This is Info file ../../info/xemacs.info, produced by Makeinfo version 1.68 from the input file xemacs.texi. INFO-DIR-SECTION XEmacs Editor START-INFO-DIR-ENTRY * XEmacs: (xemacs). XEmacs Editor. END-INFO-DIR-ENTRY This file documents the XEmacs editor. Copyright (C) 1985, 1986, 1988 Richard M. Stallman. Copyright (C) 1991, 1992, 1993, 1994 Lucid, Inc. Copyright (C) 1993, 1994 Sun Microsystems, Inc. Copyright (C) 1995 Amdahl Corporation. 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 also that the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" are included exactly as in the original, and 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 the sections entitled "The GNU Manifesto", "Distribution" and "GNU General Public License" may be included in a translation approved by the author instead of in the original English.  File: xemacs.info, Node: Changing an Option, Next: Face Customization, Prev: Customization Groups, Up: Easy Customization Changing an Option .................. Here is an example of what a user option looks like in the customization buffer: Kill Ring Max: [Hide] 30 [State]: this option is unchanged from its standard setting. Maximum length of kill ring before oldest elements are thrown away. The text following `[Hide]', `30' in this case, indicates the current value of the option. If you see `[Show]' instead of `[Hide]', it means that the value is hidden; the customization buffer initially hides values that take up several lines. Invoke `[Show]' to show the value. The line after the option name indicates the "customization state" of the option: in the example above, it says you have not changed the option yet. The word `[State]' at the beginning of this line is active; you can get a menu of various operations by invoking it with `Mouse-1' or . These operations are essential for customizing the variable. The line after the `[State]' line displays the beginning of the option's documentation string. If there are more lines of documentation, this line ends with `[More]'; invoke this to show the full documentation string. To enter a new value for `Kill Ring Max', move point to the value and edit it textually. For example, you can type `M-d', then insert another number. When you begin to alter the text, you will see the `[State]' line change to say that you have edited the value: [State]: you have edited the value as text, but not set the option. Editing the value does not actually set the option variable. To do that, you must "set" the option. To do this, invoke the word `[State]' and choose `Set for Current Session'. The state of the option changes visibly when you set it: [State]: you have set this option, but not saved it for future sessions. You don't have to worry about specifying a value that is not valid; setting the option checks for validity and will not really install an unacceptable value. While editing a value or field that is a file name, directory name, command name, or anything else for which completion is defined, you can type `M-' (`widget-complete') to do completion. Some options have a small fixed set of possible legitimate values. These options don't let you edit the value textually. Instead, an active field `[Value Menu]' appears before the value; invoke this field to edit the value. For a boolean "on or off" value, the active field says `[Toggle]', and it changes to the other value. `[Value Menu]' and `[Toggle]' edit the buffer; the changes take effect when you use the `Set for Current Session' operation. Some options have values with complex structure. For example, the value of `load-path' is a list of directories. Here is how it appears in the customization buffer: Load Path: [INS] [DEL] [Current dir?]: /usr/local/share/emacs/19.34.94/site-lisp [INS] [DEL] [Current dir?]: /usr/local/share/emacs/site-lisp [INS] [DEL] [Current dir?]: /usr/local/share/emacs/19.34.94/leim [INS] [DEL] [Current dir?]: /usr/local/share/emacs/19.34.94/lisp [INS] [DEL] [Current dir?]: /build/emacs/e19/lisp [INS] [DEL] [Current dir?]: /build/emacs/e19/lisp/gnus [INS] [State]: this item has been changed outside the customization buffer. List of directories to search for files to load.... Each directory in the list appears on a separate line, and each line has several editable or active fields. You can edit any of the directory names. To delete a directory from the list, invoke `[DEL]' on that line. To insert a new directory in the list, invoke `[INS]' at the point where you want to insert it. You can also invoke `[Current dir?]' to switch between including a specific named directory in the path, and including `nil' in the path. (`nil' in a search path means "try the current directory.") Two special commands, and `S-', are useful for moving through the customization buffer. (`widget-forward') moves forward to the next active or editable field; `S-' (`widget-backward') moves backward to the previous active or editable field. Typing on an editable field also moves forward, just like . The reason for this is that people have a tendency to type when they are finished editing a field. If you have occasion to insert a newline in an editable field, use `C-o' or `C-q C-j', Setting the option changes its value in the current Emacs session; "saving" the value changes it for future sessions as well. This works by writing code into your `~/.emacs' file so as to set the option variable again each time you start Emacs. To save the option, invoke `[State]' and select the `Save for Future Sessions' operation. You can also restore the option to its standard value by invoking `[State]' and selecting the `Reset' operation. There are actually three reset operations: `Reset to Current' If you have made some modifications and not yet set the option, this restores the text in the customization buffer to match the actual value. `Reset to