1 ;;; help.el --- help commands for Emacs
3 ;; Copyright (C) 1985, 1986, 1993 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-macro
))
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")
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 ;; If this key seq ends with a down event, discard the
105 ;; following click or drag event. Otherwise that would
106 ;; erase the message.
107 (let ((type (aref key
(1- (length key
)))))
108 (if (listp type
) (setq type
(car type
)))
110 (memq 'down
(event-modifiers type
))
112 (let ((defn (key-binding key
)))
113 (if (or (null defn
) (integerp defn
))
114 (message "%s is undefined" (key-description key
))
115 (message "%s runs the command %s"
116 (key-description key
)
117 (if (symbolp defn
) defn
(prin1-to-string defn
))))))
119 (defun print-help-return-message (&optional function
)
120 "Display or return message saying how to restore windows after help command.
121 Computes a message and applies the optional argument FUNCTION to it.
122 If FUNCTION is nil, applies `message' to it, thus printing it."
123 (and (not (get-buffer-window standard-output
))
124 (funcall (or function
'message
)
126 (substitute-command-keys
129 "Type \\[delete-other-windows] to remove help window."
130 "Type \\[switch-to-buffer] RET to remove help window.")
131 "Type \\[switch-to-buffer-other-window] RET to restore the other window."))
132 (substitute-command-keys
133 " \\[scroll-other-window] to scroll the help.")))))
135 (defun describe-key (key)
136 "Display documentation of the function invoked by KEY. KEY is a string."
137 (interactive "kDescribe key: ")
138 ;; If this key seq ends with a down event, discard the
139 ;; following click or drag event. Otherwise that would
140 ;; erase the message.
141 (let ((type (aref key
(1- (length key
)))))
142 (if (listp type
) (setq type
(car type
)))
144 (memq 'down
(event-modifiers type
))
146 (let ((defn (key-binding key
)))
147 (if (or (null defn
) (integerp defn
))
148 (message "%s is undefined" (key-description key
))
149 (with-output-to-temp-buffer "*Help*"
152 (if (documentation defn
)
153 (princ (documentation defn
))
154 (princ "not documented"))
155 (print-help-return-message)))))
157 (defun describe-mode (&optional minor
)
158 "Display documentation of current major mode.
159 If optional MINOR is non-nil (or prefix argument is given if interactive),
160 display documentation of active minor modes as well.
161 For this to work correctly for a minor mode, the mode's indicator variable
162 \(listed in `minor-mode-alist') must also be a function whose documentation
163 describes the minor mode."
165 (with-output-to-temp-buffer "*Help*"
168 (princ (documentation major-mode
))
169 (let ((minor-modes minor-mode-alist
)
170 (locals (buffer-local-variables)))
172 (let* ((minor-mode (car (car minor-modes
)))
173 (indicator (car (cdr (car minor-modes
))))
174 (local-binding (assq minor-mode locals
)))
175 ;; Document a minor mode if it is listed in minor-mode-alist,
176 ;; bound locally in this buffer, non-nil, and has a function
178 (if (and local-binding
180 (fboundp minor-mode
))
182 (princ (format "\n\n\n%s minor mode (indicator%s):\n"
183 minor-mode indicator
))
184 (princ (documentation minor-mode
)))))
185 (setq minor-modes
(cdr minor-modes
))))
186 (print-help-return-message)))
188 ;; So keyboard macro definitions are documented correctly
189 (fset 'defining-kbd-macro
(symbol-function 'start-kbd-macro
))
191 (defun describe-distribution ()
192 "Display info on how to obtain the latest version of GNU Emacs."
195 (expand-file-name "DISTRIB" data-directory
)))
197 (defun describe-copying ()
198 "Display info on how you may redistribute copies of GNU Emacs."
201 (expand-file-name "COPYING" data-directory
))
202 (goto-char (point-min)))
204 (defun describe-no-warranty ()
205 "Display info on all the kinds of warranty Emacs does NOT have."
208 (let (case-fold-search)
209 (search-forward "NO WARRANTY")
212 (defun describe-prefix-bindings ()
213 "Describe the bindings of the prefix used to reach this command.
214 The prefix described consists of all but the last event
215 of the key sequence that ran this command."
217 (let* ((key (this-command-keys))
218 (prefix (make-vector (1- (length key
)) nil
))
221 (while (< i
(length prefix
))
222 (aset prefix i
(aref key i
))
224 (describe-bindings prefix
)))
225 ;; Make C-h after a prefix, when not specifically bound,
226 ;; run describe-prefix-bindings.
227 (setq prefix-help-command
'describe-prefix-bindings
)
229 (defun view-emacs-news ()
230 "Display info on recent changes to Emacs."
232 (find-file-read-only (expand-file-name "NEWS" data-directory
)))
234 (defun view-lossage ()
235 "Display last 100 input keystrokes."
237 (with-output-to-temp-buffer "*Help*"
238 (princ (key-description (recent-keys)))
240 (set-buffer standard-output
)
241 (goto-char (point-min))
242 (while (progn (move-to-column 50) (not (eobp)))
243 (search-forward " " nil t
)
245 (print-help-return-message)))
247 (make-help-screen help-for-help
248 "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: "
249 "You have typed \\[help-for-help], the help character. Type a Help option:
251 a command-apropos. Give a substring, and see a list of commands
252 (functions interactively callable) that contain
253 that substring. See also the apropos command.
254 b describe-bindings. Display table of all key bindings.
255 c describe-key-briefly. Type a command key sequence;
256 it prints the function name that sequence runs.
257 f describe-function. Type a function name and get documentation of it.
258 i info. The info documentation reader.
