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This is Info file elisp, produced by Makeinfo-1.55 from the input file elisp.texi. This is edition 2.0 of the GNU Emacs Lisp Reference Manual, for Emacs Version 19. Published by the Free Software Foundation, 675 Massachusetts Avenue, Cambridge, MA 02139 USA Copyright (C) 1990, 1991, 1992, 1993 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation approved by the Foundation. File: elisp, Node: Inheritance and Keymaps, Next: Prefix Keys, Prev: Creating Keymaps, Up: Keymaps Inheritance and Keymaps ======================= A keymap can inherit the bindings of another keymap. Do do this, make a keymap whose "tail" is another existing keymap to inherit from. Such a keymap looks like this: (keymap BINDINGS... . OTHER-KEYMAP) The effect is that this keymap inherits all the bindings of OTHER-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 OTHER-KEYMAP using `define-key' 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 OTHER-KEYMAP. Here is an example showing how to make a keymap that inherits from `text-mode-map': (setq my-mode-map (cons 'keymap text-mode-map)) File: elisp, Node: Prefix Keys, Next: Menu Keymaps, Prev: Inheritance and Keymaps, Up: Keymaps Prefix Keys =========== A "prefix key" has an associated keymap which defines what to do with key sequences that start with the prefix key. For example, `C-x' is a prefix key, and it uses a keymap which is also stored in the variable `ctl-x-map'. Here is a list of the standard prefix keys of Emacs and their keymaps: * `esc-map' is used for events that follow ESC. Thus, the global definitions of all meta characters are actually found here. This map is also the function definition of `ESC-prefix'. * `help-map' is used for events that follow `C-h'. * `mode-specific-map' is for events that follow `C-c'. This map is not actually mode specific; its name was chosen to be informative for the user in `C-h b' (`display-bindings'), where it describes the main use of the `C-c' prefix key. * `ctl-x-map' is the variable name for the map used for events that follow `C-x'. This map is also the function definition of `Control-X-prefix'. * `ctl-x-4-map' is used for events that follow `C-x 4'. * `ctl-x-5-map' used is for events that follow `C-x 5'. * A nameless keymap is used for events that follow `C-x n'. Others are used for events following `C-x r' and `C-x a'. The binding of a prefix key is the keymap to use for looking up the events that follow 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 symbol `Control-X-prefix', whose function definition is the keymap for `C-x' commands. (The same keymap is also the value of `ctl-x-map'.) Prefix key definitions of this sort 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. *Note Active Keymaps::. If a key is defined as a prefix in more than one active map, then the 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 `find-file', just like `C-x C-f'. The key sequence `C-p 6' is not found in any active keymap. (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 - Function: define-prefix-command SYMBOL This function defines SYMBOL as a prefix command: it creates a full keymap and stores it as SYMBOL's function definition. Storing the symbol as the binding of a key makes the key a prefix key which has a name. It also sets SYMBOL as a variable, to have the keymap as its value. The function returns SYMBOL. In Emacs version 18, only the function definition of SYMBOL was set, not the value as a variable. File: elisp, Node: Menu Keymaps, Next: Active Keymaps, Prev: Prefix Keys, Up: Keymaps Menu Keymaps ============ A keymap can define a menu as well as ordinary keys and mouse button meanings. Menus are normally actuated with the mouse, but they can work with the keyboard also. * Menu: * Defining Menus:: How to make a keymap that defines a menu. * Mouse Menus:: How users actuate the menu with the mouse. * Keyboard Menus:: How they actuate it with the keyboard. * Menu Example:: Making a simple menu. * Menu Bar:: How to customize the menu bar. File: elisp, Node: Defining Menus, Next: Mouse Menus, Up: Menu Keymaps Defining Menus -------------- 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. (*Note 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-keymap' or `make-sparse-keymap' (*note Creating Keymaps::.). The individual bindings in the menu keymap should also have prompt strings; these strings become the items displayed in the menu. A binding with a prompt string looks like this: (STRING . REAL-BINDING) As far as `define-key' and `lookup-key' are concerned, the string is part of the event's binding. However, only REAL-BINDING is used for executing the key. You can also supply a second string, called the help string, as follows: (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 hope to make HELP-STRING serve as extended documentation for the menu item, available on request. The prompt string for a binding should be short--one or two words. It should describe the action of the command it corresponds to. If REAL-BINDING is `nil', then STRING appears in the menu but cannot be selected. If REAL-BINDING is a symbol, and has a non-`nil' `menu-enable' property, that property is an expression which 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 with the mouse. 