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7370e0a883
Collections can be lists of strings. Clean up lazy-completion-table. (Programmed Completion): Mention test-completion. Clarify why lambda expressions are not accepted. (Minibuffer Misc): Describe minibufferp.
1686 lines
62 KiB
Plaintext
1686 lines
62 KiB
Plaintext
@c -*-texinfo-*-
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@c This is part of the GNU Emacs Lisp Reference Manual.
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@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2001
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@c Free Software Foundation, Inc.
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@c See the file elisp.texi for copying conditions.
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@setfilename ../info/minibuf
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@node Minibuffers, Command Loop, Read and Print, Top
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@chapter Minibuffers
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@cindex arguments, reading
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@cindex complex arguments
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@cindex minibuffer
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A @dfn{minibuffer} is a special buffer that Emacs commands use to read
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arguments more complicated than the single numeric prefix argument.
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These arguments include file names, buffer names, and command names (as
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in @kbd{M-x}). The minibuffer is displayed on the bottom line of the
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frame, in the same place as the echo area, but only while it is in use
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for reading an argument.
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@menu
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* Intro to Minibuffers:: Basic information about minibuffers.
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* Text from Minibuffer:: How to read a straight text string.
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* Object from Minibuffer:: How to read a Lisp object or expression.
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* Minibuffer History:: Recording previous minibuffer inputs
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so the user can reuse them.
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* Completion:: How to invoke and customize completion.
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* Yes-or-No Queries:: Asking a question with a simple answer.
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* Multiple Queries:: Asking a series of similar questions.
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* Reading a Password:: Reading a password from the terminal.
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* Minibuffer Misc:: Various customization hooks and variables.
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@end menu
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@node Intro to Minibuffers
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@section Introduction to Minibuffers
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In most ways, a minibuffer is a normal Emacs buffer. Most operations
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@emph{within} a buffer, such as editing commands, work normally in a
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minibuffer. However, many operations for managing buffers do not apply
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to minibuffers. The name of a minibuffer always has the form @w{@samp{
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*Minibuf-@var{number}*}}, and it cannot be changed. Minibuffers are
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displayed only in special windows used only for minibuffers; these
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windows always appear at the bottom of a frame. (Sometimes frames have
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no minibuffer window, and sometimes a special kind of frame contains
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nothing but a minibuffer window; see @ref{Minibuffers and Frames}.)
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The text in the minibuffer always starts with the @dfn{prompt string},
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the text that was specified by the program that is using the minibuffer
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to tell the user what sort of input to type. This text is marked
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read-only so you won't accidentally delete or change it. It is also
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marked as a field (@pxref{Fields}), so that certain motion functions,
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including @code{beginning-of-line}, @code{forward-word},
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@code{forward-sentence}, and @code{forward-paragraph}, stop at the
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boundary between the prompt and the actual text. (In older Emacs
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versions, the prompt was displayed using a special mechanism and was not
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part of the buffer contents.)
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The minibuffer's window is normally a single line; it grows
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automatically if necessary if the contents require more space. You can
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explicitly resize it temporarily with the window sizing commands; it
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reverts to its normal size when the minibuffer is exited. You can
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resize it permanently by using the window sizing commands in the frame's
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other window, when the minibuffer is not active. If the frame contains
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just a minibuffer, you can change the minibuffer's size by changing the
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frame's size.
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If a command uses a minibuffer while there is an active minibuffer,
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this is called a @dfn{recursive minibuffer}. The first minibuffer is
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named @w{@samp{ *Minibuf-0*}}. Recursive minibuffers are named by
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incrementing the number at the end of the name. (The names begin with a
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space so that they won't show up in normal buffer lists.) Of several
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recursive minibuffers, the innermost (or most recently entered) is the
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active minibuffer. We usually call this ``the'' minibuffer. You can
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permit or forbid recursive minibuffers by setting the variable
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@code{enable-recursive-minibuffers} or by putting properties of that
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name on command symbols (@pxref{Minibuffer Misc}).
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Like other buffers, a minibuffer may use any of several local keymaps
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(@pxref{Keymaps}); these contain various exit commands and in some cases
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completion commands (@pxref{Completion}).
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@itemize @bullet
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@item
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@code{minibuffer-local-map} is for ordinary input (no completion).
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@item
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@code{minibuffer-local-ns-map} is similar, except that @key{SPC} exits
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just like @key{RET}.
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@item
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@code{minibuffer-local-completion-map} is for permissive completion.
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@item
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@code{minibuffer-local-must-match-map} is for strict completion and
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for cautious completion.
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@end itemize
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When Emacs is running in batch mode, any request to read from the
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minibuffer actually reads a line from the standard input descriptor that
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was supplied when Emacs was started.
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@node Text from Minibuffer
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@section Reading Text Strings with the Minibuffer
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Most often, the minibuffer is used to read text as a string. It can
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also be used to read a Lisp object in textual form. The most basic
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primitive for minibuffer input is @code{read-from-minibuffer}; it can do
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either one.
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In most cases, you should not call minibuffer input functions in the
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middle of a Lisp function. Instead, do all minibuffer input as part of
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reading the arguments for a command, in the @code{interactive}
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specification. @xref{Defining Commands}.
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@defun read-from-minibuffer prompt-string &optional initial-contents keymap read hist default inherit-input-method
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This function is the most general way to get input through the
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minibuffer. By default, it accepts arbitrary text and returns it as a
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string; however, if @var{read} is non-@code{nil}, then it uses
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@code{read} to convert the text into a Lisp object (@pxref{Input
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Functions}).
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The first thing this function does is to activate a minibuffer and
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display it with @var{prompt-string} as the prompt. This value must be a
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string. Then the user can edit text in the minibuffer.
