@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, 2002, 2003,
+@c 2004, 2005, 2006 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/commands
@node Command Loop, Keymaps, Minibuffers, Top
When you run Emacs, it enters the @dfn{editor command loop} almost
immediately. This loop reads key sequences, executes their definitions,
and displays the results. In this chapter, we describe how these things
-are done, and the subroutines that allow Lisp programs to do them.
+are done, and the subroutines that allow Lisp programs to do them.
@menu
* Command Overview:: How the command loop reads commands.
* Defining Commands:: Specifying how a function should read arguments.
* Interactive Call:: Calling a command, so that it will read arguments.
* Command Loop Info:: Variables set by the command loop for you to examine.
+* Adjusting Point:: Adjustment of point after a command.
* Input Events:: What input looks like when you read it.
* Reading Input:: How to read input events from the keyboard or mouse.
+* Special Events:: Events processed immediately and individually.
* Waiting:: Waiting for user input or elapsed time.
* Quitting:: How @kbd{C-g} works. How to catch or defer quitting.
* Prefix Command Arguments:: How the commands to set prefix args work.
The editor command loop runs this normal hook before each command. At
that time, @code{this-command} contains the command that is about to
run, and @code{last-command} describes the previous command.
-@xref{Hooks}.
+@xref{Command Loop Info}.
@end defvar
@defvar post-command-hook
The editor command loop runs this normal hook after each command
(including commands terminated prematurely by quitting or by errors),
and also when the command loop is first entered. At that time,
-@code{this-command} describes the command that just ran, and
-@code{last-command} describes the command before that. @xref{Hooks}.
+@code{this-command} refers to the command that just ran, and
+@code{last-command} refers to the command before that.
@end defvar
Quitting is suppressed while running @code{pre-command-hook} and
@code{post-command-hook}. If an error happens while executing one of
-these hooks, it terminates execution of the hook, but that is all it
-does.
+these hooks, it terminates execution of the hook, and clears the hook
+variable to @code{nil} so as to prevent an infinite loop of errors.
+
+ A request coming into the Emacs server (@pxref{Emacs Server,,,
+emacs, The GNU Emacs Manual}) runs these two hooks just as a keyboard
+command does.
@node Defining Commands
@section Defining Commands
@subsection Using @code{interactive}
This section describes how to write the @code{interactive} form that
-makes a Lisp function an interactively-callable command.
+makes a Lisp function an interactively-callable command, and how to
+examine a command's @code{interactive} form.
@defspec interactive arg-descriptor
@cindex argument descriptors
arguments. This leads quickly to an error if the command requires one
or more arguments.
-@item
-It may be a Lisp expression that is not a string; then it should be a
-form that is evaluated to get a list of arguments to pass to the
-command.
-@cindex argument evaluation form
-
-If this expression reads keyboard input (this includes using the
-minibuffer), keep in mind that the integer value of point or the mark
-before reading input may be incorrect after reading input. This is
-because the current buffer may be receiving subprocess output;
-if subprocess output arrives while the command is waiting for input,
-it could relocate point and the mark.
-
-Here's an example of what @emph{not} to do:
-
-@smallexample
-(interactive
- (list (region-beginning) (region-end)
- (read-string "Foo: " nil 'my-history)))
-@end smallexample
-
-@noindent
-Here's how to avoid the problem, by examining point and the mark only
-after reading the keyboard input:
-
-@smallexample
-(interactive
- (let ((string (read-string "Foo: " nil 'my-history)))
- (list (region-beginning) (region-end) string)))
-@end smallexample
-
@item
@cindex argument prompt
It may be a string; then its contents should consist of a code character
@end group
@end smallexample
-@cindex @samp{*} in interactive
+@cindex @samp{*} in @code{interactive}
@cindex read-only buffers in interactive
If the first character in the string is @samp{*}, then an error is
signaled if the buffer is read-only.
-@cindex @samp{@@} in interactive
+@cindex @samp{@@} in @code{interactive}
@c Emacs 19 feature
If the first character in the string is @samp{@@}, and if the key
sequence used to invoke the command includes any mouse events, then
Actual reading of arguments is controlled by the rest of the prompt
string (starting with the first character that is not @samp{*} or
@samp{@@}).
+
+@item
+It may be a Lisp expression that is not a string; then it should be a
+form that is evaluated to get a list of arguments to pass to the
+command. Usually this form will call various functions to read input
+from the user, most often through the minibuffer (@pxref{Minibuffers})
+or directly from the keyboard (@pxref{Reading Input}).
+@cindex argument evaluation form
+
+Providing point or the mark as an argument value is also common, but
+if you do this @emph{and} read input (whether using the minibuffer or
+not), be sure to get the integer values of point or the mark after
+reading. The current buffer may be receiving subprocess output; if
+subprocess output arrives while the command is waiting for input, it
+could relocate point and the mark.
+
+Here's an example of what @emph{not} to do:
+
+@smallexample
+(interactive
+ (list (region-beginning) (region-end)
+ (read-string "Foo: " nil 'my-history)))
+@end smallexample
+
+@noindent
+Here's how to avoid the problem, by examining point and the mark after
+reading the keyboard input:
+
+@smallexample
+(interactive
+ (let ((string (read-string "Foo: " nil 'my-history)))
+ (list (region-beginning) (region-end) string)))
+@end smallexample
@end itemize
+@cindex examining the @code{interactive} form
+@defun interactive-form function
+This function returns the @code{interactive} form of @var{function}.
+If @var{function} is an interactively callable function
+(@pxref{Interactive Call}), the value is the command's
+@code{interactive} form @code{(interactive @var{spec})}, which
+specifies how to compute its arguments. Otherwise, the value is
+@code{nil}. If @var{function} is a symbol, its function definition is
+used.
+@end defun
+
@node Interactive Codes
@comment node-name, next, previous, up
@subsection Code Characters for @code{interactive}
@item D
A directory name. The default is the current default directory of the
-current buffer, @code{default-directory} (@pxref{System Environment}).
+current buffer, @code{default-directory} (@pxref{File Name Expansion}).
Existing, Completion, Default, Prompt.
@item e
specification. If the key sequence that invoked the command has
@var{n} events that are lists, the @var{n}th @samp{e} provides the
@var{n}th such event. Events that are not lists, such as function keys
-and @sc{ASCII} characters, do not count where @samp{e} is concerned.
+and @acronym{ASCII} characters, do not count where @samp{e} is concerned.
@item f
A file name of an existing file (@pxref{File Names}). The default
@item F
A file name. The file need not exist. Completion, Default, Prompt.
+@item G
+A file name. The file need not exist. If the user enters just a
+directory name, then the value is just that directory name, with no
+file name within the directory added. Completion, Default, Prompt.
+
+@item i
+An irrelevant argument. This code always supplies @code{nil} as
+the argument's value. No I/O.
+
@item k
A key sequence (@pxref{Keymap Terminology}). This keeps reading events
until a command (or undefined command) is found in the current key
maps. The key sequence argument is represented as a string or vector.
The cursor does not move into the echo area. Prompt.
+If @samp{k} reads a key sequence that ends with a down-event, it also
+reads and discards the following up-event. You can get access to that
+up-event with the @samp{U} code character.
+
This kind of input is used by commands such as @code{describe-key} and
@code{global-set-key}.
@cindex marker argument
The position of the mark, as an integer. No I/O.
+@item M
+Arbitrary text, read in the minibuffer using the current buffer's input
+method, and returned as a string (@pxref{Input Methods,,, emacs, The GNU
+Emacs Manual}). Prompt.
+
@item n
-A number read with the minibuffer. If the input is not a number, the
-user is asked to try again. The prefix argument, if any, is not used.
+A number, read with the minibuffer. If the input is not a number, the
+user has to try again. @samp{n} never uses the prefix argument.
Prompt.
@item N
-@cindex raw prefix argument usage
-The numeric prefix argument; but if there is no prefix argument, read a
-number as with @kbd{n}. Requires a number. @xref{Prefix Command
-Arguments}. Prompt.
+The numeric prefix argument; but if there is no prefix argument, read
+a number as with @kbd{n}. The value is always a number. @xref{Prefix
+Command Arguments}. Prompt.
@item p
@cindex numeric prefix argument usage
No I/O.
@item P
+@cindex raw prefix argument usage
The raw prefix argument. (Note that this @samp{P} is upper case.) No
I/O.
@item s
Arbitrary text, read in the minibuffer and returned as a string
(@pxref{Text from Minibuffer}). Terminate the input with either
-@key{LFD} or @key{RET}. (@kbd{C-q} may be used to include either of
+@kbd{C-j} or @key{RET}. (@kbd{C-q} may be used to include either of
these characters in the input.) Prompt.
@item S
the string.) Other characters that normally terminate a symbol (e.g.,
parentheses and brackets) do not do so here. Prompt.
+@item U
+A key sequence or @code{nil}. Can be used after a @samp{k} or
+@samp{K} argument to get the up-event that was discarded (if any)
+after @samp{k} or @samp{K} read a down-event. If no up-event has been
+discarded, @samp{U} provides @code{nil} as the argument. No I/O.
+
@item v
-A variable declared to be a user option (i.e., satisfying the predicate
-@code{user-variable-p}). @xref{High-Level Completion}. Existing,
+A variable declared to be a user option (i.e., satisfying the
+predicate @code{user-variable-p}). This reads the variable using
+@code{read-variable}. @xref{Definition of read-variable}. Existing,
Completion, Prompt.
@item x
A Lisp object, specified with its read syntax, terminated with a
-@key{LFD} or @key{RET}. The object is not evaluated. @xref{Object from
+@kbd{C-j} or @key{RET}. The object is not evaluated. @xref{Object from
Minibuffer}. Prompt.
@item X
@cindex evaluated expression argument
-A Lisp form is read as with @kbd{x}, but then evaluated so that its
-value becomes the argument for the command. Prompt.
+A Lisp form's value. @samp{X} reads as @samp{x} does, then evaluates
+the form so that its value becomes the argument for the command.
+Prompt.
+
+@item z
+A coding system name (a symbol). If the user enters null input, the
+argument value is @code{nil}. @xref{Coding Systems}. Completion,
+Existing, Prompt.
+
+@item Z
+A coding system name (a symbol)---but only if this command has a prefix
+argument. With no prefix argument, @samp{Z} provides @code{nil} as the
+argument value. Completion, Existing, Prompt.