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. File: elisp, Node: Mouse Menus, Next: Keyboard Menus, Prev: Defining Menus, Up: Menu Keymaps Menus and the Mouse ------------------- The way to make a menu keymap produce a menu is to make it the definition of a prefix key. When 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 which brought about that menu item. 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 a prompt string that starts with `@'. The rest of the prompt string becomes the name of the pane. See the file `lisp/mouse.el' for an example of this. Any ordinary bindings with `@'-less prompt strings are grouped into one pane, which appears along with the other panes explicitly created for the submaps. You can also get multiple panes 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. *Note Active Keymaps::. A Lisp program can explicitly pop up a menu and receive the user's choice. You can use keymaps for this also. *Note Pop-Up Menus::. File: elisp, Node: Keyboard Menus, Next: Menu Example, Prev: Mouse Menus, Up: Menu Keymaps Menus and the Keyboard ---------------------- 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 prompt 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. 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. In a menu intended for keyboard use, each menu item must clearly indicate what character to type. The best convention to use is to make the character the first letter of the menu item prompt string. That is something users will understand without being told. This way of using menus in an Emacs-like editor was inspired by the Hierarkey system. - Variable: menu-prompt-more-char This variable specifies the character to use to ask to see the next line of a menu. Its initial value is 32, the code for SPC. File: elisp, Node: Menu Example, Next: Menu Bar, Prev: Keyboard Menus, Up: Menu Keymaps Menu Example ------------ Here is a simple example of how to set up a menu for mouse use. (defvar my-menu-map (make-sparse-keymap "Key Commands <==> Functions")) (fset 'help-for-keys my-menu-map) (define-key my-menu-map [bindings] '("List all keystroke commands" . describe-bindings)) (define-key my-menu-map [key] '("Describe key briefly" . describe-key-briefly)) (define-key my-menu-map [key-verbose] '("Describe key verbose" . describe-key)) (define-key my-menu-map [function] '("Describe Lisp function" . describe-function)) (define-key my-menu-map [where-is] '("Where is this command" . where-is)) (define-key global-map [C-S-down-mouse-1] 'help-for-keys) The symbols used in the key sequences bound in the menu are fictitious "function keys"; they don't appear on the keyboard, but that doesn't stop you from using them in the menu. Their names were chosen to be mnemonic, because they show up in the output of `where-is' and `apropos' to identify the corresponding menu items. However, if you want the menu to be usable from the keyboard as well, you must use real ASCII characters instead of fictitious function keys. File: elisp, Node: Menu Bar, Prev: Menu Example, Up: Menu Keymaps The Menu Bar ------------ Under X Windows, each frame can 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 "function key" `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 submenu containing all the subcommands of that item--the global subcommands, the local subcommands, and the minor mode subcommands, all together. In order for a frame to display a menu bar, its `menu-bar-lines' property 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 you try one or two as the value of `menu-bar-lines'. *Note X 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) ;; to be the menu bar item's definition. (define-key global-map [menu-bar words] (cons "Words" (make-sparse-keymap "Words"))) ;; Make specific subcommands in the item's submenu. (define-key global-map [menu-bar words forward] '("Forward word" . forward-word)) (define-key global-map [menu-bar words backward] '("Backward word" . backward-word)) File: elisp, Node: Active Keymaps, Next: Key Lookup, Prev: Menu Keymaps, Up: Keymaps Active Keymaps ============== 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. At all times, the current buffer's local keymap is active. Text properties can specify an alternative local map for certain parts of the buffer; see *Note Special Properties::. Each minor