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GNU Info File | 1994-08-02 | 19.2 KB | 519 lines

This is Info file elisp, produced by Makeinfo-1.55 from the input file elisp.texi. This version is newer than the second printed edition of the GNU Emacs Lisp Reference Manual. It corresponds to Emacs Version 19.19. 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. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the section entitled "GNU Emacs General Public License" is 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 section entitled "GNU Emacs General Public License" may be included in a translation approved by the Free Software Foundation instead of in the original English. File: elisp, Node: Antinews, Next: Index, Prev: Standard Hooks, Up: Top Emacs 18 Antinews ***************** For those users who live backwards in time, here is information about downgrading to Emacs version 18. We hope you will enjoy the greater simplicity that results from the absence of many Emacs 19 features. Old Features in the Lisp Language ================================= The following functions are missing or different in Emacs version 18. * The functions `delete', `member', `indirect-function', `map-y-or-n-p', and `invocation-name' have been removed. * The function `read' now skips a terminator character that terminates a symbol when reading from a buffer. Thus, if you use `read' on a buffer containing `foo(bar)' following point, it returns `foo' and leaves point after the open-parenthesis. This means there's no way you can properly read the list `(bar)', but that's the way the cookie crumbles. Because of this simplification, it's no longer necessary for an input stream function to accept an optional argument. In Emacs 18, an input stream is always called with no arguments, and should always return the next character of input. * The function `documentation' takes just one argument; `documentation-property' takes just two. * `random' no longer has the optional argument N. * You can no longer arrange to run a hook if a particular Lisp library is loaded. The variable `after-load-alist' and the function `eval-after-load' have been removed. * The function `autoload' no longer supports autoloading a keymap. * "Magic" comments of the form `;;;###autoload' are now just comments. They don't do anything in particular except look pretty. If you want a function to be autoloaded by default, edit `loaddefs.h' by hand. What do you think editors are for? * We took out the `%S' from the `format' function, and the optional argument NOESCAP from `prin1-to-string'. We removed the `print-level' variable. Compilation Features ==================== * Inline functions are nonexistent in Emacs 18. We find they make the calling function unnecessarily large. (Small size is one of the features of Emacs 18.) * We eliminated the two special forms, `eval-when-compile' and `eval-and-compile', as well as the `compile-defun' command. * When you load a Lisp file or library, you will no longer receive a warning if the directory contains both a `.elc' file and a new `.el' file that is newer. So be on your toes. * We removed the special data type for byte-code functions. Compiled functions now work by means of an interpreted function which calls the function `bytecode'. That function runs the byte code interpreter. Floating Point Numbers ====================== Emacs 18 doesn't have or need floating point arithmetic built in. It has a handy Lisp program that allows you to emulate floating point. You'll have to write programs specially to use it, though. As a result, certain macros, functions, and predicates no longer handle specifications for floating point numbers. The function `string-to-number', the predicate `floatp', and the variable `float-output-format' have all been eliminated. The functions `float', `truncate', `floor', `ceil', `round', and `logb' do not exist; neither do the functions `abs', `cos', `sin', `tan', `acos', `asin', `atan', `exp', `expt', `log10', `log', or `sqrt'. The `format' function no longer handles the specifications `%e', `%f' and `%g' for printing floating point numbers; likewise for `message'. Changes in Basic Editing Functions ================================== * `kill-new' and `kill-append', the primitives for putting text in the kill ring, have been eliminated. * The variables `interprogram-paste-function' and `interprogram-cut-function' have been removed in Emacs 18. In addition, there's no need for `mark-active' and `deactivate-mark' because there is no Transient Mark mode. We also removed the hooks `activate-mark-hook' and `deactivate-mark-hook'. * The `kill-region' function can no longer be used in read-only buffers. The `compare-buffer-substrings' and `current-kill' functions have been removed. * The variable `overwrite-mode-binary' has been removed. * The function `move-to-column' allows just one argument, COLUMN. * The search functions now just return `t' when successful. This affects the functions `search-forward', `search-backward', `word-search-forward', `word-search-backward', `re-search-forward', and `re-search-backward'. * When you do regular expression searching or matching, there is a fixed limit of ten `\(...