1 ;;; help-fns.el --- Complex help functions
3 ;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001, 2002,
4 ;; 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
5 ;; Free Software Foundation, Inc.
8 ;; Keywords: help, internal
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software: you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation, either version 3 of the License, or
15 ;; (at your option) any later version.
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
27 ;; This file contains those help commands which are complicated, and
28 ;; which may not be used in every session. For example
29 ;; `describe-function' will probably be heavily used when doing elisp
30 ;; programming, but not if just editing C files. Simpler help commands
38 (defun describe-function (function)
39 "Display the full documentation of FUNCTION (a symbol)."
41 (let ((fn (function-called-at-point))
42 (enable-recursive-minibuffers t)
44 (setq val (completing-read (if fn
45 (format "Describe function (default %s): " fn)
46 "Describe function: ")
47 obarray 'fboundp t nil nil
48 (and fn (symbol-name fn))))
49 (list (if (equal val "")
52 (message "You didn't specify a function")
53 (help-setup-xref (list #'describe-function function)
54 (called-interactively-p 'interactive))
56 (with-help-window (help-buffer)
58 ;; Use " is " instead of a colon so that
59 ;; it is easier to get out the function name using forward-sexp.
61 (describe-function-1 function)
62 (with-current-buffer standard-output
63 ;; Return the text we displayed.
66 (defun help-split-fundoc (docstring def)
67 "Split a function DOCSTRING into the actual doc and the usage info.
68 Return (USAGE . DOC) or nil if there's no usage info.
69 DEF is the function whose usage we're looking for in DOCSTRING."
70 ;; Functions can get the calling sequence at the end of the doc string.
71 ;; In cases where `function' has been fset to a subr we can't search for
72 ;; function's name in the doc string so we use `fn' as the anonymous
73 ;; function name instead.
74 (when (and docstring (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring))
76 ;; Replace `fn' with the actual function name.
77 (if (consp def) "anonymous" def)
78 (match-string 1 docstring))
79 (substring docstring 0 (match-beginning 0)))))
81 (defun help-add-fundoc-usage (docstring arglist)
82 "Add the usage info to DOCSTRING.
83 If DOCSTRING already has a usage info, then just return it unchanged.
84 The usage info is built from ARGLIST. DOCSTRING can be nil.
85 ARGLIST can also be t or a string of the form \"(FUN ARG1 ARG2 ...)\"."
86 (unless (stringp docstring) (setq docstring "Not documented"))
87 (if (or (string-match "\n\n(fn\\(\\( .*\\)?)\\)\\'" docstring) (eq arglist t))
90 (if (string-match "\n?\n\\'" docstring)
91 (if (< (- (match-end 0) (match-beginning 0)) 2) "\n" "")
93 (if (and (stringp arglist)
94 (string-match "\\`([^ ]+\\(.*\\))\\'" arglist))
95 (concat "(fn" (match-string 1 arglist) ")")
96 (format "%S" (help-make-usage 'fn arglist))))))
98 (defun help-function-arglist (def)
99 ;; Handle symbols aliased to other symbols.
100 (if (and (symbolp def) (fboundp def)) (setq def (indirect-function def)))
101 ;; If definition is a macro, find the function inside it.
102 (if (eq (car-safe def) 'macro) (setq def (cdr def)))
103 ;; and do the same for interpreted closures
104 (if (eq (car-safe def) 'closure) (setq def (cddr def)))
106 ((byte-code-function-p def) (aref def 0))
107 ((eq (car-safe def) 'lambda) (nth 1 def))
108 ((and (eq (car-safe def) 'autoload) (not (eq (nth 4 def) 'keymap)))
109 "[Arg list not available until function definition is loaded.]")
112 (defun help-make-usage (function arglist)
113 (cons (if (symbolp function) function 'anonymous)
114 (mapcar (lambda (arg)
115 (if (not (symbolp arg))
116 (if (and (consp arg) (symbolp (car arg)))
117 ;; CL style default values for optional args.
