The bindings between input events and commands are recorded in data structures called keymaps. Each binding in a keymap associates (or binds) an individual event type either to another keymap or to a command. When an event type is bound to a keymap, that keymap is used to look up the next input event; this continues until a command is found. The whole process is called key lookup.
A keymap is a table mapping event types to definitions (which can be any Lisp objects, though only certain types are meaningful for execution by the command loop). Given an event (or an event type) and a keymap, Emacs can get the event's definition. Events include characters, function keys, and mouse actions (see section Input Events).
A sequence of input events that form a unit is called a key sequence, or key for short. A sequence of one event is always a key sequence, and so are some multi-event sequences.
A keymap determines a binding or definition for any key sequence. If the key sequence is a single event, its binding is the definition of the event in the keymap. The binding of a key sequence of more than one event is found by an iterative process: the binding of the first event is found, and must be a keymap; then the second event's binding is found in that keymap, and so on until all the events in the key sequence are used up.
If the binding of a key sequence is a keymap, we call the key sequence
a prefix key. Otherwise, we call it a complete key (because
no more events can be added to it). If the binding is
we call the key undefined. Examples of prefix keys are C-c,
C-x, and C-x 4. Examples of defined complete keys are
X, RET, and C-x 4 C-f. Examples of undefined complete
keys are C-x C-g, and C-c 3. See section Prefix Keys, for more
The rule for finding the binding of a key sequence assumes that the intermediate bindings (found for the events before the last) are all keymaps; if this is not so, the sequence of events does not form a unit--it is not really one key sequence. In other words, removing one or more events from the end of any valid key sequence must always yield a prefix key. For example, C-f C-n is not a key sequence; C-f is not a prefix key, so a longer sequence starting with C-f cannot be a key sequence.
The set of possible multi-event key sequences depends on the bindings for prefix keys; therefore, it can be different for different keymaps, and can change when bindings are changed. However, a one-event sequence is always a key sequence, because it does not depend on any prefix keys for its well-formedness.
At any time, several primary keymaps are active---that is, in use for finding key bindings. These are the global map, which is shared by all buffers; the local keymap, which is usually associated with a specific major mode; and zero or more minor mode keymaps, which belong to currently enabled minor modes. (Not all minor modes have keymaps.) The local keymap bindings shadow (i.e., take precedence over) the corresponding global bindings. The minor mode keymaps shadow both local and global keymaps. See section Active Keymaps, for details.
A keymap is a list whose CAR is the symbol
remaining elements of the list define the key bindings of the keymap.
Use the function
keymapp (see below) to test whether an object is
Several kinds of elements may appear in a keymap, after the symbol
keymap that begins it:
(type . binding)
(t . binding)
nilfor that character. Such a binding of
niloverrides any default key binding in the keymap, for ASCII characters. However, default bindings are still meaningful for events other than ASCII characters. A binding of
nildoes not override lower-precedence keymaps; thus, if the local map gives a binding of
nil, Emacs uses the binding from the global map.
Keymaps do not directly record bindings for the meta characters.
Instead, meta characters are regarded for
purposes of key lookup as sequences of two characters, the first of
which is ESC (or whatever is currently the value of
meta-prefix-char). Thus, the key M-a is really represented
as ESC a, and its global binding is found at the slot for
esc-map (see section Prefix Keys).
Here as an example is the local keymap for Lisp mode, a sparse keymap. It defines bindings for DEL and TAB, plus C-c C-l, M-C-q, and M-C-x.
lisp-mode-map => (keymap ;; TAB (9 . lisp-indent-line) ;; DEL (127 . backward-delete-char-untabify) (3 keymap ;; C-c C-l (12 . run-lisp)) (27 keymap ;; M-C-q, treated as ESC C-q (17 . indent-sexp) ;; M-C-x, treated as ESC C-x (24 . lisp-send-defun)))
tif object is a keymap,
nilotherwise. More precisely, this function tests for a list whose CAR is
(keymapp '(keymap)) => t (keymapp (current-global-map)) => t
Here we describe the functions for creating keymaps.
nil, and does not bind any other kind of event.
(make-keymap) => (keymap [nil nil nil ... nil nil])
If you specify prompt, that becomes the overall prompt string for the keymap. The prompt string is useful for menu keymaps (see section Menu Keymaps).
(make-sparse-keymap) => (keymap)
(setq map (copy-keymap (current-local-map))) => (keymap ;; (This implements meta characters.) (27 keymap (83 . center-paragraph) (115 . center-line)) (9 . tab-to-tab-stop)) (eq map (current-local-map)) => nil (equal map (current-local-map)) => t
A keymap can inherit the bindings of another keymap, which we call the parent keymap. Such a keymap looks like this:
(keymap bindings... . parent-keymap)
The effect is that this keymap inherits all the bindings of parent-keymap, whatever they may be at the time a key is looked up, but can add to them or override them with bindings.
If you change the bindings in parent-keymap using
or other key-binding functions, these changes are visible in the
inheriting keymap unless shadowed by bindings. The converse is
not true: if you use
define-key to change the inheriting keymap,
that affects bindings, but has no effect on parent-keymap.
