1 ;;; help.el --- help commands for Emacs
3 ;; Copyright (C) 1985, 1986 Free Software Foundation, Inc.
6 ;; Keywords: help, internal
8 ;; This file is part of GNU Emacs.
10 ;; GNU Emacs is free software; you can redistribute it and/or modify
11 ;; it under the terms of the GNU General Public License as published by
12 ;; the Free Software Foundation; either version 2, or (at your option)
15 ;; GNU Emacs is distributed in the hope that it will be useful,
16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 ;; GNU General Public License for more details.
20 ;; You should have received a copy of the GNU General Public License
21 ;; along with GNU Emacs; see the file COPYING. If not, write to
22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
26 ;; This code implements GNU Emac's on-line help system, the one invoked by
27 ;;`M-x help-for-help'.
31 ;; Get the macro make-help-screen when this is compiled,
32 ;; or run interpreted, but not when the compiled code is loaded.
33 (eval-when-compile (require 'help-screen
))
35 (defvar help-map
(make-sparse-keymap)
36 "Keymap for characters following the Help key.")
38 (define-key global-map
(char-to-string help-char
) 'help-command
)
39 (fset 'help-command help-map
)
41 (define-key help-map
(char-to-string help-char
) 'help-for-help
)
42 (define-key help-map
"?" 'help-for-help
)
44 (define-key help-map
"\C-c" 'describe-copying
)
45 (define-key help-map
"\C-d" 'describe-distribution
)
46 (define-key help-map
"\C-w" 'describe-no-warranty
)
47 (define-key help-map
"a" 'command-apropos
)
49 (define-key help-map
"b" 'describe-bindings
)
51 (define-key help-map
"c" 'describe-key-briefly
)
52 (define-key help-map
"k" 'describe-key
)
54 (define-key help-map
"d" 'describe-function
)
55 (define-key help-map
"f" 'describe-function
)
57 (define-key help-map
"i" 'info
)
58 (define-key help-map
"\C-f" 'Info-goto-emacs-command-node
)
59 (define-key help-map
"\C-k" 'Info-goto-emacs-key-command-node
)
61 (define-key help-map
"l" 'view-lossage
)
63 (define-key help-map
"m" 'describe-mode
)
65 (define-key help-map
"\C-n" 'view-emacs-news
)
66 (define-key help-map
"n" 'view-emacs-news
)
68 (define-key help-map
"p" 'finder-by-keyword
)
69 (autoload 'finder-by-keyword
"finder.el")
71 (define-key help-map
"s" 'describe-syntax
)
73 (define-key help-map
"t" 'help-with-tutorial
)
75 (define-key help-map
"w" 'where-is
)
77 (define-key help-map
"v" 'describe-variable
)
79 (defun help-with-tutorial ()
80 "Select the Emacs learn-by-doing tutorial."
82 (let ((file (expand-file-name "~/TUTORIAL")))
83 (delete-other-windows)
84 (if (get-file-buffer file
)
85 (switch-to-buffer (get-file-buffer file
))
86 (switch-to-buffer (create-file-buffer file
))
87 (setq buffer-file-name file
)
88 (setq default-directory
(expand-file-name "~/"))
89 (setq buffer-auto-save-file-name nil
)
90 (insert-file-contents (expand-file-name "TUTORIAL" data-directory
))
91 (goto-char (point-min))
92 (search-forward "\n<<")
94 (delete-region (point) (progn (end-of-line) (point)))
95 (newline (- (window-height (selected-window))
96 (count-lines (point-min) (point))
98 (goto-char (point-min))
99 (set-buffer-modified-p nil
))))
101 (defun describe-key-briefly (key)
102 "Print the name of the function KEY invokes. KEY is a string."
103 (interactive "kDescribe key briefly: ")
104 (let ((defn (key-binding key
)))
105 (if (or (null defn
) (integerp defn
))
106 (message "%s is undefined" (key-description key
))
107 (message "%s runs the command %s"
108 (key-description key
)
109 (if (symbolp defn
) defn
(prin1-to-string defn
))))))
111 (defun print-help-return-message (&optional function
)
112 "Display or return message saying how to restore windows after help command.
113 Computes a message and applies the optional argument FUNCTION to it.
114 If FUNCTION is nil, applies `message' to it, thus printing it."
115 (and (not (get-buffer-window standard-output
))
116 (funcall (or function
'message
)
118 (substitute-command-keys
121 "Type \\[delete-other-windows] to remove help window."
122 "Type \\[switch-to-buffer] RET to remove help window.")
123 "Type \\[switch-to-buffer-other-window] RET to restore the other window."))
