2 @c This is part of the GNU Emacs Lisp Reference Manual.
3 @c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002, 2003,
4 @c 2004, 2005, 2006 Free Software Foundation, Inc.
5 @c See the file elisp.texi for copying conditions.
6 @setfilename ../info/commands
7 @node Command Loop, Keymaps, Minibuffers, Top
9 @cindex editor command loop
12 When you run Emacs, it enters the @dfn{editor command loop} almost
13 immediately. This loop reads key sequences, executes their definitions,
14 and displays the results. In this chapter, we describe how these things
15 are done, and the subroutines that allow Lisp programs to do them.
18 * Command Overview:: How the command loop reads commands.
19 * Defining Commands:: Specifying how a function should read arguments.
20 * Interactive Call:: Calling a command, so that it will read arguments.
21 * Command Loop Info:: Variables set by the command loop for you to examine.
22 * Adjusting Point:: Adjustment of point after a command.
23 * Input Events:: What input looks like when you read it.
24 * Reading Input:: How to read input events from the keyboard or mouse.
25 * Special Events:: Events processed immediately and individually.
26 * Waiting:: Waiting for user input or elapsed time.
27 * Quitting:: How @kbd{C-g} works. How to catch or defer quitting.
28 * Prefix Command Arguments:: How the commands to set prefix args work.
29 * Recursive Editing:: Entering a recursive edit,
30 and why you usually shouldn't.
31 * Disabling Commands:: How the command loop handles disabled commands.
32 * Command History:: How the command history is set up, and how accessed.
33 * Keyboard Macros:: How keyboard macros are implemented.
36 @node Command Overview
37 @section Command Loop Overview
39 The first thing the command loop must do is read a key sequence, which
40 is a sequence of events that translates into a command. It does this by
41 calling the function @code{read-key-sequence}. Your Lisp code can also
42 call this function (@pxref{Key Sequence Input}). Lisp programs can also
43 do input at a lower level with @code{read-event} (@pxref{Reading One
44 Event}) or discard pending input with @code{discard-input}
45 (@pxref{Event Input Misc}).
47 The key sequence is translated into a command through the currently
48 active keymaps. @xref{Key Lookup}, for information on how this is done.
49 The result should be a keyboard macro or an interactively callable
50 function. If the key is @kbd{M-x}, then it reads the name of another
51 command, which it then calls. This is done by the command
52 @code{execute-extended-command} (@pxref{Interactive Call}).
54 To execute a command requires first reading the arguments for it.
55 This is done by calling @code{command-execute} (@pxref{Interactive
56 Call}). For commands written in Lisp, the @code{interactive}
57 specification says how to read the arguments. This may use the prefix
58 argument (@pxref{Prefix Command Arguments}) or may read with prompting
59 in the minibuffer (@pxref{Minibuffers}). For example, the command
60 @code{find-file} has an @code{interactive} specification which says to
61 read a file name using the minibuffer. The command's function body does
62 not use the minibuffer; if you call this command from Lisp code as a
63 function, you must supply the file name string as an ordinary Lisp
66 If the command is a string or vector (i.e., a keyboard macro) then
67 @code{execute-kbd-macro} is used to execute it. You can call this
68 function yourself (@pxref{Keyboard Macros}).
70 To terminate the execution of a running command, type @kbd{C-g}. This
71 character causes @dfn{quitting} (@pxref{Quitting}).
73 @defvar pre-command-hook
74 The editor command loop runs this normal hook before each command. At
75 that time, @code{this-command} contains the command that is about to
76 run, and @code{last-command} describes the previous command.
77 @xref{Command Loop Info}.
80 @defvar post-command-hook
81 The editor command loop runs this normal hook after each command
82 (including commands terminated prematurely by quitting or by errors),
83 and also when the command loop is first entered. At that time,
84 @code{this-command} refers to the command that just ran, and
85 @code{last-command} refers to the command before that.
88 Quitting is suppressed while running @code{pre-command-hook} and
89 @code{post-command-hook}. If an error happens while executing one of
90 these hooks, it terminates execution of the hook, and clears the hook
91 variable to @code{nil} so as to prevent an infinite loop of errors.
93 A request coming into the Emacs server (@pxref{Emacs Server,,,
94 emacs, The GNU Emacs Manual}) runs these two hooks just as a keyboard
97 @node Defining Commands
98 @section Defining Commands
99 @cindex defining commands
100 @cindex commands, defining
101 @cindex functions, making them interactive
102 @cindex interactive function
104 A Lisp function becomes a command when its body contains, at top
105 level, a form that calls the special form @code{interactive}. This
106 form does nothing when actually executed, but its presence serves as a
107 flag to indicate that interactive calling is permitted. Its argument
108 controls the reading of arguments for an interactive call.
111 * Using Interactive:: General rules for @code{interactive}.
112 * Interactive Codes:: The standard letter-codes for reading arguments
114 * Interactive Examples:: Examples of how to read interactive arguments.
117 @node Using Interactive
118 @subsection Using @code{interactive}
120 This section describes how to write the @code{interactive} form that
121 makes a Lisp function an interactively-callable command, and how to
122 examine a command's @code{interactive} form.
124 @defspec interactive arg-descriptor
125 @cindex argument descriptors
126 This special form declares that the function in which it appears is a
127 command, and that it may therefore be called interactively (via
128 @kbd{M-x} or by entering a key sequence bound to it). The argument
129 @var{arg-descriptor} declares how to compute the arguments to the
130 command when the command is called interactively.
132 A command may be called from Lisp programs like any other function, but
133 then the caller supplies the arguments and @var{arg-descriptor} has no
136 The @code{interactive} form has its effect because the command loop
137 (actually, its subroutine @code{call-interactively}) scans through the
138 function definition looking for it, before calling the function. Once
139 the function is called, all its body forms including the
140 @code{interactive} form are executed, but at this time
141 @code{interactive} simply returns @code{nil} without even evaluating its
145 There are three possibilities for the argument @var{arg-descriptor}:
149 It may be omitted or @code{nil}; then the command is called with no
150 arguments. This leads quickly to an error if the command requires one
154 @cindex argument prompt
155 It may be a string; then its contents should consist of a code character
156 followed by a prompt (which some code characters use and some ignore).
157 The prompt ends either with the end of the string or with a newline.
158 Here is a simple example:
161 (interactive "bFrobnicate buffer: ")
165 The code letter @samp{b} says to read the name of an existing buffer,
166 with completion. The buffer name is the sole argument passed to the
167 command. The rest of the string is a prompt.
169 If there is a newline character in the string, it terminates the prompt.
170 If the string does not end there, then the rest of the string should
171 contain another code character and prompt, specifying another argument.
172 You can specify any number of arguments in this way.
175 The prompt string can use @samp{%} to include previous argument values
176 (starting with the first argument) in the prompt. This is done using
177 @code{format} (@pxref{Formatting Strings}). For example, here is how
178 you could read the name of an existing buffer followed by a new name to
183 (interactive "bBuffer to rename: \nsRename buffer %s to: ")
187 @cindex @samp{*} in @code{interactive}
188 @cindex read-only buffers in interactive
189 If the first character in the string is @samp{*}, then an error is
190 signaled if the buffer is read-only.
192 @cindex @samp{@@} in @code{interactive}
194 If the first character in the string is @samp{@@}, and if the key
195 sequence used to invoke the command includes any mouse events, then
196 the window associated with the first of those events is selected
197 before the command is run.
199 You can use @samp{*} and @samp{@@} together; the order does not matter.
200 Actual reading of arguments is controlled by the rest of the prompt
201 string (starting with the first character that is not @samp{*} or
205 It may be a Lisp expression that is not a string; then it should be a
206 form that is evaluated to get a list of arguments to pass to the
207 command. Usually this form will call various functions to read input
208 from the user, most often through the minibuffer (@pxref{Minibuffers})
209 or directly from the keyboard (@pxref{Reading Input}).
210 @cindex argument evaluation form
212 Providing point or the mark as an argument value is also common, but
213 if you do this @emph{and} read input (whether using the minibuffer or
214 not), be sure to get the integer values of point or the mark after
215 reading. The current buffer may be receiving subprocess output; if
216 subprocess output arrives while the command is waiting for input, it
217 could relocate point and the mark.
219 Here's an example of what @emph{not} to do:
223 (list (region-beginning) (region-end)
224 (read-string "Foo: " nil 'my-history)))
228 Here's how to avoid the problem, by examining point and the mark after
229 reading the keyboard input:
233 (let ((string (read-string "Foo: " nil 'my-history)))
234 (list (region-beginning) (region-end) string)))
237 @strong{Warning:} the argument values should not include any data
238 types that can't be printed and then read. Some facilities save
239 @code{command-history} in a file to be read in the subsequent
240 sessions; if a command's arguments contain a data type that prints
241 using @samp{#<@dots{}>} syntax, those facilities won't work.
243 There are, however, a few exceptions: it is ok to use a limited set of
244 expressions such as @code{(point)}, @code{(mark)},
245 @code{(region-beginning)}, and @code{(region-end)}, because Emacs
246 recognizes them specially and puts the expression (rather than its
247 value) into the command history. To see whether the expression you
248 wrote is one of these exceptions, run the command, then examine
249 @code{(car command-history)}.
252 @cindex examining the @code{interactive} form
253 @defun interactive-form function
254 This function returns the @code{interactive} form of @var{function}.
255 If @var{function} is an interactively callable function
256 (@pxref{Interactive Call}), the value is the command's
257 @code{interactive} form @code{(interactive @var{spec})}, which
258 specifies how to compute its arguments. Otherwise, the value is
259 @code{nil}. If @var{function} is a symbol, its function definition is
263 @node Interactive Codes
264 @comment node-name, next, previous, up
265 @subsection Code Characters for @code{interactive}
266 @cindex interactive code description
267 @cindex description for interactive codes
268 @cindex codes, interactive, description of
269 @cindex characters for interactive codes
271 The code character descriptions below contain a number of key words,
272 defined here as follows:
276 @cindex interactive completion
277 Provide completion. @key{TAB}, @key{SPC}, and @key{RET} perform name
278 completion because the argument is read using @code{completing-read}
279 (@pxref{Completion}). @kbd{?} displays a list of possible completions.
282 Require the name of an existing object. An invalid name is not
283 accepted; the commands to exit the minibuffer do not exit if the current
287 @cindex default argument string
288 A default value of some sort is used if the user enters no text in the
289 minibuffer. The default depends on the code character.
292 This code letter computes an argument without reading any input.
293 Therefore, it does not use a prompt string, and any prompt string you
296 Even though the code letter doesn't use a prompt string, you must follow
297 it with a newline if it is not the last code character in the string.
300 A prompt immediately follows the code character. The prompt ends either
301 with the end of the string or with a newline.
304 This code character is meaningful only at the beginning of the
305 interactive string, and it does not look for a prompt or a newline.
306 It is a single, isolated character.
309 @cindex reading interactive arguments
310 Here are the code character descriptions for use with @code{interactive}:
314 Signal an error if the current buffer is read-only. Special.
317 Select the window mentioned in the first mouse event in the key
318 sequence that invoked this command. Special.
321 A function name (i.e., a symbol satisfying @code{fboundp}). Existing,
325 The name of an existing buffer. By default, uses the name of the
326 current buffer (@pxref{Buffers}). Existing, Completion, Default,
330 A buffer name. The buffer need not exist. By default, uses the name of
331 a recently used buffer other than the current buffer. Completion,
335 A character. The cursor does not move into the echo area. Prompt.
338 A command name (i.e., a symbol satisfying @code{commandp}). Existing,
342 @cindex position argument
343 The position of point, as an integer (@pxref{Point}). No I/O.
346 A directory name. The default is the current default directory of the
347 current buffer, @code{default-directory} (@pxref{File Name Expansion}).
348 Existing, Completion, Default, Prompt.
351 The first or next mouse event in the key sequence that invoked the command.
352 More precisely, @samp{e} gets events that are lists, so you can look at
353 the data in the lists. @xref{Input Events}. No I/O.
355 You can use @samp{e} more than once in a single command's interactive
356 specification. If the key sequence that invoked the command has
357 @var{n} events that are lists, the @var{n}th @samp{e} provides the
358 @var{n}th such event. Events that are not lists, such as function keys
359 and @acronym{ASCII} characters, do not count where @samp{e} is concerned.
362 A file name of an existing file (@pxref{File Names}). The default
363 directory is @code{default-directory}. Existing, Completion, Default,
367 A file name. The file need not exist. Completion, Default, Prompt.
370 A file name. The file need not exist. If the user enters just a
371 directory name, then the value is just that directory name, with no
372 file name within the directory added. Completion, Default, Prompt.
375 An irrelevant argument. This code always supplies @code{nil} as
376 the argument's value. No I/O.
379 A key sequence (@pxref{Key Sequences}). This keeps reading events
380 until a command (or undefined command) is found in the current key
381 maps. The key sequence argument is represented as a string or vector.
382 The cursor does not move into the echo area. Prompt.
384 If @samp{k} reads a key sequence that ends with a down-event, it also
385 reads and discards the following up-event. You can get access to that
386 up-event with the @samp{U} code character.
388 This kind of input is used by commands such as @code{describe-key} and
389 @code{global-set-key}.
392 A key sequence, whose definition you intend to change. This works like
393 @samp{k}, except that it suppresses, for the last input event in the key
394 sequence, the conversions that are normally used (when necessary) to
395 convert an undefined key into a defined one.