118 (cons (intern (upcase (symbol-name (car arg))))
121 (let ((name (symbol-name arg)))
122 (if (string-match "\\`&" name) arg
123 (intern (upcase name))))))
126 ;; Could be this, if we make symbol-file do the work below.
127 ;; (defun help-C-file-name (subr-or-var kind)
128 ;; "Return the name of the C file where SUBR-OR-VAR is defined.
129 ;; KIND should be `var' for a variable or `subr' for a subroutine."
130 ;; (symbol-file (if (symbolp subr-or-var) subr-or-var
131 ;; (subr-name subr-or-var))
132 ;; (if (eq kind 'var) 'defvar 'defun)))
134 (defun help-C-file-name (subr-or-var kind)
135 "Return the name of the C file where SUBR-OR-VAR is defined.
136 KIND should be `var' for a variable or `subr' for a subroutine."
137 (let ((docbuf (get-buffer-create " *DOC*"))
138 (name (if (eq 'var kind)
139 (concat "V" (symbol-name subr-or-var))
140 (concat "F" (subr-name subr-or-var)))))
141 (with-current-buffer docbuf
142 (goto-char (point-min))
144 (insert-file-contents-literally
145 (expand-file-name internal-doc-file-name doc-directory)))
146 (let ((file (catch 'loop
148 (let ((pnt (search-forward (concat "
\1f" name "\n"))))
149 (re-search-backward "
\1fS\\(.*\\)")
150 (let ((file (match-string 1)))
151 (if (member file build-files)
153 (goto-char pnt))))))))
154 (if (string-match "^ns.*\\(\\.o\\|obj\\)\\'" file)
155 (setq file (replace-match ".m" t t file 1))
156 (if (string-match "\\.\\(o\\|obj\\)\\'" file)
157 (setq file (replace-match ".c" t t file))))
158 (if (string-match "\\.\\(c\\|m\\)\\'" file)
162 (defcustom help-downcase-arguments nil
163 "If non-nil, argument names in *Help* buffers are downcased."
168 (defun help-highlight-arg (arg)
169 "Highlight ARG as an argument name for a *Help* buffer.
170 Return ARG in face `help-argument-name'; ARG is also downcased
171 if the variable `help-downcase-arguments' is non-nil."
172 (propertize (if help-downcase-arguments (downcase arg) arg)
173 'face 'help-argument-name))
175 (defun help-do-arg-highlight (doc args)
176 (with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
177 (modify-syntax-entry ?\- "w")
178 (dolist (arg args doc)
179 (setq doc (replace-regexp-in-string
180 ;; This is heuristic, but covers all common cases
182 (concat "\\<" ; beginning of word
183 "\\(?:[a-z-]*-\\)?" ; for xxx-ARG
187 "\\(?:es\\|s\\|th\\)?" ; for ARGth, ARGs
188 "\\(?:-[a-z0-9-]+\\)?" ; for ARG-xxx, ARG-n
189 "\\(?:-[{([<`\"].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x'
191 (help-highlight-arg arg)
194 (defun help-highlight-arguments (usage doc &rest args)
195 (when (and usage (string-match "^(" usage))
198 (goto-char (point-min))
199 (let ((case-fold-search nil)
200 (next (not (or args (looking-at "\\["))))
202 ;; Make a list of all arguments
203 (skip-chars-forward "^ ")
205 (or opt (not (looking-at " &")) (setq opt t))
206 (if (not (re-search-forward " \\([\\[(]*\\)\\([^] &)\.]+\\)" nil t))
208 (setq args (cons (match-string 2) args))
209 (when (and opt (string= (match-string 1) "("))
210 ;; A pesky CL-style optional argument with default value,
211 ;; so let's skip over it
212 (search-backward "(")
213 (goto-char (scan-sexps (point) 1)))))
214 ;; Highlight aguments in the USAGE string
215 (setq usage (help-do-arg-highlight (buffer-string) args))
216 ;; Highlight arguments in the DOC string
217 (setq doc (and doc (help-do-arg-highlight doc args))))))
218 ;; Return value is like the one from help-split-fundoc, but highlighted
221 ;; The following function was compiled from the former functions
222 ;; `describe-simplify-lib-file-name' and `find-source-lisp-file' with
223 ;; some excerpts from `describe-function-1' and `describe-variable'.