mode may have a keymap; if it does, the keymap is active whenever the minor mode is enabled. All the active keymaps are used together to determine what command to execute when a key is entered. The key lookup proceeds as described earlier (*note Key Lookup::.), but Emacs *first* searches for the key in the minor mode maps (one map at a time); 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. Since every buffer that uses the same major mode normally uses the very same local keymap, it may appear as if the keymap is local to the mode. A change to the local keymap of a buffer (using `local-set-key', for example) will be seen also in the other buffers that share that keymap. The local keymaps that are used for Lisp mode, C mode, and several other major modes exist even if they have not yet been used. These local maps are the values of the variables `lisp-mode-map', `c-mode-map', and so on. For most other 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. *Note Minibuffers::. *Note Standard Keymaps::, for a list of standard keymaps. - Variable: global-map This variable contains the default global keymap that maps Emacs keyboard input to commands. Normally this keymap is the global keymap. The default global keymap is a full keymap that binds `self-insert-command' to all of the printing characters. - Function: current-global-map This function returns the current global keymap. This is always the same as the value of `global-map' unless you change one or the other. (current-global-map) => (keymap [set-mark-command beginning-of-line ... delete-backward-char]) - Function: current-local-map This function returns the current buffer's local keymap, or `nil' if 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))) - Function: current-minor-mode-maps This function returns a list of the keymaps of currently enabled minor modes. - Function: use-global-map KEYMAP This function makes KEYMAP the new current global keymap. It returns `nil'. It is very unusual to change the global keymap. - Function: use-local-map KEYMAP This function makes KEYMAP the new current local keymap of the current buffer. If KEYMAP is `nil', then there will be no local keymap. It returns `nil'. Most major modes use this function. - Variable: minor-mode-map-alist This variable is an alist describing keymaps that may or may not be active according to the values of certain variables. Its elements look like this: (VARIABLE . KEYMAP) The keymap KEYMAP is active whenever VARIABLE has a non-`nil' value. Typically VARIABLE is the variable which enables or disables a minor mode. *Note Keymaps and Minor Modes::. When more than one minor mode keymap is active, their order of priority is the order of `minor-mode-map-alist'. See also `minor-mode-key-binding' in *Note Functions for Key Lookup::. File: elisp, Node: Key Lookup, Next: Functions for Key Lookup, Prev: Active Keymaps, Up: Keymaps Key Lookup ========== "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 types 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). *Note Input Events::. Such a pseudo-key-sequence is insufficient for `command-execute', but it is sufficient for looking up or rebinding a 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 directly associated with an event type in a keymap. While any Lisp object may be stored as a keymap entry, not all make sense for key lookup. Here is a list of the meaningful kinds of keymap entries: `nil' `nil' means that the events used so far in the lookup form an undefined key. When a keymap fails to mention an event type at all, that is equivalent to an entry of `nil' for that type. KEYMAP The events used so far in the lookup form a prefix key. The next event of the key sequence is looked up in KEYMAP. COMMAND The events used so far in the lookup form a complete key, and COMMAND is its binding. STRING VECTOR The events used so far in the lookup form a complete key, whose binding is a keyboard macro. See *Note Keyboard Macros::, for more information. The meaning of a list depends on the types of the elements of the list. * If the CAR of LIST is the symbol `keymap', then the list is a keymap, and is treated as a keymap (see above). * If the CAR of LIST is `lambda', then the list is a lambda expression. This is presumed to be a command, and is treated as such (see above). * If the CAR of LIST is a keymap and the CDR is an event type, then this is an "indirect entry": (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-map' and whose CDR is 32 (the code for space) means, "Use the global binding of `Meta-SPC', whatever that may be." * If the CAR of LIST is a string, it serves as a menu item name if the keymap is used as a menu. For executing the key, the string is discarded and the CDR of LIST is used instead. (Any number of strings can be discarded from the front of