398 @cindex marker argument
399 The position of the mark, as an integer. No I/O.
402 Arbitrary text, read in the minibuffer using the current buffer's input
403 method, and returned as a string (@pxref{Input Methods,,, emacs, The GNU
404 Emacs Manual}). Prompt.
407 A number, read with the minibuffer. If the input is not a number, the
408 user has to try again. @samp{n} never uses the prefix argument.
412 The numeric prefix argument; but if there is no prefix argument, read
413 a number as with @kbd{n}. The value is always a number. @xref{Prefix
414 Command Arguments}. Prompt.
417 @cindex numeric prefix argument usage
418 The numeric prefix argument. (Note that this @samp{p} is lower case.)
422 @cindex raw prefix argument usage
423 The raw prefix argument. (Note that this @samp{P} is upper case.) No
427 @cindex region argument
428 Point and the mark, as two numeric arguments, smallest first. This is
429 the only code letter that specifies two successive arguments rather than
433 Arbitrary text, read in the minibuffer and returned as a string
434 (@pxref{Text from Minibuffer}). Terminate the input with either
435 @kbd{C-j} or @key{RET}. (@kbd{C-q} may be used to include either of
436 these characters in the input.) Prompt.
439 An interned symbol whose name is read in the minibuffer. Any whitespace
440 character terminates the input. (Use @kbd{C-q} to include whitespace in
441 the string.) Other characters that normally terminate a symbol (e.g.,
442 parentheses and brackets) do not do so here. Prompt.
445 A key sequence or @code{nil}. Can be used after a @samp{k} or
446 @samp{K} argument to get the up-event that was discarded (if any)
447 after @samp{k} or @samp{K} read a down-event. If no up-event has been
448 discarded, @samp{U} provides @code{nil} as the argument. No I/O.
451 A variable declared to be a user option (i.e., satisfying the
452 predicate @code{user-variable-p}). This reads the variable using
453 @code{read-variable}. @xref{Definition of read-variable}. Existing,
457 A Lisp object, specified with its read syntax, terminated with a
458 @kbd{C-j} or @key{RET}. The object is not evaluated. @xref{Object from
462 @cindex evaluated expression argument
463 A Lisp form's value. @samp{X} reads as @samp{x} does, then evaluates
464 the form so that its value becomes the argument for the command.
468 A coding system name (a symbol). If the user enters null input, the
469 argument value is @code{nil}. @xref{Coding Systems}. Completion,
473 A coding system name (a symbol)---but only if this command has a prefix
474 argument. With no prefix argument, @samp{Z} provides @code{nil} as the
475 argument value. Completion, Existing, Prompt.
478 @node Interactive Examples
479 @comment node-name, next, previous, up
480 @subsection Examples of Using @code{interactive}
481 @cindex examples of using @code{interactive}
482 @cindex @code{interactive}, examples of using
484 Here are some examples of @code{interactive}:
488 (defun foo1 () ; @r{@code{foo1} takes no arguments,}
489 (interactive) ; @r{just moves forward two words.}
495 (defun foo2 (n) ; @r{@code{foo2} takes one argument,}
496 (interactive "p") ; @r{which is the numeric prefix.}
497 (forward-word (* 2 n)))
502 (defun foo3 (n) ; @r{@code{foo3} takes one argument,}
503 (interactive "nCount:") ; @r{which is read with the Minibuffer.}
504 (forward-word (* 2 n)))
509 (defun three-b (b1 b2 b3)
510 "Select three existing buffers.
511 Put them into three windows, selecting the last one."
513 (interactive "bBuffer1:\nbBuffer2:\nbBuffer3:")
514 (delete-other-windows)
515 (split-window (selected-window) 8)
516 (switch-to-buffer b1)
518 (split-window (selected-window) 8)
519 (switch-to-buffer b2)
521 (switch-to-buffer b3))
524 (three-b "*scratch*" "declarations.texi" "*mail*")
529 @node Interactive Call
530 @section Interactive Call
531 @cindex interactive call
533 After the command loop has translated a key sequence into a command it
534 invokes that command using the function @code{command-execute}. If the
535 command is a function, @code{command-execute} calls
536 @code{call-interactively}, which reads the arguments and calls the
537 command. You can also call these functions yourself.
539 @defun commandp object &optional for-call-interactively
540 Returns @code{t} if @var{object} is suitable for calling interactively;
541 that is, if @var{object} is a command. Otherwise, returns @code{nil}.
543 The interactively callable objects include strings and vectors (treated
544 as keyboard macros), lambda expressions that contain a top-level call to
545 @code{interactive}, byte-code function objects made from such lambda
546 expressions, autoload objects that are declared as interactive
547 (non-@code{nil} fourth argument to @code{autoload}), and some of the
550 A symbol satisfies @code{commandp} if its function definition
551 satisfies @code{commandp}. Keys and keymaps are not commands.
552 Rather, they are used to look up commands (@pxref{Keymaps}).
554 If @var{for-call-interactively} is non-@code{nil}, then
555 @code{commandp} returns @code{t} only for objects that
556 @code{call-interactively} could call---thus, not for keyboard macros.
558 See @code{documentation} in @ref{Accessing Documentation}, for a
559 realistic example of using @code{commandp}.
562 @defun call-interactively command &optional record-flag keys
563 This function calls the interactively callable function @var{command},
564 reading arguments according to its interactive calling specifications.
565 It returns whatever @var{command} returns. An error is signaled if
566 @var{command} is not a function or if it cannot be called
567 interactively (i.e., is not a command). Note that keyboard macros
568 (strings and vectors) are not accepted, even though they are
569 considered commands, because they are not functions. If @var{command}
570 is a symbol, then @code{call-interactively} uses its function definition.
572 @cindex record command history
573 If @var{record-flag} is non-@code{nil}, then this command and its
574 arguments are unconditionally added to the list @code{command-history}.
575 Otherwise, the command is added only if it uses the minibuffer to read
576 an argument. @xref{Command History}.
578 The argument @var{keys}, if given, specifies the sequence of events to
579 supply if the command inquires which events were used to invoke it.
580 If @var{keys} is omitted or @code{nil}, the return value of
581 @code{this-command-keys} is used. @xref{Definition of this-command-keys}.
584 @defun command-execute command &optional record-flag keys special
585 @cindex keyboard macro execution
586 This function executes @var{command}. The argument @var{command} must
587 satisfy the @code{commandp} predicate; i.e., it must be an interactively
588 callable function or a keyboard macro.
590 A string or vector as @var{command} is executed with
591 @code{execute-kbd-macro}. A function is passed to
592 @code{call-interactively}, along with the optional @var{record-flag}
595 A symbol is handled by using its function definition in its place. A
596 symbol with an @code{autoload} definition counts as a command if it was
597 declared to stand for an interactively callable function. Such a
598 definition is handled by loading the specified library and then
599 rechecking the definition of the symbol.
601 The argument @var{special}, if given, means to ignore the prefix
602 argument and not clear it. This is used for executing special events
603 (@pxref{Special Events}).
606 @deffn Command execute-extended-command prefix-argument
607 @cindex read command name
608 This function reads a command name from the minibuffer using
609 @code{completing-read} (@pxref{Completion}). Then it uses
610 @code{command-execute} to call the specified command. Whatever that
611 command returns becomes the value of @code{execute-extended-command}.
613 @cindex execute with prefix argument
614 If the command asks for a prefix argument, it receives the value
615 @var{prefix-argument}. If @code{execute-extended-command} is called
616 interactively, the current raw prefix argument is used for
617 @var{prefix-argument}, and thus passed on to whatever command is run.
619 @c !!! Should this be @kindex?
621 @code{execute-extended-command} is the normal definition of @kbd{M-x},
622 so it uses the string @w{@samp{M-x }} as a prompt. (It would be better
623 to take the prompt from the events used to invoke
624 @code{execute-extended-command}, but that is painful to implement.) A
625 description of the value of the prefix argument, if any, also becomes
630 (execute-extended-command 1)
631 ---------- Buffer: Minibuffer ----------
632 1 M-x forward-word RET
633 ---------- Buffer: Minibuffer ----------
640 This function returns @code{t} if the containing function (the one
641 whose code includes the call to @code{interactive-p}) was called in
642 direct response to user input. This means that it was called with the
643 function @code{call-interactively}, and that a keyboard macro is
644 not running, and that Emacs is not running in batch mode.
646 If the containing function was called by Lisp evaluation (or with
647 @code{apply} or @code{funcall}), then it was not called interactively.
650 The most common use of @code{interactive-p} is for deciding whether
651 to give the user additional visual feedback (such as by printing an
652 informative message). For example:
656 ;; @r{Here's the usual way to use @code{interactive-p}.}
659 (when (interactive-p)
665 ;; @r{This function is just to illustrate the behavior.}
668 (setq foobar (list (foo) (interactive-p))))
673 ;; @r{Type @kbd{M-x foo}.}
678 ;; @r{Type @kbd{M-x bar}.}
679 ;; @r{This does not display a message.}
688 If you want to test @emph{only} whether the function was called
689 using @code{call-interactively}, add an optional argument
690 @code{print-message} which should be non-@code{nil} in an interactive
691 call, and use the @code{interactive} spec to make sure it is
692 non-@code{nil}. Here's an example:
695 (defun foo (&optional print-message)
702 Defined in this way, the function does display the message when called
703 from a keyboard macro. We use @code{"p"} because the numeric prefix
704 argument is never @code{nil}.
706 @defun called-interactively-p
707 This function returns @code{t} when the calling function was called
708 using @code{call-interactively}.
710 When possible, instead of using this function, you should use the
711 method in the example above; that method makes it possible for a
712 caller to ``pretend'' that the function was called interactively.
715 @node Command Loop Info
716 @comment node-name, next, previous, up
717 @section Information from the Command Loop
719 The editor command loop sets several Lisp variables to keep status
720 records for itself and for commands that are run.
723 This variable records the name of the previous command executed by the
724 command loop (the one before the current command). Normally the value
725 is a symbol with a function definition, but this is not guaranteed.
727 The value is copied from @code{this-command} when a command returns to
728 the command loop, except when the command has specified a prefix
729 argument for the following command.
731 This variable is always local to the current terminal and cannot be
732 buffer-local. @xref{Multiple Displays}.
735 @defvar real-last-command
736 This variable is set up by Emacs just like @code{last-command},
737 but never altered by Lisp programs.
741 @cindex current command
742 This variable records the name of the command now being executed by
743 the editor command loop. Like @code{last-command}, it is normally a symbol
744 with a function definition.
746 The command loop sets this variable just before running a command, and
747 copies its value into @code{last-command} when the command finishes
748 (unless the command specified a prefix argument for the following
751 @cindex kill command repetition
752 Some commands set this variable during their execution, as a flag for
753 whatever command runs next. In particular, the functions for killing text
754 set @code{this-command} to @code{kill-region} so that any kill commands
755 immediately following will know to append the killed text to the
759 If you do not want a particular command to be recognized as the previous
760 command in the case where it got an error, you must code that command to
761 prevent this. One way is to set @code{this-command} to @code{t} at the
762 beginning of the command, and set @code{this-command} back to its proper
763 value at the end, like this:
766 (defun foo (args@dots{})
767 (interactive @dots{})
768 (let ((old-this-command this-command))
769 (setq this-command t)
770 @r{@dots{}do the work@dots{}}
771 (setq this-command old-this-command)))
775 We do not bind @code{this-command} with @code{let} because that would
776 restore the old value in case of error---a feature of @code{let} which
777 in this case does precisely what we want to avoid.
779 @defvar this-original-command
780 This has the same value as @code{this-command} except when command
781 remapping occurs (@pxref{Remapping Commands}). In that case,
782 @code{this-command} gives the command actually run (the result of
783 remapping), and @code{this-original-command} gives the command that
784 was specified to run but remapped into another command.
787 @defun this-command-keys
788 @anchor{Definition of this-command-keys}
789 This function returns a string or vector containing the key sequence
790 that invoked the present command, plus any previous commands that
791 generated the prefix argument for this command. However, if the
792 command has called @code{read-key-sequence}, it returns the last read
793 key sequence. @xref{Key Sequence Input}. The value is a string if
794 all events in the sequence were characters that fit in a string.
800 ;; @r{Now use @kbd{C-u C-x C-e} to evaluate that.}
806 @defun this-command-keys-vector
807 Like @code{this-command-keys}, except that it always returns the events
808 in a vector, so you don't need to deal with the complexities of storing
809 input events in a string (@pxref{Strings of Events}).
812 @tindex clear-this-command-keys
813 @defun clear-this-command-keys &optional keep-record
814 This function empties out the table of events for
815 @code{this-command-keys} to return. Unless @var{keep-record} is
816 non-@code{nil}, it also empties the records that the function
817 @code{recent-keys} (@pxref{Recording Input}) will subsequently return.
818 This is useful after reading a password, to prevent the password from
819 echoing inadvertently as part of the next command in certain cases.
822 @defvar last-nonmenu-event
823 This variable holds the last input event read as part of a key sequence,
824 not counting events resulting from mouse menus.
826 One use of this variable is for telling @code{x-popup-menu} where to pop
827 up a menu. It is also used internally by @code{y-or-n-p}
828 (@pxref{Yes-or-No Queries}).