Saved' This restores the value of the option to the last saved value, and updates the text accordingly. `Reset to Standard Settings' This sets the option to its standard value, and updates the text accordingly. This also eliminates any saved value for the option, so that you will get the standard value in future Emacs sessions. The state of a group indicates whether anything in that group has been edited, set or saved. You can select `Set for Current Session', `Save for Future Sessions' and the various kinds of `Reset' operation for the group; these operations on the group apply to all options in the group and its subgroups. Near the top of the customization buffer there are two lines containing several active fields: [Set] [Save] [Reset] [Done] Invoking `[Done]' buries this customization buffer. Each of the other fields performs an operation--set, save or reset--on each of the items in the buffer that could meaningfully be set, saved or reset.  File: xemacs.info, Node: Face Customization, Next: Specific Customization, Prev: Changing an Option, Up: Easy Customization Customizing Faces ................. In addition to user options, some customization groups also include faces. When you show the contents of a group, both the user options and the faces in the group appear in the customization buffer. Here is an example of how a face looks: Custom Changed Face: (sample) [State]: this face is unchanged from its standard setting. Face used when the customize item has been changed. Parent groups: [Custom Magic Faces] Attributes: [ ] Bold: [Toggle] off (nil) [ ] Italic: [Toggle] off (nil) [ ] Underline: [Toggle] off (nil) [ ] Foreground: white (sample) [ ] Background: blue (sample) [ ] Inverse: [Toggle] off (nil) [ ] Stipple: [ ] Font Family: [ ] Size: [ ] Strikethru: off Each face attribute has its own line. The `[X]' field before the attribute name indicates whether the attribute is "enabled"; `X' means that it is. You can enable or disable the attribute by invoking that field. When the attribute is enabled, you can change the attribute value in the usual ways. Setting, saving and resetting a face work like the same operations for options (*note Changing an Option::.). A face can specify different appearances for different types of display. For example, a face can make text red on a color display, but use a bold font on a monochrome display. To specify multiple appearances for a face, select `Show Display Types' in the menu you get from invoking `[State]'.  File: xemacs.info, Node: Specific Customization, Prev: Face Customization, Up: Easy Customization Customizing Specific Items .......................... Instead of finding the options you want to change by moving down through the structure of groups, you can specify the particular option, face or group that you want to customize. `M-x customize-option OPTION ' Set up a customization buffer with just one option, OPTION. `M-x customize-face FACE ' Set up a customization buffer with just one face, FACE. `M-x customize-group GROUP ' Set up a customization buffer with just one group, GROUP. `M-x customize-apropos REGEXP ' Set up a customization buffer with all the options, faces and groups that match REGEXP. `M-x customize-saved' Set up a customization buffer containing all options and faces that you have saved with customization buffers. `M-x customize-customized' Set up a customization buffer containing all options and faces that you have customized but not saved. If you want to alter a particular user option variable with the customization buffer, and you know its name, you can use the command `M-x customize-option' and specify the option name. This sets up the customization buffer with just one option--the one that you asked for. Editing, setting and saving the value work as described above, but only for the specified option. Likewise, you can modify a specific face, chosen by name, using `M-x customize-face'. You can also set up the customization buffer with a specific group, using `M-x customize-group'. The immediate contents of the chosen group, including option variables, faces, and other groups, all appear as well. However, these subgroups' own contents start out hidden. You can show their contents in the usual way, by invoking `[Show]'. To control more precisely what to customize, you can use `M-x customize-apropos'. You specify a regular expression as argument; then all options, faces and groups whose names match this regular expression are set up in the customization buffer. If you specify an empty regular expression, this includes *all* groups, options and faces in the customization buffer (but that takes a long time). If you change option values and then decide the change was a mistake, you can use two special commands to revisit your previous changes. Use `customize-saved' to look at the options and faces that you have saved. Use `M-x customize-customized' to look at the options and faces that you have set but not saved.  File: xemacs.info, Node: Edit Options, Next: Locals, Prev: Easy Customization, Up: Variables Editing Variable Values ----------------------- `M-x list-options' Display a buffer listing names, values, and documentation of all options. `M-x edit-options' Change option values by editing a list of options. `M-x list-options' displays a list of all Emacs option variables in an Emacs buffer named `*List Options*'. Each option is shown with its documentation and its current value. Here is what a portion of it might look like: ;; exec-path: ("." "/usr/local/bin" "/usr/ucb" "/bin" "/usr/bin" "/u2/emacs/etc") *List of directories to search programs to run in subprocesses. Each element is a string (directory name) or nil (try the default directory). ;; ;; fill-column: 75 *Column beyond which automatic line-wrapping should happen. Automatically becomes local when set in any fashion. ;; `M-x edit-options' goes one step further and immediately selects the `*List Options*' buffer; this buffer uses the major mode Options mode, which provides commands that allow you to point at an option and change its value: `s' Set the variable point is in or near to a new value read using the minibuffer. `x' Toggle the variable point is in or near: if the value was `nil', it becomes `t'; otherwise it becomes `nil'. `1' Set the variable point is in or near to `t'. `0' Set the variable point is in or near to `nil'. `n' `p' Move to the next or previous variable.  