The proper way to construct a keymap with a parent is to use
set-keymap-parent; if you have code that directly constructs a
keymap with a parent, please convert the program to use
nil, this function gives keymap no parent at all.
If keymap has submaps (bindings for prefix keys), they too receive new parent keymaps that reflect what parent specifies for those prefix keys.
Here is an example showing how to make a keymap that inherits
(let ((map (make-sparse-keymap))) (set-keymap-parent map text-mode-map) map)
A prefix key is a key sequence whose binding is a keymap. The
keymap defines what to do with key sequences that extend the prefix key.
For example, C-x is a prefix key, and it uses a keymap that is
also stored in the variable
ctl-x-map. This keymap defines
bindings for key sequences starting with C-x.
Some of the standard Emacs prefix keys use keymaps that are also found in Lisp variables:
esc-mapis the global keymap for the ESC prefix key. Thus, the global definitions of all meta characters are actually found here. This map is also the function definition of
help-mapis the global keymap for the C-h prefix key.
mode-specific-mapis the global keymap for the prefix key C-c. This map is actually global, not mode-specific, but its name provides useful information about C-c in the output of C-h b (
display-bindings), since the main use of this prefix key is for mode-specific bindings.
ctl-x-mapis the global keymap used for the C-x prefix key. This map is found via the function cell of the symbol
mule-keymapis the global keymap used for the C-x RET prefix key.
ctl-x-4-mapis the global keymap used for the C-x 4 prefix key.
ctl-x-5-mapis the global keymap used for the C-x 5 prefix key.
2C-mode-mapis the global keymap used for the C-x 6 prefix key.
vc-prefix-mapis the global keymap used for the C-x v prefix key.
facemenu-keymapis the global keymap used for the M-g prefix key.
The keymap binding of a prefix key is used for looking up the event
that follows the prefix key. (It may instead be a symbol whose function
definition is a keymap. The effect is the same, but the symbol serves
as a name for the prefix key.) Thus, the binding of C-x is the
Control-X-prefix, whose function cell holds the keymap
for C-x commands. (The same keymap is also the value of
Prefix key definitions can appear in any active keymap. The definitions of C-c, C-x, C-h and ESC as prefix keys appear in the global map, so these prefix keys are always available. Major and minor modes can redefine a key as a prefix by putting a prefix key definition for it in the local map or the minor mode's map. See section Active Keymaps.
If a key is defined as a prefix in more than one active map, then its various definitions are in effect merged: the commands defined in the minor mode keymaps come first, followed by those in the local map's prefix definition, and then by those from the global map.
In the following example, we make C-p a prefix key in the local
keymap, in such a way that C-p is identical to C-x. Then
the binding for C-p C-f is the function
like C-x C-f. The key sequence C-p 6 is not found in any
(use-local-map (make-sparse-keymap)) => nil (local-set-key "\C-p" ctl-x-map) => nil (key-binding "\C-p\C-f") => find-file (key-binding "\C-p6") => nil
This function also sets symbol as a variable, with the keymap as its value. It returns symbol.
Emacs normally contains many keymaps; at any given time, just a few of them are active in that they participate in the interpretation of user input. These are the global keymap, the current buffer's local keymap, and the keymaps of any enabled minor modes.
The global keymap holds the bindings of keys that are defined
regardless of the current buffer, such as C-f. The variable
global-map holds this keymap, which is always active.
Each buffer may have another keymap, its local keymap, which may
contain new or overriding definitions for keys. The current buffer's
local keymap is always active except when
overrides it. Text properties can specify an alternative local map for
certain parts of the buffer; see section Properties with Special Meanings.
Each minor mode can have a keymap; if it does, the keymap is active when the minor mode is enabled.
overriding-local-map, if non-
another local keymap that overrides the buffer's local map and all the
minor mode keymaps.
All the active keymaps are used together to determine what command to execute when a key is entered. Emacs searches these maps one by one, in order of decreasing precedence, until it finds a binding in one of the maps. The procedure for searching a single keymap is called key lookup; see section Key Lookup.
Normally, Emacs first searches for the key in the minor mode maps, in
the order specified by
minor-mode-map-alist; if they do not
supply a binding for the key, Emacs searches the local map; if that too
has no binding, Emacs then searches the global map. However, if
overriding-local-map is non-
nil, Emacs searches that map
first, before the global map.
Since every buffer that uses the same major mode normally uses the
same local keymap, you can think of the keymap as local to the mode. A
change to the local keymap of a buffer (using
example) is seen also in the other buffers that share that keymap.
The local keymaps that are used for Lisp mode and some other major
modes exist even if they have not yet been used. These local maps are
the values of variables such as
lisp-mode-map. For most major
modes, which are less frequently used, the local keymap is constructed
only when the mode is used for the first time in a session.
The minibuffer has local keymaps, too; they contain various completion and exit commands. See section Introduction to Minibuffers.
Emacs has other keymaps that are used in a different way--translating
read-key-sequence. See section Translating Input Events.