831 @defvar last-command-event
832 @defvarx last-command-char
833 This variable is set to the last input event that was read by the
834 command loop as part of a command. The principal use of this variable
835 is in @code{self-insert-command}, which uses it to decide which
841 ;; @r{Now use @kbd{C-u C-x C-e} to evaluate that.}
847 The value is 5 because that is the @acronym{ASCII} code for @kbd{C-e}.
849 The alias @code{last-command-char} exists for compatibility with
854 @defvar last-event-frame
855 This variable records which frame the last input event was directed to.
856 Usually this is the frame that was selected when the event was
857 generated, but if that frame has redirected input focus to another
858 frame, the value is the frame to which the event was redirected.
861 If the last event came from a keyboard macro, the value is @code{macro}.
864 @node Adjusting Point
865 @section Adjusting Point After Commands
867 It is not easy to display a value of point in the middle of a
868 sequence of text that has the @code{display}, @code{composition} or
869 @code{intangible} property, or is invisible. Therefore, after a
870 command finishes and returns to the command loop, if point is within
871 such a sequence, the command loop normally moves point to the edge of
874 A command can inhibit this feature by setting the variable
875 @code{disable-point-adjustment}:
877 @defvar disable-point-adjustment
878 @tindex disable-point-adjustment
879 If this variable is non-@code{nil} when a command returns to the
880 command loop, then the command loop does not check for those text
881 properties, and does not move point out of sequences that have them.
883 The command loop sets this variable to @code{nil} before each command,
884 so if a command sets it, the effect applies only to that command.
887 @defvar global-disable-point-adjustment
888 @tindex global-disable-point-adjustment
889 If you set this variable to a non-@code{nil} value, the feature of
890 moving point out of these sequences is completely turned off.
894 @section Input Events
898 The Emacs command loop reads a sequence of @dfn{input events} that
899 represent keyboard or mouse activity. The events for keyboard activity
900 are characters or symbols; mouse events are always lists. This section
901 describes the representation and meaning of input events in detail.
904 This function returns non-@code{nil} if @var{object} is an input event
907 Note that any symbol might be used as an event or an event type.
908 @code{eventp} cannot distinguish whether a symbol is intended by Lisp
909 code to be used as an event. Instead, it distinguishes whether the
910 symbol has actually been used in an event that has been read as input in
911 the current Emacs session. If a symbol has not yet been so used,
912 @code{eventp} returns @code{nil}.
916 * Keyboard Events:: Ordinary characters--keys with symbols on them.
917 * Function Keys:: Function keys--keys with names, not symbols.
918 * Mouse Events:: Overview of mouse events.
919 * Click Events:: Pushing and releasing a mouse button.
920 * Drag Events:: Moving the mouse before releasing the button.
921 * Button-Down Events:: A button was pushed and not yet released.
922 * Repeat Events:: Double and triple click (or drag, or down).
923 * Motion Events:: Just moving the mouse, not pushing a button.
924 * Focus Events:: Moving the mouse between frames.
925 * Misc Events:: Other events the system can generate.
926 * Event Examples:: Examples of the lists for mouse events.
927 * Classifying Events:: Finding the modifier keys in an event symbol.
929 * Accessing Events:: Functions to extract info from events.
930 * Strings of Events:: Special considerations for putting
931 keyboard character events in a string.
934 @node Keyboard Events
935 @subsection Keyboard Events
937 There are two kinds of input you can get from the keyboard: ordinary
938 keys, and function keys. Ordinary keys correspond to characters; the
939 events they generate are represented in Lisp as characters. The event
940 type of a character event is the character itself (an integer); see
941 @ref{Classifying Events}.
943 @cindex modifier bits (of input character)
944 @cindex basic code (of input character)
945 An input character event consists of a @dfn{basic code} between 0 and
946 524287, plus any or all of these @dfn{modifier bits}:
957 bit in the character code indicates a character
958 typed with the meta key held down.
968 bit in the character code indicates a non-@acronym{ASCII}
971 @sc{ascii} control characters such as @kbd{C-a} have special basic
972 codes of their own, so Emacs needs no special bit to indicate them.
973 Thus, the code for @kbd{C-a} is just 1.
975 But if you type a control combination not in @acronym{ASCII}, such as
976 @kbd{%} with the control key, the numeric value you get is the code
984 (assuming the terminal supports non-@acronym{ASCII}
995 bit in the character code indicates an @acronym{ASCII} control
996 character typed with the shift key held down.
998 For letters, the basic code itself indicates upper versus lower case;
999 for digits and punctuation, the shift key selects an entirely different
1000 character with a different basic code. In order to keep within the
1001 @acronym{ASCII} character set whenever possible, Emacs avoids using the
1008 bit for those characters.
1010 However, @acronym{ASCII} provides no way to distinguish @kbd{C-A} from
1011 @kbd{C-a}, so Emacs uses the
1018 bit in @kbd{C-A} and not in
1029 bit in the character code indicates a character
1030 typed with the hyper key held down.
1040 bit in the character code indicates a character
1041 typed with the super key held down.
1051 bit in the character code indicates a character typed with
1052 the alt key held down. (On some terminals, the key labeled @key{ALT}
1053 is actually the meta key.)
1056 It is best to avoid mentioning specific bit numbers in your program.
1057 To test the modifier bits of a character, use the function
1058 @code{event-modifiers} (@pxref{Classifying Events}). When making key
1059 bindings, you can use the read syntax for characters with modifier bits
1060 (@samp{\C-}, @samp{\M-}, and so on). For making key bindings with
1061 @code{define-key}, you can use lists such as @code{(control hyper ?x)} to
1062 specify the characters (@pxref{Changing Key Bindings}). The function
1063 @code{event-convert-list} converts such a list into an event type
1064 (@pxref{Classifying Events}).
1067 @subsection Function Keys
1069 @cindex function keys
1070 Most keyboards also have @dfn{function keys}---keys that have names or
1071 symbols that are not characters. Function keys are represented in Emacs
1072 Lisp as symbols; the symbol's name is the function key's label, in lower
1073 case. For example, pressing a key labeled @key{F1} places the symbol
1074 @code{f1} in the input stream.
1076 The event type of a function key event is the event symbol itself.
1077 @xref{Classifying Events}.
1079 Here are a few special cases in the symbol-naming convention for
1083 @item @code{backspace}, @code{tab}, @code{newline}, @code{return}, @code{delete}
1084 These keys correspond to common @acronym{ASCII} control characters that have
1085 special keys on most keyboards.
1087 In @acronym{ASCII}, @kbd{C-i} and @key{TAB} are the same character. If the
1088 terminal can distinguish between them, Emacs conveys the distinction to
1089 Lisp programs by representing the former as the integer 9, and the
1090 latter as the symbol @code{tab}.
1092 Most of the time, it's not useful to distinguish the two. So normally
1093 @code{function-key-map} (@pxref{Translating Input}) is set up to map
1094 @code{tab} into 9. Thus, a key binding for character code 9 (the
1095 character @kbd{C-i}) also applies to @code{tab}. Likewise for the other
1096 symbols in this group. The function @code{read-char} likewise converts
1097 these events into characters.
1099 In @acronym{ASCII}, @key{BS} is really @kbd{C-h}. But @code{backspace}
1100 converts into the character code 127 (@key{DEL}), not into code 8
1101 (@key{BS}). This is what most users prefer.
1103 @item @code{left}, @code{up}, @code{right}, @code{down}
1105 @item @code{kp-add}, @code{kp-decimal}, @code{kp-divide}, @dots{}
1106 Keypad keys (to the right of the regular keyboard).
1107 @item @code{kp-0}, @code{kp-1}, @dots{}
1108 Keypad keys with digits.
1109 @item @code{kp-f1}, @code{kp-f2}, @code{kp-f3}, @code{kp-f4}
1111 @item @code{kp-home}, @code{kp-left}, @code{kp-up}, @code{kp-right}, @code{kp-down}
1112 Keypad arrow keys. Emacs normally translates these into the
1113 corresponding non-keypad keys @code{home}, @code{left}, @dots{}
1114 @item @code{kp-prior}, @code{kp-next}, @code{kp-end}, @code{kp-begin}, @code{kp-insert}, @code{kp-delete}
1115 Additional keypad duplicates of keys ordinarily found elsewhere. Emacs
1116 normally translates these into the like-named non-keypad keys.
1119 You can use the modifier keys @key{ALT}, @key{CTRL}, @key{HYPER},
1120 @key{META}, @key{SHIFT}, and @key{SUPER} with function keys. The way to
1121 represent them is with prefixes in the symbol name:
1127 The control modifier.
1138 Thus, the symbol for the key @key{F3} with @key{META} held down is
1139 @code{M-f3}. When you use more than one prefix, we recommend you
1140 write them in alphabetical order; but the order does not matter in
1141 arguments to the key-binding lookup and modification functions.
1144 @subsection Mouse Events
1146 Emacs supports four kinds of mouse events: click events, drag events,
1147 button-down events, and motion events. All mouse events are represented
1148 as lists. The @sc{car} of the list is the event type; this says which
1149 mouse button was involved, and which modifier keys were used with it.
1150 The event type can also distinguish double or triple button presses
1151 (@pxref{Repeat Events}). The rest of the list elements give position
1152 and time information.
1154 For key lookup, only the event type matters: two events of the same type
1155 necessarily run the same command. The command can access the full
1156 values of these events using the @samp{e} interactive code.
1157 @xref{Interactive Codes}.
1159 A key sequence that starts with a mouse event is read using the keymaps
1160 of the buffer in the window that the mouse was in, not the current
1161 buffer. This does not imply that clicking in a window selects that
1162 window or its buffer---that is entirely under the control of the command
1163 binding of the key sequence.
1166 @subsection Click Events
1168 @cindex mouse click event
1170 When the user presses a mouse button and releases it at the same
1171 location, that generates a @dfn{click} event. All mouse click event
1172 share the same format:
1175 (@var{event-type} @var{position} @var{click-count})
1179 @item @var{event-type}
1180 This is a symbol that indicates which mouse button was used. It is
1181 one of the symbols @code{mouse-1}, @code{mouse-2}, @dots{}, where the
1182 buttons are numbered left to right.
1184 You can also use prefixes @samp{A-}, @samp{C-}, @samp{H-}, @samp{M-},
1185 @samp{S-} and @samp{s-} for modifiers alt, control, hyper, meta, shift
1186 and super, just as you would with function keys.
1188 This symbol also serves as the event type of the event. Key bindings
1189 describe events by their types; thus, if there is a key binding for
1190 @code{mouse-1}, that binding would apply to all events whose
1191 @var{event-type} is @code{mouse-1}.
1193 @item @var{position}
1194 This is the position where the mouse click occurred. The actual
1195 format of @var{position} depends on what part of a window was clicked
1196 on. The various formats are described below.
1198 @item @var{click-count}
1199 This is the number of rapid repeated presses so far of the same mouse
1200 button. @xref{Repeat Events}.
1203 For mouse click events in the text area, mode line, header line, or in
1204 the marginal areas, @var{position} has this form:
1207 (@var{window} @var{pos-or-area} (@var{x} . @var{y}) @var{timestamp}
1208 @var{object} @var{text-pos} (@var{col} . @var{row})
1209 @var{image} (@var{dx} . @var{dy}) (@var{width} . @var{height}))
1214 This is the window in which the click occurred.
1216 @item @var{pos-or-area}
1217 This is the buffer position of the character clicked on in the text
1218 area, or if clicked outside the text area, it is the window area in
1219 which the click occurred. It is one of the symbols @code{mode-line},
1220 @code{header-line}, @code{vertical-line}, @code{left-margin},
1221 @code{right-margin}, @code{left-fringe}, or @code{right-fringe}.
1223 @item @var{x}, @var{y}
1224 These are the pixel-denominated coordinates of the click, relative to
1225 the top left corner of @var{window}, which is @code{(0 . 0)}.
1226 For the mode or header line, @var{y} does not have meaningful data.
1227 For the vertical line, @var{x} does not have meaningful data.
1229 @item @var{timestamp}
1230 This is the time at which the event occurred, in milliseconds.
1233 This is the object on which the click occurred. It is either
1234 @code{nil} if there is no string property, or it has the form
1235 (@var{string} . @var{string-pos}) when there is a string-type text
1236 property at the click position.
1239 This is the string on which the click occurred, including any
1242 @item @var{string-pos}
1243 This is the position in the string on which the click occurred,
1244 relevant if properties at the click need to be looked up.
1246 @item @var{text-pos}
1247 For clicks on a marginal area or on a fringe, this is the buffer
1248 position of the first visible character in the corresponding line in
1249 the window. For other events, it is the current buffer position in
1252 @item @var{col}, @var{row}
1253 These are the actual coordinates of the glyph under the @var{x},
1254 @var{y} position, possibly padded with default character width
1255 glyphs if @var{x} is beyond the last glyph on the line.
1258 This is the image object on which the click occurred. It is either
1259 @code{nil} if there is no image at the position clicked on, or it is
1260 an image object as returned by @code{find-image} if click was in an image.
1262 @item @var{dx}, @var{dy}
1263 These are the pixel-denominated coordinates of the click, relative to
1264 the top left corner of @var{object}, which is @code{(0 . 0)}. If
1265 @var{object} is @code{nil}, the coordinates are relative to the top
1266 left corner of the character glyph clicked on.