\)' pairs that you can get information about with `match-beginning' and `match-end'. Moreover, `save-match-data' does not exist; you must use an explicit `unwind-protect' to save the match data. * `translate-region' is gone. * The variables `before-change-function', `after-change-function', and `first-change-hook' have been eliminated. * The second argument to `insert-abbrev-table-description' is no longer optional. Text Properties =============== We eliminated text properties. Features for Files ================== Many file-related functions have been eliminated or simplified. Here is a basic listing of these functions. The functions `file-accessible-directory-p', `file-truename', `make-directory', `delete-directory', `set-visited-file-modtime', `directory-abbrev-alist', `abbreviate-file-name', `write-region', `write-contents-hooks', `after-save-hook', `set-default-file-modes', `default-file-modes', and `unix-sync' have been eliminated. We got rid of the "initial file name" argument to `read-file-name'. Additionally, we removed the 12th element from the list returned by `file-attributes'. `directory-files' always sorts the list of files. It's not user friendly to process the files in any haphazard order. We eliminated the variables `write-contents-hooks' and `local-write-file-hooks'. Making Certain File Names "Magic" ================================= There are no more magic filenames. Sorry, but all the mana has been used up. Frames ====== There is only one frame in Emacs 18, so all of the frame functions have been eliminated. X Window System Features ======================== We have simplified the way emacs and X interact by removing a great deal of creeping featurism. * The functions `mouse-position' and `set-mouse-position', and the special form `track-mouse' have been eliminated. * Likewise, the functions `x-set-selection', `x-set-cut-buffer', `x-close-current-connection', and `x-open-connection' have all been removed from Emacs Lisp 18. * We removed a series of functions that gave information about the X server and the screen you were using; after all, the whole point of X is that all servers are equivalent. The names of the removed functions are: `x-display-screens', `x-server-version', `x-server-vendor', `x-display-pixel-height', `x-display-mm-height', `x-display-pixel-width', `x-display-mm-width', `x-display-backing-store', `x-display-save-under', `x-display-planes', `x-display-visual-class', `x-display-color-p', and `x-display-color-cells'. Additionally, we removed the variable `x-no-window-manager' and the functions `x-synchronize' and `x-get-resource'. We didn't abolish `x-display-color-p', but we renamed it to `x-color-display-p'. We did abolish `x-color-defined-p'. * `x-popup-menu' no longer accepts a keymap for its first argument. * We removed both the function `x-rebind-key' and the related function `x-rebind-keys'. * We abolished `x-parse-geometry'. Window Actions that Were No Longer Useful ========================================= Various behaviors of windows in Emacs 19 were obsolete by the time Emacs 18 was due to come out. We have removed them. These changes are listed below. * We removed the functions `window-at', `window-minibuffer-p', `set-window-dedicated-p', `coordinates-in-window-p', `walk-windows', `window-dedicated-p', and `window-end'. * We removed the variables `pop-up-frames', `pop-up-frame-function', `display-buffer-function', and `other-window-scroll-buffer'. * The function `minibuffer-window' no longer accepts a frame as argument, since frames as objects do not exist in Emacs version 18. It returns the window used for minibuffers. * The functions `next-window' and `previous-window' no longer accept the ALL-FRAMES argument since there is just one frame. * The functions `get-lru-window', `get-largest-window', `get-buffer-window', and `get-buffer-window' also no longer take the optional argument ALL-FRAMES because there is just one frame to search. Display Features ================ * There are no overlays, and no faces. * We eliminated the mode line spec `%l' that in later versions used to display the current line number. We removed the variables `line-number-mode' and `line-number-display-limit'. * `baud-rate' is now a function rather than a variable. * You can no longer call `message' with `nil' as the only argument; therefore, you can not reliably make the contents of the minibuffer visible. * The variable `temp-buffer-show-function' has been renamed `temp-buffer-show-hook'. * We removed the function `force-mode-line-update'. Use the following idiom instead: (set-buffer-modified-p (buffer-modified-p)) * Display tables no longer exist. We know what the ASCII characters should look like, and we made them look that way. Working with Input Events ========================= The big news about input events is that we got rid of function key and mouse events. Now the only input events are characters. What's more, these characters now have to be in the range of 0 to 127, optionally with a meta bit. This makes for big simplifications. * Functions like `define-key', `global-set-key', `read-key-sequence', and `local-set-key' used to accept strings or vectors in Emacs 19; now they only accept strings. * The documentation functions (`single-key-description', `key-description', etc.) also no longer accept vectors, but they do accept strings. * We removed the `read-event', `event-start', `posn-window', `posn-point', `posn-col-row', `posn-timestamp', `scroll-bar-scale', and `event-end' functions, since they were only useful for non-character events. * We removed the `unread-command-events' and `last-event-frame' variables. * The functions `this-command-keys' and `recent-keys' now always return a string. Likewise, a keyboard macro's definition can only be a string, not a vector. * We eliminated `e' as an interactive specification since it was useful only with non-character events. * In Emacs 18, we represent Meta characters as character objects with the same encoding used in strings: 128 plus the corresponding non-Meta ASCII character. Menus ===== You can no longer define menus as keymaps; good system design requires crafting a special-purpose interface for each facility, so it can precisely fit the requirements of that facility. We decided that unifying keymaps and menus was simply too much of a strain. In Emacs 18, you can only activate menus with the mouse. Using