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When the user types a command to exit the minibuffer,
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@code{read-from-minibuffer} constructs the return value from the text in
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the minibuffer. Normally it returns a string containing that text.
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However, if @var{read} is non-@code{nil}, @code{read-from-minibuffer}
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reads the text and returns the resulting Lisp object, unevaluated.
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(@xref{Input Functions}, for information about reading.)
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The argument @var{default} specifies a default value to make available
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through the history commands. It should be a string, or @code{nil}. If
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@var{read} is non-@code{nil}, then @var{default} is also used as the
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input to @code{read}, if the user enters empty input. However, in the
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usual case (where @var{read} is @code{nil}), @code{read-from-minibuffer}
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does not return @var{default} when the user enters empty input; it
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returns an empty string, @code{""}. In this respect, it is different
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from all the other minibuffer input functions in this chapter.
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If @var{keymap} is non-@code{nil}, that keymap is the local keymap to
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use in the minibuffer. If @var{keymap} is omitted or @code{nil}, the
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value of @code{minibuffer-local-map} is used as the keymap. Specifying
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a keymap is the most important way to customize the minibuffer for
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various applications such as completion.
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The argument @var{hist} specifies which history list variable to use
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for saving the input and for history commands used in the minibuffer.
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It defaults to @code{minibuffer-history}. @xref{Minibuffer History}.
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If the variable @code{minibuffer-allow-text-properties} is
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non-@code{nil}, then the string which is returned includes whatever text
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properties were present in the minibuffer. Otherwise all the text
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properties are stripped when the value is returned.
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If the argument @var{inherit-input-method} is non-@code{nil}, then the
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minibuffer inherits the current input method (@pxref{Input Methods}) and
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the setting of @code{enable-multibyte-characters} (@pxref{Text
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Representations}) from whichever buffer was current before entering the
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minibuffer.
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If @var{initial-contents} is a string, @code{read-from-minibuffer}
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inserts it into the minibuffer, leaving point at the end, before the
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user starts to edit the text. The minibuffer appears with this text as
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its initial contents.
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Alternatively, @var{initial-contents} can be a cons cell of the form
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@code{(@var{string} . @var{position})}. This means to insert
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@var{string} in the minibuffer but put point @var{position} characters
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from the beginning, rather than at the end.
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@strong{Usage note:} The @var{initial-contents} argument and the
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@var{default} argument are two alternative features for more or less the
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same job. It does not make sense to use both features in a single call
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to @code{read-from-minibuffer}. In general, we recommend using
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@var{default}, since this permits the user to insert the default value
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when it is wanted, but does not burden the user with deleting it from
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the minibuffer on other occasions.
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@end defun
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@defun read-string prompt &optional initial history default inherit-input-method
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This function reads a string from the minibuffer and returns it. The
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arguments @var{prompt} and @var{initial} are used as in
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@code{read-from-minibuffer}. The keymap used is
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@code{minibuffer-local-map}.
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The optional argument @var{history}, if non-@code{nil}, specifies a
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history list and optionally the initial position in the list. The
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optional argument @var{default} specifies a default value to return if
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the user enters null input; it should be a string. The optional
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argument @var{inherit-input-method} specifies whether to inherit the
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current buffer's input method.
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This function is a simplified interface to the
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@code{read-from-minibuffer} function:
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@smallexample
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@group
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(read-string @var{prompt} @var{initial} @var{history} @var{default} @var{inherit})
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@equiv{}
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(let ((value
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(read-from-minibuffer @var{prompt} @var{initial} nil nil
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@var{history} @var{default} @var{inherit})))
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(if (equal value "")
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@var{default}
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value))
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@end group
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@end smallexample
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@end defun
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@defvar minibuffer-allow-text-properties
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If this variable is @code{nil}, then @code{read-from-minibuffer} strips
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all text properties from the minibuffer input before returning it.
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Since all minibuffer input uses @code{read-from-minibuffer}, this
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variable applies to all minibuffer input.
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Note that the completion functions discard text properties unconditionally,
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regardless of the value of this variable.
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@end defvar
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@defvar minibuffer-local-map
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This is the default local keymap for reading from the minibuffer. By
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default, it makes the following bindings:
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@table @asis
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@item @kbd{C-j}
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@code{exit-minibuffer}
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@item @key{RET}
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@code{exit-minibuffer}
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@item @kbd{C-g}
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@code{abort-recursive-edit}
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@item @kbd{M-n}
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@code{next-history-element}
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@item @kbd{M-p}
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@code{previous-history-element}
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@item @kbd{M-r}
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@code{next-matching-history-element}
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@item @kbd{M-s}
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@code{previous-matching-history-element}
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@end table
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@end defvar
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@c In version 18, initial is required
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@c Emacs 19 feature
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@defun read-no-blanks-input prompt &optional initial inherit-input-method
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This function reads a string from the minibuffer, but does not allow
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whitespace characters as part of the input: instead, those characters
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terminate the input. The arguments @var{prompt}, @var{initial}, and
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@var{inherit-input-method} are used as in @code{read-from-minibuffer}.
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This is a simplified interface to the @code{read-from-minibuffer}
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function, and passes the value of the @code{minibuffer-local-ns-map}
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keymap as the @var{keymap} argument for that function. Since the keymap
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@code{minibuffer-local-ns-map} does not rebind @kbd{C-q}, it @emph{is}
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possible to put a space into the string, by quoting it.