1269 For mouse clicks on a scroll-bar, @var{position} has this form:
1272 (@var{window} @var{area} (@var{portion} . @var{whole}) @var{timestamp} @var{part})
1277 This is the window whose scroll-bar was clicked on.
1280 This is the scroll bar where the click occurred. It is one of the
1281 symbols @code{vertical-scroll-bar} or @code{horizontal-scroll-bar}.
1284 This is the distance of the click from the top or left end of
1288 This is the length of the entire scroll bar.
1290 @item @var{timestamp}
1291 This is the time at which the event occurred, in milliseconds.
1294 This is the part of the scroll-bar which was clicked on. It is one
1295 of the symbols @code{above-handle}, @code{handle}, @code{below-handle},
1296 @code{up}, @code{down}, @code{top}, @code{bottom}, and @code{end-scroll}.
1299 In one special case, @var{buffer-pos} is a list containing a symbol (one
1300 of the symbols listed above) instead of just the symbol. This happens
1301 after the imaginary prefix keys for the event are inserted into the
1302 input stream. @xref{Key Sequence Input}.
1305 @subsection Drag Events
1307 @cindex mouse drag event
1309 With Emacs, you can have a drag event without even changing your
1310 clothes. A @dfn{drag event} happens every time the user presses a mouse
1311 button and then moves the mouse to a different character position before
1312 releasing the button. Like all mouse events, drag events are
1313 represented in Lisp as lists. The lists record both the starting mouse
1314 position and the final position, like this:
1318 (@var{window1} @var{buffer-pos1} (@var{x1} . @var{y1}) @var{timestamp1})
1319 (@var{window2} @var{buffer-pos2} (@var{x2} . @var{y2}) @var{timestamp2})
1323 For a drag event, the name of the symbol @var{event-type} contains the
1324 prefix @samp{drag-}. For example, dragging the mouse with button 2 held
1325 down generates a @code{drag-mouse-2} event. The second and third
1326 elements of the event give the starting and ending position of the drag.
1327 Aside from that, the data have the same meanings as in a click event
1328 (@pxref{Click Events}). You can access the second element of any mouse
1329 event in the same way, with no need to distinguish drag events from
1332 The @samp{drag-} prefix follows the modifier key prefixes such as
1333 @samp{C-} and @samp{M-}.
1335 If @code{read-key-sequence} receives a drag event that has no key
1336 binding, and the corresponding click event does have a binding, it
1337 changes the drag event into a click event at the drag's starting
1338 position. This means that you don't have to distinguish between click
1339 and drag events unless you want to.
1341 @node Button-Down Events
1342 @subsection Button-Down Events
1343 @cindex button-down event
1345 Click and drag events happen when the user releases a mouse button.
1346 They cannot happen earlier, because there is no way to distinguish a
1347 click from a drag until the button is released.
1349 If you want to take action as soon as a button is pressed, you need to
1350 handle @dfn{button-down} events.@footnote{Button-down is the
1351 conservative antithesis of drag.} These occur as soon as a button is
1352 pressed. They are represented by lists that look exactly like click
1353 events (@pxref{Click Events}), except that the @var{event-type} symbol
1354 name contains the prefix @samp{down-}. The @samp{down-} prefix follows
1355 modifier key prefixes such as @samp{C-} and @samp{M-}.
1357 The function @code{read-key-sequence} ignores any button-down events
1358 that don't have command bindings; therefore, the Emacs command loop
1359 ignores them too. This means that you need not worry about defining
1360 button-down events unless you want them to do something. The usual
1361 reason to define a button-down event is so that you can track mouse
1362 motion (by reading motion events) until the button is released.
1363 @xref{Motion Events}.
1366 @subsection Repeat Events
1367 @cindex repeat events
1368 @cindex double-click events
1369 @cindex triple-click events
1370 @cindex mouse events, repeated
1372 If you press the same mouse button more than once in quick succession
1373 without moving the mouse, Emacs generates special @dfn{repeat} mouse
1374 events for the second and subsequent presses.
1376 The most common repeat events are @dfn{double-click} events. Emacs
1377 generates a double-click event when you click a button twice; the event
1378 happens when you release the button (as is normal for all click
1381 The event type of a double-click event contains the prefix
1382 @samp{double-}. Thus, a double click on the second mouse button with
1383 @key{meta} held down comes to the Lisp program as
1384 @code{M-double-mouse-2}. If a double-click event has no binding, the
1385 binding of the corresponding ordinary click event is used to execute
1386 it. Thus, you need not pay attention to the double click feature
1387 unless you really want to.
1389 When the user performs a double click, Emacs generates first an ordinary
1390 click event, and then a double-click event. Therefore, you must design
1391 the command binding of the double click event to assume that the
1392 single-click command has already run. It must produce the desired
1393 results of a double click, starting from the results of a single click.
1395 This is convenient, if the meaning of a double click somehow ``builds
1396 on'' the meaning of a single click---which is recommended user interface
1397 design practice for double clicks.
1399 If you click a button, then press it down again and start moving the
1400 mouse with the button held down, then you get a @dfn{double-drag} event
1401 when you ultimately release the button. Its event type contains
1402 @samp{double-drag} instead of just @samp{drag}. If a double-drag event
1403 has no binding, Emacs looks for an alternate binding as if the event
1404 were an ordinary drag.
1406 Before the double-click or double-drag event, Emacs generates a
1407 @dfn{double-down} event when the user presses the button down for the
1408 second time. Its event type contains @samp{double-down} instead of just
1409 @samp{down}. If a double-down event has no binding, Emacs looks for an
1410 alternate binding as if the event were an ordinary button-down event.
1411 If it finds no binding that way either, the double-down event is
1414 To summarize, when you click a button and then press it again right
1415 away, Emacs generates a down event and a click event for the first
1416 click, a double-down event when you press the button again, and finally
1417 either a double-click or a double-drag event.
1419 If you click a button twice and then press it again, all in quick
1420 succession, Emacs generates a @dfn{triple-down} event, followed by
1421 either a @dfn{triple-click} or a @dfn{triple-drag}. The event types of
1422 these events contain @samp{triple} instead of @samp{double}. If any
1423 triple event has no binding, Emacs uses the binding that it would use
1424 for the corresponding double event.
1426 If you click a button three or more times and then press it again, the
1427 events for the presses beyond the third are all triple events. Emacs
1428 does not have separate event types for quadruple, quintuple, etc.@:
1429 events. However, you can look at the event list to find out precisely
1430 how many times the button was pressed.
1432 @defun event-click-count event
1433 This function returns the number of consecutive button presses that led
1434 up to @var{event}. If @var{event} is a double-down, double-click or
1435 double-drag event, the value is 2. If @var{event} is a triple event,
1436 the value is 3 or greater. If @var{event} is an ordinary mouse event
1437 (not a repeat event), the value is 1.
1440 @defopt double-click-fuzz
1441 To generate repeat events, successive mouse button presses must be at
1442 approximately the same screen position. The value of
1443 @code{double-click-fuzz} specifies the maximum number of pixels the
1444 mouse may be moved (horizontally or vertically) between two successive
1445 clicks to make a double-click.
1447 This variable is also the threshold for motion of the mouse to count
1451 @defopt double-click-time
1452 To generate repeat events, the number of milliseconds between
1453 successive button presses must be less than the value of
1454 @code{double-click-time}. Setting @code{double-click-time} to
1455 @code{nil} disables multi-click detection entirely. Setting it to
1456 @code{t} removes the time limit; Emacs then detects multi-clicks by
1461 @subsection Motion Events
1462 @cindex motion event
1463 @cindex mouse motion events
1465 Emacs sometimes generates @dfn{mouse motion} events to describe motion
1466 of the mouse without any button activity. Mouse motion events are
1467 represented by lists that look like this:
1470 (mouse-movement (@var{window} @var{buffer-pos} (@var{x} . @var{y}) @var{timestamp}))
1473 The second element of the list describes the current position of the
1474 mouse, just as in a click event (@pxref{Click Events}).
1476 The special form @code{track-mouse} enables generation of motion events
1477 within its body. Outside of @code{track-mouse} forms, Emacs does not
1478 generate events for mere motion of the mouse, and these events do not
1479 appear. @xref{Mouse Tracking}.
1482 @subsection Focus Events
1485 Window systems provide general ways for the user to control which window
1486 gets keyboard input. This choice of window is called the @dfn{focus}.
1487 When the user does something to switch between Emacs frames, that
1488 generates a @dfn{focus event}. The normal definition of a focus event,
1489 in the global keymap, is to select a new frame within Emacs, as the user
1490 would expect. @xref{Input Focus}.
1492 Focus events are represented in Lisp as lists that look like this:
1495 (switch-frame @var{new-frame})
1499 where @var{new-frame} is the frame switched to.
1501 Most X window managers are set up so that just moving the mouse into a
1502 window is enough to set the focus there. Emacs appears to do this,
1503 because it changes the cursor to solid in the new frame. However, there
1504 is no need for the Lisp program to know about the focus change until
1505 some other kind of input arrives. So Emacs generates a focus event only
1506 when the user actually types a keyboard key or presses a mouse button in
1507 the new frame; just moving the mouse between frames does not generate a
1510 A focus event in the middle of a key sequence would garble the
1511 sequence. So Emacs never generates a focus event in the middle of a key
1512 sequence. If the user changes focus in the middle of a key
1513 sequence---that is, after a prefix key---then Emacs reorders the events
1514 so that the focus event comes either before or after the multi-event key
1515 sequence, and not within it.
1518 @subsection Miscellaneous System Events
1520 A few other event types represent occurrences within the system.
1523 @cindex @code{delete-frame} event
1524 @item (delete-frame (@var{frame}))
1525 This kind of event indicates that the user gave the window manager
1526 a command to delete a particular window, which happens to be an Emacs frame.
1528 The standard definition of the @code{delete-frame} event is to delete @var{frame}.
1530 @cindex @code{iconify-frame} event
1531 @item (iconify-frame (@var{frame}))
1532 This kind of event indicates that the user iconified @var{frame} using
1533 the window manager. Its standard definition is @code{ignore}; since the
1534 frame has already been iconified, Emacs has no work to do. The purpose
1535 of this event type is so that you can keep track of such events if you
1538 @cindex @code{make-frame-visible} event
1539 @item (make-frame-visible (@var{frame}))
1540 This kind of event indicates that the user deiconified @var{frame} using
1541 the window manager. Its standard definition is @code{ignore}; since the
1542 frame has already been made visible, Emacs has no work to do.
1544 @cindex @code{wheel-up} event
1545 @cindex @code{wheel-down} event
1546 @item (wheel-up @var{position})
1547 @item (wheel-down @var{position})
1548 These kinds of event are generated by moving a mouse wheel. Their
1549 usual meaning is a kind of scroll or zoom.
1551 The element @var{position} is a list describing the position of the
1552 event, in the same format as used in a mouse-click event.
1554 This kind of event is generated only on some kinds of systems. On some
1555 systems, @code{mouse-4} and @code{mouse-5} are used instead. For
1556 portable code, use the variables @code{mouse-wheel-up-event} and
1557 @code{mouse-wheel-down-event} defined in @file{mwheel.el} to determine
1558 what event types to expect for the mouse wheel.
1560 @cindex @code{drag-n-drop} event
1561 @item (drag-n-drop @var{position} @var{files})
1562 This kind of event is generated when a group of files is
1563 selected in an application outside of Emacs, and then dragged and
1564 dropped onto an Emacs frame.
1566 The element @var{position} is a list describing the position of the
1567 event, in the same format as used in a mouse-click event, and
1568 @var{files} is the list of file names that were dragged and dropped.
1569 The usual way to handle this event is by visiting these files.
1571 This kind of event is generated, at present, only on some kinds of
1574 @cindex @code{help-echo} event
1576 This kind of event is generated when a mouse pointer moves onto a
1577 portion of buffer text which has a @code{help-echo} text property.
1578 The generated event has this form:
1581 (help-echo @var{frame} @var{help} @var{window} @var{object} @var{pos})
1585 The precise meaning of the event parameters and the way these
1586 parameters are used to display the help-echo text are described in
1587 @ref{Text help-echo}.
1589 @cindex @code{usr1-signal} event
1590 @cindex @code{usr2-signal} event
1593 These events are generated when the Emacs process receives the signals
1594 @code{SIGUSR1} and @code{SIGUSR2}. They contain no additional data
1595 because signals do not carry additional information.
1598 If one of these events arrives in the middle of a key sequence---that
1599 is, after a prefix key---then Emacs reorders the events so that this
1600 event comes either before or after the multi-event key sequence, not
1603 @node Event Examples
1604 @subsection Event Examples
1606 If the user presses and releases the left mouse button over the same
1607 location, that generates a sequence of events like this:
1610 (down-mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864320))
1611 (mouse-1 (#<window 18 on NEWS> 2613 (0 . 38) -864180))
1614 While holding the control key down, the user might hold down the
1615 second mouse button, and drag the mouse from one line to the next.
1616 That produces two events, as shown here:
1619 (C-down-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219))
1620 (C-drag-mouse-2 (#<window 18 on NEWS> 3440 (0 . 27) -731219)
1621 (#<window 18 on NEWS> 3510 (0 . 28) -729648))
1624 While holding down the meta and shift keys, the user might press the
1625 second mouse button on the window's mode line, and then drag the mouse
1626 into another window. That produces a pair of events like these:
1629 (M-S-down-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844))
1630 (M-S-drag-mouse-2 (#<window 18 on NEWS> mode-line (33 . 31) -457844)
1631 (#<window 20 on carlton-sanskrit.tex> 161 (33 . 3)
1635 @node Classifying Events
1636 @subsection Classifying Events
1639 Every event has an @dfn{event type}, which classifies the event for
1640 key binding purposes. For a keyboard event, the event type equals the
1641 event value; thus, the event type for a character is the character, and
1642 the event type for a function key symbol is the symbol itself. For
1643 events that are lists, the event type is the symbol in the @sc{car} of
1644 the list. Thus, the event type is always a symbol or a character.