the list in this way.) *Note Menu Keymaps::. SYMBOL The function definition of SYMBOL is used in place of SYMBOL. If that too is a symbol, then this process is repeated, any number of times. Ultimately this should lead to an object which is a keymap, a command or a keyboard macro. A list is allowed if it is a keymap or a command, but indirect entries are not understood when found via symbols. Note that keymaps and keyboard macros (strings and vectors) are not valid functions, so a symbol with a keymap, string or vector as its function definition is also invalid as a function. It is, however, valid as a key binding. If the definition is a keyboard macro, then the symbol is also valid as an argument to `command-execute' (*note Interactive Call::.). The symbol `undefined' is 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. `undefined' is used in local keymaps to override a global key binding and make the key "undefined" locally. A local binding of `nil' would fail to do this because it would not override the global binding. ANYTHING ELSE If any other type of object is found, the events used so far in the lookup form a complete key, and the object is its binding, but the binding is not executable as a command. In short, a keymap entry may be a keymap, a command, a keyboard macro, a symbol which leads to one of them, or an indirection or `nil'. 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 of `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 `C-x'. (keymap (9 . lisp-indent-line) (127 . backward-delete-char-untabify) (27 keymap (17 . indent-sexp) (24 . eval-defun))) File: elisp, Node: Functions for Key Lookup, Next: Changing Key Bindings, Prev: Key Lookup, Up: Keymaps Functions for Key Lookup ======================== Here are the functions and variables pertaining to key lookup. - Function: lookup-key KEYMAP KEY &optional ACCEPT-DEFAULTS This function returns the definition of KEY in KEYMAP. If the string or vector KEY is not a valid key sequence according to the prefix keys specified in KEYMAP (which means it is "too long" and has extra events at the end), 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-`nil', then `lookup-key' 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 an element of KEY is `t'. All the other functions described in this chapter that look up keys use `lookup-key'. (lookup-key (current-global-map) "\C-x\C-f") => find-file (lookup-key (current-global-map) "\C-x\C-f12345") => 2 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 This function does not modify the specified events in ways that discard information as `read-key-sequence' does (*note Key Sequence Input::.). In particular, it does not convert letters to lower case and it does not change drag events to clicks. - Command: undefined Used in keymaps to undefine keys. It calls `ding', but does not cause an error. - Function: key-binding KEY &optional ACCEPT-DEFAULTS This function returns the binding for KEY in the current keymaps, trying all the active keymaps. The result is `nil' if KEY is undefined in the keymaps. The argument ACCEPT-DEFAULTS controls checking for default bindings, as in `lookup-key'. An error is signaled if KEY is not a string or a vector. (key-binding "\C-x\C-f") => find-file - Function: local-key-binding KEY &optional ACCEPT-DEFAULTS This function returns the binding for KEY in the current local keymap, or `nil' if it is undefined there. The argument ACCEPT-DEFAULTS controls checking for default bindings, as in `lookup-key' (above). - Function: global-key-binding KEY &optional ACCEPT-DEFAULTS This function returns the binding for command KEY in the current global keymap, or `nil' if it is undefined there. The argument ACCEPT-DEFAULTS controls checking for default bindings, as in `lookup-key' (above). - Function: minor-mode-key-binding KEY &optional ACCEPT-DEFAULTS This function returns a list of all the active minor mode bindings of KEY. More precisely, it returns an alist of pairs `(MODENAME . BINDING)', where MODENAME is the the variable which enables the minor mode, and BINDING is KEY's binding in that mode. If KEY has no minor-mode bindings, the value is `nil'. If the first binding is a non-prefix, 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 `lookup-key' (above). - Variable: meta-prefix-char This variable is the meta-prefix character code. It is used when translating a meta character to a two-character sequence so it can be looked up in a keymap. For useful results, the value should be a prefix event (*note Prefix Keys::.). The default value is 27, which is the ASCII code for ESC. 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. 