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@smallexample
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@group
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(read-no-blanks-input @var{prompt} @var{initial})
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@equiv{}
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(read-from-minibuffer @var{prompt} @var{initial} minibuffer-local-ns-map)
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@end group
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@end smallexample
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@end defun
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@defvar minibuffer-local-ns-map
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This built-in variable is the keymap used as the minibuffer local keymap
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in the function @code{read-no-blanks-input}. By default, it makes the
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following bindings, in addition to those of @code{minibuffer-local-map}:
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@table @asis
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@item @key{SPC}
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@cindex @key{SPC} in minibuffer
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@code{exit-minibuffer}
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@item @key{TAB}
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@cindex @key{TAB} in minibuffer
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@code{exit-minibuffer}
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@item @kbd{?}
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@cindex @kbd{?} in minibuffer
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@code{self-insert-and-exit}
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@end table
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@end defvar
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@node Object from Minibuffer
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@section Reading Lisp Objects with the Minibuffer
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This section describes functions for reading Lisp objects with the
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minibuffer.
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@defun read-minibuffer prompt &optional initial
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This function reads a Lisp object using the minibuffer, and returns it
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without evaluating it. The arguments @var{prompt} and @var{initial} are
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used as in @code{read-from-minibuffer}.
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This is a simplified interface to the
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@code{read-from-minibuffer} function:
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@smallexample
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@group
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(read-minibuffer @var{prompt} @var{initial})
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@equiv{}
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(read-from-minibuffer @var{prompt} @var{initial} nil t)
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@end group
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@end smallexample
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Here is an example in which we supply the string @code{"(testing)"} as
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initial input:
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@smallexample
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@group
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(read-minibuffer
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"Enter an expression: " (format "%s" '(testing)))
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;; @r{Here is how the minibuffer is displayed:}
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@end group
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@group
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---------- Buffer: Minibuffer ----------
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Enter an expression: (testing)@point{}
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---------- Buffer: Minibuffer ----------
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@end group
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@end smallexample
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@noindent
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The user can type @key{RET} immediately to use the initial input as a
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default, or can edit the input.
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@end defun
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@defun eval-minibuffer prompt &optional initial
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This function reads a Lisp expression using the minibuffer, evaluates
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it, then returns the result. The arguments @var{prompt} and
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@var{initial} are used as in @code{read-from-minibuffer}.
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This function simply evaluates the result of a call to
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@code{read-minibuffer}:
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@smallexample
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@group
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(eval-minibuffer @var{prompt} @var{initial})
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@equiv{}
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(eval (read-minibuffer @var{prompt} @var{initial}))
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@end group
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@end smallexample
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@end defun
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@defun edit-and-eval-command prompt form
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This function reads a Lisp expression in the minibuffer, and then
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evaluates it. The difference between this command and
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@code{eval-minibuffer} is that here the initial @var{form} is not
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optional and it is treated as a Lisp object to be converted to printed
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representation rather than as a string of text. It is printed with
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@code{prin1}, so if it is a string, double-quote characters (@samp{"})
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appear in the initial text. @xref{Output Functions}.
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The first thing @code{edit-and-eval-command} does is to activate the
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minibuffer with @var{prompt} as the prompt. Then it inserts the printed
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representation of @var{form} in the minibuffer, and lets the user edit it.
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When the user exits the minibuffer, the edited text is read with
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@code{read} and then evaluated. The resulting value becomes the value
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of @code{edit-and-eval-command}.
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In the following example, we offer the user an expression with initial
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text which is a valid form already:
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@smallexample
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@group
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(edit-and-eval-command "Please edit: " '(forward-word 1))
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;; @r{After evaluation of the preceding expression,}
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;; @r{the following appears in the minibuffer:}
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@end group
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@group
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---------- Buffer: Minibuffer ----------
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Please edit: (forward-word 1)@point{}
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---------- Buffer: Minibuffer ----------
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@end group
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@end smallexample
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@noindent
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Typing @key{RET} right away would exit the minibuffer and evaluate the
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expression, thus moving point forward one word.
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@code{edit-and-eval-command} returns @code{nil} in this example.
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@end defun
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@node Minibuffer History
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@section Minibuffer History
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@cindex minibuffer history
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@cindex history list
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A @dfn{minibuffer history list} records previous minibuffer inputs so
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the user can reuse them conveniently. A history list is actually a
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symbol, not a list; it is a variable whose value is a list of strings
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(previous inputs), most recent first.
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There are many separate history lists, used for different kinds of
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inputs. It's the Lisp programmer's job to specify the right history
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list for each use of the minibuffer.
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The basic minibuffer input functions @code{read-from-minibuffer} and
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@code{completing-read} both accept an optional argument named @var{hist}
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which is how you specify the history list. Here are the possible
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values:
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@table @asis
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@item @var{variable}
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Use @var{variable} (a symbol) as the history list.
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@item (@var{variable} . @var{startpos})
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Use @var{variable} (a symbol) as the history list, and assume that the
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initial history position is @var{startpos} (an integer, counting from
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zero which specifies the most recent element of the history).
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If you specify @var{startpos}, then you should also specify that element
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of the history as the initial minibuffer contents, for consistency.
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@end table
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If you don't specify @var{hist}, then the default history list
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@code{minibuffer-history} is used. For other standard history lists,
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see below. You can also create your own history list variable; just
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initialize it to @code{nil} before the first use.
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Both @code{read-from-minibuffer} and @code{completing-read} add new
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elements to the history list automatically, and provide commands to
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allow the user to reuse items on the list. The only thing your program
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needs to do to use a history list is to initialize it and to pass its
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name to the input functions when you wish. But it is safe to modify the
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list by hand when the minibuffer input functions are not using it.
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Emacs functions that add a new element to a history list can also
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delete old elements if the list gets too long. The variable
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@code{history-length} specifies the maximum length for most history
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lists. To specify a different maximum length for a particular history
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list, put the length in the @code{history-length} property of the
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history list symbol.