224 ;; The only additional twists provided are (1) locate the defining file
225 ;; for autoloaded functions, and (2) give preference to files in the
226 ;; "install directory" (directories found via `load-path') rather than
227 ;; to files in the "compile directory" (directories found by searching
228 ;; the loaddefs.el file). We autoload it because it's also used by
229 ;; `describe-face' (instead of `describe-simplify-lib-file-name').
232 (defun find-lisp-object-file-name (object type)
233 "Guess the file that defined the Lisp object OBJECT, of type TYPE.
234 OBJECT should be a symbol associated with a function, variable, or face;
235 alternatively, it can be a function definition.
236 If TYPE is `defvar', search for a variable definition.
237 If TYPE is `defface', search for a face definition.
238 If TYPE is the value returned by `symbol-function' for a function symbol,
239 search for a function definition.
241 The return value is the absolute name of a readable file where OBJECT is
242 defined. If several such files exist, preference is given to a file
243 found via `load-path'. The return value can also be `C-source', which
244 means that OBJECT is a function or variable defined in C. If no
245 suitable file is found, return nil."
246 (let* ((autoloaded (eq (car-safe type) 'autoload))
247 (file-name (or (and autoloaded (nth 1 type))
249 object (if (memq type (list 'defvar 'defface))
254 ;; An autoloaded function: Locate the file since `symbol-function'
255 ;; has only returned a bare string here.
257 (locate-file file-name load-path '(".el" ".elc") 'readable)))
258 ((and (stringp file-name)
259 (string-match "[.]*loaddefs.el\\'" file-name))
260 ;; An autoloaded variable or face. Visit loaddefs.el in a buffer
261 ;; and try to extract the defining file. The following form is
262 ;; from `describe-function-1' and `describe-variable'.
265 (find-function-search-for-symbol object nil file-name)
268 (with-current-buffer (car location)
269 (goto-char (cdr location))
270 (when (re-search-backward
271 "^;;; Generated autoloads from \\(.*\\)" nil t)
274 (file-name-sans-extension
275 (match-string-no-properties 1))
276 load-path '(".el" ".elc") 'readable))))))))
279 ((and (not file-name) (subrp type))
280 ;; A built-in function. The form is from `describe-function-1'.
281 (if (get-buffer " *DOC*")
282 (help-C-file-name type 'subr)
284 ((and (not file-name) (symbolp object)
285 (integerp (get object 'variable-documentation)))
286 ;; A variable defined in C. The form is from `describe-variable'.
287 (if (get-buffer " *DOC*")
288 (help-C-file-name object 'var)
290 ((not (stringp file-name))
291 ;; If we don't have a file-name string by now, we lost.
294 (if (string-match "[.]elc\\'" file-name)
295 (substring-no-properties file-name 0 -1)
297 ;; When the Elisp source file can be found in the install
298 ;; directory return the name of that file - `file-name' should
299 ;; have become an absolute file name ny now.
300 (or (and (file-readable-p lib-name) lib-name)
301 ;; The library might be compressed.
302 (and (file-readable-p (concat lib-name ".gz")) lib-name))))
303 ((let* ((lib-name (file-name-nondirectory file-name))
304 ;; The next form is from `describe-simplify-lib-file-name'.
306 ;; Try converting the absolute file name to a library
307 ;; name, convert that back to a file name and see if we
308 ;; get the original one. If so, they are equivalent.
309 (if (equal file-name (locate-file lib-name load-path '("")))
310 (if (string-match "[.]elc\\'" lib-name)
311 (substring-no-properties lib-name 0 -1)
314 ;; The next three forms are from `find-source-lisp-file'.
