1 ;;; help.el --- help commands for Emacs
3 ;; Copyright (C) 1985, 1986 Free Software Foundation, Inc.
5 ;; This file is part of GNU Emacs.
7 ;; GNU Emacs is free software; you can redistribute it and/or modify
8 ;; it under the terms of the GNU General Public License as published by
9 ;; the Free Software Foundation; either version 1, or (at your option)
12 ;; GNU Emacs is distributed in the hope that it will be useful,
13 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
14 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 ;; GNU General Public License for more details.
17 ;; You should have received a copy of the GNU General Public License
18 ;; along with GNU Emacs; see the file COPYING. If not, write to
19 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
22 (defvar help-map
(make-sparse-keymap)
23 "Keymap for characters following the Help key.")
25 (define-key global-map
"\C-h" 'help-command
)
26 (fset 'help-command help-map
)
28 (define-key help-map
"\C-h" 'help-for-help
)
29 (define-key help-map
"?" 'help-for-help
)
31 (define-key help-map
"\C-c" 'describe-copying
)
32 (define-key help-map
"\C-d" 'describe-distribution
)
33 (define-key help-map
"\C-w" 'describe-no-warranty
)
34 (define-key help-map
"a" 'command-apropos
)
36 (define-key help-map
"b" 'describe-bindings
)
38 (define-key help-map
"c" 'describe-key-briefly
)
39 (define-key help-map
"k" 'describe-key
)
41 (define-key help-map
"d" 'describe-function
)
42 (define-key help-map
"f" 'describe-function
)
44 (define-key help-map
"i" 'info
)
46 (define-key help-map
"l" 'view-lossage
)
48 (define-key help-map
"m" 'describe-mode
)
50 (define-key help-map
"\C-n" 'view-emacs-news
)
51 (define-key help-map
"n" 'view-emacs-news
)
53 (define-key help-map
"s" 'describe-syntax
)
55 (define-key help-map
"t" 'help-with-tutorial
)
57 (define-key help-map
"w" 'where-is
)
59 (define-key help-map
"v" 'describe-variable
)
61 (defun help-with-tutorial ()
62 "Select the Emacs learn-by-doing tutorial."
64 (let ((file (expand-file-name "~/TUTORIAL")))
65 (delete-other-windows)
66 (if (get-file-buffer file
)
67 (switch-to-buffer (get-file-buffer file
))
68 (switch-to-buffer (create-file-buffer file
))
69 (setq buffer-file-name file
)
70 (setq default-directory
(expand-file-name "~/"))
71 (setq auto-save-file-name nil
)
72 (insert-file-contents (expand-file-name "TUTORIAL" data-directory
))
73 (goto-char (point-min))
74 (search-forward "\n<<")
76 (delete-region (point) (progn (end-of-line) (point)))
77 (newline (- (window-height (selected-window))
78 (count-lines (point-min) (point))
80 (goto-char (point-min))
81 (set-buffer-modified-p nil
))))
83 (defun describe-key-briefly (key)
84 "Print the name of the function KEY invokes. KEY is a string."
85 (interactive "kDescribe key briefly: ")
86 (let ((defn (key-binding key
)))
87 (if (or (null defn
) (integerp defn
))
88 (message "%s is undefined" (key-description key
))
89 (message "%s runs the command %s"
91 (if (symbolp defn
) defn
(prin1-to-string defn
))))))
93 (defun print-help-return-message (&optional function
)
94 "Display or return message saying how to restore windows after help command.
95 Computes a message and applies the optional argument FUNCTION to it.
96 If FUNCTION is nil, applies `message' to it, thus printing it."
97 (and (not (get-buffer-window standard-output
))
98 (funcall (or function
'message
)
100 (substitute-command-keys
103 "Type \\[delete-other-windows] to remove help window."
104 "Type \\[switch-to-buffer] RET to remove help window.")
105 "Type \\[switch-to-buffer-other-window] RET to restore the other window."))
106 (substitute-command-keys
107 " \\[scroll-other-window] to scroll the help.")))))
109 (defun describe-key (key)
110 "Display documentation of the function invoked by KEY. KEY is a string."
111 (interactive "kDescribe key: ")
112 (let ((defn (key-binding key
)))
113 (if (or (null defn
) (integerp defn
))
114 (message "%s is undefined" (key-description key
))
115 (with-output-to-temp-buffer "*Help*"
118 (if (documentation defn
)
119 (princ (documentation defn
))
120 (princ "not documented"))
121 (print-help-return-message)))))
123 (defun describe-mode (&optional minor
)
124 "Display documentation of current major mode.