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@defvar history-length
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The value of this variable specifies the maximum length for all
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history lists that don't specify their own maximum lengths. If the
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value is @code{t}, that means there no maximum (don't delete old
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elements).
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@end defvar
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Here are some of the standard minibuffer history list variables:
|
|
|
|
@defvar minibuffer-history
|
|
The default history list for minibuffer history input.
|
|
@end defvar
|
|
|
|
@defvar query-replace-history
|
|
A history list for arguments to @code{query-replace} (and similar
|
|
arguments to other commands).
|
|
@end defvar
|
|
|
|
@defvar file-name-history
|
|
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 regular expression arguments.
|
|
@end defvar
|
|
|
|
@defvar extended-command-history
|
|
A history list for arguments that are names of extended commands.
|
|
@end defvar
|
|
|
|
@defvar shell-command-history
|
|
A history list for arguments that are shell commands.
|
|
@end defvar
|
|
|
|
@defvar read-expression-history
|
|
A history list for arguments that are Lisp expressions to evaluate.
|
|
@end defvar
|
|
|
|
@node Completion
|
|
@section Completion
|
|
@cindex completion
|
|
|
|
@dfn{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 @kbd{C-x b} (@code{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 @key{TAB} (@code{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 @code{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 @code{completing-read} provides a higher-level interface
|
|
for completion. A call to @code{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.
|
|
|
|
@menu
|
|
* Basic Completion:: Low-level functions for completing strings.
|
|
(These are too low level to use the minibuffer.)
|
|
* Minibuffer Completion:: Invoking the minibuffer with completion.
|
|
* Completion Commands:: Minibuffer commands that do 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:: Writing your own completion-function.
|
|
@end menu
|
|
|
|
@node Basic Completion
|
|
@subsection Basic Completion Functions
|
|
|
|
The 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.
|
|
|
|
@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 a list of strings, an alist, an obarray, 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
|
|
permissible completion equals @var{string}, it matches. If no permissible
|
|
completions match, @code{try-completion} returns @code{nil}. If only
|
|
one permissible completion matches, and the match is exact, then
|
|
@code{try-completion} returns @code{t}. Otherwise, the value is the
|
|
longest initial sequence common to all the permissible completions that
|
|
match.
|
|
|
|
If @var{collection} is an alist (@pxref{Association Lists}), the
|
|
@sc{car}s of the alist elements form the set of permissible completions.
|
|
|
|
@cindex obarray in completion
|
|
If @var{collection} is an obarray (@pxref{Creating Symbols}), the names
|
|
of all symbols in the obarray form the set of permissible completions. The
|
|
global variable @code{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 @code{intern}.
|
|
Also, you cannot intern a given symbol in more than one obarray.
|
|
|
|
You can also use a symbol that is a function as @var{collection}. Then
|
|
the function is solely responsible for performing completion;
|
|
@code{try-completion} returns whatever this function returns. The
|
|
function is called with three arguments: @var{string}, @var{predicate}
|
|
and @code{nil}. (The reason for the third argument is so that the same
|
|
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. 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 from the
|
|
list, a cons cell from the alist (the @sc{car} of which is a string)
|
|
or a symbol (@emph{not} a symbol name) from the obarray.
|
|
|
|
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
|
|
example, there is only one possible match, and it is exact, so the value
|
|
is @code{t}.
|
|
|
|
@smallexample
|
|
@group
|
|
(try-completion
|
|
"foo"
|
|
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4)))
|
|
@result{} "fooba"
|
|
@end group
|
|
|
|
@group
|
|
(try-completion "foo" '(("barfoo" 2) ("foo" 3)))
|
|
@result{} t
|
|
@end group
|
|
@end smallexample
|
|
|
|
In the following example, numerous symbols begin with the characters
|
|
@samp{forw}, and all of them begin with the word @samp{forward}. In
|
|
most of the symbols, this is followed with a @samp{-}, but not in all,
|
|
so no more than @samp{forward} can be completed.
|
|
|
|
@smallexample
|
|
@group
|
|
(try-completion "forw" obarray)
|
|
@result{} "forward"
|
|
@end group
|
|
@end smallexample
|
|
|
|
Finally, in the following example, only two of the three possible
|
|
matches pass the predicate @code{test} (the string @samp{foobaz} is
|
|
too short). Both of those begin with the string @samp{foobar}.
|
|
|
|
@smallexample
|
|
@group
|
|
(defun test (s)
|
|
(> (length (car s)) 6))
|
|
@result{} test
|
|
@end group
|
|
@group
|
|
(try-completion
|
|
"foo"
|
|
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
|
|
'test)
|
|
@result{} "foobar"
|
|
@end group
|
|
@end smallexample
|
|
@end defun
|
|
|
|
@defun all-completions string collection &optional predicate nospace
|
|
This function returns a list of all possible completions of
|
|
@var{string}. The arguments to this function (aside from @var{nospace})
|
|
are the same as those of @code{try-completion}. If @var{nospace} is
|
|
non-@code{nil}, completions that start with a space are ignored unless
|
|
@var{string} also starts with a space.
|
|
|
|
If @var{collection} is a function, it is called with three arguments:
|
|
@var{string}, @var{predicate} and @code{t}; then @code{all-completions}
|
|
returns whatever the function returns. @xref{Programmed Completion}.
