1 ;;; help-fns.el --- Complex help functions
3 ;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001
4 ;; Free Software Foundation, Inc.
7 ;; Keywords: help, internal
9 ;; This file is part of GNU Emacs.
11 ;; GNU Emacs is free software; you can redistribute it and/or modify
12 ;; it under the terms of the GNU General Public License as published by
13 ;; the Free Software Foundation; either version 2, or (at your option)
16 ;; GNU Emacs is distributed in the hope that it will be useful,
17 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
18 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 ;; GNU General Public License for more details.
21 ;; You should have received a copy of the GNU General Public License
22 ;; along with GNU Emacs; see the file COPYING. If not, write to the
23 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
24 ;; Boston, MA 02111-1307, USA.
28 ;; This file contains those help commands which are complicated, and
29 ;; which may not be used in every session. For example
30 ;; `describe-function' will probably be heavily used when doing elisp
31 ;; programming, but not if just editing C files. Simpler help commands
40 (defun help-with-tutorial (&optional arg)
41 "Select the Emacs learn-by-doing tutorial.
42 If there is a tutorial version written in the language
43 of the selected language environment, that version is used.
44 If there's no tutorial in that language, `TUTORIAL' is selected.
45 With arg, you are asked to choose which language."
48 (read-language-name 'tutorial "Language: " "English")
49 (if (get-language-info current-language-environment 'tutorial)
50 current-language-environment
53 (setq filename (get-language-info lang 'tutorial))
54 (setq file (expand-file-name (concat "~/" filename)))
55 (delete-other-windows)
56 (if (get-file-buffer file)
57 (switch-to-buffer (get-file-buffer file))
58 (switch-to-buffer (create-file-buffer file))
59 (setq buffer-file-name file)
60 (setq default-directory (expand-file-name "~/"))
61 (setq buffer-auto-save-file-name nil)
62 (insert-file-contents (expand-file-name filename data-directory))
63 (goto-char (point-min))
64 (search-forward "\n<<")
66 (delete-region (point) (progn (end-of-line) (point)))
67 (let ((n (- (window-height (selected-window))
68 (count-lines (point-min) (point))
72 ;; Some people get confused by the large gap.
74 (insert "[Middle of page left blank for didactic purposes. "
75 "Text continues below]")
76 (newline (- n (/ n 2)))))
77 (goto-char (point-min))
78 (set-buffer-modified-p nil))))
81 (defun locate-library (library &optional nosuffix path interactive-call)
82 "Show the precise file name of Emacs library LIBRARY.
83 This command searches the directories in `load-path' like `M-x load-library'
84 to find the file that `M-x load-library RET LIBRARY RET' would load.
85 Optional second arg NOSUFFIX non-nil means don't add suffixes `load-suffixes'
86 to the specified name LIBRARY.
88 If the optional third arg PATH is specified, that list of directories
89 is used instead of `load-path'.
91 When called from a program, the file name is normaly returned as a
92 string. When run interactively, the argument INTERACTIVE-CALL is t,
93 and the file name is displayed in the echo area."
94 (interactive (list (read-string "Locate library: ")
98 (dolist (dir (or path load-path))
99 (dolist (suf (append (unless nosuffix load-suffixes) '("")))
100 (let ((try (expand-file-name (concat library suf) dir)))
101 (and (file-readable-p try)
102 (null (file-directory-p try))
105 (message "Library is file %s" (abbreviate-file-name try)))
106 (throw 'answer try))))))
108 (message "No library %s in search path" library))
115 (defun describe-function (function)
116 "Display the full documentation of FUNCTION (a symbol)."
118 (let ((fn (function-called-at-point))
119 (enable-recursive-minibuffers t)
121 (setq val (completing-read (if fn
122 (format "Describe function (default %s): " fn)
123 "Describe function: ")
124 obarray 'fboundp t nil nil (symbol-name fn)))
125 (list (if (equal val "")
128 (message "You didn't specify a function")
129 (help-setup-xref (list #'describe-function function) (interactive-p))
131 (with-output-to-temp-buffer (help-buffer)
133 ;; Use " is " instead of a colon so that
134 ;; it is easier to get out the function name using forward-sexp.
136 (describe-function-1 function)
137 (print-help-return-message)
138 (with-current-buffer standard-output
139 ;; Return the text we displayed.
143 (defun describe-function-1 (function)
144 (let* ((def (if (symbolp function)
145 (symbol-function function)
148 (beg (if (commandp def) "an interactive " "a ")))
150 (cond ((or (stringp def)
154 (if (eq 'unevalled (cdr (subr-arity def)))
155 (concat beg "special form")
156 (concat beg "built-in function")))
157 ((byte-code-function-p def)
158 (concat beg "compiled Lisp function"))
160 (while (symbolp (symbol-function def))
161 (setq def (symbol-function def)))
162 (format "an alias for `%s'" def))
163 ((eq (car-safe def) 'lambda)
164 (concat beg "Lisp function"))
165 ((eq (car-safe def) 'macro)
167 ((eq (car-safe def) 'autoload)
168 (setq file-name (nth 1 def))
169 (format "%s autoloaded %s"
170 (if (commandp def) "an interactive" "an")
171 (if (eq (nth 4 def) 'keymap) "keymap"
172 (if (nth 4 def) "Lisp macro" "Lisp function"))
174 ;; perhaps use keymapp here instead
175 ((eq (car-safe def) 'keymap)
177 (elts (cdr-safe def)))
179 (if (char-table-p (car-safe elts))
182 (setq elts (cdr-safe elts)))
188 (with-current-buffer standard-output
191 (if (re-search-backward "alias for `\\([^`']+\\)'" nil t)
192 (help-xref-button 1 'help-function def)))))
194 (setq file-name (symbol-file function)))
198 ;; We used to add .el to the file name,
199 ;; but that's completely wrong when the user used load-file.