File: xemacs.info, Node: Locals, Next: File Variables, Prev: Edit Options, Up: Variables Local Variables --------------- `M-x make-local-variable' Make a variable have a local value in the current buffer. `M-x kill-local-variable' Make a variable use its global value in the current buffer. `M-x make-variable-buffer-local' Mark a variable so that setting it will make it local to the buffer that is current at that time. You can make any variable "local" to a specific Emacs buffer. This means that the variable's value in that buffer is independent of its value in other buffers. A few variables are always local in every buffer. All other Emacs variables have a "global" value which is in effect in all buffers that have not made the variable local. Major modes always make the variables they set local to the buffer. This is why changing major modes in one buffer has no effect on other buffers. `M-x make-local-variable' reads the name of a variable and makes it local to the current buffer. Further changes in this buffer will not affect others, and changes in the global value will not affect this buffer. `M-x make-variable-buffer-local' reads the name of a variable and changes the future behavior of the variable so that it automatically becomes local when it is set. More precisely, once you have marked a variable in this way, the usual ways of setting the variable will automatically invoke `make-local-variable' first. We call such variables "per-buffer" variables. Some important variables have been marked per-buffer already. They include `abbrev-mode', `auto-fill-function', `case-fold-search', `comment-column', `ctl-arrow', `fill-column', `fill-prefix', `indent-tabs-mode', `left-margin', `mode-line-format', `overwrite-mode', `selective-display-ellipses', `selective-display', `tab-width', and `truncate-lines'. Some other variables are always local in every buffer, but they are used for internal purposes. Note: the variable `auto-fill-function' was formerly named `auto-fill-hook'. If you want a variable to cease to be local to the current buffer, call `M-x kill-local-variable' and provide the name of a variable to the prompt. The global value of the variable is again in effect in this buffer. Setting the major mode kills all the local variables of the buffer. To set the global value of a variable, regardless of whether the variable has a local value in the current buffer, you can use the Lisp function `setq-default'. It works like `setq'. If there is a local value in the current buffer, the local value is not affected by `setq-default'; thus, the new global value may not be visible until you switch to another buffer, as in the case of: (setq-default fill-column 75) `setq-default' is the only way to set the global value of a variable that has been marked with `make-variable-buffer-local'. Programs can look at a variable's default value with `default-value'. This function takes a symbol as an argument and returns its default value. The argument is evaluated; usually you must quote it explicitly, as in the case of: (default-value 'fill-column)  File: xemacs.info, Node: File Variables, Prev: Locals, Up: Variables Local Variables in Files ------------------------ A file can contain a "local variables list", which specifies the values to use for certain Emacs variables when that file is edited. Visiting the file checks for a local variables list and makes each variable in the list local to the buffer in which the file is visited, with the value specified in the file. A local variables list goes near the end of the file, in the last page. (It is often best to put it on a page by itself.) The local variables list starts with a line containing the string `Local Variables:', and ends with a line containing the string `End:'. In between come the variable names and values, one set per line, as `VARIABLE: VALUE'. The VALUEs are not evaluated; they are used literally. The line which starts the local variables list does not have to say just `Local Variables:'. If there is other text before `Local Variables:', that text is called the "prefix", and if there is other text after, that is called the "suffix". If a prefix or suffix are present, each entry in the local variables list should have the prefix before it and the suffix after it. This includes the `End:' line. The prefix and suffix are included to disguise the local variables list as a comment so the compiler or text formatter will ignore it. If you do not need to disguise the local variables list as a comment in this way, there is no need to include a prefix or a suffix. Two "variable" names are special in a local variables list: a value for the variable `mode' sets the major mode, and a value for the variable `eval' is simply evaluated as an expression and the value is ignored. These are not real variables; setting them in any other context does not have the same effect. If `mode' is used in a local variables list, it should be the first entry in the list. Here is an example of a local variables list: ;;; Local Variables: *** ;;; mode:lisp *** ;;; comment-column:0 *** ;;; comment-start: ";;; " *** ;;; comment-end:"***" *** ;;; End: *** Note that the prefix is `;;; ' and the suffix is ` ***'. Note also that comments in the file begin with and