@end table
@node Interactive Examples
@comment node-name, next, previous, up
@subsection Examples of Using @code{interactive}
@cindex examples of using @code{interactive}
-@cindex @code{interactive}, examples of using
+@cindex @code{interactive}, examples of using
Here are some examples of @code{interactive}:
@section Interactive Call
@cindex interactive call
- After the command loop has translated a key sequence into a
-definition, it invokes that definition using the function
-@code{command-execute}. If the definition is a function that is a
-command, @code{command-execute} calls @code{call-interactively}, which
-reads the arguments and calls the command. You can also call these
-functions yourself.
+ After the command loop has translated a key sequence into a command it
+invokes that command using the function @code{command-execute}. If the
+command is a function, @code{command-execute} calls
+@code{call-interactively}, which reads the arguments and calls the
+command. You can also call these functions yourself.
-@defun commandp object
+@defun commandp object &optional for-call-interactively
Returns @code{t} if @var{object} is suitable for calling interactively;
-that is, if @var{object} is a command. Otherwise, returns @code{nil}.
+that is, if @var{object} is a command. Otherwise, returns @code{nil}.
The interactively callable objects include strings and vectors (treated
as keyboard macros), lambda expressions that contain a top-level call to
(non-@code{nil} fourth argument to @code{autoload}), and some of the
primitive functions.
-A symbol is @code{commandp} if its function definition is
-@code{commandp}.
+A symbol satisfies @code{commandp} if its function definition
+satisfies @code{commandp}. Keys and keymaps are not commands.
+Rather, they are used to look up commands (@pxref{Keymaps}).
-Keys and keymaps are not commands. Rather, they are used to look up
-commands (@pxref{Keymaps}).
+If @var{for-call-interactively} is non-@code{nil}, then
+@code{commandp} returns @code{t} only for objects that
+@code{call-interactively} could call---thus, not for keyboard macros.
See @code{documentation} in @ref{Accessing Documentation}, for a
realistic example of using @code{commandp}.
@end defun
-@defun call-interactively command &optional record-flag
+@defun call-interactively command &optional record-flag keys
This function calls the interactively callable function @var{command},
reading arguments according to its interactive calling specifications.
-An error is signaled if @var{command} is not a function or if it cannot
-be called interactively (i.e., is not a command). Note that keyboard
-macros (strings and vectors) are not accepted, even though they are
-considered commands, because they are not functions.
+It returns whatever @var{command} returns. An error is signaled if
+@var{command} is not a function or if it cannot be called
+interactively (i.e., is not a command). Note that keyboard macros
+(strings and vectors) are not accepted, even though they are
+considered commands, because they are not functions. If @var{command}
+is a symbol, then @code{call-interactively} uses its function definition.
@cindex record command history
If @var{record-flag} is non-@code{nil}, then this command and its
arguments are unconditionally added to the list @code{command-history}.
Otherwise, the command is added only if it uses the minibuffer to read
an argument. @xref{Command History}.
+
+The argument @var{keys}, if given, specifies the sequence of events to
+supply if the command inquires which events were used to invoke it.
+If @var{keys} is omitted or @code{nil}, the return value of
+@code{this-command-keys} is used. @xref{Definition of this-command-keys}.
@end defun
-@defun command-execute command &optional record-flag
+@defun command-execute command &optional record-flag keys special
@cindex keyboard macro execution
-This function executes @var{command} as an editing command. The
-argument @var{command} must satisfy the @code{commandp} predicate; i.e.,
-it must be an interactively callable function or a keyboard macro.
+This function executes @var{command}. The argument @var{command} must
+satisfy the @code{commandp} predicate; i.e., it must be an interactively
+callable function or a keyboard macro.
A string or vector as @var{command} is executed with
@code{execute-kbd-macro}. A function is passed to
-@code{call-interactively}, along with the optional @var{record-flag}.
+@code{call-interactively}, along with the optional @var{record-flag}
+and @var{keys}.
A symbol is handled by using its function definition in its place. A
symbol with an @code{autoload} definition counts as a command if it was
declared to stand for an interactively callable function. Such a
definition is handled by loading the specified library and then
rechecking the definition of the symbol.
+
+The argument @var{special}, if given, means to ignore the prefix
+argument and not clear it. This is used for executing special events
+(@pxref{Special Events}).
@end defun
@deffn Command execute-extended-command prefix-argument
@end deffn
@defun interactive-p
-This function returns @code{t} if the containing function (the one that
-called @code{interactive-p}) was called interactively, with the function
-@code{call-interactively}. (It makes no difference whether
-@code{call-interactively} was called from Lisp or directly from the
-editor command loop.) If the containing function was called by Lisp
-evaluation (or with @code{apply} or @code{funcall}), then it was not
-called interactively.
-
-The most common use of @code{interactive-p} is for deciding whether to
-print an informative message. As a special exception,
-@code{interactive-p} returns @code{nil} whenever a keyboard macro is
-being run. This is to suppress the informative messages and speed
-execution of the macro.
-
-For example:
+This function returns @code{t} if the containing function (the one
+whose code includes the call to @code{interactive-p}) was called in
+direct response to user input. This means that it was called with the
+function @code{call-interactively}, and that a keyboard macro is
+not running, and that Emacs is not running in batch mode.
+
+If the containing function was called by Lisp evaluation (or with
+@code{apply} or @code{funcall}), then it was not called interactively.
+@end defun
+
+ The most common use of @code{interactive-p} is for deciding whether
+to give the user additional visual feedback (such as by printing an
+informative message). For example:
@example
@group
+;; @r{Here's the usual way to use @code{interactive-p}.}
(defun foo ()
(interactive)
- (and (interactive-p)
- (message "foo")))
+ (when (interactive-p)
+ (message "foo")))
@result{} foo
@end group
@group
+;; @r{This function is just to illustrate the behavior.}
(defun bar ()
(interactive)
(setq foobar (list (foo) (interactive-p))))
@group
;; @r{Type @kbd{M-x bar}.}
-;; @r{This does not print anything.}
+;; @r{This does not display a message.}
@end group
@group
@result{} (nil t)
@end group
@end example
+
+ If you want to test @emph{only} whether the function was called
+using @code{call-interactively}, add an optional argument
+@code{print-message} which should be non-@code{nil} in an interactive
+call, and use the @code{interactive} spec to make sure it is
+non-@code{nil}. Here's an example:
+
+@example
+(defun foo (&optional print-message)
+ (interactive "p")
+ (when print-message
+ (message "foo")))
+@end example
+
+@noindent
+Defined in this way, the function does display the message when called
+from a keyboard macro. We use @code{"p"} because the numeric prefix
+argument is never @code{nil}.
+
+@defun called-interactively-p
+This function returns @code{t} when the calling function was called
+using @code{call-interactively}.
+
+When possible, instead of using this function, you should use the
+method in the example above; that method makes it possible for a
+caller to ``pretend'' that the function was called interactively.
@end defun
@node Command Loop Info
@section Information from the Command Loop
The editor command loop sets several Lisp variables to keep status
-records for itself and for commands that are run.
+records for itself and for commands that are run.
@defvar last-command
This variable records the name of the previous command executed by the
is a symbol with a function definition, but this is not guaranteed.
The value is copied from @code{this-command} when a command returns to
-the command loop, except when the command specifies a prefix argument
-for the following command.
+the command loop, except when the command has specified a prefix
+argument for the following command.
This variable is always local to the current terminal and cannot be
buffer-local. @xref{Multiple Displays}.
@end defvar
+@defvar real-last-command
+This variable is set up by Emacs just like @code{last-command},
+but never altered by Lisp programs.
+@end defvar
+
@defvar this-command
@cindex current command
This variable records the name of the command now being executed by
The command loop sets this variable just before running a command, and
copies its value into @code{last-command} when the command finishes
-(unless the command specifies a prefix argument for the following
+(unless the command specified a prefix argument for the following
command).
@cindex kill command repetition
(setq this-command old-this-command)))
@end example
+@noindent
+We do not bind @code{this-command} with @code{let} because that would
+restore the old value in case of error---a feature of @code{let} which
+in this case does precisely what we want to avoid.
+
+@defvar this-original-command
+This has the same value as @code{this-command} except when command
+remapping occurs (@pxref{Remapping Commands}). In that case,
+@code{this-command} gives the command actually run (the result of
+remapping), and @code{this-original-command} gives the command that
+was specified to run but remapped into another command.
+@end defvar
+
@defun this-command-keys
+@anchor{Definition of this-command-keys}
This function returns a string or vector containing the key sequence
that invoked the present command, plus any previous commands that
-generated the prefix argument for this command. The value is a string
-if all those events were characters. @xref{Input Events}.
+generated the prefix argument for this command. However, if the
+command has called @code{read-key-sequence}, it returns the last read
+key sequence. @xref{Key Sequence Input}. The value is a string if
+all events in the sequence were characters that fit in a string.
+@xref{Input Events}.
@example
@group
@end example
@end defun
+@defun this-command-keys-vector
+Like @code{this-command-keys}, except that it always returns the events
+in a vector, so you don't need to deal with the complexities of storing
+input events in a string (@pxref{Strings of Events}).
+@end defun
+
+@tindex clear-this-command-keys
+@defun clear-this-command-keys &optional keep-record
+This function empties out the table of events for
+@code{this-command-keys} to return. Unless @var{keep-record} is
+non-@code{nil}, it also empties the records that the function
+@code{recent-keys} (@pxref{Recording Input}) will subsequently return.
+This is useful after reading a password, to prevent the password from
+echoing inadvertently as part of the next command in certain cases.
+@end defun
+
@defvar last-nonmenu-event
-This variable holds the last input event read as part of a key
-sequence, not counting events resulting from mouse menus.
+This variable holds the last input event read as part of a key sequence,
+not counting events resulting from mouse menus.
-One use of this variable is to figure out a good default location to
-pop up another menu.
+One use of this variable is for telling @code{x-popup-menu} where to pop
+up a menu. It is also used internally by @code{y-or-n-p}
+(@pxref{Yes-or-No Queries}).
@end defvar
@defvar last-command-event
@end example
@noindent
-The value is 5 because that is the @sc{ASCII} code for @kbd{C-e}.
+The value is 5 because that is the @acronym{ASCII} code for @kbd{C-e}.
The alias @code{last-command-char} exists for compatibility with
Emacs version 18.
generated, but if that frame has redirected input focus to another
frame, the value is the frame to which the event was redirected.
@xref{Input Focus}.
+
+If the last event came from a keyboard macro, the value is @code{macro}.