1646 Two events of the same type are equivalent where key bindings are
1647 concerned; thus, they always run the same command. That does not
1648 necessarily mean they do the same things, however, as some commands look
1649 at the whole event to decide what to do. For example, some commands use
1650 the location of a mouse event to decide where in the buffer to act.
1652 Sometimes broader classifications of events are useful. For example,
1653 you might want to ask whether an event involved the @key{META} key,
1654 regardless of which other key or mouse button was used.
1656 The functions @code{event-modifiers} and @code{event-basic-type} are
1657 provided to get such information conveniently.
1659 @defun event-modifiers event
1660 This function returns a list of the modifiers that @var{event} has. The
1661 modifiers are symbols; they include @code{shift}, @code{control},
1662 @code{meta}, @code{alt}, @code{hyper} and @code{super}. In addition,
1663 the modifiers list of a mouse event symbol always contains one of
1664 @code{click}, @code{drag}, and @code{down}. For double or triple
1665 events, it also contains @code{double} or @code{triple}.
1667 The argument @var{event} may be an entire event object, or just an
1668 event type. If @var{event} is a symbol that has never been used in an
1669 event that has been read as input in the current Emacs session, then
1670 @code{event-modifiers} can return @code{nil}, even when @var{event}
1671 actually has modifiers.
1673 Here are some examples:
1676 (event-modifiers ?a)
1678 (event-modifiers ?A)
1680 (event-modifiers ?\C-a)
1682 (event-modifiers ?\C-%)
1684 (event-modifiers ?\C-\S-a)
1685 @result{} (control shift)
1686 (event-modifiers 'f5)
1688 (event-modifiers 's-f5)
1690 (event-modifiers 'M-S-f5)
1691 @result{} (meta shift)
1692 (event-modifiers 'mouse-1)
1694 (event-modifiers 'down-mouse-1)
1698 The modifiers list for a click event explicitly contains @code{click},
1699 but the event symbol name itself does not contain @samp{click}.
1702 @defun event-basic-type event
1703 This function returns the key or mouse button that @var{event}
1704 describes, with all modifiers removed. The @var{event} argument is as
1705 in @code{event-modifiers}. For example:
1708 (event-basic-type ?a)
1710 (event-basic-type ?A)
1712 (event-basic-type ?\C-a)
1714 (event-basic-type ?\C-\S-a)
1716 (event-basic-type 'f5)
1718 (event-basic-type 's-f5)
1720 (event-basic-type 'M-S-f5)
1722 (event-basic-type 'down-mouse-1)
1727 @defun mouse-movement-p object
1728 This function returns non-@code{nil} if @var{object} is a mouse movement
1732 @defun event-convert-list list
1733 This function converts a list of modifier names and a basic event type
1734 to an event type which specifies all of them. The basic event type
1735 must be the last element of the list. For example,
1738 (event-convert-list '(control ?a))
1740 (event-convert-list '(control meta ?a))
1741 @result{} -134217727
1742 (event-convert-list '(control super f1))
1747 @node Accessing Events
1748 @subsection Accessing Events
1749 @cindex mouse events, accessing the data
1750 @cindex accessing data of mouse events
1752 This section describes convenient functions for accessing the data in
1753 a mouse button or motion event.
1755 These two functions return the starting or ending position of a
1756 mouse-button event, as a list of this form:
1759 (@var{window} @var{pos-or-area} (@var{x} . @var{y}) @var{timestamp}
1760 @var{object} @var{text-pos} (@var{col} . @var{row})
1761 @var{image} (@var{dx} . @var{dy}) (@var{width} . @var{height}))
1764 @defun event-start event
1765 This returns the starting position of @var{event}.
1767 If @var{event} is a click or button-down event, this returns the
1768 location of the event. If @var{event} is a drag event, this returns the
1769 drag's starting position.
1772 @defun event-end event
1773 This returns the ending position of @var{event}.
1775 If @var{event} is a drag event, this returns the position where the user
1776 released the mouse button. If @var{event} is a click or button-down
1777 event, the value is actually the starting position, which is the only
1778 position such events have.
1781 @cindex mouse position list, accessing
1782 These functions take a position list as described above, and
1783 return various parts of it.
1785 @defun posn-window position
1786 Return the window that @var{position} is in.
1789 @defun posn-area position
1790 Return the window area recorded in @var{position}. It returns @code{nil}
1791 when the event occurred in the text area of the window; otherwise, it
1792 is a symbol identifying the area in which the event occurred.
1795 @defun posn-point position
1796 Return the buffer position in @var{position}. When the event occurred
1797 in the text area of the window, in a marginal area, or on a fringe,
1798 this is an integer specifying a buffer position. Otherwise, the value
1802 @defun posn-x-y position
1803 Return the pixel-based x and y coordinates in @var{position}, as a
1804 cons cell @code{(@var{x} . @var{y})}. These coordinates are relative
1805 to the window given by @code{posn-window}.
1807 This example shows how to convert these window-relative coordinates
1808 into frame-relative coordinates:
1811 (defun frame-relative-coordinates (position)
1812 "Return frame-relative coordinates from POSITION."
1813 (let* ((x-y (posn-x-y position))
1814 (window (posn-window position))
1815 (edges (window-inside-pixel-edges window)))
1816 (cons (+ (car x-y) (car edges))
1817 (+ (cdr x-y) (cadr edges)))))
1821 @defun posn-col-row position
1822 Return the row and column (in units of the frame's default character
1823 height and width) of @var{position}, as a cons cell @code{(@var{col} .
1824 @var{row})}. These are computed from the @var{x} and @var{y} values
1825 actually found in @var{position}.
1828 @defun posn-actual-col-row position
1829 Return the actual row and column in @var{position}, as a cons cell
1830 @code{(@var{col} . @var{row})}. The values are the actual row number
1831 in the window, and the actual character number in that row. It returns
1832 @code{nil} if @var{position} does not include actual positions values.
1833 You can use @code{posn-col-row} to get approximate values.
1836 @defun posn-string position
1837 Return the string object in @var{position}, either @code{nil}, or a
1838 cons cell @code{(@var{string} . @var{string-pos})}.
1841 @defun posn-image position
1842 Return the image object in @var{position}, either @code{nil}, or an
1843 image @code{(image ...)}.
1846 @defun posn-object position
1847 Return the image or string object in @var{position}, either
1848 @code{nil}, an image @code{(image ...)}, or a cons cell
1849 @code{(@var{string} . @var{string-pos})}.
1852 @defun posn-object-x-y position
1853 Return the pixel-based x and y coordinates relative to the upper left
1854 corner of the object in @var{position} as a cons cell @code{(@var{dx}
1855 . @var{dy})}. If the @var{position} is a buffer position, return the
1856 relative position in the character at that position.
1859 @defun posn-object-width-height position
1860 Return the pixel width and height of the object in @var{position} as a
1861 cons cell @code{(@var{width} . @var{height})}. If the @var{position}
1862 is a buffer position, return the size of the character at that position.
1865 @cindex mouse event, timestamp
1866 @cindex timestamp of a mouse event
1867 @defun posn-timestamp position
1868 Return the timestamp in @var{position}. This is the time at which the
1869 event occurred, in milliseconds.
1872 These functions compute a position list given particular buffer
1873 position or screen position. You can access the data in this position
1874 list with the functions described above.
1876 @defun posn-at-point &optional pos window
1877 This function returns a position list for position @var{pos} in
1878 @var{window}. @var{pos} defaults to point in @var{window};
1879 @var{window} defaults to the selected window.
1881 @code{posn-at-point} returns @code{nil} if @var{pos} is not visible in
1885 @defun posn-at-x-y x y &optional frame-or-window whole
1886 This function returns position information corresponding to pixel
1887 coordinates @var{x} and @var{y} in a specified frame or window,
1888 @var{frame-or-window}, which defaults to the selected window.
1889 The coordinates @var{x} and @var{y} are relative to the
1890 frame or window used.
1891 If @var{whole} is @code{nil}, the coordinates are relative
1892 to the window text area, otherwise they are relative to
1893 the entire window area including scroll bars, margins and fringes.
1896 These functions are useful for decoding scroll bar events.
1898 @defun scroll-bar-event-ratio event
1899 This function returns the fractional vertical position of a scroll bar
1900 event within the scroll bar. The value is a cons cell
1901 @code{(@var{portion} . @var{whole})} containing two integers whose ratio
1902 is the fractional position.
1905 @defun scroll-bar-scale ratio total
1906 This function multiplies (in effect) @var{ratio} by @var{total},
1907 rounding the result to an integer. The argument @var{ratio} is not a
1908 number, but rather a pair @code{(@var{num} . @var{denom})}---typically a
1909 value returned by @code{scroll-bar-event-ratio}.
1911 This function is handy for scaling a position on a scroll bar into a
1912 buffer position. Here's how to do that:
1917 (posn-x-y (event-start event))
1918 (- (point-max) (point-min))))
1921 Recall that scroll bar events have two integers forming a ratio, in place
1922 of a pair of x and y coordinates.
1925 @node Strings of Events
1926 @subsection Putting Keyboard Events in Strings
1927 @cindex keyboard events in strings
1928 @cindex strings with keyboard events
1930 In most of the places where strings are used, we conceptualize the
1931 string as containing text characters---the same kind of characters found
1932 in buffers or files. Occasionally Lisp programs use strings that
1933 conceptually contain keyboard characters; for example, they may be key
1934 sequences or keyboard macro definitions. However, storing keyboard
1935 characters in a string is a complex matter, for reasons of historical
1936 compatibility, and it is not always possible.
1938 We recommend that new programs avoid dealing with these complexities
1939 by not storing keyboard events in strings. Here is how to do that:
1943 Use vectors instead of strings for key sequences, when you plan to use
1944 them for anything other than as arguments to @code{lookup-key} and
1945 @code{define-key}. For example, you can use
1946 @code{read-key-sequence-vector} instead of @code{read-key-sequence}, and
1947 @code{this-command-keys-vector} instead of @code{this-command-keys}.
1950 Use vectors to write key sequence constants containing meta characters,
1951 even when passing them directly to @code{define-key}.
1954 When you have to look at the contents of a key sequence that might be a
1955 string, use @code{listify-key-sequence} (@pxref{Event Input Misc})
1956 first, to convert it to a list.
1959 The complexities stem from the modifier bits that keyboard input
1960 characters can include. Aside from the Meta modifier, none of these
1961 modifier bits can be included in a string, and the Meta modifier is
1962 allowed only in special cases.
1964 The earliest GNU Emacs versions represented meta characters as codes
1965 in the range of 128 to 255. At that time, the basic character codes
1966 ranged from 0 to 127, so all keyboard character codes did fit in a
1967 string. Many Lisp programs used @samp{\M-} in string constants to stand
1968 for meta characters, especially in arguments to @code{define-key} and
1969 similar functions, and key sequences and sequences of events were always
1970 represented as strings.
1972 When we added support for larger basic character codes beyond 127, and
1973 additional modifier bits, we had to change the representation of meta
1974 characters. Now the flag that represents the Meta modifier in a
1982 and such numbers cannot be included in a string.
1984 To support programs with @samp{\M-} in string constants, there are
1985 special rules for including certain meta characters in a string.
1986 Here are the rules for interpreting a string as a sequence of input
1991 If the keyboard character value is in the range of 0 to 127, it can go
1992 in the string unchanged.
1995 The meta variants of those characters, with codes in the range of
2004 @math{2^{27} + 127},
2009 can also go in the string, but you must change their
2010 numeric values. You must set the
2024 bit, resulting in a value between 128 and 255. Only a unibyte string
2025 can include these codes.
2028 Non-@acronym{ASCII} characters above 256 can be included in a multibyte string.
2031 Other keyboard character events cannot fit in a string. This includes
2032 keyboard events in the range of 128 to 255.
2035 Functions such as @code{read-key-sequence} that construct strings of
2036 keyboard input characters follow these rules: they construct vectors
2037 instead of strings, when the events won't fit in a string.
2039 When you use the read syntax @samp{\M-} in a string, it produces a
2040 code in the range of 128 to 255---the same code that you get if you
2041 modify the corresponding keyboard event to put it in the string. Thus,
2042 meta events in strings work consistently regardless of how they get into
2045 However, most programs would do well to avoid these issues by
2046 following the recommendations at the beginning of this section.
2049 @section Reading Input
2051 The editor command loop reads key sequences using the function
2052 @code{read-key-sequence}, which uses @code{read-event}. These and other
2053 functions for event input are also available for use in Lisp programs.
2054 See also @code{momentary-string-display} in @ref{Temporary Displays},
2055 and @code{sit-for} in @ref{Waiting}. @xref{Terminal Input}, for
2056 functions and variables for controlling terminal input modes and
2057 debugging terminal input. @xref{Translating Input}, for features you
2058 can use for translating or modifying input events while reading them.