202 ;; Make a hyperlink to the library.
203 (with-current-buffer standard-output
205 (re-search-backward "`\\([^`']+\\)'" nil t)
206 (help-xref-button 1 'help-function-def function file-name)))))
209 (when (commandp function)
210 (let* ((binding (and (symbolp function) (commandp function)
211 (key-binding function nil t)))
212 (remapped (and (symbolp binding) (commandp binding) binding))
213 (keys (where-is-internal
214 (or remapped function) overriding-local-map nil nil)))
216 (princ "It is remapped to `")
217 (princ (symbol-name remapped))
220 (princ (if remapped " which is bound to " "It is bound to "))
221 ;; FIXME: This list can be very long (f.ex. for self-insert-command).
222 (princ (mapconcat 'key-description keys ", ")))
223 (when (or remapped keys)
226 ;; Handle symbols aliased to other symbols.
227 (setq def (indirect-function def))
228 ;; If definition is a macro, find the function inside it.
229 (if (eq (car-safe def) 'macro)
230 (setq def (cdr def)))
231 (let ((arglist (cond ((byte-code-function-p def)
232 (car (append def nil)))
233 ((eq (car-safe def) 'lambda)
235 ((and (eq (car-safe def) 'autoload)
236 (not (eq (nth 4 def) 'keymap)))
237 (concat "[Arg list not available until "
238 "function definition is loaded.]"))
240 (cond ((listp arglist)
241 (princ (cons (if (symbolp function) function "anonymous")
242 (mapcar (lambda (arg)
243 (if (memq arg '(&optional &rest))
245 (intern (upcase (symbol-name arg)))))
251 (let ((doc (documentation function)))
256 (with-current-buffer standard-output
258 ;; Builtins get the calling sequence at the end of
259 ;; the doc string. Move it to the same place as
260 ;; for other functions.
262 ;; In cases where `function' has been fset to a
263 ;; subr we can't search for function's name in
264 ;; the doc string. Kluge round that using the
265 ;; printed representation. The arg list then
266 ;; shows the wrong function name, but that
267 ;; might be a useful hint.
268 (let* ((rep (prin1-to-string def))
270 (string-match " \\([^ ]+\\)>$" rep)
271 (match-string 1 rep))))
272 (if (looking-at (format "(%s[ )]" (regexp-quote name)))
273 (let ((start (point-marker)))
274 (goto-char (point-min))
276 (insert-buffer-substring (current-buffer) start)
278 (delete-region (1- start) (point-max)))
279 (goto-char (point-min))
282 "[Missing arglist. Please make a bug report.]\n")))
283 (goto-char (point-max)))))
284 (princ "not documented")))))
290 (defun variable-at-point ()
291 "Return the bound variable symbol found around point.
292 Return 0 if there is no such symbol."
294 (with-syntax-table emacs-lisp-mode-syntax-table
296 (or (not (zerop (skip-syntax-backward "_w")))
297 (eq (char-syntax (following-char)) ?w)
298 (eq (char-syntax (following-char)) ?_)
300 (skip-chars-forward "'")
301 (let ((obj (read (current-buffer))))
302 (or (and (symbolp obj) (boundp obj) obj)
307 (defun describe-variable (variable &optional buffer)
308 "Display the full documentation of VARIABLE (a symbol).
309 Returns the documentation as a string, also.
310 If VARIABLE has a buffer-local value in BUFFER (default to the current buffer),
311 it is displayed along with the global value."