+@end defvar
+
+@node Adjusting Point
+@section Adjusting Point After Commands
+
+ It is not easy to display a value of point in the middle of a
+sequence of text that has the @code{display}, @code{composition} or
+@code{intangible} property, or is invisible. Therefore, after a
+command finishes and returns to the command loop, if point is within
+such a sequence, the command loop normally moves point to the edge of
+the sequence.
+
+ A command can inhibit this feature by setting the variable
+@code{disable-point-adjustment}:
+
+@defvar disable-point-adjustment
+@tindex disable-point-adjustment
+If this variable is non-@code{nil} when a command returns to the
+command loop, then the command loop does not check for those text
+properties, and does not move point out of sequences that have them.
+
+The command loop sets this variable to @code{nil} before each command,
+so if a command sets it, the effect applies only to that command.
+@end defvar
+
+@defvar global-disable-point-adjustment
+@tindex global-disable-point-adjustment
+If you set this variable to a non-@code{nil} value, the feature of
+moving point out of these sequences is completely turned off.
@end defvar
@node Input Events
describes the representation and meaning of input events in detail.
@defun eventp object
-This function returns non-@code{nil} if @var{object} is an input event.
+This function returns non-@code{nil} if @var{object} is an input event
+or event type.
+
+Note that any symbol might be used as an event or an event type.
+@code{eventp} cannot distinguish whether a symbol is intended by Lisp
+code to be used as an event. Instead, it distinguishes whether the
+symbol has actually been used in an event that has been read as input in
+the current Emacs session. If a symbol has not yet been so used,
+@code{eventp} returns @code{nil}.
@end defun
@menu
* Repeat Events:: Double and triple click (or drag, or down).
* Motion Events:: Just moving the mouse, not pushing a button.
* Focus Events:: Moving the mouse between frames.
-* Misc Events:: Other events window systems can generate.
+* Misc Events:: Other events the system can generate.
* Event Examples:: Examples of the lists for mouse events.
* Classifying Events:: Finding the modifier keys in an event symbol.
Event types.
There are two kinds of input you can get from the keyboard: ordinary
keys, and function keys. Ordinary keys correspond to characters; the
-events they generate are represented in Lisp as characters. In Emacs
-versions 18 and earlier, characters were the only events. The event
-type of a character event is the character itself (an integer);
-see @ref{Classifying Events}.
+events they generate are represented in Lisp as characters. The event
+type of a character event is the character itself (an integer); see
+@ref{Classifying Events}.
@cindex modifier bits (of input character)
@cindex basic code (of input character)
An input character event consists of a @dfn{basic code} between 0 and
-255, plus any or all of these @dfn{modifier bits}:
+524287, plus any or all of these @dfn{modifier bits}:
@table @asis
@item meta
The
-@iftex
-$2^{27}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{27}}
+@end tex
+@ifnottex
2**27
-@end ifinfo
+@end ifnottex
bit in the character code indicates a character
typed with the meta key held down.
@item control
The
-@iftex
-$2^{26}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{26}}
+@end tex
+@ifnottex
2**26
-@end ifinfo
-bit in the character code indicates a non-@sc{ASCII}
+@end ifnottex
+bit in the character code indicates a non-@acronym{ASCII}
control character.
-@sc{ASCII} control characters such as @kbd{C-a} have special basic
+@sc{ascii} control characters such as @kbd{C-a} have special basic
codes of their own, so Emacs needs no special bit to indicate them.
Thus, the code for @kbd{C-a} is just 1.
-But if you type a control combination not in @sc{ASCII}, such as
+But if you type a control combination not in @acronym{ASCII}, such as
@kbd{%} with the control key, the numeric value you get is the code
for @kbd{%} plus
-@iftex
-$2^{26}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{26}}
+@end tex
+@ifnottex
2**26
-@end ifinfo
-(assuming the terminal supports non-@sc{ASCII}
+@end ifnottex
+(assuming the terminal supports non-@acronym{ASCII}
control characters).
@item shift
The
-@iftex
-$2^{25}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{25}}
+@end tex
+@ifnottex
2**25
-@end ifinfo
-bit in the character code indicates an @sc{ASCII} control
+@end ifnottex
+bit in the character code indicates an @acronym{ASCII} control
character typed with the shift key held down.
-For letters, the basic code indicates upper versus lower case; for
-digits and punctuation, the shift key selects an entirely different
-character with a different basic code. In order to keep within
-the @sc{ASCII} character set whenever possible, Emacs avoids using
-the
-@iftex
-$2^{25}$
-@end iftex
-@ifinfo
+For letters, the basic code itself indicates upper versus lower case;
+for digits and punctuation, the shift key selects an entirely different
+character with a different basic code. In order to keep within the
+@acronym{ASCII} character set whenever possible, Emacs avoids using the
+@tex
+@math{2^{25}}
+@end tex
+@ifnottex
2**25
-@end ifinfo
+@end ifnottex
bit for those characters.
-However, @sc{ASCII} provides no way to distinguish @kbd{C-A} from
+However, @acronym{ASCII} provides no way to distinguish @kbd{C-A} from
@kbd{C-a}, so Emacs uses the
-@iftex
-$2^{25}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{25}}
+@end tex
+@ifnottex
2**25
-@end ifinfo
+@end ifnottex
bit in @kbd{C-A} and not in
@kbd{C-a}.
@item hyper
The
-@iftex
-$2^{24}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{24}}
+@end tex
+@ifnottex
2**24
-@end ifinfo
+@end ifnottex
bit in the character code indicates a character
typed with the hyper key held down.
@item super
The
-@iftex
-$2^{23}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{23}}
+@end tex
+@ifnottex
2**23
-@end ifinfo
+@end ifnottex
bit in the character code indicates a character
typed with the super key held down.
@item alt
The
-@iftex
-$2^{22}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{22}}
+@end tex
+@ifnottex
2**22
-@end ifinfo
+@end ifnottex
bit in the character code indicates a character typed with
the alt key held down. (On some terminals, the key labeled @key{ALT}
is actually the meta key.)
@cindex function keys
Most keyboards also have @dfn{function keys}---keys that have names or
-symbols that are not characters. Function keys are represented in Lisp
-as symbols; the symbol's name is the function key's label, in lower
+symbols that are not characters. Function keys are represented in Emacs
+Lisp as symbols; the symbol's name is the function key's label, in lower
case. For example, pressing a key labeled @key{F1} places the symbol
@code{f1} in the input stream.
@table @asis
@item @code{backspace}, @code{tab}, @code{newline}, @code{return}, @code{delete}
-These keys correspond to common @sc{ASCII} control characters that have
+These keys correspond to common @acronym{ASCII} control characters that have
special keys on most keyboards.
-In @sc{ASCII}, @kbd{C-i} and @key{TAB} are the same character. If the
+In @acronym{ASCII}, @kbd{C-i} and @key{TAB} are the same character. If the
terminal can distinguish between them, Emacs conveys the distinction to
Lisp programs by representing the former as the integer 9, and the
latter as the symbol @code{tab}.
symbols in this group. The function @code{read-char} likewise converts
these events into characters.
-In @sc{ASCII}, @key{BS} is really @kbd{C-h}. But @code{backspace}
+In @acronym{ASCII}, @key{BS} is really @kbd{C-h}. But @code{backspace}
converts into the character code 127 (@key{DEL}), not into code 8
(@key{BS}). This is what most users prefer.
@item @code{kp-f1}, @code{kp-f2}, @code{kp-f3}, @code{kp-f4}
Keypad PF keys.
@item @code{kp-home}, @code{kp-left}, @code{kp-up}, @code{kp-right}, @code{kp-down}
-Keypad arrow keys. Emacs normally translates these
-into the non-keypad keys @code{home}, @code{left}, @dots{}
+Keypad arrow keys. Emacs normally translates these into the
+corresponding non-keypad keys @code{home}, @code{left}, @dots{}
@item @code{kp-prior}, @code{kp-next}, @code{kp-end}, @code{kp-begin}, @code{kp-insert}, @code{kp-delete}
Additional keypad duplicates of keys ordinarily found elsewhere. Emacs
normally translates these into the like-named non-keypad keys.
@cindex mouse click event
When the user presses a mouse button and releases it at the same
-location, that generates a @dfn{click} event. Mouse click events have
-this form:
+location, that generates a @dfn{click} event. All mouse click event
+share the same format:
@example
-(@var{event-type}
- (@var{window} @var{buffer-pos} (@var{x} . @var{y}) @var{timestamp})
- @var{click-count})
+(@var{event-type} @var{position} @var{click-count})
@end example
-Here is what the elements normally mean:
-
@table @asis
@item @var{event-type}
This is a symbol that indicates which mouse button was used. It is
@code{mouse-1}, that binding would apply to all events whose
@var{event-type} is @code{mouse-1}.
+@item @var{position}
+This is the position where the mouse click occurred. The actual
+format of @var{position} depends on what part of a window was clicked
+on. The various formats are described below.
+
+@item @var{click-count}
+This is the number of rapid repeated presses so far of the same mouse
+button. @xref{Repeat Events}.
+@end table
+
+For mouse click events in the text area, mode line, header line, or in
+the marginal areas, @var{position} has this form:
+
+@example
+(@var{window} @var{pos-or-area} (@var{x} . @var{y}) @var{timestamp}
+ @var{object} @var{text-pos} (@var{col} . @var{row})
+ @var{image} (@var{dx} . @var{dy}) (@var{width} . @var{height}))
+@end example
+
+@table @asis
@item @var{window}
This is the window in which the click occurred.
+@item @var{pos-or-area}
+This is the buffer position of the character clicked on in the text
+area, or if clicked outside the text area, it is the window area in
+which the click occurred. It is one of the symbols @code{mode-line},
+@code{header-line}, @code{vertical-line}, @code{left-margin},
+@code{right-margin}, @code{left-fringe}, or @code{right-fringe}.
+
@item @var{x}, @var{y}
These are the pixel-denominated coordinates of the click, relative to
the top left corner of @var{window}, which is @code{(0 . 0)}.
-
-@item @var{buffer-pos}
-This is the buffer position of the character clicked on.
+For the mode or header line, @var{y} does not have meaningful data.
+For the vertical line, @var{x} does not have meaningful data.
@item @var{timestamp}
-This is the time at which the event occurred, in milliseconds. (Since
-this value wraps around the entire range of Emacs Lisp integers in about
-five hours, it is useful only for relating the times of nearby events.)
-
-@item @var{click-count}
-This is the number of rapid repeated presses so far of the same mouse
-button. @xref{Repeat Events}.
+This is the time at which the event occurred, in milliseconds.