2060 For higher-level input facilities, see @ref{Minibuffers}.
2063 * Key Sequence Input:: How to read one key sequence.
2064 * Reading One Event:: How to read just one event.
2065 * Invoking the Input Method:: How reading an event uses the input method.
2066 * Quoted Character Input:: Asking the user to specify a character.
2067 * Event Input Misc:: How to reread or throw away input events.
2070 @node Key Sequence Input
2071 @subsection Key Sequence Input
2072 @cindex key sequence input
2074 The command loop reads input a key sequence at a time, by calling
2075 @code{read-key-sequence}. Lisp programs can also call this function;
2076 for example, @code{describe-key} uses it to read the key to describe.
2078 @defun read-key-sequence prompt &optional continue-echo dont-downcase-last switch-frame-ok command-loop
2079 @cindex key sequence
2080 This function reads a key sequence and returns it as a string or
2081 vector. It keeps reading events until it has accumulated a complete key
2082 sequence; that is, enough to specify a non-prefix command using the
2083 currently active keymaps. (Remember that a key sequence that starts
2084 with a mouse event is read using the keymaps of the buffer in the
2085 window that the mouse was in, not the current buffer.)
2087 If the events are all characters and all can fit in a string, then
2088 @code{read-key-sequence} returns a string (@pxref{Strings of Events}).
2089 Otherwise, it returns a vector, since a vector can hold all kinds of
2090 events---characters, symbols, and lists. The elements of the string or
2091 vector are the events in the key sequence.
2093 Reading a key sequence includes translating the events in various
2094 ways. @xref{Translating Input}.
2096 The argument @var{prompt} is either a string to be displayed in the
2097 echo area as a prompt, or @code{nil}, meaning not to display a prompt.
2098 The argument @var{continue-echo}, if non-@code{nil}, means to echo
2099 this key as a continuation of the previous key.
2101 Normally any upper case event is converted to lower case if the
2102 original event is undefined and the lower case equivalent is defined.
2103 The argument @var{dont-downcase-last}, if non-@code{nil}, means do not
2104 convert the last event to lower case. This is appropriate for reading
2105 a key sequence to be defined.
2107 The argument @var{switch-frame-ok}, if non-@code{nil}, means that this
2108 function should process a @code{switch-frame} event if the user
2109 switches frames before typing anything. If the user switches frames
2110 in the middle of a key sequence, or at the start of the sequence but
2111 @var{switch-frame-ok} is @code{nil}, then the event will be put off
2112 until after the current key sequence.
2114 The argument @var{command-loop}, if non-@code{nil}, means that this
2115 key sequence is being read by something that will read commands one
2116 after another. It should be @code{nil} if the caller will read just
2119 In the following example, Emacs displays the prompt @samp{?} in the
2120 echo area, and then the user types @kbd{C-x C-f}.
2123 (read-key-sequence "?")
2126 ---------- Echo Area ----------
2128 ---------- Echo Area ----------
2134 The function @code{read-key-sequence} suppresses quitting: @kbd{C-g}
2135 typed while reading with this function works like any other character,
2136 and does not set @code{quit-flag}. @xref{Quitting}.
2139 @defun read-key-sequence-vector prompt &optional continue-echo dont-downcase-last switch-frame-ok command-loop
2140 This is like @code{read-key-sequence} except that it always
2141 returns the key sequence as a vector, never as a string.
2142 @xref{Strings of Events}.
2145 @cindex upper case key sequence
2146 @cindex downcasing in @code{lookup-key}
2147 If an input character is upper-case (or has the shift modifier) and
2148 has no key binding, but its lower-case equivalent has one, then
2149 @code{read-key-sequence} converts the character to lower case. Note
2150 that @code{lookup-key} does not perform case conversion in this way.
2152 The function @code{read-key-sequence} also transforms some mouse events.
2153 It converts unbound drag events into click events, and discards unbound
2154 button-down events entirely. It also reshuffles focus events and
2155 miscellaneous window events so that they never appear in a key sequence
2156 with any other events.
2158 @cindex @code{header-line} prefix key
2159 @cindex @code{mode-line} prefix key
2160 @cindex @code{vertical-line} prefix key
2161 @cindex @code{horizontal-scroll-bar} prefix key
2162 @cindex @code{vertical-scroll-bar} prefix key
2163 @cindex @code{menu-bar} prefix key
2164 @cindex mouse events, in special parts of frame
2165 When mouse events occur in special parts of a window, such as a mode
2166 line or a scroll bar, the event type shows nothing special---it is the
2167 same symbol that would normally represent that combination of mouse
2168 button and modifier keys. The information about the window part is kept
2169 elsewhere in the event---in the coordinates. But
2170 @code{read-key-sequence} translates this information into imaginary
2171 ``prefix keys'', all of which are symbols: @code{header-line},
2172 @code{horizontal-scroll-bar}, @code{menu-bar}, @code{mode-line},
2173 @code{vertical-line}, and @code{vertical-scroll-bar}. You can define
2174 meanings for mouse clicks in special window parts by defining key
2175 sequences using these imaginary prefix keys.
2177 For example, if you call @code{read-key-sequence} and then click the
2178 mouse on the window's mode line, you get two events, like this:
2181 (read-key-sequence "Click on the mode line: ")
2182 @result{} [mode-line
2184 (#<window 6 on NEWS> mode-line
2185 (40 . 63) 5959987))]
2188 @defvar num-input-keys
2190 This variable's value is the number of key sequences processed so far in
2191 this Emacs session. This includes key sequences read from the terminal
2192 and key sequences read from keyboard macros being executed.
2195 @node Reading One Event
2196 @subsection Reading One Event
2197 @cindex reading a single event
2198 @cindex event, reading only one
2200 The lowest level functions for command input are those that read a
2203 None of the three functions below suppresses quitting.
2205 @defun read-event &optional prompt inherit-input-method
2206 This function reads and returns the next event of command input, waiting
2207 if necessary until an event is available. Events can come directly from
2208 the user or from a keyboard macro.
2210 If the optional argument @var{prompt} is non-@code{nil}, it should be a
2211 string to display in the echo area as a prompt. Otherwise,
2212 @code{read-event} does not display any message to indicate it is waiting
2213 for input; instead, it prompts by echoing: it displays descriptions of
2214 the events that led to or were read by the current command. @xref{The
2217 If @var{inherit-input-method} is non-@code{nil}, then the current input
2218 method (if any) is employed to make it possible to enter a
2219 non-@acronym{ASCII} character. Otherwise, input method handling is disabled
2220 for reading this event.
2222 If @code{cursor-in-echo-area} is non-@code{nil}, then @code{read-event}
2223 moves the cursor temporarily to the echo area, to the end of any message
2224 displayed there. Otherwise @code{read-event} does not move the cursor.
2226 If @code{read-event} gets an event that is defined as a help character,
2227 then in some cases @code{read-event} processes the event directly without
2228 returning. @xref{Help Functions}. Certain other events, called
2229 @dfn{special events}, are also processed directly within
2230 @code{read-event} (@pxref{Special Events}).
2232 Here is what happens if you call @code{read-event} and then press the
2233 right-arrow function key:
2243 @defun read-char &optional prompt inherit-input-method
2244 This function reads and returns a character of command input. If the
2245 user generates an event which is not a character (i.e. a mouse click or
2246 function key event), @code{read-char} signals an error. The arguments
2247 work as in @code{read-event}.
2249 In the first example, the user types the character @kbd{1} (@acronym{ASCII}
2250 code 49). The second example shows a keyboard macro definition that
2251 calls @code{read-char} from the minibuffer using @code{eval-expression}.
2252 @code{read-char} reads the keyboard macro's very next character, which
2253 is @kbd{1}. Then @code{eval-expression} displays its return value in
2263 ;; @r{We assume here you use @kbd{M-:} to evaluate this.}
2264 (symbol-function 'foo)
2265 @result{} "^[:(read-char)^M1"
2268 (execute-kbd-macro 'foo)
2275 @defun read-char-exclusive &optional prompt inherit-input-method
2276 This function reads and returns a character of command input. If the
2277 user generates an event which is not a character,
2278 @code{read-char-exclusive} ignores it and reads another event, until it
2279 gets a character. The arguments work as in @code{read-event}.
2282 @defvar num-nonmacro-input-events
2283 This variable holds the total number of input events received so far
2284 from the terminal---not counting those generated by keyboard macros.
2287 @node Invoking the Input Method
2288 @subsection Invoking the Input Method
2290 The event-reading functions invoke the current input method, if any
2291 (@pxref{Input Methods}). If the value of @code{input-method-function}
2292 is non-@code{nil}, it should be a function; when @code{read-event} reads
2293 a printing character (including @key{SPC}) with no modifier bits, it
2294 calls that function, passing the character as an argument.
2296 @defvar input-method-function
2297 If this is non-@code{nil}, its value specifies the current input method
2300 @strong{Warning:} don't bind this variable with @code{let}. It is often
2301 buffer-local, and if you bind it around reading input (which is exactly
2302 when you @emph{would} bind it), switching buffers asynchronously while
2303 Emacs is waiting will cause the value to be restored in the wrong
2307 The input method function should return a list of events which should
2308 be used as input. (If the list is @code{nil}, that means there is no
2309 input, so @code{read-event} waits for another event.) These events are
2310 processed before the events in @code{unread-command-events}
2311 (@pxref{Event Input Misc}). Events
2312 returned by the input method function are not passed to the input method
2313 function again, even if they are printing characters with no modifier
2316 If the input method function calls @code{read-event} or
2317 @code{read-key-sequence}, it should bind @code{input-method-function} to
2318 @code{nil} first, to prevent recursion.
2320 The input method function is not called when reading the second and
2321 subsequent events of a key sequence. Thus, these characters are not
2322 subject to input method processing. The input method function should
2323 test the values of @code{overriding-local-map} and
2324 @code{overriding-terminal-local-map}; if either of these variables is
2325 non-@code{nil}, the input method should put its argument into a list and
2326 return that list with no further processing.
2328 @node Quoted Character Input
2329 @subsection Quoted Character Input
2330 @cindex quoted character input
2332 You can use the function @code{read-quoted-char} to ask the user to
2333 specify a character, and allow the user to specify a control or meta
2334 character conveniently, either literally or as an octal character code.
2335 The command @code{quoted-insert} uses this function.
2337 @defun read-quoted-char &optional prompt
2338 @cindex octal character input
2339 @cindex control characters, reading
2340 @cindex nonprinting characters, reading
2341 This function is like @code{read-char}, except that if the first
2342 character read is an octal digit (0-7), it reads any number of octal
2343 digits (but stopping if a non-octal digit is found), and returns the
2344 character represented by that numeric character code. If the
2345 character that terminates the sequence of octal digits is @key{RET},
2346 it is discarded. Any other terminating character is used as input
2347 after this function returns.
2349 Quitting is suppressed when the first character is read, so that the
2350 user can enter a @kbd{C-g}. @xref{Quitting}.
2352 If @var{prompt} is supplied, it specifies a string for prompting the
2353 user. The prompt string is always displayed in the echo area, followed
2354 by a single @samp{-}.
2356 In the following example, the user types in the octal number 177 (which
2360 (read-quoted-char "What character")
2363 ---------- Echo Area ----------
2364 What character @kbd{1 7 7}-
2365 ---------- Echo Area ----------
2373 @node Event Input Misc
2374 @subsection Miscellaneous Event Input Features
2376 This section describes how to ``peek ahead'' at events without using
2377 them up, how to check for pending input, and how to discard pending
2378 input. See also the function @code{read-passwd} (@pxref{Reading a
2381 @defvar unread-command-events
2383 @cindex peeking at input
2384 This variable holds a list of events waiting to be read as command
2385 input. The events are used in the order they appear in the list, and
2386 removed one by one as they are used.
2388 The variable is needed because in some cases a function reads an event
2389 and then decides not to use it. Storing the event in this variable
2390 causes it to be processed normally, by the command loop or by the
2391 functions to read command input.
2393 @cindex prefix argument unreading
2394 For example, the function that implements numeric prefix arguments reads
2395 any number of digits. When it finds a non-digit event, it must unread
2396 the event so that it can be read normally by the command loop.
2397 Likewise, incremental search uses this feature to unread events with no
2398 special meaning in a search, because these events should exit the search
2399 and then execute normally.
2401 The reliable and easy way to extract events from a key sequence so as to
2402 put them in @code{unread-command-events} is to use
2403 @code{listify-key-sequence} (@pxref{Strings of Events}).
2405 Normally you add events to the front of this list, so that the events
2406 most recently unread will be reread first.
2409 @defun listify-key-sequence key
2410 This function converts the string or vector @var{key} to a list of
2411 individual events, which you can put in @code{unread-command-events}.
2414 @defvar unread-command-char
2415 This variable holds a character to be read as command input.
2416 A value of -1 means ``empty''.
2418 This variable is mostly obsolete now that you can use
2419 @code{unread-command-events} instead; it exists only to support programs
2420 written for Emacs versions 18 and earlier.
2423 @defun input-pending-p
2424 @cindex waiting for command key input
2425 This function determines whether any command input is currently
2426 available to be read. It returns immediately, with value @code{t} if
2427 there is available input, @code{nil} otherwise. On rare occasions it
2428 may return @code{t} when no input is available.
2431 @defvar last-input-event
2432 @defvarx last-input-char
2433 This variable records the last terminal input event read, whether
2434 as part of a command or explicitly by a Lisp program.
