window.
-@end defvar
+@node Minibuffer Contents
+@section Minibuffer Contents
-Finally, some functions and variables deal with recursive minibuffers
-(@pxref{Recursive Editing}):
-
-@defun minibuffer-depth
-This function returns the current depth of activations of the
-minibuffer, a nonnegative integer. If no minibuffers are active, it
-returns zero.
-@end defun
+ These functions access the minibuffer prompt and contents.
@defun minibuffer-prompt
This function returns the prompt string of the currently active
minibuffer. If no minibuffer is active, it returns @code{nil}.
@end defun
+@defun minibuffer-prompt-end
+@tindex minibuffer-prompt-end
+This function returns the current
+position of the end of the minibuffer prompt, if a minibuffer is
+current. Otherwise, it returns the minimum valid buffer position.
+@end defun
+
@defun minibuffer-prompt-width
-This function returns the display width of the prompt string of the
-currently active minibuffer. If no minibuffer is active, it returns 0.
+This function returns the current display-width of the minibuffer
+prompt, if a minibuffer is current. Otherwise, it returns zero.
+@end defun
+
+@defun minibuffer-contents
+@tindex minibuffer-contents
+This function returns the editable
+contents of the minibuffer (that is, everything except the prompt) as
+a string, if a minibuffer is current. Otherwise, it returns the
+entire contents of the current buffer.
+@end defun
+
+@defun minibuffer-contents-no-properties
+@tindex minibuffer-contents-no-properties
+This is like @code{minibuffer-contents}, except that it does not copy text
+properties, just the characters themselves. @xref{Text Properties}.
+@end defun
+
+@defun minibuffer-completion-contents
+@tindex minibuffer-completion-contents
+This is like @code{minibuffer-contents}, except that it returns only
+the contents before point. That is the part that completion commands
+operate on. @xref{Minibuffer Completion}.
+@end defun
+
+@defun delete-minibuffer-contents
+@tindex delete-minibuffer-contents
+This function erases the editable contents of the minibuffer (that is,
+everything except the prompt), if a minibuffer is current. Otherwise,
+it erases the entire current buffer.
+@end defun
+
+@node Recursive Mini
+@section Recursive Minibuffers
+
+ These functions and variables deal with recursive minibuffers
+(@pxref{Recursive Editing}):
+
+@defun minibuffer-depth
+This function returns the current depth of activations of the
+minibuffer, a nonnegative integer. If no minibuffers are active, it
+returns zero.
@end defun
@defopt enable-recursive-minibuffers
If this variable is non-@code{nil}, you can invoke commands (such as
-@code{find-file}) that use minibuffers even while in the minibuffer
-window. Such invocation produces a recursive editing level for a new
+@code{find-file}) that use minibuffers even while the minibuffer window
+is active. 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 this variable is @code{nil}, you cannot invoke minibuffer
+commands when the minibuffer window is active, not even if you switch to
+another window to do it.
@end defopt
@c Emacs 19 feature
If a command name has a property @code{enable-recursive-minibuffers}
that is non-@code{nil}, then the command can use the minibuffer to read
-arguments even if it is invoked from the minibuffer. The minibuffer
-command @code{next-matching-history-element} (normally bound to
-@kbd{M-s} in the minibuffer) uses this feature.
+arguments even if it is invoked from the minibuffer. A command can
+also achieve this by binding @code{enable-recursive-minibuffers}
+to @code{t} in the interactive declaration (@pxref{Using Interactive}).
+The minibuffer command @code{next-matching-history-element} (normally
+@kbd{M-s} in the minibuffer) does the latter.
+
+@node Minibuffer Misc
+@section Minibuffer Miscellany
+
+@defun minibufferp &optional buffer-or-name
+This function returns non-@code{nil} if @var{buffer-or-name} is a
+minibuffer. If @var{buffer-or-name} is omitted, it tests the current
+buffer.
+@end defun
+
+@defvar minibuffer-setup-hook
+This is a normal hook that is run whenever the minibuffer is entered.
+@xref{Hooks}.
+@end defvar
+
+@defvar minibuffer-exit-hook
+This is a normal hook that is run whenever the minibuffer is exited.
+@xref{Hooks}.
+@end defvar
+
+@defvar minibuffer-help-form
+@anchor{Definition of minibuffer-help-form}
+The current value of this variable is used to rebind @code{help-form}
+locally inside the minibuffer (@pxref{Help Functions}).
+@end defvar
+
+@defvar minibuffer-scroll-window
+@anchor{Definition of minibuffer-scroll-window}
+If the value of this variable is non-@code{nil}, it should be a window
+object. When the function @code{scroll-other-window} is called in the
+minibuffer, it scrolls this window.
+@end defvar
+
+@defun minibuffer-selected-window
+This function returns the window which was selected when the
+minibuffer was entered. If selected window is not a minibuffer
+window, it returns @code{nil}.
+@end defun
+
+@defopt max-mini-window-height
+This variable specifies the maximum height for resizing minibuffer
+windows. If a float, it specifies a fraction of the height of the
+frame. If an integer, it specifies a number of lines.
+@end defopt
+
+@defun minibuffer-message string
+This function displays @var{string} temporarily at the end of the
+minibuffer text, for two seconds, or until the next input event
+arrives, whichever comes first.
+@end defun
+
+@ignore
+ arch-tag: bba7f945-9078-477f-a2ce-18818a6e1218
+@end ignore