See section Standard Keymaps, for a list of standard keymaps.
self-insert-commandto all of the printing characters.
It is normal practice to change the bindings in the global map, but you should not assign this variable any value other than the keymap it starts out with.
global-mapunless you change one or the other.
(current-global-map) => (keymap [set-mark-command beginning-of-line ... delete-backward-char])
nilif it has none. In the following example, the keymap for the `*scratch*' buffer (using Lisp Interaction mode) is a sparse keymap in which the entry for ESC, ASCII code 27, is another sparse keymap.
(current-local-map) => (keymap (10 . eval-print-last-sexp) (9 . lisp-indent-line) (127 . backward-delete-char-untabify) (27 keymap (24 . eval-defun) (17 . indent-sexp)))
It is very unusual to change the global keymap.
nil, then the buffer has no local keymap.
nil. Most major mode commands use this function.
(variable . keymap)
The keymap keymap is active whenever variable has a
nil value. Typically variable is the variable that
enables or disables a minor mode. See section Keymaps and Minor Modes.
Note that elements of
minor-mode-map-alist do not have the same
structure as elements of
minor-mode-alist. The map must be the
CDR of the element; a list with the map as the CADR will not
do. The CADR can be either a keymap (a list) or a symbol
whose function definition is a keymap.
When more than one minor mode keymap is active, their order of priority
is the order of
minor-mode-map-alist. But you should design
minor modes so that they don't interfere with each other. If you do
this properly, the order will not matter.
(variable . keymap).
If a variable appears as an element of
minor-mode-overriding-map-alist, the map specified by that
element totally replaces any map specified for the same variable in
minor-mode-overriding-map-alist is automatically buffer-local in
nil, this variable holds a keymap to use instead of the buffer's local keymap and instead of all the minor mode keymaps. This keymap, if any, overrides all other maps that would have been active, except for the current global map.
nil, this variable holds a keymap to use instead of
overriding-local-map, the buffer's local keymap and all the minor mode keymaps.
This variable is always local to the current terminal and cannot be buffer-local. See section Multiple Displays. It is used to implement incremental search mode.
nil, the value of
overriding-terminal-local-mapcan affect the display of the menu bar. The default value is
nil, so those map variables have no effect on the menu bar.
Note that these two map variables do affect the execution of key sequences entered using the menu bar, even if they do not affect the menu bar display. So if a menu bar key sequence comes in, you should clear the variables before looking up and executing that key sequence. Modes that use the variables would typically do this anyway; normally they respond to events that they do not handle by "unreading" them and exiting.
read-event. See section Special Events.
Key lookup is the process of finding the binding of a key sequence from a given keymap. Actual execution of the binding is not part of key lookup.
Key lookup uses just the event type of each event in the key sequence;
the rest of the event is ignored. In fact, a key sequence used for key
lookup may designate mouse events with just their types (symbols)
instead of with entire mouse events (lists). See section Input Events. Such
a "key-sequence" is insufficient for
command-execute to run,
but it is sufficient for looking up or rebinding a key.
When the key sequence consists of multiple events, key lookup processes the events sequentially: the binding of the first event is found, and must be a keymap; then the second event's binding is found in that keymap, and so on until all the events in the key sequence are used up. (The binding thus found for the last event may or may not be a keymap.) Thus, the process of key lookup is defined in terms of a simpler process for looking up a single event in a keymap. How that is done depends on the type of object associated with the event in that keymap.
Let's use the term keymap entry to describe the value found by
looking up an event type in a keymap. (This doesn't include the item
string and other extra elements in menu key bindings, because
lookup-key and other key lookup functions don't include them in
the returned value.) While any Lisp object may be stored in a keymap as
a keymap entry, not all make sense for key lookup. Here is a table of
the meaningful kinds of keymap entries:
nilmeans that the events used so far in the lookup form an undefined key. When a keymap fails to mention an event type at all, and has no default binding, that is equivalent to a binding of
nilfor that event type.
keymap, then the list is a keymap, and is treated as a keymap (see above).
lambda, then the list is a lambda expression. This is presumed to be a command, and is treated as such (see above).
(othermap . othertype)When key lookup encounters an indirect entry, it looks up instead the binding of othertype in othermap and uses that. This feature permits you to define one key as an alias for another key. For example, an entry whose CAR is the keymap called
esc-mapand whose CDR is 32 (the code for SPC) means, "Use the global binding of Meta-SPC, whatever that may be."
command-execute(see section Interactive Call). The symbol
undefinedis worth special mention: it means to treat the key as undefined. Strictly speaking, the key is defined, and its binding is the command
undefined; but that command does the same thing that is done automatically for an undefined key: it rings the bell (by calling
ding) but does not signal an error.
undefinedis used in local keymaps to override a global key binding and make the key "undefined" locally. A local binding of
nilwould fail to do this because it would not override the global binding.