124 (substitute-command-keys
125 " \\[scroll-other-window] to scroll the help.")))))
127 (defun describe-key (key)
128 "Display documentation of the function invoked by KEY. KEY is a string."
129 (interactive "kDescribe key: ")
130 (let ((defn (key-binding key
)))
131 (if (or (null defn
) (integerp defn
))
132 (message "%s is undefined" (key-description key
))
133 (with-output-to-temp-buffer "*Help*"
136 (if (documentation defn
)
137 (princ (documentation defn
))
138 (princ "not documented"))
139 (print-help-return-message)))))
141 (defun describe-mode (&optional minor
)
142 "Display documentation of current major mode.
143 If optional MINOR is non-nil (or prefix argument is given if interactive),
144 display documentation of active minor modes as well.
145 For this to work correctly for a minor mode, the mode's indicator variable
146 (listed in `minor-mode-alist') must also be a function whose documentation
147 describes the minor mode."
149 (with-output-to-temp-buffer "*Help*"
152 (princ (documentation major-mode
))
153 (let ((minor-modes minor-mode-alist
)
154 (locals (buffer-local-variables)))
156 (let* ((minor-mode (car (car minor-modes
)))
157 (indicator (car (cdr (car minor-modes
))))
158 (local-binding (assq minor-mode locals
)))
159 ;; Document a minor mode if it is listed in minor-mode-alist,
160 ;; bound locally in this buffer, non-nil, and has a function
162 (if (and local-binding
164 (fboundp minor-mode
))
166 (princ (format "\n\n\n%s minor mode (indicator%s):\n"
167 minor-mode indicator
))
168 (princ (documentation minor-mode
)))))
169 (setq minor-modes
(cdr minor-modes
))))
170 (print-help-return-message)))
172 ;; So keyboard macro definitions are documented correctly
173 (fset 'defining-kbd-macro
(symbol-function 'start-kbd-macro
))
175 (defun describe-distribution ()
176 "Display info on how to obtain the latest version of GNU Emacs."
179 (expand-file-name "DISTRIB" data-directory
)))
181 (defun describe-copying ()
182 "Display info on how you may redistribute copies of GNU Emacs."
185 (expand-file-name "COPYING" data-directory
))
186 (goto-char (point-min)))
188 (defun describe-no-warranty ()
189 "Display info on all the kinds of warranty Emacs does NOT have."
192 (let (case-fold-search)
193 (search-forward "NO WARRANTY")
196 (defun view-emacs-news ()
197 "Display info on recent changes to Emacs."
199 (find-file-read-only (expand-file-name "NEWS" data-directory
)))
201 (defun view-lossage ()
202 "Display last 100 input keystrokes."
204 (with-output-to-temp-buffer "*Help*"
205 (princ (key-description (recent-keys)))
207 (set-buffer standard-output
)
208 (goto-char (point-min))
209 (while (progn (move-to-column 50) (not (eobp)))
210 (search-forward " " nil t
)
212 (print-help-return-message)))
214 (make-help-screen help-for-help
215 "A B C F I K L M N P S T V W C-c C-d C-n C-w. Type \\[help-for-help] again for more help: "
216 "You have typed \\[help-for-help], the help character. Type a Help option:
218 A command-apropos. Give a substring, and see a list of commands
219 (functions interactively callable) that contain
220 that substring. See also the apropos command.
221 B describe-bindings. Display table of all key bindings.
222 C describe-key-briefly. Type a command key sequence;
223 it prints the function name that sequence runs.
224 F describe-function. Type a function name and get documentation of it.
225 I info. The info documentation reader.
226 K describe-key. Type a command key sequence;
227 it displays the full documentation.
228 L view-lossage. Shows last 100 characters you typed.
229 M describe-mode. Print documentation of current major mode,
230 which describes the commands peculiar to it.
231 N view-emacs-news. Shows emacs news file.
232 P finder-by-keyword. Find packages matching a given topic keyword.
233 S describe-syntax. Display contents of syntax table, plus explanations
234 T help-with-tutorial. Select the Emacs learn-by-doing tutorial.
235 V describe-variable. Type name of a variable;
236 it displays the variable's documentation and value.
237 W where-is. Type command name; it prints which keystrokes
239 C-c print Emacs copying permission (General Public License).
240 C-d print Emacs ordering information.
241 C-n print news of recent Emacs changes.
242 C-w print information on absence of warranty for GNU Emacs."
245 ;; Return a function which is called by the list containing point.
246 ;; If that gives no function, return a function whose name is around point.
247 ;; If that doesn't give a function, return nil.