2436 In the example below, the Lisp program reads the character @kbd{1},
2437 @acronym{ASCII} code 49. It becomes the value of @code{last-input-event},
2438 while @kbd{C-e} (we assume @kbd{C-x C-e} command is used to evaluate
2439 this expression) remains the value of @code{last-command-event}.
2443 (progn (print (read-char))
2444 (print last-command-event)
2452 The alias @code{last-input-char} exists for compatibility with
2456 @defmac while-no-input body@dots{}
2457 This construct runs the @var{body} forms and returns the value of the
2458 last one---but only if no input arrives. If any input arrives during
2459 the execution of the @var{body} forms, it aborts them (working much
2460 like a quit). The @code{while-no-input} form returns @code{nil} if
2461 aborted by a real quit, and returns @code{t} if aborted by arrival of
2464 If a part of @var{body} binds @code{inhibit-quit} to non-@code{nil},
2465 arrival of input during those parts won't cause an abort until
2466 the end of that part.
2468 If you want to be able to distinguish all possible values computed
2469 by @var{body} from both kinds of abort conditions, write the code
2475 (progn . @var{body})))
2479 @defun discard-input
2481 @cindex discard input
2482 @cindex terminate keyboard macro
2483 This function discards the contents of the terminal input buffer and
2484 cancels any keyboard macro that might be in the process of definition.
2485 It returns @code{nil}.
2487 In the following example, the user may type a number of characters right
2488 after starting the evaluation of the form. After the @code{sleep-for}
2489 finishes sleeping, @code{discard-input} discards any characters typed
2493 (progn (sleep-for 2)
2499 @node Special Events
2500 @section Special Events
2502 @cindex special events
2503 Special events are handled at a very low level---as soon as they are
2504 read. The @code{read-event} function processes these events itself, and
2505 never returns them. Instead, it keeps waiting for the first event
2506 that is not special and returns that one.
2508 Events that are handled in this way do not echo, they are never grouped
2509 into key sequences, and they never appear in the value of
2510 @code{last-command-event} or @code{(this-command-keys)}. They do not
2511 discard a numeric argument, they cannot be unread with
2512 @code{unread-command-events}, they may not appear in a keyboard macro,
2513 and they are not recorded in a keyboard macro while you are defining
2516 These events do, however, appear in @code{last-input-event} immediately
2517 after they are read, and this is the way for the event's definition to
2518 find the actual event.
2520 The events types @code{iconify-frame}, @code{make-frame-visible} and
2521 @code{delete-frame} are normally handled in this way. The keymap which
2522 defines how to handle special events---and which events are special---is
2523 in the variable @code{special-event-map} (@pxref{Active Keymaps}).
2526 @section Waiting for Elapsed Time or Input
2530 The wait functions are designed to wait for a certain amount of time
2531 to pass or until there is input. For example, you may wish to pause in
2532 the middle of a computation to allow the user time to view the display.
2533 @code{sit-for} pauses and updates the screen, and returns immediately if
2534 input comes in, while @code{sleep-for} pauses without updating the
2537 @defun sit-for seconds &optional nodisp
2538 This function performs redisplay (provided there is no pending input
2539 from the user), then waits @var{seconds} seconds, or until input is
2540 available. The value is @code{t} if @code{sit-for} waited the full
2541 time with no input arriving (see @code{input-pending-p} in @ref{Event
2542 Input Misc}). Otherwise, the value is @code{nil}.
2544 The argument @var{seconds} need not be an integer. If it is a floating
2545 point number, @code{sit-for} waits for a fractional number of seconds.
2546 Some systems support only a whole number of seconds; on these systems,
2547 @var{seconds} is rounded down.
2549 If @var{seconds} is negative, force a redisplay even if there is
2550 pending input. So use @code{(sit-for -1)} to force a redisplay.
2552 The expression @code{(sit-for 0)} is a convenient way to request a
2553 redisplay, without any delay, if there is no pending input. @xref{Forcing Redisplay}.
2555 If @var{nodisp} is non-@code{nil}, then @code{sit-for} does not
2556 redisplay, but it still returns as soon as input is available (or when
2557 the timeout elapses).
2559 Iconifying or deiconifying a frame makes @code{sit-for} return, because
2560 that generates an event. @xref{Misc Events}.
2562 The usual purpose of @code{sit-for} is to give the user time to read
2563 text that you display.
2565 It is also possible to call @code{sit-for} with three arguments,
2566 as @code{(sit-for @var{seconds} @var{millisec} @var{nodisp})},
2567 but that is considered obsolete.
2570 @defun sleep-for seconds &optional millisec
2571 This function simply pauses for @var{seconds} seconds without updating
2572 the display. It pays no attention to available input. It returns
2575 The argument @var{seconds} need not be an integer. If it is a floating
2576 point number, @code{sleep-for} waits for a fractional number of seconds.
2577 Some systems support only a whole number of seconds; on these systems,
2578 @var{seconds} is rounded down.
2580 The optional argument @var{millisec} specifies an additional waiting
2581 period measured in milliseconds. This adds to the period specified by
2582 @var{seconds}. If the system doesn't support waiting fractions of a
2583 second, you get an error if you specify nonzero @var{millisec}.
2585 Use @code{sleep-for} when you wish to guarantee a delay.
2588 @xref{Time of Day}, for functions to get the current time.
2594 @cindex interrupt Lisp functions
2596 Typing @kbd{C-g} while a Lisp function is running causes Emacs to
2597 @dfn{quit} whatever it is doing. This means that control returns to the
2598 innermost active command loop.
2600 Typing @kbd{C-g} while the command loop is waiting for keyboard input
2601 does not cause a quit; it acts as an ordinary input character. In the
2602 simplest case, you cannot tell the difference, because @kbd{C-g}
2603 normally runs the command @code{keyboard-quit}, whose effect is to quit.
2604 However, when @kbd{C-g} follows a prefix key, they combine to form an
2605 undefined key. The effect is to cancel the prefix key as well as any
2608 In the minibuffer, @kbd{C-g} has a different definition: it aborts out
2609 of the minibuffer. This means, in effect, that it exits the minibuffer
2610 and then quits. (Simply quitting would return to the command loop
2611 @emph{within} the minibuffer.) The reason why @kbd{C-g} does not quit
2612 directly when the command reader is reading input is so that its meaning
2613 can be redefined in the minibuffer in this way. @kbd{C-g} following a
2614 prefix key is not redefined in the minibuffer, and it has its normal
2615 effect of canceling the prefix key and prefix argument. This too
2616 would not be possible if @kbd{C-g} always quit directly.
2618 When @kbd{C-g} does directly quit, it does so by setting the variable
2619 @code{quit-flag} to @code{t}. Emacs checks this variable at appropriate
2620 times and quits if it is not @code{nil}. Setting @code{quit-flag}
2621 non-@code{nil} in any way thus causes a quit.
2623 At the level of C code, quitting cannot happen just anywhere; only at the
2624 special places that check @code{quit-flag}. The reason for this is
2625 that quitting at other places might leave an inconsistency in Emacs's
2626 internal state. Because quitting is delayed until a safe place, quitting
2627 cannot make Emacs crash.
2629 Certain functions such as @code{read-key-sequence} or
2630 @code{read-quoted-char} prevent quitting entirely even though they wait
2631 for input. Instead of quitting, @kbd{C-g} serves as the requested
2632 input. In the case of @code{read-key-sequence}, this serves to bring
2633 about the special behavior of @kbd{C-g} in the command loop. In the
2634 case of @code{read-quoted-char}, this is so that @kbd{C-q} can be used
2635 to quote a @kbd{C-g}.
2637 @cindex prevent quitting
2638 You can prevent quitting for a portion of a Lisp function by binding
2639 the variable @code{inhibit-quit} to a non-@code{nil} value. Then,
2640 although @kbd{C-g} still sets @code{quit-flag} to @code{t} as usual, the
2641 usual result of this---a quit---is prevented. Eventually,
2642 @code{inhibit-quit} will become @code{nil} again, such as when its
2643 binding is unwound at the end of a @code{let} form. At that time, if
2644 @code{quit-flag} is still non-@code{nil}, the requested quit happens
2645 immediately. This behavior is ideal when you wish to make sure that
2646 quitting does not happen within a ``critical section'' of the program.
2648 @cindex @code{read-quoted-char} quitting
2649 In some functions (such as @code{read-quoted-char}), @kbd{C-g} is
2650 handled in a special way that does not involve quitting. This is done
2651 by reading the input with @code{inhibit-quit} bound to @code{t}, and
2652 setting @code{quit-flag} to @code{nil} before @code{inhibit-quit}
2653 becomes @code{nil} again. This excerpt from the definition of
2654 @code{read-quoted-char} shows how this is done; it also shows that
2655 normal quitting is permitted after the first character of input.
2658 (defun read-quoted-char (&optional prompt)
2659 "@dots{}@var{documentation}@dots{}"
2660 (let ((message-log-max nil) done (first t) (code 0) char)
2662 (let ((inhibit-quit first)
2664 (and prompt (message "%s-" prompt))
2665 (setq char (read-event))
2666 (if inhibit-quit (setq quit-flag nil)))
2667 @r{@dots{}set the variable @code{code}@dots{}})
2672 If this variable is non-@code{nil}, then Emacs quits immediately, unless
2673 @code{inhibit-quit} is non-@code{nil}. Typing @kbd{C-g} ordinarily sets
2674 @code{quit-flag} non-@code{nil}, regardless of @code{inhibit-quit}.
2677 @defvar inhibit-quit
2678 This variable determines whether Emacs should quit when @code{quit-flag}
2679 is set to a value other than @code{nil}. If @code{inhibit-quit} is
2680 non-@code{nil}, then @code{quit-flag} has no special effect.
2683 @defmac with-local-quit body@dots{}
2684 This macro executes @var{body} forms in sequence, but allows quitting, at
2685 least locally, within @var{body} even if @code{inhibit-quit} was
2686 non-@code{nil} outside this construct. It returns the value of the
2687 last form in @var{body}, unless exited by quitting, in which case
2688 it returns @code{nil}.
2690 If @code{inhibit-quit} is @code{nil} on entry to @code{with-local-quit},
2691 it only executes the @var{body}, and setting @code{quit-flag} causes
2692 a normal quit. However, if @code{inhibit-quit} is non-@code{nil} so
2693 that ordinary quitting is delayed, a non-@code{nil} @code{quit-flag}
2694 triggers a special kind of local quit. This ends the execution of
2695 @var{body} and exits the @code{with-local-quit} body with
2696 @code{quit-flag} still non-@code{nil}, so that another (ordinary) quit
2697 will happen as soon as that is allowed. If @code{quit-flag} is
2698 already non-@code{nil} at the beginning of @var{body}, the local quit
2699 happens immediately and the body doesn't execute at all.
2701 This macro is mainly useful in functions that can be called from
2702 timers, process filters, process sentinels, @code{pre-command-hook},
2703 @code{post-command-hook}, and other places where @code{inhibit-quit} is
2704 normally bound to @code{t}.
2707 @deffn Command keyboard-quit
2708 This function signals the @code{quit} condition with @code{(signal 'quit
2709 nil)}. This is the same thing that quitting does. (See @code{signal}
2713 You can specify a character other than @kbd{C-g} to use for quitting.
2714 See the function @code{set-input-mode} in @ref{Terminal Input}.
2716 @node Prefix Command Arguments
2717 @section Prefix Command Arguments
2718 @cindex prefix argument
2719 @cindex raw prefix argument
2720 @cindex numeric prefix argument
2722 Most Emacs commands can use a @dfn{prefix argument}, a number
2723 specified before the command itself. (Don't confuse prefix arguments
2724 with prefix keys.) The prefix argument is at all times represented by a
2725 value, which may be @code{nil}, meaning there is currently no prefix
2726 argument. Each command may use the prefix argument or ignore it.
2728 There are two representations of the prefix argument: @dfn{raw} and
2729 @dfn{numeric}. The editor command loop uses the raw representation
2730 internally, and so do the Lisp variables that store the information, but
2731 commands can request either representation.
2733 Here are the possible values of a raw prefix argument:
2737 @code{nil}, meaning there is no prefix argument. Its numeric value is
2738 1, but numerous commands make a distinction between @code{nil} and the
2742 An integer, which stands for itself.
2745 A list of one element, which is an integer. This form of prefix
2746 argument results from one or a succession of @kbd{C-u}'s with no
2747 digits. The numeric value is the integer in the list, but some
2748 commands make a distinction between such a list and an integer alone.
2751 The symbol @code{-}. This indicates that @kbd{M--} or @kbd{C-u -} was
2752 typed, without following digits. The equivalent numeric value is
2753 @minus{}1, but some commands make a distinction between the integer
2754 @minus{}1 and the symbol @code{-}.
2757 We illustrate these possibilities by calling the following function with
2762 (defun display-prefix (arg)
2763 "Display the value of the raw prefix arg."