125 If optional MINOR is non-nil (or prefix argument is given if interactive),
126 display documentation of active minor modes as well.
127 For this to work correctly for a minor mode, the mode's indicator variable
128 (listed in `minor-mode-alist') must also be a function whose documentation
129 describes the minor mode."
131 (with-output-to-temp-buffer "*Help*"
134 (princ (documentation major-mode
))
135 (let ((minor-modes minor-mode-alist
)
136 (locals (buffer-local-variables)))
138 (let* ((minor-mode (car (car minor-modes
)))
139 (indicator (car (cdr (car minor-modes
))))
140 (local-binding (assq minor-mode locals
)))
141 ;; Document a minor mode if it is listed in minor-mode-alist,
142 ;; bound locally in this buffer, non-nil, and has a function
144 (if (and local-binding
146 (fboundp minor-mode
))
148 (princ (format "\n\n\n%s minor mode (indicator%s):\n"
149 minor-mode indicator
))
150 (princ (documentation minor-mode
)))))
151 (setq minor-modes
(cdr minor-modes
))))
152 (print-help-return-message)))
154 ;; So keyboard macro definitions are documented correctly
155 (fset 'defining-kbd-macro
(symbol-function 'start-kbd-macro
))
157 (defun describe-distribution ()
158 "Display info on how to obtain the latest version of GNU Emacs."
161 (expand-file-name "DISTRIB" data-directory
)))
163 (defun describe-copying ()
164 "Display info on how you may redistribute copies of GNU Emacs."
167 (expand-file-name "COPYING" data-directory
))
168 (goto-char (point-min)))
170 (defun describe-no-warranty ()
171 "Display info on all the kinds of warranty Emacs does NOT have."
174 (let (case-fold-search)
175 (search-forward "NO WARRANTY")
178 (defun view-emacs-news ()
179 "Display info on recent changes to Emacs."
181 (find-file-read-only (expand-file-name "NEWS" data-directory
)))
183 (defun view-lossage ()
184 "Display last 100 input keystrokes."
186 (with-output-to-temp-buffer "*Help*"
187 (princ (key-description (recent-keys)))
189 (set-buffer standard-output
)
190 (goto-char (point-min))
191 (while (progn (move-to-column 50) (not (eobp)))
192 (search-forward " " nil t
)
194 (print-help-return-message)))
196 (defun help-for-help ()
197 "You have typed C-h, the help character. Type a Help option:
199 A command-apropos. Give a substring, and see a list of commands
200 (functions interactively callable) that contain
201 that substring. See also the apropos command.
202 B describe-bindings. Display table of all key bindings.
203 C describe-key-briefly. Type a command key sequence;
204 it prints the function name that sequence runs.
205 F describe-function. Type a function name and get documentation of it.
206 I info. The info documentation reader.
207 K describe-key. Type a command key sequence;
208 it displays the full documentation.
209 L view-lossage. Shows last 100 characters you typed.
210 M describe-mode. Print documentation of current major mode,
211 which describes the commands peculiar to it.
212 N view-emacs-news. Shows emacs news file.
213 S describe-syntax. Display contents of syntax table, plus explanations
214 T help-with-tutorial. Select the Emacs learn-by-doing tutorial.
215 V describe-variable. Type name of a variable;
216 it displays the variable's documentation and value.
217 W where-is. Type command name; it prints which keystrokes
219 C-c print Emacs copying permission (General Public License).
220 C-d print Emacs ordering information.
221 C-n print news of recent Emacs changes.
222 C-w print information on absence of warranty for GNU Emacs."
225 "A B C F I K L M N S T V W C-c C-d C-n C-w. Type C-h again for more help: ")
226 (let ((char (read-char)))
227 (if (or (= char ?\C-h
) (= char ??
))
228 (save-window-excursion
229 (switch-to-buffer "*Help*")
230 (delete-other-windows)
232 (insert (documentation 'help-for-help
))
233 (goto-char (point-min))
234 (while (memq char
'(?\C-h ?? ?\C-v ?\ ?
\177 ?\M-v
))
235 (if (memq char
'(?\C-v ?\
))
237 (if (memq char
'(?
\177 ?\M-v
))
239 (message "A B C F I K L M N S T V W C-c C-d C-n C-w%s: "
240 (if (pos-visible-in-window-p (point-max))
241 "" " or Space to scroll"))
242 (let ((cursor-in-echo-area t
))
243 (setq char
(read-char))))))
244 (let ((defn (cdr (assq (downcase char
) (cdr help-map
)))))
245 (if defn
(call-interactively defn
) (ding)))))
248 ;; Return a function which is called by the list containing point.