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! File: elisp, Node: Changing Key Bindings, Next: Key Binding Commands, Prev: Functions for Key Lookup, Up: Keymaps Changing Key Bindings ===================== The way to rebind a key is to change its entry in a keymap. You can change the global keymap, so that the change is effective in all buffers (except those that override the global binding with a local one). Or you can change the current buffer's local map, which usually affects all buffers using the same major mode. The `global-set-key' and `local-set-key' functions are convenient interfaces for these operations. Or you can use `define-key' and specify explicitly which map to change. 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) 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. In writing the key sequence to rebind, it is useful to use the special escape sequences for control and meta characters (*note 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 single `M-x', `"\C-f"' is read as containing a single `C-f', and `"\M-\C-x"' and `"\C-\M-x"' are both read as containing a single `C-M-x'. 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. However, you can use event types (symbols) as shorthand for events that are lists. - Function: define-key KEYMAP KEY BINDING This function sets the binding for KEY in KEYMAP. (If KEY is more than one event long, the change is actually made in another keymap reached from KEYMAP.) The argument BINDING can be any Lisp object, but only certain types are meaningful. (For a list of meaningful types, see *Note Key Lookup::.) The value returned by `define-key' is BINDING. 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 may be defined as specified. The following example creates a sparse keymap and makes a number of bindings: (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 `foo' in the `ctl-x-map'. (define-key map "\C-p\C-f" 'foo) => 'foo map => (keymap ; Note `foo' in `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. - Function: substitute-key-definition OLDDEF NEWDEF KEYMAP &optional OLDMAP This function replaces OLDDEF with NEWDEF for any keys in KEYMAP that were bound to OLDDEF. In other words, OLDDEF is replaced with NEWDEF wherever it appears. The function returns `nil'. 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 NEWMAP, 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)) - Function: suppress-keymap KEYMAP &optional NODIGITS This function changes the contents of the full keymap KEYMAP by replacing the self-insertion commands for numbers with the `digit-argument' function, unless NODIGITS is non-`nil', and by replacing the functions for the rest of the printing characters with `undefined'. This means that ordinary insertion of text is impossible in a buffer with a local keymap on which `suppress-keymap' has been called. `suppress-keymap' returns `nil'. The `suppress-keymap' function does not make it impossible to modify a buffer, as it does not suppress commands such as `yank' and `quoted-insert'. To prevent any modification of a buffer, make it read-only (*note 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 example, suppressing `global-map' would make it impossible to use most of Emacs. Most often, `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) ... File: elisp, Node: Key Binding Commands, Next: Scanning Keymaps, Prev: Changing Key Bindings, Up: Keymaps Commands for Binding Keys ========================= This section describes some convenient interactive interfaces for changing key bindings. They work by calling `define-key'. - Command: global-set-key KEY DEFINITION This function sets the binding of KEY in the current global map to DEFINITION. (global-set-key KEY DEFINITION) == (define-key (current-global-map) KEY DEFINITION) - Command: global-unset-key KEY This function removes the binding of KEY from the current global map. One use of this function is in preparation for defining a longer key which uses it implicitly 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 `define-key': (global-unset-key KEY) == (define-key (current-global-map) KEY nil) - Command: local-set-key KEY DEFINITION This function sets the binding of KEY in the current local keymap to DEFINITION. (local-set-key KEY DEFINITION) == (define-key (current-local-map) KEY DEFINITION) - Command: local-unset-key KEY This function removes the binding of KEY from the current local map. (local-unset-key KEY) == (define-key (current-local-map) KEY nil) File: elisp, Node: Scanning Keymaps, Prev: Key Binding Commands, Up: Keymaps Scanning Keymaps ================ This section describes functions used to scan all the current keymaps for the sake of printing help information. - Function: accessible-keymaps KEYMAP This function returns a list of all the keymaps that can be accessed (via prefix keys) from KEYMAP. The value is an association list with elements of the form `(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 no events. 