+
+@item @var{object}
+This is the object on which the click occurred. It is either
+@code{nil} if there is no string property, or it has the form
+(@var{string} . @var{string-pos}) when there is a string-type text
+property at the click position.
+
+@item @var{string}
+This is the string on which the click occurred, including any
+properties.
+
+@item @var{string-pos}
+This is the position in the string on which the click occurred,
+relevant if properties at the click need to be looked up.
+
+@item @var{text-pos}
+For clicks on a marginal area or on a fringe, this is the buffer
+position of the first visible character in the corresponding line in
+the window. For other events, it is the current buffer position in
+the window.
+
+@item @var{col}, @var{row}
+These are the actual coordinates of the glyph under the @var{x},
+@var{y} position, possibly padded with default character width
+glyphs if @var{x} is beyond the last glyph on the line.
+
+@item @var{image}
+This is the image object on which the click occurred. It is either
+@code{nil} if there is no image at the position clicked on, or it is
+an image object as returned by @code{find-image} if click was in an image.
+
+@item @var{dx}, @var{dy}
+These are the pixel-denominated coordinates of the click, relative to
+the top left corner of @var{object}, which is @code{(0 . 0)}. If
+@var{object} is @code{nil}, the coordinates are relative to the top
+left corner of the character glyph clicked on.
@end table
-The meanings of @var{buffer-pos}, @var{x} and @var{y} are somewhat
-different when the event location is in a special part of the screen,
-such as the mode line or a scroll bar.
+For mouse clicks on a scroll-bar, @var{position} has this form:
+
+@example
+(@var{window} @var{area} (@var{portion} . @var{whole}) @var{timestamp} @var{part})
+@end example
+
+@table @asis
+@item @var{window}
+This is the window whose scroll-bar was clicked on.
+
+@item @var{area}
+This is the scroll bar where the click occurred. It is one of the
+symbols @code{vertical-scroll-bar} or @code{horizontal-scroll-bar}.
-If the location is in a scroll bar, then @var{buffer-pos} is the symbol
-@code{vertical-scroll-bar} or @code{horizontal-scroll-bar}, and the pair
-@code{(@var{x} . @var{y})} is replaced with a pair @code{(@var{portion}
-. @var{whole})}, where @var{portion} is the distance of the click from
-the top or left end of the scroll bar, and @var{whole} is the length of
-the entire scroll bar.
+@item @var{portion}
+This is the distance of the click from the top or left end of
+the scroll bar.
-If the position is on a mode line or the vertical line separating
-@var{window} from its neighbor to the right, then @var{buffer-pos} is
-the symbol @code{mode-line} or @code{vertical-line}. For the mode line,
-@var{y} does not have meaningful data. For the vertical line, @var{x}
-does not have meaningful data.
+@item @var{whole}
+This is the length of the entire scroll bar.
+
+@item @var{timestamp}
+This is the time at which the event occurred, in milliseconds.
+
+@item @var{part}
+This is the part of the scroll-bar which was clicked on. It is one
+of the symbols @code{above-handle}, @code{handle}, @code{below-handle},
+@code{up}, @code{down}, @code{top}, @code{bottom}, and @code{end-scroll}.
+@end table
In one special case, @var{buffer-pos} is a list containing a symbol (one
of the symbols listed above) instead of just the symbol. This happens
@end example
For a drag event, the name of the symbol @var{event-type} contains the
-prefix @samp{drag-}. The second and third elements of the event give
-the starting and ending position of the drag. Aside from that, the data
-have the same meanings as in a click event (@pxref{Click Events}). You
-can access the second element of any mouse event in the same way, with
-no need to distinguish drag events from others.
+prefix @samp{drag-}. For example, dragging the mouse with button 2 held
+down generates a @code{drag-mouse-2} event. The second and third
+elements of the event give the starting and ending position of the drag.
+Aside from that, the data have the same meanings as in a click event
+(@pxref{Click Events}). You can access the second element of any mouse
+event in the same way, with no need to distinguish drag events from
+others.
The @samp{drag-} prefix follows the modifier key prefixes such as
@samp{C-} and @samp{M-}.
name contains the prefix @samp{down-}. The @samp{down-} prefix follows
modifier key prefixes such as @samp{C-} and @samp{M-}.
-The function @code{read-key-sequence}, and therefore the Emacs command
-loop as well, ignore any button-down events that don't have command
-bindings. This means that you need not worry about defining button-down
-events unless you want them to do something. The usual reason to define
-a button-down event is so that you can track mouse motion (by reading
-motion events) until the button is released. @xref{Motion Events}.
+The function @code{read-key-sequence} ignores any button-down events
+that don't have command bindings; therefore, the Emacs command loop
+ignores them too. This means that you need not worry about defining
+button-down events unless you want them to do something. The usual
+reason to define a button-down event is so that you can track mouse
+motion (by reading motion events) until the button is released.
+@xref{Motion Events}.
@node Repeat Events
@subsection Repeat Events
@cindex repeat events
@cindex double-click events
@cindex triple-click events
+@cindex mouse events, repeated
If you press the same mouse button more than once in quick succession
without moving the mouse, Emacs generates special @dfn{repeat} mouse
@key{meta} held down comes to the Lisp program as
@code{M-double-mouse-2}. If a double-click event has no binding, the
binding of the corresponding ordinary click event is used to execute
-it. Thus, you need not pay attention to the double click feature
+it. Thus, you need not pay attention to the double click feature
unless you really want to.
When the user performs a double click, Emacs generates first an ordinary
(not a repeat event), the value is 1.
@end defun
-@defvar double-click-time
+@defopt double-click-fuzz
To generate repeat events, successive mouse button presses must be at
-the same screen position, and the number of milliseconds between
+approximately the same screen position. The value of
+@code{double-click-fuzz} specifies the maximum number of pixels the
+mouse may be moved (horizontally or vertically) between two successive
+clicks to make a double-click.
+
+This variable is also the threshold for motion of the mouse to count
+as a drag.
+@end defopt
+
+@defopt double-click-time
+To generate repeat events, the number of milliseconds between
successive button presses must be less than the value of
@code{double-click-time}. Setting @code{double-click-time} to
@code{nil} disables multi-click detection entirely. Setting it to
@code{t} removes the time limit; Emacs then detects multi-clicks by
position only.
-@end defvar
+@end defopt
@node Motion Events
@subsection Motion Events
represented by lists that look like this:
@example
-(mouse-movement
- (@var{window} @var{buffer-pos} (@var{x} . @var{y}) @var{timestamp}))
+(mouse-movement (@var{window} @var{buffer-pos} (@var{x} . @var{y}) @var{timestamp}))
@end example
The second element of the list describes the current position of the
The special form @code{track-mouse} enables generation of motion events
within its body. Outside of @code{track-mouse} forms, Emacs does not
generate events for mere motion of the mouse, and these events do not
-appear.
-
-@defspec track-mouse body@dots{}
-This special form executes @var{body}, with generation of mouse motion
-events enabled. Typically @var{body} would use @code{read-event}
-to read the motion events and modify the display accordingly.
-
-When the user releases the button, that generates a click event.
-Typically, @var{body} should return when it sees the click event, and
-discard that event.
-@end defspec
+appear. @xref{Mouse Tracking}.
@node Focus Events
@subsection Focus Events
sequence, and not within it.
@node Misc Events
-@subsection Miscellaneous Window System Events
+@subsection Miscellaneous System Events
-A few other event types represent occurrences within the window system.
+A few other event types represent occurrences within the system.
@table @code
@cindex @code{delete-frame} event
This kind of event indicates that the user deiconified @var{frame} using
the window manager. Its standard definition is @code{ignore}; since the
frame has already been made visible, Emacs has no work to do.
+
+@cindex @code{wheel-up} event
+@cindex @code{wheel-down} event
+@item (wheel-up @var{position})
+@item (wheel-down @var{position})
+These kinds of event are generated by moving a mouse wheel. Their
+usual meaning is a kind of scroll or zoom.
+
+The element @var{position} is a list describing the position of the
+event, in the same format as used in a mouse-click event.
+
+This kind of event is generated only on some kinds of systems. On some
+systems, @code{mouse-4} and @code{mouse-5} are used instead. For
+portable code, use the variables @code{mouse-wheel-up-event} and
+@code{mouse-wheel-down-event} defined in @file{mwheel.el} to determine
+what event types to expect for the mouse wheel.
+
+@cindex @code{drag-n-drop} event
+@item (drag-n-drop @var{position} @var{files})
+This kind of event is generated when a group of files is
+selected in an application outside of Emacs, and then dragged and
+dropped onto an Emacs frame.
+
+The element @var{position} is a list describing the position of the
+event, in the same format as used in a mouse-click event, and
+@var{files} is the list of file names that were dragged and dropped.
+The usual way to handle this event is by visiting these files.
+
+This kind of event is generated, at present, only on some kinds of
+systems.
+
+@cindex @code{help-echo} event
+@item help-echo
+This kind of event is generated when a mouse pointer moves onto a
+portion of buffer text which has a @code{help-echo} text property.
+The generated event has this form:
+
+@example
+(help-echo @var{frame} @var{help} @var{window} @var{object} @var{pos})
+@end example
+
+@noindent
+The precise meaning of the event parameters and the way these
+parameters are used to display the help-echo text are described in
+@ref{Text help-echo}.
+
+@cindex @code{usr1-signal} event
+@cindex @code{usr2-signal} event
+@item usr1-signal
+@itemx usr2-signal
+These events are generated when the Emacs process receives the signals
+@code{SIGUSR1} and @code{SIGUSR2}. They contain no additional data
+because signals do not carry additional information.
@end table
If one of these events arrives in the middle of a key sequence---that
modifiers are symbols; they include @code{shift}, @code{control},
@code{meta}, @code{alt}, @code{hyper} and @code{super}. In addition,
the modifiers list of a mouse event symbol always contains one of
-@code{click}, @code{drag}, and @code{down}.
+@code{click}, @code{drag}, and @code{down}. For double or triple
+events, it also contains @code{double} or @code{triple}.
-The argument @var{event} may be an entire event object, or just an event
-type.
+The argument @var{event} may be an entire event object, or just an
+event type. If @var{event} is a symbol that has never been used in an
+event that has been read as input in the current Emacs session, then
+@code{event-modifiers} can return @code{nil}, even when @var{event}
+actually has modifiers.