248 (defun function-called-at-point ()
249 (or (condition-case ()
252 (narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
256 (setq obj
(read (current-buffer)))
257 (and (symbolp obj
) (fboundp obj
) obj
))))
262 (skip-chars-forward "'")
263 (let ((obj (read (current-buffer))))
264 (and (symbolp obj
) (fboundp obj
) obj
)))
267 (defun describe-function (function)
268 "Display the full documentation of FUNCTION (a symbol)."
270 (let ((fn (function-called-at-point))
271 (enable-recursive-minibuffers t
)
273 (setq val
(completing-read (if fn
274 (format "Describe function (default %s): " fn
)
275 "Describe function: ")
277 (list (if (equal val
"")
279 (with-output-to-temp-buffer "*Help*"
282 (let* ((def (symbol-function function
))
283 (beg (if (commandp def
) "an interactive " "a ")))
284 (princ (cond ((or (stringp def
)
288 (concat beg
"built-in function."))
289 ((byte-code-function-p def
)
290 (concat beg
"compiled Lisp function."))
292 (format "alias for `%s'." def
))
293 ((eq (car-safe def
) 'lambda
)
294 (concat beg
"Lisp function."))
295 ((eq (car-safe def
) 'macro
)
297 ((eq (car-safe def
) 'mocklisp
)
298 "a mocklisp function.")
299 ((eq (car-safe def
) 'autoload
)
300 (format "%s autoloaded Lisp %s."
301 (if (commandp def
) "an interactive" "an")
302 (if (nth 4 def
) "macro" "function")
303 ;;; Including the file name made this line too long.
308 (let ((arglist (cond ((byte-code-function-p def
)
309 (car (append def nil
)))
310 ((eq (car-safe def
) 'lambda
)
315 (princ (cons function
316 (mapcar (lambda (arg)
317 (if (memq arg
'(&optional
&rest
))
319 (intern (upcase (symbol-name arg
)))))
322 (if (documentation function
)
324 (princ (documentation function
)))
325 (princ "not documented"))
327 (print-help-return-message)
328 ;; Return the text we displayed.
329 (save-excursion (set-buffer standard-output
) (buffer-string))))
331 (defun variable-at-point ()
335 (skip-chars-forward "'")
336 (let ((obj (read (current-buffer))))
337 (and (symbolp obj
) (boundp obj
) obj
)))
340 (defun describe-variable (variable)
341 "Display the full documentation of VARIABLE (a symbol).
342 Returns the documentation as a string, also."
344 (let ((v (variable-at-point))
345 (enable-recursive-minibuffers t
)
347 (setq val
(completing-read (if v
348 (format "Describe variable (default %s): " v
)
349 "Describe variable: ")
351 (list (if (equal val
"")
353 (with-output-to-temp-buffer "*Help*"
355 (princ "'s value is ")
356 (if (not (boundp variable
))
358 (prin1 (symbol-value variable
)))
360 (princ "Documentation:")
362 (let ((doc (documentation-property variable
'variable-documentation
)))
364 (princ (substitute-command-keys doc
))
365 (princ "not documented as a variable.")))
366 (print-help-return-message)
367 ;; Return the text we displayed.
368 (save-excursion (set-buffer standard-output
) (buffer-string))))
370 (defun command-apropos (string)
371 "Like apropos but lists only symbols that are names of commands
372 \(interactively callable functions). Argument REGEXP is a regular expression
373 that is matched against command symbol names. Returns list of symbols and
374 documentation found."
375 (interactive "sCommand apropos (regexp): ")
377 (let ((standard-output (get-buffer-create "*Help*")))
378 (print-help-return-message 'identity
))))
379 (if (apropos string t
'commandp
)
380 (and message
(message message
)))))
382 (defun locate-library (library &optional nosuffix
)
383 "Show the full path name of Emacs library LIBRARY.
384 This command searches the directories in `load-path' like `M-x load-library'
385 to find the file that `M-x load-library RET LIBRARY RET' would load.
386 Optional second arg NOSUFFIX non-nil means don't add suffixes `.elc' or `.el'
387 to the specified name LIBRARY (a la calling `load' instead of `load-library')."
388 (interactive "sLocate library: ")
394 (let ((try (expand-file-name (concat library suf
) dir
)))
395 (and (file-readable-p try
)
396 (null (file-directory-p try
))
398 (message "Library is file %s" try
)
399 (throw 'answer try
)))))
400 (if nosuffix
'("") '(".elc" ".el" ""))))
402 (message "No library %s in search path" library
)
405 ;;; help.el ends here