|
|
|
|
Here is an example, using the function @code{test} shown in the
|
|
example for @code{try-completion}:
|
|
|
|
@smallexample
|
|
@group
|
|
(defun test (s)
|
|
(> (length (car s)) 6))
|
|
@result{} test
|
|
@end group
|
|
|
|
@group
|
|
(all-completions
|
|
"foo"
|
|
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
|
|
'test)
|
|
@result{} ("foobar1" "foobar2")
|
|
@end group
|
|
@end smallexample
|
|
@end defun
|
|
|
|
@defun test-completion string collection &optional predicate
|
|
This function returns non-@code{nil} if @var{string} is a valid
|
|
completion possibility specified by @var{collection} and
|
|
@var{predicate}. The other arguments are the same as in
|
|
@code{try-completion}. For instance, if @var{collection} is a list,
|
|
this is true if @var{string} appears in the list and @var{predicate}
|
|
is satisfied.
|
|
|
|
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.
|
|
@end defvar
|
|
|
|
@defmac lazy-completion-table var fun &rest args
|
|
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 the arguments @var{args}. The
|
|
value @var{fun} returns becomes the permanent value of @var{var}.
|
|
|
|
Here are two examples of use:
|
|
|
|
@example
|
|
(defvar foo (lazy-completion-table foo make-my-alist 'global))
|
|
|
|
(make-local-variable 'bar)
|
|
(setq bar (lazy-completion-table foo make-my-alist 'local)
|
|
@end example
|
|
@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 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.
|
|
|
|
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{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}. The value of @var{default} (if non-@code{nil}) is also
|
|
available to the user through the history commands.
|
|
|
|
The user can exit with null input by typing @key{RET} with an empty
|
|
minibuffer. Then @code{completing-read} returns @code{""}. This is how
|
|
the user requests whatever default the command uses for the value being
|
|
read. The user can return using @key{RET} in this way regardless of the
|
|
value of @var{require-match}, and regardless of whether the empty string
|
|
is included in @var{collection}.
|
|
|
|
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
|
|
@code{minibuffer-local-must-match-map} if @var{require-match} is
|
|
non-@code{nil}. @xref{Completion Commands}.
|
|
|
|
The argument @var{hist} specifies which history list variable to use for
|
|
saving the input and for minibuffer history commands. It defaults to
|
|
@code{minibuffer-history}. @xref{Minibuffer History}.
|
|
|
|
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.
|
|
In most cases, we recommend using @var{default}, and not @var{initial}.
|
|
|
|
@strong{We discourage use of a non-@code{nil} value for
|
|
@var{initial}}, because it is an intrusive interface. The history
|
|
list feature (which did not exist when we introduced @var{initial})
|
|
offers a far more convenient and general way for the user to get the
|
|
default and edit it, and it is always available.
|
|
|
|
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.
|
|
|
|
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}.
|
|
|
|
Here's an example of using @code{completing-read}:
|
|
|
|
@smallexample
|
|
@group
|
|
(completing-read
|
|
"Complete a foo: "
|
|
'(("foobar1" 1) ("barfoo" 2) ("foobaz" 3) ("foobar2" 4))
|
|
nil t "fo")
|
|
@end group
|
|
|
|
@group
|
|
;; @r{After evaluation of the preceding expression,}
|
|
;; @r{the following appears in the minibuffer:}
|
|
|
|
---------- Buffer: Minibuffer ----------
|
|
Complete a foo: fo@point{}
|
|
---------- Buffer: Minibuffer ----------
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
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}.
|
|
@end defun
|
|
|
|
@node Completion Commands
|
|
@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 @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-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
|
|
@code{completing-read} passes to @code{try-completion}. It is used by
|
|
minibuffer completion commands such as @code{minibuffer-complete-word}.
|
|
@end defvar
|
|
|
|
@defvar minibuffer-completion-predicate
|
|
This variable's value is the predicate that @code{completing-read}
|
|
passes to @code{try-completion}. The variable is also used by the other
|
|
minibuffer completion functions.
|
|
@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,
|
|
@code{minibuffer-complete-word} does not add any characters beyond the
|
|
first character that is not a word constituent. @xref{Syntax Tables}.
|
|
@end deffn
|
|
|
|
@deffn Command minibuffer-complete
|
|
This function completes the minibuffer contents as far as possible.
|
|
@end deffn
|
|
|
|
@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 @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}
|
|
using the value of the variable @code{minibuffer-completion-table} as
|
|
the @var{collection} argument, and the value of
|
|
@code{minibuffer-completion-predicate} as the @var{predicate} argument.
|
|
The list of completions is displayed as text in a buffer named
|
|
@samp{*Completions*}.
|
|
@end deffn
|
|
|
|
@defun display-completion-list completions
|
|
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.
|
|
|
|
This function is called by @code{minibuffer-completion-help}. The
|
|
most common way to use it is together with
|
|
@code{with-output-to-temp-buffer}, like this:
|
|
|
|
@example
|
|
(with-output-to-temp-buffer "*Completions*"
|
|
(display-completion-list
|
|
(all-completions (buffer-string) my-alist)))
|
|
@end example
|
|
@end defun
|
|
|
|
@defopt completion-auto-help
|
|
If this variable is non-@code{nil}, the completion commands
|
|
automatically display a list of possible completions whenever nothing
|
|
can be completed because the next character is not uniquely determined.
|
|
@end defopt
|
|
|
|
@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
|
|
return if the user exits with an empty minibuffer. If non-@code{nil},
|
|
it should be a string or a buffer. It is mentioned in the prompt, but
|
|
is not inserted in the minibuffer as initial input.
|
|
|
|
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.)
|
|
|
|
In the following example, the user enters @samp{minibuffer.t}, and
|
|
then types @key{RET}. The argument @var{existing} is @code{t}, and the
|
|
only buffer name starting with the given input is
|
|
@samp{minibuffer.texi}, so that name is the value.