Here are some examples:
@example
(event-modifiers ?a)
@result{} nil
+(event-modifiers ?A)
+ @result{} (shift)
(event-modifiers ?\C-a)
@result{} (control)
(event-modifiers ?\C-%)
@defun event-basic-type event
This function returns the key or mouse button that @var{event}
-describes, with all modifiers removed. For example:
+describes, with all modifiers removed. The @var{event} argument is as
+in @code{event-modifiers}. For example:
@example
(event-basic-type ?a)
@defun event-convert-list list
This function converts a list of modifier names and a basic event type
-to an event type which specifies all of them. For example,
+to an event type which specifies all of them. The basic event type
+must be the last element of the list. For example,
@example
(event-convert-list '(control ?a))
@node Accessing Events
@subsection Accessing Events
+@cindex mouse events, accessing the data
+@cindex accessing data of mouse events
This section describes convenient functions for accessing the data in
a mouse button or motion event.
These two functions return the starting or ending position of a
-mouse-button event. The position is a list of this form:
+mouse-button event, as a list of this form:
@example
-(@var{window} @var{buffer-position} (@var{x} . @var{y}) @var{timestamp})
+(@var{window} @var{pos-or-area} (@var{x} . @var{y}) @var{timestamp}
+ @var{object} @var{text-pos} (@var{col} . @var{row})
+ @var{image} (@var{dx} . @var{dy}) (@var{width} . @var{height}))
@end example
@defun event-start event
position such events have.
@end defun
- These five functions take a position as described above, and return
-various parts of it.
+@cindex mouse position list, accessing
+ These functions take a position list as described above, and
+return various parts of it.
@defun posn-window position
Return the window that @var{position} is in.
@end defun
+@defun posn-area position
+Return the window area recorded in @var{position}. It returns @code{nil}
+when the event occurred in the text area of the window; otherwise, it
+is a symbol identifying the area in which the event occurred.
+@end defun
+
@defun posn-point position
-Return the buffer position in @var{position}. This is an integer.
+Return the buffer position in @var{position}. When the event occurred
+in the text area of the window, in a marginal area, or on a fringe,
+this is an integer specifying a buffer position. Otherwise, the value
+is undefined.
@end defun
@defun posn-x-y position
-Return the pixel-based x and y coordinates in @var{position}, as a cons
-cell @code{(@var{x} . @var{y})}.
+Return the pixel-based x and y coordinates in @var{position}, as a
+cons cell @code{(@var{x} . @var{y})}. These coordinates are relative
+to the window given by @code{posn-window}.
+
+This example shows how to convert these window-relative coordinates
+into frame-relative coordinates:
+
+@example
+(defun frame-relative-coordinates (position)
+ "Return frame-relative coordinates from POSITION."
+ (let* ((x-y (posn-x-y position))
+ (window (posn-window position))
+ (edges (window-inside-pixel-edges window)))
+ (cons (+ (car x-y) (car edges))
+ (+ (cdr x-y) (cadr edges)))))
+@end example
@end defun
@defun posn-col-row position
-Return the row and column (in units of characters) of @var{position}, as
-a cons cell @code{(@var{col} . @var{row})}. These are computed from the
-@var{x} and @var{y} values actually found in @var{position}.
+Return the row and column (in units of the frame's default character
+height and width) of @var{position}, as a cons cell @code{(@var{col} .
+@var{row})}. These are computed from the @var{x} and @var{y} values
+actually found in @var{position}.
@end defun
+@defun posn-actual-col-row position
+Return the actual row and column in @var{position}, as a cons cell
+@code{(@var{col} . @var{row})}. The values are the actual row number
+in the window, and the actual character number in that row. It returns
+@code{nil} if @var{position} does not include actual positions values.
+You can use @code{posn-col-row} to get approximate values.
+@end defun
+
+@defun posn-string position
+Return the string object in @var{position}, either @code{nil}, or a
+cons cell @code{(@var{string} . @var{string-pos})}.
+@end defun
+
+@defun posn-image position
+Return the image object in @var{position}, either @code{nil}, or an
+image @code{(image ...)}.
+@end defun
+
+@defun posn-object position
+Return the image or string object in @var{position}, either
+@code{nil}, an image @code{(image ...)}, or a cons cell
+@code{(@var{string} . @var{string-pos})}.
+@end defun
+
+@defun posn-object-x-y position
+Return the pixel-based x and y coordinates relative to the upper left
+corner of the object in @var{position} as a cons cell @code{(@var{dx}
+. @var{dy})}. If the @var{position} is a buffer position, return the
+relative position in the character at that position.
+@end defun
+
+@defun posn-object-width-height position
+Return the pixel width and height of the object in @var{position} as a
+cons cell @code{(@var{width} . @var{height})}. If the @var{position}
+is a buffer position, return the size of the character at that position.
+@end defun
+
+@cindex mouse event, timestamp
+@cindex timestamp of a mouse event
@defun posn-timestamp position
-Return the timestamp in @var{position}.
+Return the timestamp in @var{position}. This is the time at which the
+event occurred, in milliseconds.
+@end defun
+
+ These functions compute a position list given particular buffer
+position or screen position. You can access the data in this position
+list with the functions described above.
+
+@defun posn-at-point &optional pos window
+This function returns a position list for position @var{pos} in
+@var{window}. @var{pos} defaults to point in @var{window};
+@var{window} defaults to the selected window.
+
+@code{posn-at-point} returns @code{nil} if @var{pos} is not visible in
+@var{window}.
@end defun
+@defun posn-at-x-y x y &optional frame-or-window whole
+This function returns position information corresponding to pixel
+coordinates @var{x} and @var{y} in a specified frame or window,
+@var{frame-or-window}, which defaults to the selected window.
+The coordinates @var{x} and @var{y} are relative to the
+frame or window used.
+If @var{whole} is @code{nil}, the coordinates are relative
+to the window text area, otherwise they are relative to
+the entire window area including scroll bars, margins and fringes.
+@end defun
+
+ These functions are useful for decoding scroll bar events.
+
@defun scroll-bar-event-ratio event
This function returns the fractional vertical position of a scroll bar
event within the scroll bar. The value is a cons cell
(- (point-max) (point-min))))
@end example
-Recall that scroll bar events have two integers forming ratio in place
+Recall that scroll bar events have two integers forming a ratio, in place
of a pair of x and y coordinates.
@end defun
@node Strings of Events
@subsection Putting Keyboard Events in Strings
+@cindex keyboard events in strings
+@cindex strings with keyboard events
In most of the places where strings are used, we conceptualize the
string as containing text characters---the same kind of characters found
in buffers or files. Occasionally Lisp programs use strings that
conceptually contain keyboard characters; for example, they may be key
-sequences or keyboard macro definitions. There are special rules for
-how to put keyboard characters into a string, because they are not
-limited to the range of 0 to 255 as text characters are.
-
- A keyboard character typed using the @key{META} key is called a
-@dfn{meta character}. The numeric code for such an event includes the
-@iftex
-$2^{27}$
-@end iftex
-@ifinfo
+sequences or keyboard macro definitions. However, storing keyboard
+characters in a string is a complex matter, for reasons of historical
+compatibility, and it is not always possible.
+
+ We recommend that new programs avoid dealing with these complexities
+by not storing keyboard events in strings. Here is how to do that:
+
+@itemize @bullet
+@item
+Use vectors instead of strings for key sequences, when you plan to use
+them for anything other than as arguments to @code{lookup-key} and
+@code{define-key}. For example, you can use
+@code{read-key-sequence-vector} instead of @code{read-key-sequence}, and
+@code{this-command-keys-vector} instead of @code{this-command-keys}.
+
+@item
+Use vectors to write key sequence constants containing meta characters,
+even when passing them directly to @code{define-key}.
+
+@item
+When you have to look at the contents of a key sequence that might be a
+string, use @code{listify-key-sequence} (@pxref{Event Input Misc})
+first, to convert it to a list.
+@end itemize
+
+ The complexities stem from the modifier bits that keyboard input
+characters can include. Aside from the Meta modifier, none of these
+modifier bits can be included in a string, and the Meta modifier is
+allowed only in special cases.
+
+ The earliest GNU Emacs versions represented meta characters as codes
+in the range of 128 to 255. At that time, the basic character codes
+ranged from 0 to 127, so all keyboard character codes did fit in a
+string. Many Lisp programs used @samp{\M-} in string constants to stand
+for meta characters, especially in arguments to @code{define-key} and
+similar functions, and key sequences and sequences of events were always
+represented as strings.
+
+ When we added support for larger basic character codes beyond 127, and
+additional modifier bits, we had to change the representation of meta
+characters. Now the flag that represents the Meta modifier in a
+character is
+@tex
+@math{2^{27}}
+@end tex
+@ifnottex
2**27
-@end ifinfo
-bit; it does not even come close to fitting in a string. However,
-earlier Emacs versions used a different representation for these
-characters, which gave them codes in the range of 128 to 255. That did
-fit in a string, and many Lisp programs contain string constants that
-use @samp{\M-} to express meta characters, especially as the argument to
-@code{define-key} and similar functions.
-
- We provide backward compatibility to run those programs using special
-rules for how to put a keyboard character event in a string. Here are
-the rules:
+@end ifnottex
+and such numbers cannot be included in a string.
+
+ To support programs with @samp{\M-} in string constants, there are
+special rules for including certain meta characters in a string.
+Here are the rules for interpreting a string as a sequence of input
+characters:
@itemize @bullet
@item
@item
The meta variants of those characters, with codes in the range of
-@iftex
-$2^{27}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{27}}
+@end tex
+@ifnottex
2**27
-@end ifinfo
+@end ifnottex
to
-@iftex
-$2^{27} + 127$,
-@end iftex
-@ifinfo
+@tex
+@math{2^{27} + 127},
+@end tex
+@ifnottex
2**27+127,
-@end ifinfo
+@end ifnottex
can also go in the string, but you must change their
numeric values. You must set the
-@iftex
-$2^{7}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{7}}
+@end tex
+@ifnottex
2**7
-@end ifinfo
+@end ifnottex
bit instead of the
-@iftex
-$2^{27}$
-@end iftex
-@ifinfo
+@tex
+@math{2^{27}}
+@end tex
+@ifnottex
2**27
-@end ifinfo
-bit,
-resulting in a value between 128 and 255.
+@end ifnottex
+bit, resulting in a value between 128 and 255. Only a unibyte string
+can include these codes.
+
+@item
+Non-@acronym{ASCII} characters above 256 can be included in a multibyte string.
@item
Other keyboard character events cannot fit in a string. This includes
keyboard events in the range of 128 to 255.