end with the same strings. Presumably the file contains code in a language which is enough like Lisp for Lisp mode to be useful but in which comments start and end differently. The prefix and suffix are used in the local variables list to make the list look like several lines of comments when the compiler or interpreter for that language reads the file. The start of the local variables list must be no more than 3000 characters from the end of the file, and must be in the last page if the file is divided into pages. Otherwise, Emacs will not notice it is there. The purpose is twofold: a stray `Local Variables:' not in the last page does not confuse Emacs, and Emacs never needs to search a long file that contains no page markers and has no local variables list. You may be tempted to turn on Auto Fill mode with a local variable list. That is inappropriate. Whether you use Auto Fill mode or not is a matter of personal taste, not a matter of the contents of particular files. If you want to use Auto Fill, set up major mode hooks with your `.emacs' file to turn it on (when appropriate) for you alone (*note Init File::.). Don't try to use a local variable list that would impose your taste on everyone working with the file. XEmacs allows you to specify local variables in the first line of a file, in addition to specifying them in the `Local Variables' section at the end of a file. If the first line of a file contains two occurrences of ``-*-'', XEmacs uses the information between them to determine what the major mode and variable settings should be. For example, these are all legal: ;;; -*- mode: emacs-lisp -*- ;;; -*- mode: postscript; version-control: never -*- ;;; -*- tags-file-name: "/foo/bar/TAGS" -*- For historical reasons, the syntax ``-*- modename -*-'' is allowed as well; for example, you can use: ;;; -*- emacs-lisp -*- The variable `enable-local-variables' controls the use of local variables lists in files you visit. The value can be `t', `nil', or something else. A value of `t' means local variables lists are obeyed; `nil' means they are ignored; anything else means query. The command `M-x normal-mode' always obeys local variables lists and ignores this variable.  File: xemacs.info, Node: Keyboard Macros, Next: Key Bindings, Prev: Variables, Up: Customization Keyboard Macros =============== A "keyboard macro" is a command defined by the user to abbreviate a sequence of keys. For example, if you discover that you are about to type `C-n C-d' forty times, you can speed your work by defining a keyboard macro to invoke `C-n C-d' and calling it with a repeat count of forty. `C-x (' Start defining a keyboard macro (`start-kbd-macro'). `C-x )' End the definition of a keyboard macro (`end-kbd-macro'). `C-x e' Execute the most recent keyboard macro (`call-last-kbd-macro'). `C-u C-x (' Re-execute last keyboard macro, then add more keys to its definition. `C-x q' When this point is reached during macro execution, ask for confirmation (`kbd-macro-query'). `M-x name-last-kbd-macro' Give a command name (for the duration of the session) to the most recently defined keyboard macro. `M-x insert-kbd-macro' Insert in the buffer a keyboard macro's definition, as Lisp code. Keyboard macros differ from other Emacs commands in that they are written in the Emacs command language rather than in Lisp. This makes it easier for the novice to write them and makes them more convenient as temporary hacks. However, the Emacs command language is not powerful enough as a programming language to be useful for writing anything general or complex. For such things, Lisp must be used. You define a keyboard macro by executing the commands which are its definition. Put differently, as you are defining a keyboard macro, the definition is being executed for the first time. This way, you see what the effects of your commands are, and don't have to figure them out in your head. When you are finished, the keyboard macro is defined and also has been executed once. You can then execute the same set of commands again by invoking the macro. * Menu: * Basic Kbd Macro:: Defining and running keyboard macros. * Save Kbd Macro:: Giving keyboard macros names; saving them in files. * Kbd Macro Query:: Keyboard macros that do different things each use.  File: xemacs.info, Node: Basic Kbd Macro, Next: Save Kbd Macro, Up: Keyboard Macros Basic Use --------- To start defining a keyboard macro, type `C-x (' (`start-kbd-macro'). From then on, anything you type continues to be executed, but also becomes part of the definition of the macro. `Def' appears in the mode line to remind you of what is going on. When you are finished, the `C-x )' command (`end-kbd-macro') terminates the definition, without becoming part of it. For example, C-x ( M-f foo C-x ) defines a macro to move forward a word and then insert `foo'. You can give `C-x )' a repeat count as an argument, in which case it repeats the macro that many times right after defining it, but defining the macro counts as the first repetition (since it is executed as you define it). If you give `C-x )' an argument of 4, it executes the macro immediately 3 additional times. An argument of zero to `C-x e' or `C-x )' means repeat the macro indefinitely (until it gets an error or you type `C-g'). Once you have defined a macro, you can invoke it again with the `C-x e' command (`call-last-kbd-macro'). You can give the command a repeat count numeric argument to execute the macro many times. To repeat an operation at regularly spaced places in the text, define a macro and include as part of the macro the commands to move to the next place you want to use it. For example, if you want to change each line, you should position point at the start of a line, and define a macro to change that line and leave point at the start of the next line. Repeating the macro will then operate on successive lines. After you have terminated the definition of a keyboard macro, you can add to the end of its definition by typing `C-u C-x ('. This is equivalent to plain `C-x (' followed by retyping the whole definition so far. As a consequence it re-executes the macro as previously defined.  