|
|
|
|
@example
|
|
(read-buffer "Buffer name? " "foo" t)
|
|
@group
|
|
;; @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: Minibuffer ----------
|
|
@end group
|
|
|
|
@group
|
|
;; @r{The user types @kbd{minibuffer.t @key{RET}}.}
|
|
@result{} "minibuffer.texi"
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@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{nil}.
|
|
|
|
@example
|
|
(read-command "Command name? ")
|
|
|
|
@group
|
|
;; @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 ----------
|
|
@end group
|
|
@end example
|
|
|
|
@noindent
|
|
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
|
|
@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
|
|
@example
|
|
@group
|
|
(read-command @var{prompt})
|
|
@equiv{}
|
|
(intern (completing-read @var{prompt} obarray
|
|
'commandp t nil))
|
|
@end group
|
|
@end example
|
|
@end defun
|
|
|
|
@defun read-variable prompt &optional default
|
|
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{nil}.
|
|
|
|
@example
|
|
@group
|
|
(read-variable "Variable name? ")
|
|
|
|
;; @r{After evaluation of the preceding expression,}
|
|
;; @r{the following prompt appears,}
|
|
;; @r{with an empty minibuffer:}
|
|
@end group
|
|
|
|
@group
|
|
---------- Buffer: Minibuffer ----------
|
|
Variable name? @point{}
|
|
---------- Buffer: Minibuffer ----------
|
|
@end group
|
|
@end example
|
|
|
|
@noindent
|
|
If the user then types @kbd{fill-p @key{RET}}, @code{read-variable}
|
|
returns @code{fill-prefix}.
|
|
|
|
This function is similar to @code{read-command}, but uses the
|
|
predicate @code{user-variable-p} instead of @code{commandp}:
|
|
|
|
@cindex @code{user-variable-p} example
|
|
@example
|
|
@group
|
|
(read-variable @var{prompt})
|
|
@equiv{}
|
|
(intern
|
|
(completing-read @var{prompt} obarray
|
|
'user-variable-p t nil))
|
|
@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}.
|
|
|
|
@node Reading File Names
|
|
@subsection Reading File Names
|
|
|
|
Here is another high-level completion function, designed for reading a
|
|
file name. It provides special features including automatic insertion
|
|
of the default directory.
|
|
|
|
@defun read-file-name prompt &optional directory default existing initial
|
|
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.
|
|
|
|
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
|
|
valid if possible, and then refuses to exit if it is not valid. If the
|
|
value of @var{existing} is neither @code{nil} nor @code{t}, then
|
|
@key{RET} also requires confirmation after completion. If
|
|
@var{existing} is @code{nil}, then the name of a nonexistent file is
|
|
acceptable.
|
|
|
|
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}.
|
|
|
|
@c Emacs 19 feature
|
|
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}. @strong{Note:} we
|
|
recommend using @var{default} rather than @var{initial} in most cases.
|
|
|
|
Here is an example:
|
|
|
|
@example
|
|
@group
|
|
(read-file-name "The file is ")
|
|
|
|
;; @r{After evaluation of the preceding expression,}
|
|
;; @r{the following appears in the minibuffer:}
|
|
@end group
|
|
|
|
@group
|
|
---------- Buffer: Minibuffer ----------
|
|
The file is /gp/gnu/elisp/@point{}
|
|
---------- Buffer: Minibuffer ----------
|
|
@end group
|
|
@end example
|
|
|
|
@noindent
|
|
Typing @kbd{manual @key{TAB}} results in the following:
|
|
|
|
@example
|
|
@group
|
|
---------- Buffer: Minibuffer ----------
|
|
The file is /gp/gnu/elisp/manual.texi@point{}
|
|
---------- Buffer: Minibuffer ----------
|
|
@end group
|
|
@end example
|
|
|
|
@c Wordy to avoid overfull hbox in smallbook mode.
|
|
@noindent
|
|
If the user types @key{RET}, @code{read-file-name} returns the file name
|
|
as the string @code{"/gp/gnu/elisp/manual.texi"}.
|
|
@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 (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.
|
|
|
|
For example:
|
|
|
|
@example
|
|
@group
|
|
;; @r{Here the minibuffer starts out with the default directory.}
|
|
(let ((insert-default-directory t))
|
|
(read-file-name "The file is "))
|
|
@end group
|
|
|
|
@group
|
|
---------- Buffer: Minibuffer ----------
|
|
The file is ~lewis/manual/@point{}
|
|
---------- Buffer: Minibuffer ----------
|
|
@end group
|
|
|
|
@group
|
|
;; @r{Here the minibuffer is empty and only the prompt}
|
|
;; @r{appears on its line.}
|
|
(let ((insert-default-directory nil))
|
|
(read-file-name "The file is "))
|
|
@end group
|
|
|
|
@group
|
|
---------- Buffer: Minibuffer ----------
|
|
The file is @point{}
|
|
---------- Buffer: Minibuffer ----------
|
|
@end group
|
|
@end example
|
|
@end defopt
|
|
|
|
@node Programmed Completion
|
|
@subsection Programmed Completion
|
|
@cindex programmed completion
|
|
|
|
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 @dfn{programmed completion}.
|
|
|
|
To use this feature, pass a symbol with a function definition as the
|
|
@var{collection} argument to @code{completing-read}. The function
|
|
@code{completing-read} arranges to pass your completion function along
|
|
to @code{try-completion} and @code{all-completions}, which will then let
|
|
your function do all the work.
|
|
|
|
The completion function should accept three arguments:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
The string to be completed.
|
|
|
|
@item
|
|
The predicate function to filter possible matches, or @code{nil} if
|
|
none. Your function should call the predicate for each possible match,
|
|
and ignore the possible match if the predicate returns @code{nil}.