2770 Here are the results of calling @code{display-prefix} with various
2771 raw prefix arguments:
2774 M-x display-prefix @print{} nil
2776 C-u M-x display-prefix @print{} (4)
2778 C-u C-u M-x display-prefix @print{} (16)
2780 C-u 3 M-x display-prefix @print{} 3
2782 M-3 M-x display-prefix @print{} 3 ; @r{(Same as @code{C-u 3}.)}
2784 C-u - M-x display-prefix @print{} -
2786 M-- M-x display-prefix @print{} - ; @r{(Same as @code{C-u -}.)}
2788 C-u - 7 M-x display-prefix @print{} -7
2790 M-- 7 M-x display-prefix @print{} -7 ; @r{(Same as @code{C-u -7}.)}
2793 Emacs uses two variables to store the prefix argument:
2794 @code{prefix-arg} and @code{current-prefix-arg}. Commands such as
2795 @code{universal-argument} that set up prefix arguments for other
2796 commands store them in @code{prefix-arg}. In contrast,
2797 @code{current-prefix-arg} conveys the prefix argument to the current
2798 command, so setting it has no effect on the prefix arguments for future
2801 Normally, commands specify which representation to use for the prefix
2802 argument, either numeric or raw, in the @code{interactive} specification.
2803 (@xref{Using Interactive}.) Alternatively, functions may look at the
2804 value of the prefix argument directly in the variable
2805 @code{current-prefix-arg}, but this is less clean.
2807 @defun prefix-numeric-value arg
2808 This function returns the numeric meaning of a valid raw prefix argument
2809 value, @var{arg}. The argument may be a symbol, a number, or a list.
2810 If it is @code{nil}, the value 1 is returned; if it is @code{-}, the
2811 value @minus{}1 is returned; if it is a number, that number is returned;
2812 if it is a list, the @sc{car} of that list (which should be a number) is
2816 @defvar current-prefix-arg
2817 This variable holds the raw prefix argument for the @emph{current}
2818 command. Commands may examine it directly, but the usual method for
2819 accessing it is with @code{(interactive "P")}.
2823 The value of this variable is the raw prefix argument for the
2824 @emph{next} editing command. Commands such as @code{universal-argument}
2825 that specify prefix arguments for the following command work by setting
2829 @defvar last-prefix-arg
2830 The raw prefix argument value used by the previous command.
2833 The following commands exist to set up prefix arguments for the
2834 following command. Do not call them for any other reason.
2836 @deffn Command universal-argument
2837 This command reads input and specifies a prefix argument for the
2838 following command. Don't call this command yourself unless you know
2842 @deffn Command digit-argument arg
2843 This command adds to the prefix argument for the following command. The
2844 argument @var{arg} is the raw prefix argument as it was before this
2845 command; it is used to compute the updated prefix argument. Don't call
2846 this command yourself unless you know what you are doing.
2849 @deffn Command negative-argument arg
2850 This command adds to the numeric argument for the next command. The
2851 argument @var{arg} is the raw prefix argument as it was before this
2852 command; its value is negated to form the new prefix argument. Don't
2853 call this command yourself unless you know what you are doing.
2856 @node Recursive Editing
2857 @section Recursive Editing
2858 @cindex recursive command loop
2859 @cindex recursive editing level
2860 @cindex command loop, recursive
2862 The Emacs command loop is entered automatically when Emacs starts up.
2863 This top-level invocation of the command loop never exits; it keeps
2864 running as long as Emacs does. Lisp programs can also invoke the
2865 command loop. Since this makes more than one activation of the command
2866 loop, we call it @dfn{recursive editing}. A recursive editing level has
2867 the effect of suspending whatever command invoked it and permitting the
2868 user to do arbitrary editing before resuming that command.
2870 The commands available during recursive editing are the same ones
2871 available in the top-level editing loop and defined in the keymaps.
2872 Only a few special commands exit the recursive editing level; the others
2873 return to the recursive editing level when they finish. (The special
2874 commands for exiting are always available, but they do nothing when
2875 recursive editing is not in progress.)
2877 All command loops, including recursive ones, set up all-purpose error
2878 handlers so that an error in a command run from the command loop will
2881 @cindex minibuffer input
2882 Minibuffer input is a special kind of recursive editing. It has a few
2883 special wrinkles, such as enabling display of the minibuffer and the
2884 minibuffer window, but fewer than you might suppose. Certain keys
2885 behave differently in the minibuffer, but that is only because of the
2886 minibuffer's local map; if you switch windows, you get the usual Emacs
2889 @cindex @code{throw} example
2891 @cindex exit recursive editing
2893 To invoke a recursive editing level, call the function
2894 @code{recursive-edit}. This function contains the command loop; it also
2895 contains a call to @code{catch} with tag @code{exit}, which makes it
2896 possible to exit the recursive editing level by throwing to @code{exit}
2897 (@pxref{Catch and Throw}). If you throw a value other than @code{t},
2898 then @code{recursive-edit} returns normally to the function that called
2899 it. The command @kbd{C-M-c} (@code{exit-recursive-edit}) does this.
2900 Throwing a @code{t} value causes @code{recursive-edit} to quit, so that
2901 control returns to the command loop one level up. This is called
2902 @dfn{aborting}, and is done by @kbd{C-]} (@code{abort-recursive-edit}).
2904 Most applications should not use recursive editing, except as part of
2905 using the minibuffer. Usually it is more convenient for the user if you
2906 change the major mode of the current buffer temporarily to a special
2907 major mode, which should have a command to go back to the previous mode.
2908 (The @kbd{e} command in Rmail uses this technique.) Or, if you wish to
2909 give the user different text to edit ``recursively'', create and select
2910 a new buffer in a special mode. In this mode, define a command to
2911 complete the processing and go back to the previous buffer. (The
2912 @kbd{m} command in Rmail does this.)
2914 Recursive edits are useful in debugging. You can insert a call to
2915 @code{debug} into a function definition as a sort of breakpoint, so that
2916 you can look around when the function gets there. @code{debug} invokes
2917 a recursive edit but also provides the other features of the debugger.
2919 Recursive editing levels are also used when you type @kbd{C-r} in
2920 @code{query-replace} or use @kbd{C-x q} (@code{kbd-macro-query}).
2922 @defun recursive-edit
2923 @cindex suspend evaluation
2924 This function invokes the editor command loop. It is called
2925 automatically by the initialization of Emacs, to let the user begin
2926 editing. When called from a Lisp program, it enters a recursive editing
2929 In the following example, the function @code{simple-rec} first
2930 advances point one word, then enters a recursive edit, printing out a
2931 message in the echo area. The user can then do any editing desired, and
2932 then type @kbd{C-M-c} to exit and continue executing @code{simple-rec}.
2935 (defun simple-rec ()
2937 (message "Recursive edit in progress")
2940 @result{} simple-rec
2946 @deffn Command exit-recursive-edit
2947 This function exits from the innermost recursive edit (including
2948 minibuffer input). Its definition is effectively @code{(throw 'exit
2952 @deffn Command abort-recursive-edit
2953 This function aborts the command that requested the innermost recursive
2954 edit (including minibuffer input), by signaling @code{quit}
2955 after exiting the recursive edit. Its definition is effectively
2956 @code{(throw 'exit t)}. @xref{Quitting}.
2959 @deffn Command top-level
2960 This function exits all recursive editing levels; it does not return a
2961 value, as it jumps completely out of any computation directly back to
2962 the main command loop.
2965 @defun recursion-depth
2966 This function returns the current depth of recursive edits. When no
2967 recursive edit is active, it returns 0.
2970 @node Disabling Commands
2971 @section Disabling Commands
2972 @cindex disabled command
2974 @dfn{Disabling a command} marks the command as requiring user
2975 confirmation before it can be executed. Disabling is used for commands
2976 which might be confusing to beginning users, to prevent them from using
2977 the commands by accident.
2980 The low-level mechanism for disabling a command is to put a
2981 non-@code{nil} @code{disabled} property on the Lisp symbol for the
2982 command. These properties are normally set up by the user's
2983 init file (@pxref{Init File}) with Lisp expressions such as this:
2986 (put 'upcase-region 'disabled t)
2990 For a few commands, these properties are present by default (you can
2991 remove them in your init file if you wish).
2993 If the value of the @code{disabled} property is a string, the message
2994 saying the command is disabled includes that string. For example:
2997 (put 'delete-region 'disabled
2998 "Text deleted this way cannot be yanked back!\n")
3001 @xref{Disabling,,, emacs, The GNU Emacs Manual}, for the details on
3002 what happens when a disabled command is invoked interactively.
3003 Disabling a command has no effect on calling it as a function from Lisp
3006 @deffn Command enable-command command
3007 Allow @var{command} (a symbol) to be executed without special
3008 confirmation from now on, and alter the user's init file (@pxref{Init
3009 File}) so that this will apply to future sessions.
3012 @deffn Command disable-command command
3013 Require special confirmation to execute @var{command} from now on, and
3014 alter the user's init file so that this will apply to future sessions.
3017 @defvar disabled-command-function
3018 The value of this variable should be a function. When the user
3019 invokes a disabled command interactively, this function is called
3020 instead of the disabled command. It can use @code{this-command-keys}
3021 to determine what the user typed to run the command, and thus find the
3024 The value may also be @code{nil}. Then all commands work normally,
3027 By default, the value is a function that asks the user whether to
3031 @node Command History
3032 @section Command History
3033 @cindex command history
3034 @cindex complex command
3035 @cindex history of commands
3037 The command loop keeps a history of the complex commands that have
3038 been executed, to make it convenient to repeat these commands. A
3039 @dfn{complex command} is one for which the interactive argument reading
3040 uses the minibuffer. This includes any @kbd{M-x} command, any
3041 @kbd{M-:} command, and any command whose @code{interactive}
3042 specification reads an argument from the minibuffer. Explicit use of
3043 the minibuffer during the execution of the command itself does not cause
3044 the command to be considered complex.
3046 @defvar command-history
3047 This variable's value is a list of recent complex commands, each
3048 represented as a form to evaluate. It continues to accumulate all
3049 complex commands for the duration of the editing session, but when it
3050 reaches the maximum size (@pxref{Minibuffer History}), the oldest
3051 elements are deleted as new ones are added.
3056 @result{} ((switch-to-buffer "chistory.texi")
3057 (describe-key "^X^[")
3058 (visit-tags-table "~/emacs/src/")
3059 (find-tag "repeat-complex-command"))
3064 This history list is actually a special case of minibuffer history
3065 (@pxref{Minibuffer History}), with one special twist: the elements are
3066 expressions rather than strings.
3068 There are a number of commands devoted to the editing and recall of
3069 previous commands. The commands @code{repeat-complex-command}, and
3070 @code{list-command-history} are described in the user manual
3071 (@pxref{Repetition,,, emacs, The GNU Emacs Manual}). Within the
3072 minibuffer, the usual minibuffer history commands are available.
3074 @node Keyboard Macros
3075 @section Keyboard Macros
3076 @cindex keyboard macros
3078 A @dfn{keyboard macro} is a canned sequence of input events that can
3079 be considered a command and made the definition of a key. The Lisp
3080 representation of a keyboard macro is a string or vector containing the
3081 events. Don't confuse keyboard macros with Lisp macros
3084 @defun execute-kbd-macro kbdmacro &optional count loopfunc
3085 This function executes @var{kbdmacro} as a sequence of events. If
3086 @var{kbdmacro} is a string or vector, then the events in it are executed
3087 exactly as if they had been input by the user. The sequence is
3088 @emph{not} expected to be a single key sequence; normally a keyboard
3089 macro definition consists of several key sequences concatenated.
3091 If @var{kbdmacro} is a symbol, then its function definition is used in
3092 place of @var{kbdmacro}. If that is another symbol, this process repeats.
3093 Eventually the result should be a string or vector. If the result is
3094 not a symbol, string, or vector, an error is signaled.
3096 The argument @var{count} is a repeat count; @var{kbdmacro} is executed that
3097 many times. If @var{count} is omitted or @code{nil}, @var{kbdmacro} is
3098 executed once. If it is 0, @var{kbdmacro} is executed over and over until it
3099 encounters an error or a failing search.
3101 If @var{loopfunc} is non-@code{nil}, it is a function that is called,
3102 without arguments, prior to each iteration of the macro. If
3103 @var{loopfunc} returns @code{nil}, then this stops execution of the macro.
3105 @xref{Reading One Event}, for an example of using @code{execute-kbd-macro}.
3108 @defvar executing-kbd-macro
3109 This variable contains the string or vector that defines the keyboard
3110 macro that is currently executing. It is @code{nil} if no macro is
3111 currently executing. A command can test this variable so as to behave
3112 differently when run from an executing macro. Do not set this variable
3116 @defvar defining-kbd-macro
3117 This variable is non-@code{nil} if and only if a keyboard macro is
3118 being defined. A command can test this variable so as to behave
3119 differently while a macro is being defined. The value is
3120 @code{append} while appending to the definition of an existing macro.
3121 The commands @code{start-kbd-macro}, @code{kmacro-start-macro} and
3122 @code{end-kbd-macro} set this variable---do not set it yourself.
3124 The variable is always local to the current terminal and cannot be
3125 buffer-local. @xref{Multiple Displays}.
3128 @defvar last-kbd-macro
3129 This variable is the definition of the most recently defined keyboard
3130 macro. Its value is a string or vector, or @code{nil}.
3132 The variable is always local to the current terminal and cannot be
3133 buffer-local. @xref{Multiple Displays}.
3136 @defvar kbd-macro-termination-hook
3137 This normal hook (@pxref{Standard Hooks}) is run when a keyboard
3138 macro terminates, regardless of what caused it to terminate (reaching
3139 the macro end or an error which ended the macro prematurely).
3143 arch-tag: e34944ad-7d5c-4980-be00-36a5fe54d4b1