In short, a keymap entry may be a keymap, a command, a keyboard macro,
a symbol that leads to one of them, or an indirection or
Here is an example of a sparse keymap with two characters bound to
commands and one bound to another keymap. This map is the normal value
emacs-lisp-mode-map. Note that 9 is the code for TAB,
127 for DEL, 27 for ESC, 17 for C-q and 24 for
(keymap (9 . lisp-indent-line) (127 . backward-delete-char-untabify) (27 keymap (17 . indent-sexp) (24 . eval-defun)))
Here are the functions and variables pertaining to key lookup.
lookup-key. Here are examples:
(lookup-key (current-global-map) "\C-x\C-f") => find-file (lookup-key (current-global-map) "\C-x\C-f12345") => 2
If the string or vector key is not a valid key sequence according to the prefix keys specified in keymap, it must be "too long" and have extra events at the end that do not fit into a single key sequence. Then the value is a number, the number of events at the front of key that compose a complete key.
If accept-defaults is non-
considers default bindings as well as bindings for the specific events
in key. Otherwise,
lookup-key reports only bindings for
the specific sequence key, ignoring default bindings except when
you explicitly ask about them. (To do this, supply
t as an
element of key; see section Format of Keymaps.)
If key contains a meta character, that character is implicitly
replaced by a two-character sequence: the value of
meta-prefix-char, followed by the corresponding non-meta
character. Thus, the first example below is handled by conversion into
the second example.
(lookup-key (current-global-map) "\M-f") => forward-word (lookup-key (current-global-map) "\ef") => forward-word
read-key-sequence, this function does not modify the
specified events in ways that discard information (see section Key Sequence Input). In particular, it does not convert letters to lower case and
it does not change drag events to clicks.
nilif key is undefined in the keymaps.
The argument accept-defaults controls checking for default
bindings, as in
An error is signaled if key is not a string or a vector.
(key-binding "\C-x\C-f") => find-file
nilif it is undefined there.
The argument accept-defaults controls checking for default bindings,
nilif it is undefined there.
The argument accept-defaults controls checking for default bindings,
(modename . binding), where modename is the variable that enables the minor mode, and binding is key's binding in that mode. If key has no minor-mode bindings, the value is
If the first binding found is not a prefix definition (a keymap or a symbol defined as a keymap), all subsequent bindings from other minor modes are omitted, since they would be completely shadowed. Similarly, the list omits non-prefix bindings that follow prefix bindings.
The argument accept-defaults controls checking for default
bindings, as in
As long as the value of
meta-prefix-char remains 27, key
lookup translates M-b into ESC b, which is normally
defined as the
backward-word command. However, if you set
meta-prefix-char to 24, the code for C-x, then Emacs will
translate M-b into C-x b, whose standard binding is the
switch-to-buffer command. Here is an illustration:
meta-prefix-char ; The default value. => 27 (key-binding "\M-b") => backward-word ?\C-x ; The print representation => 24 ; of a character. (setq meta-prefix-char 24) => 24 (key-binding "\M-b") => switch-to-buffer ; Now, typing M-b is ; like typing C-x b. (setq meta-prefix-char 27) ; Avoid confusion! => 27 ; Restore the default value!
The way to rebind a key is to change its entry in a keymap. If you
change a binding in the global keymap, the change is effective in all
buffers (though it has no direct effect in buffers that shadow the
global binding with a local one). If you change the current buffer's
local map, that usually affects all buffers using the same major mode.
local-set-key functions are
convenient interfaces for these operations (see section Commands for Binding Keys). You can also use
define-key, a more general
function; then you must specify explicitly the map to change.
In writing the key sequence to rebind, it is good to use the special
escape sequences for control and meta characters (see section String Type).
The syntax `\C-' means that the following character is a control
character and `\M-' means that the following character is a meta
character. Thus, the string
"\M-x" is read as containing a
"\C-f" is read as containing a single
"\C-\M-x" are both read as
containing a single C-M-x. You can also use this escape syntax in
vectors, as well as others that aren't allowed in strings; one example
is `[?\C-\H-x home]'. See section Character Type.
The key definition and lookup functions accept an alternate syntax for
event types in a key sequence that is a vector: you can use a list
containing modifier names plus one base event (a character or function
key name). For example,
(control ?a) is equivalent to
(hyper control left) is equivalent to
C-H-left. One advantage of such lists is that the precise
numeric codes for the modifier bits don't appear in compiled files.
For the functions below, an error is signaled if keymap is not a keymap or if key is not a string or vector representing a key sequence. You can use event types (symbols) as shorthand for events that are lists.
Every prefix of key must be a prefix key (i.e., bound to a keymap)
or undefined; otherwise an error is signaled. If some prefix of
key is undefined, then
define-key defines it as a prefix
key so that the rest of key can be defined as specified.
If there was previously no binding for key in keymap, the new binding is added at the beginning of keymap. The order of bindings in a keymap makes no difference in most cases, but it does matter for menu keymaps (see section Menu Keymaps).