259 k describe-key. Type a command key sequence;
260 it displays the full documentation.
261 l view-lossage. Shows last 100 characters you typed.
262 m describe-mode. Print documentation of current major mode,
263 which describes the commands peculiar to it.
264 n view-emacs-news. Shows emacs news file.
265 p finder-by-keyword. Find packages matching a given topic keyword.
266 s describe-syntax. Display contents of syntax table, plus explanations
267 t help-with-tutorial. Select the Emacs learn-by-doing tutorial.
268 v describe-variable. Type name of a variable;
269 it displays the variable's documentation and value.
270 w where-is. Type command name; it prints which keystrokes
272 C-c print Emacs copying permission (General Public License).
273 C-d print Emacs ordering information.
274 C-n print news of recent Emacs changes.
275 C-w print information on absence of warranty for GNU Emacs."
278 ;; Return a function which is called by the list containing point.
279 ;; If that gives no function, return a function whose name is around point.
280 ;; If that doesn't give a function, return nil.
281 (defun function-called-at-point ()
282 (or (condition-case ()
285 (narrow-to-region (max (point-min) (- (point) 1000)) (point-max))
289 (setq obj
(read (current-buffer)))
290 (and (symbolp obj
) (fboundp obj
) obj
))))
295 (skip-chars-forward "'")
296 (let ((obj (read (current-buffer))))
297 (and (symbolp obj
) (fboundp obj
) obj
)))
300 (defun describe-function (function)
301 "Display the full documentation of FUNCTION (a symbol)."
303 (let ((fn (function-called-at-point))
304 (enable-recursive-minibuffers t
)
306 (setq val
(completing-read (if fn
307 (format "Describe function (default %s): " fn
)
308 "Describe function: ")
310 (list (if (equal val
"")
312 (with-output-to-temp-buffer "*Help*"
315 (let* ((def (symbol-function function
))
316 (beg (if (commandp def
) "an interactive " "a ")))
317 (princ (cond ((or (stringp def
)
321 (concat beg
"built-in function."))
322 ((byte-code-function-p def
)
323 (concat beg
"compiled Lisp function."))
325 (format "alias for `%s'." def
))
326 ((eq (car-safe def
) 'lambda
)
327 (concat beg
"Lisp function."))
328 ((eq (car-safe def
) 'macro
)
330 ((eq (car-safe def
) 'mocklisp
)
331 "a mocklisp function.")
332 ((eq (car-safe def
) 'autoload
)
333 (format "%s autoloaded Lisp %s."
334 (if (commandp def
) "an interactive" "an")
335 (if (nth 4 def
) "macro" "function")
336 ;;; Including the file name made this line too long.
341 (let ((arglist (cond ((byte-code-function-p def
)
342 (car (append def nil
)))
343 ((eq (car-safe def
) 'lambda
)
348 (princ (cons function
349 (mapcar (lambda (arg)
350 (if (memq arg
'(&optional
&rest
))
352 (intern (upcase (symbol-name arg
)))))
355 (if (documentation function
)
357 (princ (documentation function
)))
358 (princ "not documented"))
360 (print-help-return-message)
361 ;; Return the text we displayed.
362 (save-excursion (set-buffer standard-output
) (buffer-string))))
364 (defun variable-at-point ()
368 (skip-chars-forward "'")
369 (let ((obj (read (current-buffer))))
370 (and (symbolp obj
) (boundp obj
) obj
)))
373 (defun describe-variable (variable)
374 "Display the full documentation of VARIABLE (a symbol).
375 Returns the documentation as a string, also."
377 (let ((v (variable-at-point))
378 (enable-recursive-minibuffers t
)
380 (setq val
(completing-read (if v
381 (format "Describe variable (default %s): " v
)
382 "Describe variable: ")
384 (list (if (equal val
"")
386 (with-output-to-temp-buffer "*Help*"
388 (princ "'s value is ")
389 (if (not (boundp variable
))
391 (prin1 (symbol-value variable
)))
393 (princ "Documentation:")
395 (let ((doc (documentation-property variable
'variable-documentation
)))
397 (princ (substitute-command-keys doc
))
398 (princ "not documented as a variable.")))
399 (print-help-return-message)
400 ;; Return the text we displayed.
401 (save-excursion (set-buffer standard-output
) (buffer-string))))
403 (defun command-apropos (string)
404 "Like apropos but lists only symbols that are names of commands
405 \(interactively callable functions). Argument REGEXP is a regular expression
406 that is matched against command symbol names. Returns list of symbols and
407 documentation found."
408 (interactive "sCommand apropos (regexp): ")
410 (let ((standard-output (get-buffer-create "*Help*")))
411 (print-help-return-message 'identity
))))
412 (if (apropos string t
'commandp
)
413 (and message
(message message
)))))
415 (defun locate-library (library &optional nosuffix
)
416 "Show the full path name of Emacs library LIBRARY.
417 This command searches the directories in `load-path' like `M-x load-library'
418 to find the file that `M-x load-library RET LIBRARY RET' would load.
419 Optional second arg NOSUFFIX non-nil means don't add suffixes `.elc' or `.el'
420 to the specified name LIBRARY (a la calling `load' instead of `load-library')."
421 (interactive "sLocate library: ")
427 (let ((try (expand-file-name (concat library suf
) dir
)))
428 (and (file-readable-p try
)
429 (null (file-directory-p try
))
431 (message "Library is file %s" try
)
432 (throw 'answer try
)))))
433 (if nosuffix
'("") '(".elc" ".el" ""))))
435 (message "No library %s in search path" library
)
438 ;;; help.el ends here