315 (elc-file (locate-file
317 (if (string-match "\\.el\\'" file-name)
320 load-path nil 'readable))
323 (insert-file-contents-literally elc-file nil 0 256)
326 (string-match ";;; from file \\(.*\\.el\\)" str)
327 (match-string 1 str))))
328 (and src-file (file-readable-p src-file) src-file))))))
330 (declare-function ad-get-advice-info "advice" (function))
333 (defun describe-function-1 (function)
334 (let* ((advised (and (symbolp function) (featurep 'advice)
335 (ad-get-advice-info function)))
336 ;; If the function is advised, use the symbol that has the
337 ;; real definition, if that symbol is already set up.
340 (let ((origname (cdr (assq 'origname advised))))
341 (and (fboundp origname) origname)))
343 ;; Get the real definition.
344 (def (if (symbolp real-function)
345 (symbol-function real-function)
348 (beg (if (commandp def) "an interactive " "a "))
349 (pt1 (with-current-buffer (help-buffer) (point)))
352 (cond ((or (stringp def) (vectorp def))
355 (if (eq 'unevalled (cdr (subr-arity def)))
356 (concat beg "special form")
357 (concat beg "built-in function")))
358 ((byte-code-function-p def)
359 (concat beg "compiled Lisp function"))
360 ((and (funvecp def) (eq (aref def 0) 'curry))
361 (if (symbolp (aref def 1))
362 (format "a curried function calling `%s'" (aref def 1))
363 "a curried function"))
365 (format "a function-vector (funvec) of type `%s'"
368 (while (and (fboundp def)
369 (symbolp (symbol-function def)))
370 (setq def (symbol-function def)))
371 ;; Handle (defalias 'foo 'bar), where bar is undefined.
372 (or (fboundp def) (setq errtype 'alias))
373 (format "an alias for `%s'" def))
374 ((eq (car-safe def) 'lambda)
375 (concat beg "Lisp function"))
376 ((eq (car-safe def) 'macro)
378 ((eq (car-safe def) 'closure)
379 (concat beg "Lisp closure"))
380 ((eq (car-safe def) 'autoload)
381 (format "%s autoloaded %s"
382 (if (commandp def) "an interactive" "an")
383 (if (eq (nth 4 def) 'keymap) "keymap"
384 (if (nth 4 def) "Lisp macro" "Lisp function"))))
387 (elts (cdr-safe def)))
389 (if (char-table-p (car-safe elts))
392 (setq elts (cdr-safe elts)))
398 (if (eq errtype 'alias)
399 (princ ",\nwhich is not defined. Please make a bug report.")
400 (with-current-buffer standard-output
403 (when (re-search-backward "alias for `\\([^`']+\\)'" nil t)
404 (help-xref-button 1 'help-function def)))))
406 (setq file-name (find-lisp-object-file-name function def))
409 ;; We used to add .el to the file name,
410 ;; but that's completely wrong when the user used load-file.
411 (princ (if (eq file-name 'C-source)
413 (file-name-nondirectory file-name)))
415 ;; Make a hyperlink to the library.
416 (with-current-buffer standard-output
418 (re-search-backward "`\\([^`']+\\)'" nil t)
419 (help-xref-button 1 'help-function-def function file-name))))
421 (with-current-buffer (help-buffer)
422 (fill-region-as-paragraph (save-excursion (goto-char pt1) (forward-line 0) (point))
425 (when (commandp function)
426 (let ((pt2 (with-current-buffer (help-buffer) (point)))
427 (remapped (command-remapping function)))
428 (unless (memq remapped '(ignore undefined))
429 (let ((keys (where-is-internal
430 (or remapped function) overriding-local-map nil nil))
432 (if (and (eq function 'self-insert-command)
433 (vectorp (car-safe keys))
434 (consp (aref (car keys) 0)))
435 (princ "It is bound to many ordinary text characters.\n")
436 ;; Which non-control non-meta keys run this command?