@end itemize
- Functions such as @code{read-key-sequence} that can construct strings
-of keyboard input characters follow these rules. They construct vectors
+ Functions such as @code{read-key-sequence} that construct strings of
+keyboard input characters follow these rules: they construct vectors
instead of strings, when the events won't fit in a string.
When you use the read syntax @samp{\M-} in a string, it produces a
meta events in strings work consistently regardless of how they get into
the strings.
- The reason we changed the representation of meta characters as
-keyboard events is to make room for basic character codes beyond 127,
-and support meta variants of such larger character codes.
-
- New programs can avoid dealing with these special compatibility rules
-by using vectors instead of strings for key sequences when there is any
-possibility that they might contain meta characters, and by using
-@code{listify-key-sequence} to access a string of events.
-
-@defun listify-key-sequence key
-This function converts the string or vector @var{key} to a list of
-events, which you can put in @code{unread-command-events}. Converting a
-vector is simple, but converting a string is tricky because of the
-special representation used for meta characters in a string.
-@end defun
+ However, most programs would do well to avoid these issues by
+following the recommendations at the beginning of this section.
@node Reading Input
@section Reading Input
- The editor command loop reads keyboard input using the function
+ The editor command loop reads key sequences using the function
@code{read-key-sequence}, which uses @code{read-event}. These and other
-functions for keyboard input are also available for use in Lisp
-programs. See also @code{momentary-string-display} in @ref{Temporary
-Displays}, and @code{sit-for} in @ref{Waiting}. @xref{Terminal Input},
-for functions and variables for controlling terminal input modes and
+functions for event input are also available for use in Lisp programs.
+See also @code{momentary-string-display} in @ref{Temporary Displays},
+and @code{sit-for} in @ref{Waiting}. @xref{Terminal Input}, for
+functions and variables for controlling terminal input modes and
debugging terminal input. @xref{Translating Input}, for features you
can use for translating or modifying input events while reading them.
@menu
* Key Sequence Input:: How to read one key sequence.
* Reading One Event:: How to read just one event.
+* Invoking the Input Method:: How reading an event uses the input method.
* Quoted Character Input:: Asking the user to specify a character.
* Event Input Misc:: How to reread or throw away input events.
@end menu
@code{read-key-sequence}. Lisp programs can also call this function;
for example, @code{describe-key} uses it to read the key to describe.
-@defun read-key-sequence prompt
+@defun read-key-sequence prompt &optional continue-echo dont-downcase-last switch-frame-ok command-loop
@cindex key sequence
This function reads a key sequence and returns it as a string or
-vector. It keeps reading events until it has accumulated a full key
+vector. It keeps reading events until it has accumulated a complete key
sequence; that is, enough to specify a non-prefix command using the
-currently active keymaps.
+currently active keymaps. (Remember that a key sequence that starts
+with a mouse event is read using the keymaps of the buffer in the
+window that the mouse was in, not the current buffer.)
If the events are all characters and all can fit in a string, then
@code{read-key-sequence} returns a string (@pxref{Strings of Events}).
events---characters, symbols, and lists. The elements of the string or
vector are the events in the key sequence.
-The function @code{read-key-sequence} suppresses quitting: @kbd{C-g}
-typed while reading with this function works like any other character,
-and does not set @code{quit-flag}. @xref{Quitting}.
+Reading a key sequence includes translating the events in various
+ways. @xref{Translating Input}.
+
+The argument @var{prompt} is either a string to be displayed in the
+echo area as a prompt, or @code{nil}, meaning not to display a prompt.
+The argument @var{continue-echo}, if non-@code{nil}, means to echo
+this key as a continuation of the previous key.
+
+Normally any upper case event is converted to lower case if the
+original event is undefined and the lower case equivalent is defined.
+The argument @var{dont-downcase-last}, if non-@code{nil}, means do not
+convert the last event to lower case. This is appropriate for reading
+a key sequence to be defined.
+
+The argument @var{switch-frame-ok}, if non-@code{nil}, means that this
+function should process a @code{switch-frame} event if the user
+switches frames before typing anything. If the user switches frames
+in the middle of a key sequence, or at the start of the sequence but
+@var{switch-frame-ok} is @code{nil}, then the event will be put off
+until after the current key sequence.
-The argument @var{prompt} is either a string to be displayed in the echo
-area as a prompt, or @code{nil}, meaning not to display a prompt.
+The argument @var{command-loop}, if non-@code{nil}, means that this
+key sequence is being read by something that will read commands one
+after another. It should be @code{nil} if the caller will read just
+one key sequence.
-In the example below, the prompt @samp{?} is displayed in the echo area,
-and the user types @kbd{C-x C-f}.
+In the following example, Emacs displays the prompt @samp{?} in the
+echo area, and then the user types @kbd{C-x C-f}.
@example
(read-key-sequence "?")
@result{} "^X^F"
@end group
@end example
+
+The function @code{read-key-sequence} suppresses quitting: @kbd{C-g}
+typed while reading with this function works like any other character,
+and does not set @code{quit-flag}. @xref{Quitting}.
@end defun
-@defvar num-input-keys
-@c Emacs 19 feature
-This variable's value is the number of key sequences processed so far in
-this Emacs session. This includes key sequences read from the terminal
-and key sequences read from keyboard macros being executed.
-@end defvar
+@defun read-key-sequence-vector prompt &optional continue-echo dont-downcase-last switch-frame-ok command-loop
+This is like @code{read-key-sequence} except that it always
+returns the key sequence as a vector, never as a string.
+@xref{Strings of Events}.
+@end defun
@cindex upper case key sequence
@cindex downcasing in @code{lookup-key}
-If an input character is an upper-case letter and has no key binding,
-but its lower-case equivalent has one, then @code{read-key-sequence}
-converts the character to lower case. Note that @code{lookup-key} does
-not perform case conversion in this way.
+If an input character is upper-case (or has the shift modifier) and
+has no key binding, but its lower-case equivalent has one, then
+@code{read-key-sequence} converts the character to lower case. Note
+that @code{lookup-key} does not perform case conversion in this way.
The function @code{read-key-sequence} also transforms some mouse events.
It converts unbound drag events into click events, and discards unbound
miscellaneous window events so that they never appear in a key sequence
with any other events.
+@cindex @code{header-line} prefix key
+@cindex @code{mode-line} prefix key
+@cindex @code{vertical-line} prefix key
+@cindex @code{horizontal-scroll-bar} prefix key
+@cindex @code{vertical-scroll-bar} prefix key
+@cindex @code{menu-bar} prefix key
+@cindex mouse events, in special parts of frame
When mouse events occur in special parts of a window, such as a mode
line or a scroll bar, the event type shows nothing special---it is the
same symbol that would normally represent that combination of mouse
-button and modifier keys. The information about the window part is
-kept elsewhere in the event---in the coordinates. But
+button and modifier keys. The information about the window part is kept
+elsewhere in the event---in the coordinates. But
@code{read-key-sequence} translates this information into imaginary
-prefix keys, all of which are symbols: @code{mode-line},
-@code{vertical-line}, @code{horizontal-scroll-bar} and
-@code{vertical-scroll-bar}.
-
-You can define meanings for mouse clicks in special window parts by
-defining key sequences using these imaginary prefix keys.
+``prefix keys'', all of which are symbols: @code{header-line},
+@code{horizontal-scroll-bar}, @code{menu-bar}, @code{mode-line},
+@code{vertical-line}, and @code{vertical-scroll-bar}. You can define
+meanings for mouse clicks in special window parts by defining key
+sequences using these imaginary prefix keys.
For example, if you call @code{read-key-sequence} and then click the
mouse on the window's mode line, you get two events, like this:
(40 . 63) 5959987))]
@end example
+@defvar num-input-keys
+@c Emacs 19 feature
+This variable's value is the number of key sequences processed so far in
+this Emacs session. This includes key sequences read from the terminal
+and key sequences read from keyboard macros being executed.
+@end defvar
+
@node Reading One Event
@subsection Reading One Event
+@cindex reading a single event
+@cindex event, reading only one
The lowest level functions for command input are those that read a
single event.
-@defun read-event
+None of the three functions below suppresses quitting.
+
+@defun read-event &optional prompt inherit-input-method
This function reads and returns the next event of command input, waiting
if necessary until an event is available. Events can come directly from
the user or from a keyboard macro.
-The function @code{read-event} does not display any message to indicate
-it is waiting for input; use @code{message} first, if you wish to
-display one. If you have not displayed a message, @code{read-event}
-prompts by echoing: it displays descriptions of the events that led to
-or were read by the current command. @xref{The Echo Area}.
+If the optional argument @var{prompt} is non-@code{nil}, it should be a
+string to display in the echo area as a prompt. Otherwise,
+@code{read-event} does not display any message to indicate it is waiting
+for input; instead, it prompts by echoing: it displays descriptions of
+the events that led to or were read by the current command. @xref{The
+Echo Area}.
+
+If @var{inherit-input-method} is non-@code{nil}, then the current input
+method (if any) is employed to make it possible to enter a
+non-@acronym{ASCII} character. Otherwise, input method handling is disabled
+for reading this event.
If @code{cursor-in-echo-area} is non-@code{nil}, then @code{read-event}
moves the cursor temporarily to the echo area, to the end of any message
displayed there. Otherwise @code{read-event} does not move the cursor.
+If @code{read-event} gets an event that is defined as a help character,
+then in some cases @code{read-event} processes the event directly without
+returning. @xref{Help Functions}. Certain other events, called
+@dfn{special events}, are also processed directly within
+@code{read-event} (@pxref{Special Events}).
+
Here is what happens if you call @code{read-event} and then press the
right-arrow function key:
@end example
@end defun
-@defun read-char
-This function reads and returns a character of command input. It
-discards any events that are not characters, until it gets a character.
+@defun read-char &optional prompt inherit-input-method
+This function reads and returns a character of command input. If the
+user generates an event which is not a character (i.e. a mouse click or
+function key event), @code{read-char} signals an error. The arguments
+work as in @code{read-event}.
-In the first example, the user types the character @kbd{1} (@sc{ASCII}
+In the first example, the user types the character @kbd{1} (@acronym{ASCII}
code 49). The second example shows a keyboard macro definition that
calls @code{read-char} from the minibuffer using @code{eval-expression}.
@code{read-char} reads the keyboard macro's very next character, which
@end example
@end defun
+@defun read-char-exclusive &optional prompt inherit-input-method
+This function reads and returns a character of command input. If the
+user generates an event which is not a character,
+@code{read-char-exclusive} ignores it and reads another event, until it
+gets a character. The arguments work as in @code{read-event}.