313 (let ((v (variable-at-point))
314 (enable-recursive-minibuffers t)
316 (setq val (completing-read (if (symbolp v)
318 "Describe variable (default %s): " v)
319 "Describe variable: ")
320 obarray 'boundp t nil nil
321 (if (symbolp v) (symbol-name v))))
322 (list (if (equal val "")
324 (unless (bufferp buffer) (setq buffer (current-buffer)))
325 (if (not (symbolp variable))
326 (message "You did not specify a variable")
329 (help-setup-xref (list #'describe-variable variable buffer)
331 (with-output-to-temp-buffer (help-buffer)
332 (with-current-buffer buffer
334 (if (not (boundp variable))
338 (let ((val (symbol-value variable)))
339 (with-current-buffer standard-output
340 (princ "'s value is ")
342 (let ((from (point)))
344 (help-xref-on-pp from (point))
345 (if (< (point) (+ from 20))
348 (delete-char -1)))))))
350 (when (local-variable-p variable)
351 (princ (format "Local in buffer %s; " (buffer-name)))
352 (if (not (default-boundp variable))
353 (princ "globally void")
354 (let ((val (default-value variable)))
355 (with-current-buffer standard-output
356 (princ "global value is ")
358 ;; Fixme: pp can take an age if you happen to
359 ;; ask for a very large expression. We should
360 ;; probably print it raw once and check it's a
361 ;; sensible size before prettyprinting. -- fx
362 (let ((from (point)))
364 (help-xref-on-pp from (point))
365 (if (< (point) (+ from 20))
368 (delete-char -1)))))))
371 (with-current-buffer standard-output
372 (when (> (count-lines (point-min) (point-max)) 10)
373 ;; Note that setting the syntax table like below
374 ;; makes forward-sexp move over a `'s' at the end
376 (set-syntax-table emacs-lisp-mode-syntax-table)
377 (goto-char (point-min))
381 (delete-region (point) (progn (end-of-line) (point)))
382 (insert " value is shown below.\n\n")
384 (insert "\n\nValue:"))))
385 ;; Add a note for variables that have been make-var-buffer-local.
386 (when (and (local-variable-if-set-p variable)
387 (or (not (local-variable-p variable))
389 (local-variable-if-set-p variable))))
392 (insert "Automatically becomes buffer-local when set in any fashion.\n"))))
393 (princ "Documentation:")
395 (let ((doc (documentation-property variable 'variable-documentation)))
396 (princ (or doc "not documented as a variable.")))
398 ;; Make a link to customize if this variable can be customized.
399 ;; Note, it is not reliable to test only for a custom-type property
400 ;; because those are only present after the var's definition
402 (if (or (get variable 'custom-type) ; after defcustom
403 (get variable 'custom-loads) ; from loaddefs.el
404 (get variable 'standard-value)) ; from cus-start.el
405 (let ((customize-label "customize"))
408 (princ (concat "You can " customize-label " this variable."))
409 (with-current-buffer standard-output
412 (concat "\\(" customize-label "\\)") nil t)
413 (help-xref-button 1 'help-customize-variable variable)))))
414 ;; Make a hyperlink to the library if appropriate. (Don't
415 ;; change the format of the buffer's initial line in case
416 ;; anything expects the current format.)
417 (let ((file-name (symbol-file variable)))
418 (when (equal file-name "loaddefs.el")
419 ;; Find the real def site of the preloaded variable.
422 (find-variable-noselect variable file-name)
425 (with-current-buffer (car location)
426 (goto-char (cdr location))
427 (when (re-search-backward
428 "^;;; Generated autoloads from \\(.*\\)" nil t)
429 (setq file-name (match-string 1)))))))
431 (princ "\n\nDefined in `")
434 (with-current-buffer standard-output
436 (re-search-backward "`\\([^`']+\\)'" nil t)
437 (help-xref-button 1 'help-variable-def
438 variable file-name)))))
440 (print-help-return-message)
442 (set-buffer standard-output)
443 ;; Return the text we displayed.
444 (buffer-string))))))))
448 (defun describe-syntax (&optional buffer)
449 "Describe the syntax specifications in the syntax table of BUFFER.
450 The descriptions are inserted in a help buffer, which is then displayed.
451 BUFFER defaults to the current buffer."
453 (setq buffer (or buffer (current-buffer)))
454 (help-setup-xref (list #'describe-syntax buffer) (interactive-p))
455 (with-output-to-temp-buffer (help-buffer)
456 (let ((table (with-current-buffer buffer (syntax-table))))
457 (with-current-buffer standard-output
458 (describe-vector table 'internal-describe-syntax-value)
459 (while (setq table (char-table-parent table))
460 (insert "\nThe parent syntax table is:")
461 (describe-vector table 'internal-describe-syntax-value))))))
463 (defun help-describe-category-set (value)
465 ((null value) "default")
466 ((char-table-p value) "deeper char-table ...")
467 (t (condition-case err
468 (category-set-mnemonics value)
469 (error "invalid"))))))
472 (defun describe-categories (&optional buffer)
473 "Describe the category specifications in the current category table.
474 The descriptions are inserted in a buffer, which is then displayed."
476 (setq buffer (or buffer (current-buffer)))
477 (help-setup-xref (list #'describe-categories buffer) (interactive-p))
478 (with-output-to-temp-buffer (help-buffer)
479 (let ((table (with-current-buffer buffer (category-table))))
480 (with-current-buffer standard-output
481 (describe-vector table 'help-describe-category-set)
482 (let ((docs (char-table-extra-slot table 0)))
483 (if (or (not (vectorp docs)) (/= (length docs) 95))
484 (insert "Invalid first extra slot in this char table\n")
485 (insert "Meanings of mnemonic characters are:\n")
487 (let ((elt (aref docs i)))
489 (insert (+ i ?\ ) ": " elt "\n"))))
490 (while (setq table (char-table-parent table))
491 (insert "\nThe parent category table is:")
492 (describe-vector table 'help-describe-category-set))))))))
496 ;;; help-fns.el ends here