|
|
|
|
@item
|
|
A flag specifying the type of operation.
|
|
@end itemize
|
|
|
|
There are three flag values for three operations:
|
|
|
|
@itemize @bullet
|
|
@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 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
|
|
should return a list of all possible completions of the specified
|
|
string.
|
|
|
|
@item
|
|
@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 that are functions) as well as function
|
|
symbols as @var{collection}, but this is impossible. Lists as
|
|
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
|
|
@cindex querying the user
|
|
@cindex yes-or-no questions
|
|
|
|
This section describes functions used to ask the user a yes-or-no
|
|
question. The function @code{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. @code{yes-or-no-p} is suitable for
|
|
more momentous questions, since it requires three or four characters to
|
|
answer.
|
|
|
|
If either of these functions 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 or pop-up menu to ask the question. Otherwise, it
|
|
uses keyboard input. You can force use of the mouse or use of keyboard
|
|
input by binding @code{last-nonmenu-event} to a suitable value around
|
|
the call.
|
|
|
|
Strictly speaking, @code{yes-or-no-p} uses the minibuffer and
|
|
@code{y-or-n-p} does not; but it seems best to describe them together.
|
|
|
|
@defun y-or-n-p prompt
|
|
This function asks the user a question, expecting input in the echo
|
|
area. It returns @code{t} if the user types @kbd{y}, @code{nil} if the
|
|
user types @kbd{n}. This function also accepts @key{SPC} to mean yes
|
|
and @key{DEL} to mean no. It accepts @kbd{C-]} to mean ``quit'', like
|
|
@kbd{C-g}, because the question might look like a minibuffer and for
|
|
that reason the user might try to use @kbd{C-]} to get out. The answer
|
|
is a single character, with no @key{RET} needed to terminate it. Upper
|
|
and lower case are equivalent.
|
|
|
|
``Asking the question'' means printing @var{prompt} in the echo area,
|
|
followed by the string @w{@samp{(y or n) }}. If the input is not one of
|
|
the expected answers (@kbd{y}, @kbd{n}, @kbd{@key{SPC}},
|
|
@kbd{@key{DEL}}, or something that quits), the function responds
|
|
@samp{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 answers and their meanings, even @samp{y} and @samp{n}, are not
|
|
hardwired. The keymap @code{query-replace-map} specifies them.
|
|
@xref{Search and Replace}.
|
|
|
|
In the following example, the user first types @kbd{q}, which is
|
|
invalid. At the next prompt the user types @kbd{y}.
|
|
|
|
@smallexample
|
|
@group
|
|
(y-or-n-p "Do you need a lift? ")
|
|
|
|
;; @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)
|
|
---------- Echo area ----------
|
|
@end group
|
|
|
|
;; @r{If the user then types @kbd{q}, the following appears:}
|
|
|
|
@group
|
|
---------- Echo area ----------
|
|
Please answer y or n. Do you need a lift? (y or n)
|
|
---------- Echo area ----------
|
|
@end group
|
|
|
|
;; @r{When the user types a valid answer,}
|
|
;; @r{it is displayed after the question:}
|
|
|
|
@group
|
|
---------- Echo area ----------
|
|
Do you need a lift? (y or n) y
|
|
---------- Echo area ----------
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
We show successive lines of echo area messages, but only one actually
|
|
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},
|
|
@code{nil} if the user types @samp{no}. The user must type @key{RET} to
|
|
finalize the response. Upper and lower case are equivalent.
|
|
|
|
@code{yes-or-no-p} starts by displaying @var{prompt} in the echo area,
|
|
followed by @w{@samp{(yes or no) }}. The user must type one of the
|
|
expected responses; otherwise, the function responds @samp{Please answer
|
|
yes or no.}, waits about two seconds and repeats the request.
|
|
|
|
@code{yes-or-no-p} requires more work from the user than
|
|
@code{y-or-n-p} and is appropriate for more crucial decisions.
|
|
|
|
Here is an example:
|
|
|
|
@smallexample
|
|
@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{with an empty minibuffer:}
|
|
@end group
|
|
|
|
@group
|
|
---------- Buffer: minibuffer ----------
|
|
Do you really want to remove everything? (yes or no)
|
|
---------- Buffer: minibuffer ----------
|
|
@end group
|
|
@end smallexample
|
|
|
|
@noindent
|
|
If the user first types @kbd{y @key{RET}}, which is invalid because this
|
|
function demands the entire word @samp{yes}, it responds by displaying
|
|
these prompts, with a brief pause between them:
|
|
|
|
@smallexample
|
|
@group
|
|
---------- Buffer: minibuffer ----------
|
|
Please answer yes or no.
|
|
Do you really want to remove everything? (yes or no)
|
|
---------- Buffer: minibuffer ----------
|
|
@end group
|
|
@end smallexample
|
|
@end defun
|
|
|
|
@node Multiple Queries
|
|
@section Asking Multiple Y-or-N Questions
|
|
|
|
When you have a series of similar questions to ask, such as ``Do you
|
|
want to save this buffer'' for each buffer in turn, you should use
|
|
@code{map-y-or-n-p} to ask the collection of questions, rather than
|
|
asking each question individually. This gives the user certain
|
|
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 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
|
|
a function, it should expect no arguments, and should return either the
|
|
next object to ask about, or @code{nil} meaning stop asking questions.
|
|
|
|
The argument @var{prompter} specifies how to ask each question. If
|
|
@var{prompter} is a string, the question text is computed like this:
|
|
|
|
@example
|
|
(format @var{prompter} @var{object})
|
|
@end example
|
|
|
|
@noindent
|
|
where @var{object} is the next object to ask about (as obtained from
|
|
@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. 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
|
|
each object that the user says yes for. Its argument is always an
|
|
object obtained from @var{list}.