Here is an example that creates a sparse keymap and makes a number of bindings in it:
(setq map (make-sparse-keymap)) => (keymap) (define-key map "\C-f" 'forward-char) => forward-char map => (keymap (6 . forward-char)) ;; Build sparse submap for C-x and bind f in that. (define-key map "\C-xf" 'forward-word) => forward-word map => (keymap (24 keymap ; C-x (102 . forward-word)) ; f (6 . forward-char)) ; C-f ;; Bind C-p to the
ctl-x-map. (define-key map "\C-p" ctl-x-map) ;;
ctl-x-map=> [nil ... find-file ... backward-kill-sentence] ;; Bind C-f to
ctl-x-map. (define-key map "\C-p\C-f" 'foo) => 'foo map => (keymap ; Note
ctl-x-map. (16 keymap [nil ... foo ... backward-kill-sentence]) (24 keymap (102 . forward-word)) (6 . forward-char))
Note that storing a new binding for C-p C-f actually works by
changing an entry in
ctl-x-map, and this has the effect of
changing the bindings of both C-p C-f and C-x C-f in the
default global map.
For example, this redefines C-x C-f, if you do it in an Emacs with standard bindings:
(substitute-key-definition 'find-file 'find-file-read-only (current-global-map))
If oldmap is non-
nil, then its bindings determine which
keys to rebind. The rebindings still happen in keymap, not in
oldmap. Thus, you can change one map under the control of the
bindings in another. For example,
(substitute-key-definition 'delete-backward-char 'my-funny-delete my-map global-map)
puts the special deletion command in
my-map for whichever keys
are globally bound to the standard deletion command.
Here is an example showing a keymap before and after substitution:
(setq map '(keymap (?1 . olddef-1) (?2 . olddef-2) (?3 . olddef-1))) => (keymap (49 . olddef-1) (50 . olddef-2) (51 . olddef-1)) (substitute-key-definition 'olddef-1 'newdef map) => nil map => (keymap (49 . newdef) (50 . olddef-2) (51 . newdef))
undefined. This makes ordinary insertion of text impossible.
If nodigits is
digits to run
digit-argument, and - to run
negative-argument. Otherwise it makes them undefined like the
rest of the printing characters.
suppress-keymap function does not make it impossible to
modify a buffer, as it does not suppress commands such as
quoted-insert. To prevent any modification of a buffer, make
it read-only (see section Read-Only Buffers).
Since this function modifies keymap, you would normally use it
on a newly created keymap. Operating on an existing keymap
that is used for some other purpose is likely to cause trouble; for
global-map would make it impossible to use
most of Emacs.
suppress-keymap is used to initialize local
keymaps of modes such as Rmail and Dired where insertion of text is not
desirable and the buffer is read-only. Here is an example taken from
the file `emacs/lisp/dired.el', showing how the local keymap for
Dired mode is set up:
(setq dired-mode-map (make-keymap)) (suppress-keymap dired-mode-map) (define-key dired-mode-map "r" 'dired-rename-file) (define-key dired-mode-map "\C-d" 'dired-flag-file-deleted) (define-key dired-mode-map "d" 'dired-flag-file-deleted) (define-key dired-mode-map "v" 'dired-view-file) (define-key dired-mode-map "e" 'dired-find-file) (define-key dired-mode-map "f" 'dired-find-file) ...
This section describes some convenient interactive interfaces for
changing key bindings. They work by calling
People often use
global-set-key in their `.emacs' file for
simple customization. For example,
(global-set-key "\C-x\C-\\" 'next-line)
(global-set-key [?\C-x ?\C-\\] 'next-line)
(global-set-key [(control ?x) (control ?\\)] 'next-line)
redefines C-x C-\ to move down a line.
(global-set-key [M-mouse-1] 'mouse-set-point)
redefines the first (leftmost) mouse button, typed with the Meta key, to set point where you click.
(global-set-key key definition) == (define-key (current-global-map) key definition)
One use of this function is in preparation for defining a longer key that uses key as a prefix--which would not be allowed if key has a non-prefix binding. For example:
(global-unset-key "\C-l") => nil (global-set-key "\C-l\C-l" 'redraw-display) => nil
This function is implemented simply using
(global-unset-key key) == (define-key (current-global-map) key nil)
(local-set-key key definition) == (define-key (current-local-map) key definition)
(local-unset-key key) == (define-key (current-local-map) key nil)
This section describes functions used to scan all the current keymaps for the sake of printing help information.
(key . map), where key is a prefix key whose definition in keymap is map.
The elements of the alist are ordered so that the key increases
in length. The first element is always
("" . keymap),
because the specified keymap is accessible from itself with a prefix of
If prefix is given, it should be a prefix key sequence; then
accessible-keymaps includes only the submaps whose prefixes start
with prefix. These elements look just as they do in the value of
(accessible-keymaps); the only difference is that some elements
In the example below, the returned alist indicates that the key
ESC, which is displayed as `^[', is a prefix key whose
definition is the sparse keymap
(keymap (83 . center-paragraph)
(115 . foo)).
(accessible-keymaps (current-local-map)) =>(("" keymap (27 keymap ; Note this keymap for ESC is repeated below. (83 . center-paragraph) (115 . center-line)) (9 . tab-to-tab-stop)) ("^[" keymap (83 . center-paragraph) (115 . foo)))
In the following example, C-h is a prefix key that uses a sparse
keymap starting with
(keymap (118 . describe-variable)...).