438 (if (member (event-modifiers (aref key 0)) '(nil (shift)))
439 (push key non-modified-keys)))
441 (princ "It is remapped to `")
442 (princ (symbol-name remapped))
446 (princ (if remapped ", which is bound to " "It is bound to "))
447 ;; If lots of ordinary text characters run this command,
448 ;; don't mention them one by one.
449 (if (< (length non-modified-keys) 10)
450 (princ (mapconcat 'key-description keys ", "))
451 (dolist (key non-modified-keys)
452 (setq keys (delq key keys)))
455 (princ (mapconcat 'key-description keys ", "))
456 (princ ", and many ordinary text characters"))
457 (princ "many ordinary text characters"))))
458 (when (or remapped keys non-modified-keys)
462 (with-current-buffer (help-buffer)
463 (fill-region-as-paragraph pt2 (point))
464 (unless (looking-back "\n\n")
466 ;; Note that list* etc do not get this property until
467 ;; cl-hack-byte-compiler runs, after bytecomp is loaded.
468 (when (and (symbolp function)
469 (eq (get function 'byte-compile)
470 'cl-byte-compile-compiler-macro))
471 (princ "This function has a compiler macro")
472 (let ((lib (get function 'compiler-macro-file)))
474 (princ (format " in `%s'" lib))
475 (with-current-buffer standard-output
477 (re-search-backward "`\\([^`']+\\)'" nil t)
478 (help-xref-button 1 'help-function-cmacro function lib)))))
480 (let* ((advertised (gethash def advertised-signature-table t))
481 (arglist (if (listp advertised)
482 advertised (help-function-arglist def)))
483 (doc (documentation function))
484 (usage (help-split-fundoc doc function)))
485 (with-current-buffer standard-output
486 ;; If definition is a keymap, skip arglist note.
487 (unless (keymapp function)
488 (if usage (setq doc (cdr usage)))
490 ((and usage (not (listp advertised))) (car usage))
492 (format "%S" (help-make-usage function arglist)))
493 ((stringp arglist) arglist)
494 ;; Maybe the arglist is in the docstring of a symbol
495 ;; this one is aliased to.
496 ((let ((fun real-function))
497 (while (and (symbolp fun)
498 (setq fun (symbol-function fun))
499 (not (setq usage (help-split-fundoc
506 (format "\nMacro: %s" (format-kbd-macro def)))
507 ((and (funvecp def) (eq (aref def 0) 'curry))
508 ;; Describe a curried-function's function and args
510 (mapconcat (lambda (arg)
511 (setq slot (1+ slot))
515 (format " Function: %S" arg))
517 (format "Argument %d: %S"
522 (t "[Missing arglist. Please make a bug report.]")))
523 (high (help-highlight-arguments use doc)))
524 (let ((fill-begin (point)))
525 (insert (car high) "\n")
526 (fill-region fill-begin (point))))
527 (setq doc (cdr high))))
528 (let* ((obsolete (and
529 ;; function might be a lambda construct.
531 (get function 'byte-obsolete-info)))
532 (use (car obsolete)))
534 (princ "\nThis function is obsolete")
535 (when (nth 2 obsolete)
536 (insert (format " since %s" (nth 2 obsolete))))
537 (insert (cond ((stringp use) (concat ";\n" use))
538 (use (format ";\nuse `%s' instead." use))
542 (or doc "Not documented.")))))))
548 (defun variable-at-point (&optional any-symbol)
549 "Return the bound variable symbol found at or before point.