+@end defun
+
+@defvar num-nonmacro-input-events
+This variable holds the total number of input events received so far
+from the terminal---not counting those generated by keyboard macros.
+@end defvar
+
+@node Invoking the Input Method
+@subsection Invoking the Input Method
+
+ The event-reading functions invoke the current input method, if any
+(@pxref{Input Methods}). If the value of @code{input-method-function}
+is non-@code{nil}, it should be a function; when @code{read-event} reads
+a printing character (including @key{SPC}) with no modifier bits, it
+calls that function, passing the character as an argument.
+
+@defvar input-method-function
+If this is non-@code{nil}, its value specifies the current input method
+function.
+
+@strong{Warning:} don't bind this variable with @code{let}. It is often
+buffer-local, and if you bind it around reading input (which is exactly
+when you @emph{would} bind it), switching buffers asynchronously while
+Emacs is waiting will cause the value to be restored in the wrong
+buffer.
+@end defvar
+
+ The input method function should return a list of events which should
+be used as input. (If the list is @code{nil}, that means there is no
+input, so @code{read-event} waits for another event.) These events are
+processed before the events in @code{unread-command-events}
+(@pxref{Event Input Misc}). Events
+returned by the input method function are not passed to the input method
+function again, even if they are printing characters with no modifier
+bits.
+
+ If the input method function calls @code{read-event} or
+@code{read-key-sequence}, it should bind @code{input-method-function} to
+@code{nil} first, to prevent recursion.
+
+ The input method function is not called when reading the second and
+subsequent events of a key sequence. Thus, these characters are not
+subject to input method processing. The input method function should
+test the values of @code{overriding-local-map} and
+@code{overriding-terminal-local-map}; if either of these variables is
+non-@code{nil}, the input method should put its argument into a list and
+return that list with no further processing.
+
@node Quoted Character Input
@subsection Quoted Character Input
@cindex quoted character input
@cindex control characters, reading
@cindex nonprinting characters, reading
This function is like @code{read-char}, except that if the first
-character read is an octal digit (0-7), it reads up to two more octal digits
-(but stopping if a non-octal digit is found) and returns the
-character represented by those digits in octal.
+character read is an octal digit (0-7), it reads any number of octal
+digits (but stopping if a non-octal digit is found), and returns the
+character represented by that numeric character code. If the
+character that terminates the sequence of octal digits is @key{RET},
+it is discarded. Any other terminating character is used as input
+after this function returns.
Quitting is suppressed when the first character is read, so that the
user can enter a @kbd{C-g}. @xref{Quitting}.
@group
---------- Echo Area ----------
-What character-@kbd{177}
+What character @kbd{1 7 7}-
---------- Echo Area ----------
@result{} 127
This section describes how to ``peek ahead'' at events without using
them up, how to check for pending input, and how to discard pending
-input.
+input. See also the function @code{read-passwd} (@pxref{Reading a
+Password}).
@defvar unread-command-events
@cindex next input
input. The events are used in the order they appear in the list, and
removed one by one as they are used.
-The variable is needed because in some cases a function reads a event
+The variable is needed because in some cases a function reads an event
and then decides not to use it. Storing the event in this variable
causes it to be processed normally, by the command loop or by the
functions to read command input.
For example, the function that implements numeric prefix arguments reads
any number of digits. When it finds a non-digit event, it must unread
the event so that it can be read normally by the command loop.
-Likewise, incremental search uses this feature to unread events with no
+Likewise, incremental search uses this feature to unread events with no
special meaning in a search, because these events should exit the search
and then execute normally.
The reliable and easy way to extract events from a key sequence so as to
put them in @code{unread-command-events} is to use
@code{listify-key-sequence} (@pxref{Strings of Events}).
+
+Normally you add events to the front of this list, so that the events
+most recently unread will be reread first.
@end defvar
+@defun listify-key-sequence key
+This function converts the string or vector @var{key} to a list of
+individual events, which you can put in @code{unread-command-events}.
+@end defun
+
@defvar unread-command-char
This variable holds a character to be read as command input.
A value of -1 means ``empty''.
@end defun
@defvar last-input-event
+@defvarx last-input-char
This variable records the last terminal input event read, whether
as part of a command or explicitly by a Lisp program.
In the example below, the Lisp program reads the character @kbd{1},
-@sc{ASCII} code 49. It becomes the value of @code{last-input-event},
+@acronym{ASCII} code 49. It becomes the value of @code{last-input-event},
while @kbd{C-e} (we assume @kbd{C-x C-e} command is used to evaluate
this expression) remains the value of @code{last-command-event}.
@end group
@end example
-@vindex last-input-char
The alias @code{last-input-char} exists for compatibility with
Emacs version 18.
@end defvar
+@defmac while-no-input body@dots{}
+This construct runs the @var{body} forms and returns the value of the
+last one---but only if no input arrives. If any input arrives during
+the execution of the @var{body} forms, it aborts them (working much
+like a quit). The @code{while-no-input} form returns @code{nil} if
+aborted by a real quit, and returns @code{t} if aborted by arrival of
+other input.
+
+If a part of @var{body} binds @code{inhibit-quit} to non-@code{nil},
+arrival of input during those parts won't cause an abort until
+the end of that part.
+
+If you want to be able to distingish all possible values computed
+by @var{body} from both kinds of abort conditions, write the code
+like this:
+
+@example
+(while-no-input
+ (list
+ (progn . @var{body})))
+@end example
+@end defmac
+
@defun discard-input
@cindex flush input
@cindex discard input
In the following example, the user may type a number of characters right
after starting the evaluation of the form. After the @code{sleep-for}
-finishes sleeping, @code{discard-input} discards any characters typed
+finishes sleeping, @code{discard-input} discards any characters typed
during the sleep.
@example
@end example
@end defun
+@node Special Events
+@section Special Events
+
+@cindex special events
+Special events are handled at a very low level---as soon as they are
+read. The @code{read-event} function processes these events itself, and
+never returns them. Instead, it keeps waiting for the first event
+that is not special and returns that one.
+
+Events that are handled in this way do not echo, they are never grouped
+into key sequences, and they never appear in the value of
+@code{last-command-event} or @code{(this-command-keys)}. They do not
+discard a numeric argument, they cannot be unread with
+@code{unread-command-events}, they may not appear in a keyboard macro,
+and they are not recorded in a keyboard macro while you are defining
+one.
+
+These events do, however, appear in @code{last-input-event} immediately
+after they are read, and this is the way for the event's definition to
+find the actual event.
+
+The events types @code{iconify-frame}, @code{make-frame-visible} and
+@code{delete-frame} are normally handled in this way. The keymap which
+defines how to handle special events---and which events are special---is
+in the variable @code{special-event-map} (@pxref{Active Keymaps}).
+
@node Waiting
@section Waiting for Elapsed Time or Input
@cindex pausing
input comes in, while @code{sleep-for} pauses without updating the
screen.
-@defun sit-for seconds &optional millisec nodisp
+@defun sit-for seconds &optional nodisp
This function performs redisplay (provided there is no pending input
from the user), then waits @var{seconds} seconds, or until input is
available. The value is @code{t} if @code{sit-for} waited the full
-time with no input arriving (see @code{input-pending-p} in @ref{Event
+time with no input arriving (see @code{input-pending-p} in @ref{Event
Input Misc}). Otherwise, the value is @code{nil}.
The argument @var{seconds} need not be an integer. If it is a floating
Some systems support only a whole number of seconds; on these systems,
@var{seconds} is rounded down.
-The optional argument @var{millisec} specifies an additional waiting
-period measured in milliseconds. This adds to the period specified by
-@var{seconds}. If the system doesn't support waiting fractions of a
-second, you get an error if you specify nonzero @var{millisec}.
-
-@cindex forcing redisplay
-Redisplay is always preempted if input arrives, and does not happen at
-all if input is available before it starts. Thus, there is no way to
-force screen updating if there is pending input; however, if there is no
-input pending, you can force an update with no delay by using
-@code{(sit-for 0)}.
+The expression @code{(sit-for 0)} is a convenient way to request a
+redisplay, without any delay. @xref{Forcing Redisplay}.
If @var{nodisp} is non-@code{nil}, then @code{sit-for} does not
redisplay, but it still returns as soon as input is available (or when
The usual purpose of @code{sit-for} is to give the user time to read
text that you display.
+
+It is also possible to call @code{sit-for} with three arguments,
+as @code{(sit-for @var{seconds} @var{millisec} @var{nodisp})},
+but that is considered obsolete.
@end defun
@defun sleep-for seconds &optional millisec
@section Quitting
@cindex @kbd{C-g}
@cindex quitting
+@cindex interrupt Lisp functions
Typing @kbd{C-g} while a Lisp function is running causes Emacs to
@dfn{quit} whatever it is doing. This means that control returns to the
does not cause a quit; it acts as an ordinary input character. In the
simplest case, you cannot tell the difference, because @kbd{C-g}
normally runs the command @code{keyboard-quit}, whose effect is to quit.
-However, when @kbd{C-g} follows a prefix key, the result is an undefined
-key. The effect is to cancel the prefix key as well as any prefix
-argument.
+However, when @kbd{C-g} follows a prefix key, they combine to form an
+undefined key. The effect is to cancel the prefix key as well as any
+prefix argument.
In the minibuffer, @kbd{C-g} has a different definition: it aborts out
of the minibuffer. This means, in effect, that it exits the minibuffer
At the level of C code, quitting cannot happen just anywhere; only at the
special places that check @code{quit-flag}. The reason for this is
that quitting at other places might leave an inconsistency in Emacs's
-internal state. Because quitting is delayed until a safe place, quitting
+internal state. Because quitting is delayed until a safe place, quitting
cannot make Emacs crash.
Certain functions such as @code{read-key-sequence} or
input. In the case of @code{read-key-sequence}, this serves to bring
about the special behavior of @kbd{C-g} in the command loop. In the
case of @code{read-quoted-char}, this is so that @kbd{C-q} can be used
-to quote a @kbd{C-g}.
+to quote a @kbd{C-g}.