Another prefix, C-x 4, uses a keymap which is also the value of
ctl-x-4-map. The event
mode-line is one of
several dummy events used as prefixes for mouse actions in special parts
of a window.
(accessible-keymaps (current-global-map)) => (("" keymap [set-mark-command beginning-of-line ... delete-backward-char]) ("^H" keymap (118 . describe-variable) ... (8 . help-for-help)) ("^X" keymap [x-flush-mouse-queue ... backward-kill-sentence]) ("^[" keymap [mark-sexp backward-sexp ... backward-kill-word]) ("^X4" keymap (15 . display-buffer) ...) ([mode-line] keymap (S-mouse-2 . mouse-split-window-horizontally) ...))
These are not all the keymaps you would see in actuality.
where-iscommand (see section `Help' in The GNU Emacs Manual). It returns a list of key sequences (of any length) that are bound to command in a set of keymaps.
The argument command can be any object; it is compared with all
keymap entries using
If keymap is
nil, then the maps used are the current active
overriding-local-map (that is, pretending
its value is
nil). If keymap is non-
nil, then the
maps searched are keymap and the global keymap.
Usually it's best to use
overriding-local-map as the expression
for keymap. Then
where-is-internal searches precisely the
keymaps that are active. To search only the global map, pass
(keymap) (an empty keymap) as keymap.
If firstonly is
non-ascii, then the value is a single
string representing the first key sequence found, rather than a list of
all possible key sequences. If firstonly is
t, then the
value is the first key sequence, except that key sequences consisting
entirely of ASCII characters (or meta variants of ASCII
characters) are preferred to all other key sequences.
If noindirect is non-
follow indirect keymap bindings. This makes it possible to search for
an indirect definition itself.
(where-is-internal 'describe-function) => ("\^hf" "\^hd")
If prefix is non-
nil, it should be a prefix key; then the
listing includes only keys that start with prefix.
The listing describes meta characters as ESC followed by the corresponding non-meta character.
When several characters with consecutive ASCII codes have the
same definition, they are shown together, as
`firstchar..lastchar'. In this instance, you need to
know the ASCII codes to understand which characters this means.
For example, in the default global map, the characters `SPC
.. ~' are described by a single line. SPC is ASCII 32,
~ is ASCII 126, and the characters between them include all
the normal printing characters, (e.g., letters, digits, punctuation,
etc.); all these characters are bound to
A keymap can define a menu as well as bindings for keyboard keys and mouse button. Menus are usually actuated with the mouse, but they can work with the keyboard also.
A keymap is suitable for menu use if it has an overall prompt
string, which is a string that appears as an element of the keymap.
(See section Format of Keymaps.) The string should describe the purpose of
the menu. The easiest way to construct a keymap with a prompt string is
to specify the string as an argument when you call
make-sparse-keymap (see section Creating Keymaps).
The order of items in the menu is the same as the order of bindings in
the keymap. Since
define-key puts new bindings at the front, you
should define the menu items starting at the bottom of the menu and
moving to the top, if you care about the order. When you add an item to
an existing menu, you can specify its position in the menu using
define-key-after (see section Modifying Menus).
The simpler and older way to define a menu keymap binding looks like this:
(item-string . real-binding)
The CAR, item-string, is the string to be displayed in the menu. It should be short--preferably one to three words. It should describe the action of the command it corresponds to.
You can also supply a second string, called the help string, as follows:
(item-string help-string . real-binding)
Currently Emacs does not actually use help-string; it knows only how to ignore help-string in order to extract real-binding. In the future we may use help-string as extended documentation for the menu item, available on request.
As far as
define-key is concerned, item-string and
help-string are part of the event's binding. However,
lookup-key returns just real-binding, and only
real-binding is used for executing the key.
If real-binding is
nil, then item-string appears in
the menu but cannot be selected.
If real-binding is a symbol and has a non-
menu-enable property, that property is an expression that
controls whether the menu item is enabled. Every time the keymap is
used to display a menu, Emacs evaluates the expression, and it enables
the menu item only if the expression's value is non-
nil. When a
menu item is disabled, it is displayed in a "fuzzy" fashion, and
cannot be selected.
The menu bar does not recalculate which items are enabled every time you
look at a menu. This is because the X toolkit requires the whole tree
of menus in advance. To force recalculation of the menu bar, call
force-mode-line-update (see section Mode Line Format).
You've probably noticed that menu items show the equivalent keyboard key sequence (if any) to invoke the same command. To save time on recalculation, menu display caches this information in a sublist in the binding, like this:
(item-string [help-string] (key-binding-data) . real-binding)
Don't put these sublists in the menu item yourself; menu display calculates them automatically. Don't mention keyboard equivalents in the item strings themselves, since that is redundant.
An extended-format menu item is a more flexible and also cleaner
alternative to the simple format. It consists of a list that starts
with the symbol
menu-item. To define a non-selectable string,
the item looks like this:
where a string consisting of two or more dashes specifies a separator line.