550 Return 0 if there is no such symbol.
551 If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
552 (with-syntax-table emacs-lisp-mode-syntax-table
553 (or (condition-case ()
555 (or (not (zerop (skip-syntax-backward "_w")))
556 (eq (char-syntax (following-char)) ?w)
557 (eq (char-syntax (following-char)) ?_)
559 (skip-chars-forward "'")
560 (let ((obj (read (current-buffer))))
561 (and (symbolp obj) (boundp obj) obj)))
563 (let* ((str (find-tag-default))
564 (sym (if str (intern-soft str))))
565 (if (and sym (or any-symbol (boundp sym)))
568 (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
569 (setq sym (intern-soft (match-string 1 str)))
570 (and (or any-symbol (boundp sym)) sym)))))
573 (defun describe-variable-custom-version-info (variable)
574 (let ((custom-version (get variable 'custom-version))
575 (cpv (get variable 'custom-package-version))
579 (format "This variable was introduced, or its default value was changed, in\nversion %s of Emacs.\n"
582 (let* ((package (car-safe cpv))
583 (version (if (listp (cdr-safe cpv))
586 (pkg-versions (assq package customize-package-emacs-version-alist))
587 (emacsv (cdr (assoc version pkg-versions))))
588 (if (and package version)
590 (format (concat "This variable was introduced, or its default value was changed, in\nversion %s of the %s package"
592 (format " that is part of Emacs %s" emacsv))
594 version package))))))
598 (defun describe-variable (variable &optional buffer frame)
599 "Display the full documentation of VARIABLE (a symbol).
600 Returns the documentation as a string, also.
601 If VARIABLE has a buffer-local value in BUFFER or FRAME
602 \(default to the current buffer and current frame),
603 it is displayed along with the global value."
605 (let ((v (variable-at-point))
606 (enable-recursive-minibuffers t)
608 (setq val (completing-read (if (symbolp v)
610 "Describe variable (default %s): " v)
611 "Describe variable: ")
615 (get vv 'variable-documentation)))
617 (if (symbolp v) (symbol-name v))))
618 (list (if (equal val "")
621 (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
622 (unless (frame-live-p frame) (setq frame (selected-frame)))
623 (if (not (symbolp variable))
624 (message "You did not specify a variable")
626 (let ((valvoid (not (with-current-buffer buffer (boundp variable))))
627 val val-start-pos locus)
628 ;; Extract the value before setting up the output buffer,
629 ;; in case `buffer' *is* the output buffer.
631 (with-selected-frame frame
632 (with-current-buffer buffer
633 (setq val (symbol-value variable)
634 locus (variable-binding-locus variable)))))
635 (help-setup-xref (list #'describe-variable variable buffer)
636 (called-interactively-p 'interactive))
637 (with-help-window (help-buffer)
638 (with-current-buffer buffer
640 (setq file-name (find-lisp-object-file-name variable 'defvar))
644 (princ " is a variable defined in `")
645 (princ (if (eq file-name 'C-source)
647 (file-name-nondirectory file-name)))
649 (with-current-buffer standard-output
651 (re-search-backward "`\\([^`']+\\)'" nil t)
652 (help-xref-button 1 'help-variable-def
653 variable file-name)))
655 (princ "It is void as a variable.")
658 (princ " is void as a variable.")
662 (with-current-buffer standard-output
663 (setq val-start-pos (point))
666 (let ((from (point)))
668 ;; Hyperlinks in variable's value are quite frequently
669 ;; inappropriate e.g C-h v <RET> features <RET>
670 ;; (help-xref-on-pp from (point))
671 (if (< (point) (+ from 20))
672 (delete-region (1- from) from)))))
677 (princ (format "%socal in buffer %s; "
678 (if (get variable 'permanent-local)
681 (princ (format "It is a frame-local variable; ")))
682 (if (not (default-boundp variable))
683 (princ "globally void")
684 (let ((val (default-value variable)))
685 (with-current-buffer standard-output
686 (princ "global value is ")
688 ;; Fixme: pp can take an age if you happen to
689 ;; ask for a very large expression. We should
690 ;; probably print it raw once and check it's a
691 ;; sensible size before prettyprinting. -- fx
692 (let ((from (point)))
694 ;; See previous comment for this function.
695 ;; (help-xref-on-pp from (point))
696 (if (< (point) (+ from 20))
697 (delete-region (1- from) from))))))
700 ;; If the value is large, move it to the end.