+@cindex prevent quitting
You can prevent quitting for a portion of a Lisp function by binding
the variable @code{inhibit-quit} to a non-@code{nil} value. Then,
although @kbd{C-g} still sets @code{quit-flag} to @code{t} as usual, the
@example
(defun read-quoted-char (&optional prompt)
"@dots{}@var{documentation}@dots{}"
- (let ((count 0) (code 0) char)
- (while (< count 3)
- (let ((inhibit-quit (zerop count))
- (help-form nil))
- (and prompt (message "%s-" prompt))
- (setq char (read-char))
- (if inhibit-quit (setq quit-flag nil)))
- @dots{})
- (logand 255 code)))
+ (let ((message-log-max nil) done (first t) (code 0) char)
+ (while (not done)
+ (let ((inhibit-quit first)
+ @dots{})
+ (and prompt (message "%s-" prompt))
+ (setq char (read-event))
+ (if inhibit-quit (setq quit-flag nil)))
+ @r{@dots{}set the variable @code{code}@dots{}})
+ code))
@end example
@defvar quit-flag
non-@code{nil}, then @code{quit-flag} has no special effect.
@end defvar
+@defmac with-local-quit body@dots{}
+This macro executes @var{body} forms in sequence, but allows quitting, at
+least locally, within @var{body} even if @code{inhibit-quit} was
+non-@code{nil} outside this construct. It returns the value of the
+last form in @var{body}, unless exited by quitting, in which case
+it returns @code{nil}.
+
+If @code{inhibit-quit} is @code{nil} on entry to @code{with-local-quit},
+it only executes the @var{body}, and setting @code{quit-flag} causes
+a normal quit. However, if @code{inhibit-quit} is non-@code{nil} so
+that ordinary quitting is delayed, a non-@code{nil} @code{quit-flag}
+triggers a special kind of local quit. This ends the execution of
+@var{body} and exits the @code{with-local-quit} body with
+@code{quit-flag} still non-@code{nil}, so that another (ordinary) quit
+will happen as soon as that is allowed. If @code{quit-flag} is
+already non-@code{nil} at the beginning of @var{body}, the local quit
+happens immediately and the body doesn't execute at all.
+
+This macro is mainly useful in functions that can be called from
+timers, process filters, process sentinels, @code{pre-command-hook},
+@code{post-command-hook}, and other places where @code{inhibit-quit} is
+normally bound to @code{t}.
+@end defmac
+
@deffn Command keyboard-quit
This function signals the @code{quit} condition with @code{(signal 'quit
nil)}. This is the same thing that quitting does. (See @code{signal}
You can specify a character other than @kbd{C-g} to use for quitting.
See the function @code{set-input-mode} in @ref{Terminal Input}.
-
+
@node Prefix Command Arguments
@section Prefix Command Arguments
@cindex prefix argument
M-3 M-x display-prefix @print{} 3 ; @r{(Same as @code{C-u 3}.)}
-C-u - M-x display-prefix @print{} -
+C-u - M-x display-prefix @print{} -
M-- M-x display-prefix @print{} - ; @r{(Same as @code{C-u -}.)}
-C-u - 7 M-x display-prefix @print{} -7
+C-u - 7 M-x display-prefix @print{} -7
M-- 7 M-x display-prefix @print{} -7 ; @r{(Same as @code{C-u -7}.)}
@end example
commands.
Normally, commands specify which representation to use for the prefix
-argument, either numeric or raw, in the @code{interactive} declaration.
+argument, either numeric or raw, in the @code{interactive} specification.
(@xref{Using Interactive}.) Alternatively, functions may look at the
value of the prefix argument directly in the variable
@code{current-prefix-arg}, but this is less clean.
@defvar current-prefix-arg
This variable holds the raw prefix argument for the @emph{current}
-command. Commands may examine it directly, but the usual way to access
-it is with @code{(interactive "P")}.
+command. Commands may examine it directly, but the usual method for
+accessing it is with @code{(interactive "P")}.
@end defvar
@defvar prefix-arg
The value of this variable is the raw prefix argument for the
-@emph{next} editing command. Commands that specify prefix arguments for
-the following command work by setting this variable.
+@emph{next} editing command. Commands such as @code{universal-argument}
+that specify prefix arguments for the following command work by setting
+this variable.
@end defvar
- Do not call the functions @code{universal-argument},
-@code{digit-argument}, or @code{negative-argument} unless you intend to
-let the user enter the prefix argument for the @emph{next} command.
+@defvar last-prefix-arg
+The raw prefix argument value used by the previous command.
+@end defvar
+
+ The following commands exist to set up prefix arguments for the
+following command. Do not call them for any other reason.
@deffn Command universal-argument
This command reads input and specifies a prefix argument for the
@deffn Command exit-recursive-edit
This function exits from the innermost recursive edit (including
minibuffer input). Its definition is effectively @code{(throw 'exit
-nil)}.
+nil)}.
@end deffn
@deffn Command abort-recursive-edit
This function aborts the command that requested the innermost recursive
-edit (including minibuffer input), by signaling @code{quit}
+edit (including minibuffer input), by signaling @code{quit}
after exiting the recursive edit. Its definition is effectively
@code{(throw 'exit t)}. @xref{Quitting}.
@end deffn
The low-level mechanism for disabling a command is to put a
non-@code{nil} @code{disabled} property on the Lisp symbol for the
command. These properties are normally set up by the user's
-@file{.emacs} file with Lisp expressions such as this:
+init file (@pxref{Init File}) with Lisp expressions such as this:
@example
(put 'upcase-region 'disabled t)
@end example
@noindent
-For a few commands, these properties are present by default and may be
-removed by the @file{.emacs} file.
+For a few commands, these properties are present by default (you can
+remove them in your init file if you wish).
If the value of the @code{disabled} property is a string, the message
saying the command is disabled includes that string. For example:
programs.
@deffn Command enable-command command
-Allow @var{command} to be executed without special confirmation from now
-on, and (if the user confirms) alter the user's @file{.emacs} file so
-that this will apply to future sessions.
+Allow @var{command} (a symbol) to be executed without special
+confirmation from now on, and alter the user's init file (@pxref{Init
+File}) so that this will apply to future sessions.
@end deffn
@deffn Command disable-command command
Require special confirmation to execute @var{command} from now on, and
-(if the user confirms) alter the user's @file{.emacs} file so that this
-will apply to future sessions.
+alter the user's init file so that this will apply to future sessions.
@end deffn
-@defvar disabled-command-hook
-This normal hook is run instead of a disabled command, when the user
-invokes the disabled command interactively. The hook functions can use
-@code{this-command-keys} to determine what the user typed to run the
-command, and thus find the command itself. @xref{Hooks}.
+@defvar disabled-command-function
+The value of this variable should be a function. When the user
+invokes a disabled command interactively, this function is called
+instead of the disabled command. It can use @code{this-command-keys}
+to determine what the user typed to run the command, and thus find the
+command itself.
-By default, @code{disabled-command-hook} contains a function that asks
-the user whether to proceed.
+The value may also be @code{nil}. Then all commands work normally,
+even disabled ones.
+
+By default, the value is a function that asks the user whether to
+proceed.
@end defvar
@node Command History
@defvar command-history
This variable's value is a list of recent complex commands, each
represented as a form to evaluate. It continues to accumulate all
-complex commands for the duration of the editing session, but all but
-the first (most recent) thirty elements are deleted when a garbage
-collection takes place (@pxref{Garbage Collection}).
+complex commands for the duration of the editing session, but when it
+reaches the maximum size (@pxref{Minibuffer History}), the oldest
+elements are deleted as new ones are added.
@example
@group
previous commands. The commands @code{repeat-complex-command}, and
@code{list-command-history} are described in the user manual
(@pxref{Repetition,,, emacs, The GNU Emacs Manual}). Within the
-minibuffer, the history commands used are the same ones available in any
-minibuffer.
+minibuffer, the usual minibuffer history commands are available.
@node Keyboard Macros
@section Keyboard Macros
events. Don't confuse keyboard macros with Lisp macros
(@pxref{Macros}).
-@defun execute-kbd-macro macro &optional count
-This function executes @var{macro} as a sequence of events. If
-@var{macro} is a string or vector, then the events in it are executed
+@defun execute-kbd-macro kbdmacro &optional count loopfunc
+This function executes @var{kbdmacro} as a sequence of events. If
+@var{kbdmacro} is a string or vector, then the events in it are executed
exactly as if they had been input by the user. The sequence is
@emph{not} expected to be a single key sequence; normally a keyboard
macro definition consists of several key sequences concatenated.
-If @var{macro} is a symbol, then its function definition is used in
-place of @var{macro}. If that is another symbol, this process repeats.
+If @var{kbdmacro} is a symbol, then its function definition is used in
+place of @var{kbdmacro}. If that is another symbol, this process repeats.
Eventually the result should be a string or vector. If the result is
not a symbol, string, or vector, an error is signaled.
-The argument @var{count} is a repeat count; @var{macro} is executed that
-many times. If @var{count} is omitted or @code{nil}, @var{macro} is
-executed once. If it is 0, @var{macro} is executed over and over until it
-encounters an error or a failing search.
+The argument @var{count} is a repeat count; @var{kbdmacro} is executed that
+many times. If @var{count} is omitted or @code{nil}, @var{kbdmacro} is
+executed once. If it is 0, @var{kbdmacro} is executed over and over until it
+encounters an error or a failing search.
+
+If @var{loopfunc} is non-@code{nil}, it is a function that is called,
+without arguments, prior to each iteration of the macro. If
+@var{loopfunc} returns @code{nil}, then this stops execution of the macro.
+
+@xref{Reading One Event}, for an example of using @code{execute-kbd-macro}.
@end defun
-@defvar executing-macro
+@defvar executing-kbd-macro
This variable contains the string or vector that defines the keyboard
macro that is currently executing. It is @code{nil} if no macro is
-currently executing. A command can test this variable to behave
+currently executing. A command can test this variable so as to behave
differently when run from an executing macro. Do not set this variable
yourself.
@end defvar
@defvar defining-kbd-macro
-This variable indicates whether a keyboard macro is being defined. A
-command can test this variable to behave differently while a macro is
-being defined. The commands @code{start-kbd-macro} and
+This variable is non-@code{nil} if and only if a keyboard macro is
+being defined. A command can test this variable so as to behave
+differently while a macro is being defined. The value is
+@code{append} while appending to the definition of an existing macro.
+The commands @code{start-kbd-macro}, @code{kmacro-start-macro} and
@code{end-kbd-macro} set this variable---do not set it yourself.
The variable is always local to the current terminal and cannot be
buffer-local. @xref{Multiple Displays}.
@end defvar
+@defvar kbd-macro-termination-hook
+This normal hook (@pxref{Standard Hooks}) is run when a keyboard
+macro terminates, regardless of what caused it to terminate (reaching
+the macro end or an error which ended the macro prematurely).
+@end defvar
+
+@ignore
+ arch-tag: e34944ad-7d5c-4980-be00-36a5fe54d4b1
+@end ignore