File: xemacs.info, Node: Save Kbd Macro, Next: Kbd Macro Query, Prev: Basic Kbd Macro, Up: Keyboard Macros Naming and Saving Keyboard Macros --------------------------------- To save a keyboard macro for longer than until you define the next one, you must give it a name using `M-x name-last-kbd-macro'. This reads a name as an argument using the minibuffer and defines that name to execute the macro. The macro name is a Lisp symbol, and defining it in this way makes it a valid command name for calling with `M-x' or for binding a key to with `global-set-key' (*note Keymaps::.). If you specify a name that has a prior definition other than another keyboard macro, Emacs prints an error message and nothing is changed. Once a macro has a command name, you can save its definition in a file. You can then use it in another editing session. First visit the file you want to save the definition in. Then use the command: M-x insert-kbd-macro MACRONAME This inserts some Lisp code that, when executed later, will define the same macro with the same definition it has now. You need not understand Lisp code to do this, because `insert-kbd-macro' writes the Lisp code for you. Then save the file. You can load the file with `load-file' (*note Lisp Libraries::.). If the file you save in is your initialization file `~/.emacs' (*note Init File::.), then the macro will be defined each time you run Emacs. If you give `insert-kbd-macro' a prefix argument, it creates additional Lisp code to record the keys (if any) that you have bound to the keyboard macro, so that the macro is reassigned the same keys when you load the file.  File: xemacs.info, Node: Kbd Macro Query, Prev: Save Kbd Macro, Up: Keyboard Macros Executing Macros With Variations -------------------------------- You can use `C-x q' (`kbd-macro-query'), to get an effect similar to that of `query-replace'. The macro asks you each time whether to make a change. When you are defining the macro, type `C-x q' at the point where you want the query to occur. During macro definition, the `C-x q' does nothing, but when you invoke the macro, `C-x q' reads a character from the terminal to decide whether to continue. The special answers to a `C-x q' query are , , `C-d', `C-l', and `C-r'. Any other character terminates execution of the keyboard macro and is then read as a command. means to continue. means to skip the remainder of this repetition of the macro, starting again from the beginning in the next repetition. `C-d' means to skip the remainder of this repetition and cancel further repetition. `C-l' redraws the frame and asks you again for a character to specify what to do. `C-r' enters a recursive editing level, in which you can perform editing that is not part of the macro. When you exit the recursive edit using `C-M-c', you are asked again how to continue with the keyboard macro. If you type a at this time, the rest of the macro definition is executed. It is up to you to leave point and the text in a state such that the rest of the macro will do what you want. `C-u C-x q', which is `C-x q' with a numeric argument, performs a different function. It enters a recursive edit reading input from the keyboard, both when you type it during the definition of the macro and when it is executed from the macro. During definition, the editing you do inside the recursive edit does not become part of the macro. During macro execution, the recursive edit gives you a chance to do some particularized editing. *Note Recursive Edit::.  File: xemacs.info, Node: Key Bindings, Next: Syntax, Prev: Keyboard Macros, Up: Customization Customizing Key Bindings ======================== This section deals with the "keymaps" that define the bindings between keys and functions, and shows how you can customize these bindings. A command is a Lisp function whose definition provides for interactive use. Like every Lisp function, a command has a function name, which is a Lisp symbol whose name usually consists of lower case letters and hyphens. * Menu: * Keymaps:: Definition of the keymap data structure. Names of Emacs's standard keymaps. * Rebinding:: How to redefine one key's meaning conveniently. * Disabling:: Disabling a command means confirmation is required before it can be executed. This is done to protect beginners from surprises.  File: xemacs.info, Node: Keymaps, Next: Rebinding, Up: Key Bindings Keymaps ------- The bindings between characters and command functions are recorded in data structures called "keymaps". Emacs has many of these. One, the "global" keymap, defines the meanings of the single-character keys that are defined regardless of major mode. It is the value of the variable `global-map'. Each major mode has another keymap, its "local keymap", which contains overriding definitions for the single-character keys that are redefined in that mode. Each buffer records which local keymap is installed for it at any time, and the current buffer's local keymap is the only one that directly affects command execution. The local keymaps for Lisp mode, C mode, and many other major modes always exist even when not in use. They are the values of the variables `lisp-mode-map', `c-mode-map', and so on. For less frequently used major modes, the local keymap is sometimes constructed only when the mode is used for the first time in a session, to save space. There are local keymaps for the minibuffer, too; they contain various completion and exit commands. * `minibuffer-local-map' is used for ordinary input (no completion). * `minibuffer-local-ns-map' is