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 `(keymap (118 . describe-variable)...)'. Another prefix, `C-x 4', uses a keymap which happens to be `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 an actual case. - Function: where-is-internal COMMAND &optional KEYMAP FIRSTONLY This function returns a list of key sequences (of any length) that are bound to COMMAND in KEYMAP and the global keymap. The argument COMMAND can be any object; it is compared with all keymap entries using `eq'. If KEYMAP is not supplied, then the global map alone is used. If FIRSTONLY is non-`nil', then the value is a single string representing the first key sequence found, rather than a list of all possible key sequences. This function is used by `where-is' (*note Help: (emacs)Help.). (where-is-internal 'describe-function) => ("\^hf" "\^hd") - Command: describe-bindings This function creates a listing of all defined keys, and their definitions. The listing is put in a buffer named `*Help*', which is then displayed in a window. A meta character is shown as ESC followed by the corresponding non-meta character. Control characters are indicated with `C-'. 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 `self-insert-command'. File: elisp, Node: Modes, Next: Documentation, Prev: Keymaps, Up: Top Major and Minor Modes ********************* A "mode" is a set of definitions that customize Emacs and can be turned on and off while you edit. There are two varieties of modes: "major modes", which are mutually exclusive and used for editing particular kinds of text, and "minor modes", which provide features that may be enabled individually. This chapter covers both major and minor modes, the way they are indicated in the mode line, and how they run hooks supplied by the user. Related topics such as keymaps and syntax tables are covered in separate chapters. (*Note Keymaps::, and *Note Syntax Tables::.) * Menu: * Major Modes:: Defining major modes. * Minor Modes:: Defining minor modes. * Mode Line Format:: Customizing the text that appears in the mode line. * Hooks:: How to use hooks; how to write code that provides hooks. File: elisp, Node: Major Modes, Next: Minor Modes, Prev: Modes, Up: Modes Major Modes =========== Major modes specialize Emacs for editing particular kinds of text. Each buffer has only one major mode at a time. The least specialized major mode is called "Fundamental mode". This mode has no mode-specific definitions or variable settings, so each Emacs command behaves in its default manner, and each option is in its default state. All other major modes redefine various keys and options. For example, Lisp Interaction mode provides special key bindings for LFD (`eval-print-last-sexp'), TAB (`lisp-indent-line'), and other keys. When you need to write several editing commands to help you perform a specialized editing task, creating a new major mode is usually a good idea. In practice, writing a major mode is easy (in contrast to writing a minor mode, which is often difficult). If the new mode is similar to an old one, it is often unwise to modify the old one to serve two purposes, since it may become harder to use and maintain. Instead, copy and rename an existing major mode definition and alter it for its new function. For example, Rmail Edit mode, which is in `emacs/lisp/rmailedit.el', is a major mode that is very similar to Text mode except that it provides three additional commands. Its definition is distinct from that of Text mode, but was derived from it. Rmail Edit mode is an example of a case where one piece of text is put temporarily into a different major mode so it can be edited in a different way (with ordinary Emacs commands rather than Rmail). In such cases, the temporary major mode usually has a command to switch back to the buffer's usual mode (Rmail mode, in this case). You might be tempted to present the temporary redefinitions inside a recursive edit and restore the usual ones when the user exits; but this is a bad idea because it constrains the user's options when it is done in more than one buffer: recursive edits must be exited most-recently-entered first. Using alternative major modes avoids this limitation. *Note Recursive Editing::. The standard GNU Emacs Lisp library directory contains the code for several major modes, in files including `text-mode.el', `texinfo.el', `lisp-mode.el', `c-mode.el', and `rmail.el'. You can look at these libraries to see how modes are written. Text mode is perhaps the simplest major mode aside from Fundamental mode. Rmail mode is a rather complicated, full-featured mode. * Menu: * Major Mode Conventions:: Coding conventions for keymaps, etc. * Example Major Modes:: Text mode and Lisp modes. * Auto Major Mode:: How Emacs chooses the major mode automatically. * Mode Help:: Finding out how to use a mode.