249 ;; If that gives no function, return a function whose name is around point.
250 ;; If that doesn't give a function, return nil.
251 (defun function-called-at-point ()
252 (or (condition-case ()
255 (narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
259 (setq obj
(read (current-buffer)))
260 (and (symbolp obj
) (fboundp obj
) obj
))))
265 (skip-chars-forward "'")
266 (let ((obj (read (current-buffer))))
267 (and (symbolp obj
) (fboundp obj
) obj
)))
270 (defun describe-function (function)
271 "Display the full documentation of FUNCTION (a symbol)."
273 (let ((fn (function-called-at-point))
274 (enable-recursive-minibuffers t
)
276 (setq val
(completing-read (if fn
277 (format "Describe function (default %s): " fn
)
278 "Describe function: ")
280 (list (if (equal val
"")
282 (with-output-to-temp-buffer "*Help*"
285 (let* ((def (symbol-function function
))
286 (beg (if (commandp def
) "an interactive " "a ")))
287 (princ (cond ((stringp def
) "a keyboard macro.")
289 (concat beg
"built-in function."))
290 ((compiled-function-p def
)
291 (concat beg
"compiled Lisp function."))
293 (format "alias for `%s'." def
))
294 ((eq (car-safe def
) 'lambda
)
295 (concat beg
"Lisp function."))
296 ((eq (car-safe def
) 'macro
)
298 ((eq (car-safe def
) 'mocklisp
)
299 "a mocklisp function.")
300 ((eq (car-safe def
) 'autoload
)
301 (format "%sLisp %s to autoload from `%s'."
303 (if (nth 4 def
) "macro" "function")
307 (if (documentation function
)
308 (princ (documentation function
))
309 (princ "not documented"))
310 (print-help-return-message)
311 ;; Return the text we displayed.
312 (save-excursion (set-buffer standard-output
) (buffer-string))))
314 (defun variable-at-point ()
318 (skip-chars-forward "'")
319 (let ((obj (read (current-buffer))))
320 (and (symbolp obj
) (boundp obj
) obj
)))
323 (defun describe-variable (variable)
324 "Display the full documentation of VARIABLE (a symbol).
325 Returns the documentation as a string, also."
327 (let ((v (variable-at-point))
328 (enable-recursive-minibuffers t
)
330 (setq val
(completing-read (if v
331 (format "Describe variable (default %s): " v
)
332 "Describe variable: ")
334 (list (if (equal val
"")
336 (with-output-to-temp-buffer "*Help*"
338 (princ "'s value is ")
339 (if (not (boundp variable
))
341 (prin1 (symbol-value variable
)))
343 (princ "Documentation:")
345 (let ((doc (documentation-property variable
'variable-documentation
)))
347 (princ (substitute-command-keys doc
))
348 (princ "not documented as a variable.")))
349 (print-help-return-message)
350 ;; Return the text we displayed.
351 (save-excursion (set-buffer standard-output
) (buffer-string))))
353 (defun command-apropos (string)
354 "Like apropos but lists only symbols that are names of commands
355 \(interactively callable functions). Argument REGEXP is a regular expression
356 that is matched against command symbol names. Returns list of symbols and
357 documentation found."
358 (interactive "sCommand apropos (regexp): ")
360 (let ((standard-output (get-buffer-create "*Help*")))
361 (print-help-return-message 'identity
))))
362 (apropos string
'commandp
)
363 (and message
(message message
))))
365 (defun locate-library (library &optional nosuffix
)
366 "Show the full path name of Emacs library LIBRARY.
367 This command searches the directories in `load-path' like `M-x load-library'
368 to find the file that `M-x load-library RET LIBRARY RET' would load.
369 Optional second arg NOSUFFIX non-nil means don't add suffixes `.elc' or `.el'
370 to the specified name LIBRARY (a la calling `load' instead of `load-library')."
371 (interactive "sLocate library: ")
377 (let ((try (expand-file-name (concat library suf
) dir
)))
378 (and (file-readable-p try
)
379 (null (file-directory-p try
))
381 (message "Library is file %s" try
)
382 (throw 'answer try
)))))
383 (if nosuffix
'("") '(".elc" ".el" ""))))
385 (message "No library %s in search path" library
)
388 ;;; help.el ends here