similar, except that exits just like . This is used mainly for Mocklisp compatibility. * `minibuffer-local-completion-map' is for permissive completion. * `minibuffer-local-must-match-map' is for strict completion and for cautious completion. * `repeat-complex-command-map' is for use in `C-x '. * `isearch-mode-map' contains the bindings of the special keys which are bound in the pseudo-mode entered with `C-s' and `C-r'. Finally, each prefix key has a keymap which defines the key sequences that start with it. For example, `ctl-x-map' is the keymap used for characters following a `C-x'. * `ctl-x-map' is the variable name for the map used for characters that follow `C-x'. * `help-map' is used for characters that follow `C-h'. * `esc-map' is for characters that follow . All Meta characters are actually defined by this map. * `ctl-x-4-map' is for characters that follow `C-x 4'. * `mode-specific-map' is for characters that follow `C-c'. The definition of a prefix key is the keymap to use for looking up the following character. Sometimes the definition is actually a Lisp symbol whose function definition is the following character keymap. The effect is the same, but it provides a command name for the prefix key that you can use as a description of what the prefix key is for. Thus the binding of `C-x' is the symbol `Ctl-X-Prefix', whose function definition is the keymap for `C-x' commands, the value of `ctl-x-map'. Prefix key definitions can appear in either the global map or a local map. The definitions of `C-c', `C-x', `C-h', and as prefix keys appear in the global map, so these prefix keys are always available. Major modes can locally redefine a key as a prefix by putting a prefix key definition for it in the local map. A mode can also put a prefix definition of a global prefix character such as `C-x' into its local map. This is how major modes override the definitions of certain keys that start with `C-x'. This case is special, because the local definition does not entirely replace the global one. When both the global and local definitions of a key are other keymaps, the next character is looked up in both keymaps, with the local definition overriding the global one. The character after the `C-x' is looked up in both the major mode's own keymap for redefined `C-x' commands and in `ctl-x-map'. If the major mode's own keymap for `C-x' commands contains `nil', the definition from the global keymap for `C-x' commands is used.  File: xemacs.info, Node: Rebinding, Next: Disabling, Prev: Keymaps, Up: Key Bindings Changing Key Bindings --------------------- You can redefine an Emacs key by changing its entry in a keymap. You can change the global keymap, in which case the change is effective in all major modes except those that have their own overriding local definitions for the same key. Or you can change the current buffer's local map, which affects all buffers using the same major mode. * Menu: * Interactive Rebinding:: Changing Key Bindings Interactively * Programmatic Rebinding:: Changing Key Bindings Programmatically * Key Bindings Using Strings::Using Strings for Changing Key Bindings  File: xemacs.info, Node: Interactive Rebinding, Next: Programmatic Rebinding, Up: Rebinding Changing Key Bindings Interactively ................................... `M-x global-set-key KEY CMD ' Defines KEY globally to run CMD. `M-x local-set-key KEYS CMD ' Defines KEY locally (in the major mode now in effect) to run CMD. `M-x local-unset-key KEYS ' Removes the local binding of KEY. CMD is a symbol naming an interactively-callable function. When called interactively, KEY is the next complete key sequence that you type. When called as a function, KEY is a string, a vector of events, or a vector of key-description lists as described in the `define-key' function description. The binding goes in the current buffer's local map, which is shared with other buffers in the same major mode. The following example: M-x global-set-key C-f next-line redefines `C-f' to move down a line. The fact that CMD is read second makes it serve as a kind of confirmation for KEY. These functions offer no way to specify a particular prefix keymap as the one to redefine in, but that is not necessary, as you can include prefixes in KEY. KEY is read by reading characters one by one until they amount to a complete key (that is, not a prefix key). Thus, if you type `C-f' for KEY, Emacs enters the minibuffer immediately to read CMD. But if you type `C-x', another character is read; if that character is `4', another character is read, and so on. For example, M-x global-set-key C-x 4 $ spell-other-window redefines `C-x 4 $' to run the (fictitious) command `spell-other-window'. The most general way to modify a keymap is the function `define-key', used in Lisp code (such as your `.emacs' file). `define-key' takes three arguments: the keymap, the key to modify in it, and the new definition. *Note Init File::, for an example. `substitute-key-definition' is used similarly; it takes three arguments, an old definition, a new definition, and a keymap, and redefines in that keymap all keys that were previously defined with the old definition to have the new definition instead.  