To define a real menu item which can be selected, the extended format item looks like this:
(menu-item item-name real-binding . item-property-list)
Here, item-name is an expression which evaluates to the menu item string. Thus, the string need not be a constant. The third element, real-binding, is the command to execute. The tail of the list, item-property-list, has the form of a property list which contains other information. Here is a table of the properties that are supported:
nilmeans yes). If the item does not appear, then the menu is displayed as if this item were not defined at all.
:button (type . selected)
:radio. The CDR, selected, should be a form; the result of evaluating it says whether this button is currently selected. A toggle is a menu item which is labeled as either "on" or "off" according to the value of selected. The command itself should toggle selected, setting it to
tif it is
nil, and to
nilif it is
t. Here is how the menu item to toggle the
debug-on-errorflag is defined:
(menu-item "Debug on Error" toggle-debug-on-error :button (:toggle . (and (boundp 'debug-on-error) debug-on-error))This works because
toggle-debug-on-erroris defined as a command which toggles the variable
debug-on-error. Radio buttons are a group of menu items, in which at any time one and only one is "selected." There should be a variable whose value says which one is selected at any time. The selected form for each radio button in the group should check whether the variable has the right value for selecting that button. Clicking on the button should set the variable so that the button you clicked on becomes selected.
:keysproperty and finds the keyboard equivalent anyway.
Sometimes it is useful to make menu items that use the "same"
command but with different enable conditions. The best way to do this
in Emacs now is with extended menu items; before that feature existed,
it could be done by defining alias commands and using them in menu
items. Here's an example that makes two aliases for
toggle-read-only and gives them different enable conditions:
(defalias 'make-read-only 'toggle-read-only) (put 'make-read-only 'menu-enable '(not buffer-read-only)) (defalias 'make-writable 'toggle-read-only) (put 'make-writable 'menu-enable 'buffer-read-only)
When using aliases in menus, often it is useful to display the
equivalent key bindings for the "real" command name, not the aliases
(which typically don't have any key bindings except for the menu
itself). To request this, give the alias symbol a non-
menu-alias property. Thus,
(put 'make-read-only 'menu-alias t) (put 'make-writable 'menu-alias t)
causes menu items for
show the keyboard bindings for
The usual way to make a menu keymap produce a menu is to make it the definition of a prefix key. (A Lisp program can explicitly pop up a menu and receive the user's choice--see section Pop-Up Menus.)
If the prefix key ends with a mouse event, Emacs handles the menu keymap by popping up a visible menu, so that the user can select a choice with the mouse. When the user clicks on a menu item, the event generated is whatever character or symbol has the binding that brought about that menu item. (A menu item may generate a series of events if the menu has multiple levels or comes from the menu bar.)
It's often best to use a button-down event to trigger the menu. Then the user can select a menu item by releasing the button.
A single keymap can appear as multiple menu panes, if you explicitly arrange for this. The way to do this is to make a keymap for each pane, then create a binding for each of those maps in the main keymap of the menu. Give each of these bindings an item string that starts with `@'. The rest of the item string becomes the name of the pane. See the file `lisp/mouse.el' for an example of this. Any ordinary bindings with `@'-less item strings are grouped into one pane, which appears along with the other panes explicitly created for the submaps.
X toolkit menus don't have panes; instead, they can have submenus. Every nested keymap becomes a submenu, whether the item string starts with `@' or not. In a toolkit version of Emacs, the only thing special about `@' at the beginning of an item string is that the `@' doesn't appear in the menu item.
You can also produce multiple panes or submenus from separate keymaps. The full definition of a prefix key always comes from merging the definitions supplied by the various active keymaps (minor mode, local, and global). When more than one of these keymaps is a menu, each of them makes a separate pane or panes (when Emacs does not use an X-toolkit) or a separate submenu (when using an X-toolkit). See section Active Keymaps.
When a prefix key ending with a keyboard event (a character or function key) has a definition that is a menu keymap, the user can use the keyboard to choose a menu item.
Emacs displays the menu alternatives (the item strings of the bindings)
in the echo area. If they don't all fit at once, the user can type
SPC to see the next line of alternatives. Successive uses of
SPC eventually get to the end of the menu and then cycle around to
the beginning. (The variable
which character is used for this; SPC is the default.)
When the user has found the desired alternative from the menu, he or she should type the corresponding character--the one whose binding is that alternative.
This way of using menus in an Emacs-like editor was inspired by the Hierarkey system.