|
|
|
|
If the argument @var{help} is given, it should be a list of this form:
|
|
|
|
@example
|
|
(@var{singular} @var{plural} @var{action})
|
|
@end example
|
|
|
|
@noindent
|
|
where @var{singular} is a string containing a singular noun that
|
|
describes the objects conceptually being acted on, @var{plural} is the
|
|
corresponding plural noun, and @var{action} is a transitive verb
|
|
describing what @var{actor} does.
|
|
|
|
If you don't specify @var{help}, the default is @code{("object"
|
|
"objects" "act on")}.
|
|
|
|
Each time a question is asked, the user may enter @kbd{y}, @kbd{Y}, or
|
|
@key{SPC} to act on that object; @kbd{n}, @kbd{N}, or @key{DEL} to skip
|
|
that object; @kbd{!} to act on all following objects; @key{ESC} or
|
|
@kbd{q} to exit (skip all following objects); @kbd{.} (period) to act on
|
|
the current object and then exit; or @kbd{C-h} to get help. These are
|
|
the same answers that @code{query-replace} accepts. The keymap
|
|
@code{query-replace-map} defines their meaning for @code{map-y-or-n-p}
|
|
as well as for @code{query-replace}; see @ref{Search and Replace}.
|
|
|
|
You can use @var{action-alist} to specify additional possible answers
|
|
and what they mean. It is an alist of elements of the form
|
|
@code{(@var{char} @var{function} @var{help})}, each of which defines one
|
|
additional answer. In this element, @var{char} is a character (the
|
|
answer); @var{function} is a function of one argument (an object from
|
|
@var{list}); @var{help} is a string.
|
|
|
|
When the user responds with @var{char}, @code{map-y-or-n-p} calls
|
|
@var{function}. If it returns non-@code{nil}, the object is considered
|
|
``acted upon'', and @code{map-y-or-n-p} advances to the next object in
|
|
@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
|
|
or pop-up menu to ask the question. In this case, it does not use
|
|
keyboard input or the echo area. You can force use of the mouse or use
|
|
of keyboard input by binding @code{last-nonmenu-event} to a suitable
|
|
value around the call.
|
|
|
|
The return value of @code{map-y-or-n-p} is the number of objects acted on.
|
|
@end defun
|
|
|
|
@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 Misc
|
|
@section Minibuffer Miscellany
|
|
|
|
This section describes some basic functions and variables related to
|
|
minibuffers.
|
|
|
|
@deffn Command exit-minibuffer
|
|
This command exits the active minibuffer. It is normally bound to
|
|
keys in minibuffer local keymaps.
|
|
@end deffn
|
|
|
|
@deffn Command self-insert-and-exit
|
|
This command exits the active minibuffer after inserting the last
|
|
character typed on the keyboard (found in @code{last-command-char};
|
|
@pxref{Command Loop Info}).
|
|
@end deffn
|
|
|
|
@deffn Command previous-history-element n
|
|
This command replaces the minibuffer contents with the value of the
|
|
@var{n}th previous (older) history element.
|
|
@end deffn
|
|
|
|
@deffn Command next-history-element n
|
|
This command replaces the minibuffer contents with the value of the
|
|
@var{n}th more recent history element.
|
|
@end deffn
|
|
|
|
@deffn Command previous-matching-history-element pattern n
|
|
This command replaces the minibuffer contents with the value of the
|
|
@var{n}th previous (older) history element that matches @var{pattern} (a
|
|
regular expression).
|
|
@end deffn
|
|
|
|
@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
|
|
|
|
@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, available starting in Emacs 21, 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-contents
|
|
@tindex minibuffer-contents
|
|
This function, available starting in Emacs 21, 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 delete-minibuffer-contents
|
|
@tindex delete-minibuffer-contents
|
|
This function, available starting in Emacs 21, erases the editable
|
|
contents of the minibuffer (that is, everything except the prompt), if
|
|
a minibuffer is current. Otherwise, it erases the entire buffer.
|
|
@end defun
|
|
|
|
@defun minibuffer-prompt-width
|
|
This function returns the current display-width of the minibuffer
|
|
prompt, if a minibuffer is current. Otherwise, it returns zero.
|
|
@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
|
|
The current value of this variable is used to rebind @code{help-form}
|
|
locally inside the minibuffer (@pxref{Help Functions}).
|
|
@end defvar
|
|
|
|
@defun minibufferp &optional buffer
|
|
This function returns non-@code{nil} if @var{buffer} is a minibuffer.
|
|
If @var{buffer} is omitted, it tests the current buffer.
|
|
@end defun
|
|
|
|
@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 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
|
|
|
|
@c Emacs 19 feature
|
|
@defun window-minibuffer-p window
|
|
This function returns non-@code{nil} if @var{window} is a minibuffer window.
|
|
@end defun
|
|
|
|
It is not correct to determine whether a given window is a minibuffer by
|
|
comparing it with the result of @code{(minibuffer-window)}, because
|
|
there can be more than one minibuffer window if there is more than one
|
|
frame.
|
|
|
|
@defun minibuffer-window-active-p window
|
|
This function returns non-@code{nil} if @var{window}, assumed to be
|
|
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
|
|
|
|
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
|
|
|
|
@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 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.
|
|
|
|
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 @kbd{M-s} in the
|
|
minibuffer) uses this feature.
|
|
|
|
@defun minibuffer-message string &optional timeout
|
|
This function displays @var{string} temporarily at the end of the
|
|
minibuffer text, for @var{timeout} seconds. (The default is 2
|
|
seconds.)
|
|
@end defun
|