File: xemacs.info, Node: Programmatic Rebinding, Next: Key Bindings Using Strings, Prev: Interactive Rebinding, Up: Rebinding Changing Key Bindings Programmatically ...................................... You can use the functions `global-set-key' and `define-key' to rebind keys under program control. ``(global-set-key KEYS CMD)'' Defines KEYS globally to run CMD. ``(define-key KEYMAP KEYS DEF)'' Defines KEYS to run DEF in the keymap KEYMAP. KEYMAP is a keymap object. KEYS is the sequence of keystrokes to bind. DEF is anything that can be a key's definition: * `nil', meaning key is undefined in this keymap * A command, that is, a Lisp function suitable for interactive calling * A string or key sequence vector, which is treated as a keyboard macro * A keymap to define a prefix key * A symbol so that when the key is looked up, the symbol stands for its function definition, which should at that time be one of the above, or another symbol whose function definition is used, and so on * A cons, `(string . defn)', meaning that DEFN is the definition (DEFN should be a valid definition in its own right) * A cons, `(keymap . char)', meaning use the definition of CHAR in map KEYMAP For backward compatibility, XEmacs allows you to specify key sequences as strings. However, the preferred method is to use the representations of key sequences as vectors of keystrokes. *Note Keystrokes::, for more information about the rules for constructing key sequences. Emacs allows you to abbreviate representations for key sequences in most places where there is no ambiguity. Here are some rules for abbreviation: * The keysym by itself is equivalent to a list of just that keysym, i.e., `f1' is equivalent to `(f1)'. * A keystroke by itself is equivalent to a vector containing just that keystroke, i.e., `(control a)' is equivalent to `[(control a)]'. * You can use ASCII codes for keysyms that have them. i.e., `65' is equivalent to `A'. (This is not so much an abbreviation as an alternate representation.) Here are some examples of programmatically binding keys: ;;; Bind `my-command' to (global-set-key 'f1 'my-command) ;;; Bind `my-command' to Shift-f1 (global-set-key '(shift f1) 'my-command) ;;; Bind `my-command' to C-c Shift-f1 (global-set-key '[(control c) (shift f1)] 'my-command) ;;; Bind `my-command' to the middle mouse button. (global-set-key 'button2 'my-command) ;;; Bind `my-command' to ;;; in the keymap that is in force when you are running `dired'. (define-key dired-mode-map '(meta control button3) 'my-command)  File: xemacs.info, Node: Key Bindings Using Strings, Prev: Programmatic Rebinding, Up: Rebinding Using Strings for Changing Key Bindings ....................................... For backward compatibility, you can still use strings to represent key sequences. Thus you can use commands like the following: ;;; Bind `end-of-line' to C-f (global-set-key "\C-f" 'end-of-line) Note, however, that in some cases you may be binding more than one key sequence by using a single command. This situation can arise because in ASCII, `C-i' and have the same representation. Therefore, when Emacs sees: (global-set-key "\C-i" 'end-of-line) it is unclear whether the user intended to bind `C-i' or . The solution XEmacs adopts is to bind both of these key sequences. After binding a command to two key sequences with a form like: (define-key global-map "\^X\^I" 'command-1) it is possible to redefine only one of those sequences like so: (define-key global-map [(control x) (control i)] 'command-2) (define-key global-map [(control x) tab] 'command-3) This applies only when running under a window system. If you are talking to Emacs through an ASCII-only channel, you do not get any of these features. Here is a table of pairs of key sequences that behave in a similar fashion: control h backspace control l clear control i tab control m return control j linefeed control [ escape control @ control space  File: xemacs.info, Node: Disabling, Prev: Rebinding, Up: Key Bindings Disabling Commands ------------------ Disabling a command marks it as requiring confirmation before it can be executed. The purpose of disabling a command is to prevent beginning users from executing it by accident and being confused. The direct mechanism for disabling a command is to have a non-`nil' `disabled' property on the Lisp symbol for the command. These properties are normally set by the user's `.emacs' file with Lisp expressions such as: (put 'delete-region 'disabled t) If the value of the `disabled' property is a string, that string is included in the message printed when the command is used: (put 'delete-region 'disabled "Text deleted this way cannot be yanked back!\n") You can disable a command either by editing the `.emacs' file directly or with the command `M-x disable-command', which edits the `.emacs' file for you. *Note Init File::. When you attempt to invoke a disabled command interactively in Emacs, a window is displayed containing the command's name, its documentation, and some instructions on what to do next; then Emacs asks for input saying whether to execute the command as requested, enable it and execute, or cancel it. If you decide to enable the command, you are asked whether to do this permanently or just for the current session. Enabling permanently works by automatically editing your `.emacs' file. You can use `M-x enable-command' at any time to enable any command permanently. Whether a command is disabled is independent of what key is used to invoke it; it also applies if the command is invoked using `M-x'. Disabling a command has no effect on calling it as a function from Lisp programs.  File: xemacs.info, Node: Syntax, Next: Init File, Prev: Key Bindings, Up: Customization The Syntax Table ================ All the Emacs commands which parse words or balance parentheses are controlled by the "syntax table". The syntax table specifies which characters are opening delimiters, which are parts of words, which are string quotes, and so on. Actually, each major mode has its own syntax table (though sometimes related major modes use the same one) which it installs in each buffer that uses that major mode. The syntax table installed in the current buffer is the one that all commands use, so we call it "the" syntax table. A syntax table is a Lisp object, a vector of length 256 whose elements are numbers. * Menu: * Entry: Syntax Entry. What the syntax table records for each character. * Change: Syntax Change. How to change the information.  