them with a keyboard was too confusing for too many users. Emacs 18 has no menu bars. All functions and variables related to the menu bar have been eliminated. Changes in Minibuffer Features ============================== The minibuffer history feature has been eliminated. Thus, we removed the optional argument HIST from the minibuffer input functions `read-from-minibuffer' and `completing-read'. The INITIAL argument to `read-from-minibuffer' and other minibuffer input functions can no longer be a cons cell `(STRING . POSITION)'. In the function `read-no-blanks-input', the INITIAL argument is no longer optional. New Features for Defining Commands ================================== * The special meaning of `@' in an interactive specification has been eliminated. * Emacs 18 does not support use of format-style `%'-sequences in the prompt strings in interactive specifications. * The property `enable-recursive-minibuffers' no longer has any special meaning. Removed Features for Reading Input ================================== We removed the third argument (META) from the function `set-input-mode'. Consequently, we added the variable `meta-flag'; set it to `t' to enable use of a Meta key, and to `nil' to disable it. (Those are the only two alternatives.) We also removed the variable `extra-keyboard-modifiers'. We removed the function `keyboard-translate' and the variables `num-input-keys' and `function-key-map'. Removed Syntax Table Features ============================= * We eliminated the functions `skip-syntax-forward', `skip-syntax-backward', `forward-comment'. * We removed the syntax flag for "prefix syntax" and the flag for the alternate comment style. Emacs 18 supports only one style of comment in any given syntax table. * We abolished the variable `words-include-escapes'. The Case Table ============== Case tables do not exist in Emacs 18. Due to this change, we have removed the associated functions `set-standard-case-table', `standard-case-table', `current-case-table', `set-case-table', and `set-case-syntax-pair'. Features for Dealing with Buffers ================================= * We eliminated several functions for dealing with buffers: `buffer-modified-tick' and `generate-new-buffer-name'. * We renamed `buffer-disable-undo' to `buffer-flush-undo'--a more picturesque name, you will agree. * The function `other-buffer' takes just one argument in Emacs 18. * The function `rename-buffer' now requires you to specify precisely the new name you want. * We removed the local variable `list-buffers-directory'. * We got rid of the hook `kill-buffer-hook'. Local Variables Features ======================== * The function `kill-all-local-variables' always eliminates all buffer-local variables of the current buffer. No more exceptions. * Making a variable buffer-local when it is void now sets it to `nil'. * We eliminated the functions `default-boundp', because it is no longer possible for the default binding of a variable to be void. * The special forms `defconst' and `defvar' now set the variable's local value rather than its default value when the variable is local in the current buffer. Features for Subprocesses ========================= `call-process' and `call-process-region' no longer indicate the termination status of the subprocess. We call on users to have faith that the subprocess executed properly. * The standard asynchronous subprocess features do not work on VMS; instead, special VMS asynchronous subprocess functions have been added. Since they are only for VMS, we can't be bothered documenting them; sorry. Use the source, Luke! * The function `signal-process' has been removed. * We eliminated the transaction queue feature, and the associated functions `tq-create', `tq-enqueue', and `tq-close'. Dealing with Times And Time Delays ================================== * We removed the functions `current-time', `current-time-zone', `run-at-time', and `cancel-timer'. * The function `current-time-string' no longer accepts any optional arguments. * The functions `sit-for' and `sleep-for' no longer allow an optional argument to let you specify the time period in milliseconds; just in seconds. Additionally, we took out the optional third argument NODISP from `sit-for'. * We removed the optional second and third arguments from the `accept-process-output' function. It accepts just one argument, the process. Features not Available for Lisp Debuggers ========================================= * In Emacs 18, you can no longer specify to invoke the Lisp debugger only upon encountering certain types of errors. Any non-`nil' value for the variable `debug-on-error' says to invoke the debugger for any error whatever. * We removed the variable `command-debug-status' and the function `backtrace-frame'. Memory Allocation Changes ========================= We removed the function `memory-limit'. The list returned by `garbage-collect' no longer contains an element to describe floating point numbers, since there aren't any floating point numbers in Emacs 18. Hook Changes ============ * We removed the hooks `pre-abbrev-expand-hook', `pre-command-hook', `post-command-hook', and `auto-save-hook'. * We removed the variable `revert-buffer-insert-file-contents-function'. * We also removed the new function `add-hook'; you will have to set your hooks by hand. If you want to get really into the swing of things, set your hook variables the archaic way: store just one function rather than a list of functions. But that is optional. * The variable `lisp-indent-hook' has been renamed to `lisp-indent-function'. * The variable `auto-fill-function' has been renamed to `auto-fill-hook'. * The `blink-paren-function' has been renamed to `blink-paren-hook'. * The variable `temp-buffer-show-function' has been renamed to `temp-buffer-show-hook'.