Here is a complete example of defining a menu keymap. It is the definition of the `Print' submenu in the `Tools' menu in the menu bar, and it uses the simple menu item format (see section Simple Menu Items). First we create the keymap, and give it a name:
(defvar menu-bar-print-menu (make-sparse-keymap "Print"))
Next we define the menu items:
(define-key menu-bar-print-menu [ps-print-region] '("Postscript Print Region" . ps-print-region-with-faces)) (define-key menu-bar-print-menu [ps-print-buffer] '("Postscript Print Buffer" . ps-print-buffer-with-faces)) (define-key menu-bar-print-menu [separator-ps-print] '("--")) (define-key menu-bar-print-menu [print-region] '("Print Region" . print-region)) (define-key menu-bar-print-menu [print-buffer] '("Print Buffer" . print-buffer))
Note the symbols which the bindings are "made for"; these appear
inside square brackets, in the key sequence being defined. In some
cases, this symbol is the same as the command name; sometimes it is
different. These symbols are treated as "function keys", but they are
not real function keys on the keyboard. They do not affect the
functioning of the menu itself, but they are "echoed" in the echo area
when the user selects from the menu, and they appear in the output of
The binding whose definition is
("--") is a separator line.
Like a real menu item, the separator has a key symbol, in this case
separator-ps-print. If one menu has two separators, they must
have two different key symbols.
Here is code to define enable conditions for two of the commands in the menu:
(put 'print-region 'menu-enable 'mark-active) (put 'ps-print-region-with-faces 'menu-enable 'mark-active)
Here is how we make this menu appear as an item in the parent menu:
(define-key menu-bar-tools-menu [print] (cons "Print" menu-bar-print-menu))
Note that this incorporates the submenu keymap, which is the value of
menu-bar-print-menu, rather than the symbol
menu-bar-print-menu itself. Using that symbol in the parent menu
item would be meaningless because
menu-bar-print-menu is not a
If you wanted to attach the same print menu to a mouse click, you can do it this way:
(define-key global-map [C-S-down-mouse-1] menu-bar-print-menu)
We could equally well use an extended menu item (see section Extended Menu Items) for
print-region, like this:
(define-key menu-bar-print-menu [print-region] '(menu-item "Print Region" print-region :enable (mark-active)))
With the extended menu item, the enable condition is specified inside the menu item itself. If we wanted to make this item disappear from the menu entirely when the mark is inactive, we could do it this way:
(define-key menu-bar-print-menu [print-region] '(menu-item "Print Region" print-region :visible (mark-active)))
Most window systems allow each frame to have a menu bar---a
permanently displayed menu stretching horizontally across the top of the
frame. The items of the menu bar are the subcommands of the fake
menu-bar, as defined by all the active keymaps.
To add an item to the menu bar, invent a fake "function key" of your
own (let's call it key), and make a binding for the key sequence
[menu-bar key]. Most often, the binding is a menu keymap,
so that pressing a button on the menu bar item leads to another menu.
When more than one active keymap defines the same fake function key for the menu bar, the item appears just once. If the user clicks on that menu bar item, it brings up a single, combined menu containing all the subcommands of that item--the global subcommands, the local subcommands, and the minor mode subcommands.
overriding-local-map is normally ignored when
determining the menu bar contents. That is, the menu bar is computed
from the keymaps that would be active if
nil. See section Active Keymaps.
In order for a frame to display a menu bar, its
parameter must be greater than zero. Emacs uses just one line for the
menu bar itself; if you specify more than one line, the other lines
serve to separate the menu bar from the windows in the frame. We
recommend 1 or 2 as the value of
menu-bar-lines. See section Window Frame Parameters.
Here's an example of setting up a menu bar item:
(modify-frame-parameters (selected-frame) '((menu-bar-lines . 2))) ;; Make a menu keymap (with a prompt string) ;; and make it the menu bar item's definition. (define-key global-map [menu-bar words] (cons "Words" (make-sparse-keymap "Words"))) ;; Define specific subcommands in this menu. (define-key global-map [menu-bar words forward] '("Forward word" . forward-word)) (define-key global-map [menu-bar words backward] '("Backward word" . backward-word))
A local keymap can cancel a menu bar item made by the global keymap by
rebinding the same fake function key with
undefined as the
binding. For example, this is how Dired suppresses the `Edit' menu
(define-key dired-mode-map [menu-bar edit] 'undefined)
edit is the fake function key used by the global map for the
`Edit' menu bar item. The main reason to suppress a global
menu bar item is to regain space for mode-specific items.
This variable holds a list of fake function keys for items to display at
the end of the menu bar rather than in normal sequence. The default
(help-menu); thus, the `Help' menu item normally appears
at the end of the menu bar, following local menu items.
When you insert a new item in an existing menu, you probably want to
put it in a particular place among the menu's existing items. If you
define-key to add the item, it normally goes at the front of
the menu. To put it elsewhere in the menu, use
define-key, but position the binding in map after the binding for the event after. The argument key should be of length one--a vector or string with just one element. But after should be a single event type--a symbol or a character, not a sequence. The new binding goes after the binding for after. If after is
t, then the new binding goes last, at the end of the keymap.
Here is an example:
(define-key-after my-menu [drink] '("Drink" . drink-command) 'eat)
makes a binding for the fake function key DRINK and puts it right after the binding for EAT.
Here is how to insert an item called `Work' in the `Signals'
menu of Shell mode, after the item
(define-key-after (lookup-key shell-mode-map [menu-bar signals]) [work] '("Work" . work-command) 'break)