File: xemacs.info, Node: Syntax Entry, Next: Syntax Change, Up: Syntax Information About Each Character -------------------------------- The syntax table entry for a character is a number that encodes six pieces of information: * The syntactic class of the character, represented as a small integer * The matching delimiter, for delimiter characters only (the matching delimiter of `(' is `)', and vice versa) * A flag saying whether the character is the first character of a two-character comment starting sequence * A flag saying whether the character is the second character of a two-character comment starting sequence * A flag saying whether the character is the first character of a two-character comment ending sequence * A flag saying whether the character is the second character of a two-character comment ending sequence The syntactic classes are stored internally as small integers, but are usually described to or by the user with characters. For example, `(' is used to specify the syntactic class of opening delimiters. Here is a table of syntactic classes, with the characters that specify them. ` ' The class of whitespace characters. `w' The class of word-constituent characters. `_' The class of characters that are part of symbol names but not words. This class is represented by `_' because the character `_' has this class in both C and Lisp. `.' The class of punctuation characters that do not fit into any other special class. `(' The class of opening delimiters. `)' The class of closing delimiters. `'' The class of expression-adhering characters. These characters are part of a symbol if found within or adjacent to one, and are part of a following expression if immediately preceding one, but are like whitespace if surrounded by whitespace. `"' The class of string-quote characters. They match each other in pairs, and the characters within the pair all lose their syntactic significance except for the `\' and `/' classes of escape characters, which can be used to include a string-quote inside the string. `$' The class of self-matching delimiters. This is intended for TeX's `$', which is used both to enter and leave math mode. Thus, a pair of matching `$' characters surround each piece of math mode TeX input. A pair of adjacent `$' characters act like a single one for purposes of matching. `/' The class of escape characters that always just deny the following character its special syntactic significance. The character after one of these escapes is always treated as alphabetic. `\' The class of C-style escape characters. In practice, these are treated just like `/'-class characters, because the extra possibilities for C escapes (such as being followed by digits) have no effect on where the containing expression ends. `<' The class of comment-starting characters. Only single-character comment starters (such as `;' in Lisp mode) are represented this way. `>' The class of comment-ending characters. Newline has this syntax in Lisp mode. The characters flagged as part of two-character comment delimiters can have other syntactic functions most of the time. For example, `/' and `*' in C code, when found separately, have nothing to do with comments. The comment-delimiter significance overrides when the pair of characters occur together in the proper order. Only the list and sexp commands use the syntax table to find comments; the commands specifically for comments have other variables that tell them where to find comments. Moreover, the list and sexp commands notice comments only if `parse-sexp-ignore-comments' is non-`nil'. This variable is set to `nil' in modes where comment-terminator sequences are liable to appear where there is no comment, for example, in Lisp mode where the comment terminator is a newline but not every newline ends a comment.  File: xemacs.info, Node: Syntax Change, Prev: Syntax Entry, Up: Syntax Altering Syntax Information --------------------------- It is possible to alter a character's syntax table entry by storing a new number in the appropriate element of the syntax table, but it would be hard to determine what number to use. Emacs therefore provides a command that allows you to specify the syntactic properties of a character in a convenient way. `M-x modify-syntax-entry' is the command to change a character's syntax. It can be used interactively and is also used by major modes to initialize their own syntax tables. Its first argument is the character to change. The second argument is a string that specifies the new syntax. When called from Lisp code, there is a third, optional argument, which specifies the syntax table in which to make the change. If not supplied, or if this command is called interactively, the third argument defaults to the current buffer's syntax table. 1. The first character in the string specifies the syntactic class. It is one of the characters in the previous table (*note Syntax Entry::.). 2. The second character is the matching delimiter. For a character that is not an opening or closing delimiter, this should be a space, and may be omitted if no following characters are needed. 3. The remaining characters are flags. The flag characters allowed are: `1' Flag this character as the first of a two-character comment starting sequence. `2' Flag this character as the second of a two-character comment starting sequence. `3' Flag this character as the first of a two-character comment ending sequence. `4' Flag this character as the second of a two-character comment ending sequence. Use `C-h s' (`describe-syntax') to display a description of the contents of the current syntax table. The description of each character includes both the string you have to pass to `modify-syntax-entry' to set up that character's current syntax, and some English to explain that string if necessary.