701 (with-current-buffer standard-output
702 (when (> (count-lines (point-min) (point-max)) 10)
703 ;; Note that setting the syntax table like below
704 ;; makes forward-sexp move over a `'s' at the end
706 (set-syntax-table emacs-lisp-mode-syntax-table)
707 (goto-char val-start-pos)
708 ;; The line below previously read as
709 ;; (delete-region (point) (progn (end-of-line) (point)))
710 ;; which suppressed display of the buffer local value for
712 (when (looking-at "value is") (replace-match ""))
714 (insert "\n\nValue:")
715 (set (make-local-variable 'help-button-cache)
717 (insert "value is shown ")
718 (insert-button "below"
719 'action help-button-cache
721 'help-echo "mouse-2, RET: show value")
725 (let* ((alias (condition-case nil
726 (indirect-variable variable)
728 (obsolete (get variable 'byte-obsolete-variable))
730 (safe-var (get variable 'safe-local-variable))
731 (doc (or (documentation-property variable 'variable-documentation)
732 (documentation-property alias 'variable-documentation)))
734 ;; Add a note for variables that have been make-var-buffer-local.
735 (when (and (local-variable-if-set-p variable)
736 (or (not (local-variable-p variable))
738 (local-variable-if-set-p variable))))
740 (princ " Automatically becomes buffer-local when set in any fashion.\n"))
742 ;; Mention if it's an alias
743 (unless (eq alias variable)
745 (princ (format " This variable is an alias for `%s'.\n" alias)))
749 (princ " This variable is obsolete")
750 (if (cdr obsolete) (princ (format " since %s" (cdr obsolete))))
751 (princ (cond ((stringp use) (concat ";\n " use))
752 (use (format ";\n use `%s' instead." (car obsolete)))
756 (when (member (cons variable val) file-local-variables-alist)
758 (if (member (cons variable val) dir-local-variables-alist)
759 (let ((file (and (buffer-file-name)
760 (not (file-remote-p (buffer-file-name)))
761 (dir-locals-find-file (buffer-file-name)))))
762 (princ " This variable is a directory local variable")
764 (princ (concat "\n from the file \""
770 (princ " This variable is a file local variable.\n")))
772 (when (memq variable ignored-local-variables)
774 (princ " This variable is ignored when used as a file local \
777 ;; Can be both risky and safe, eg auto-fill-function.
778 (when (risky-local-variable-p variable)
780 (princ " This variable is potentially risky when used as a \
781 file local variable.\n")
782 (when (assq variable safe-local-variable-values)
783 (princ " However, you have added it to \
784 `safe-local-variable-values'.\n")))
788 (princ " This variable is safe as a file local variable ")
789 (princ "if its value\n satisfies the predicate ")
790 (princ (if (byte-code-function-p safe-var)
791 "which is byte-compiled expression.\n"
792 (format "`%s'.\n" safe-var))))
794 (if extra-line (terpri))
795 (princ "Documentation:\n")
796 (with-current-buffer standard-output
797 (insert (or doc "Not documented as a variable."))))
799 ;; Make a link to customize if this variable can be customized.
800 (when (custom-variable-p variable)
801 (let ((customize-label "customize"))
804 (princ (concat "You can " customize-label " this variable."))
805 (with-current-buffer standard-output
808 (concat "\\(" customize-label "\\)") nil t)
809 (help-xref-button 1 'help-customize-variable variable))))
810 ;; Note variable's version or package version
811 (let ((output (describe-variable-custom-version-info variable)))
817 (with-current-buffer standard-output
818 ;; Return the text we displayed.
819 (buffer-string))))))))
823 (defun describe-syntax (&optional buffer)
824 "Describe the syntax specifications in the syntax table of BUFFER.
825 The descriptions are inserted in a help buffer, which is then displayed.
826 BUFFER defaults to the current buffer."
828 (setq buffer (or buffer (current-buffer)))
829 (help-setup-xref (list #'describe-syntax buffer)
830 (called-interactively-p 'interactive))
831 (with-help-window (help-buffer)
832 (let ((table (with-current-buffer buffer (syntax-table))))
833 (with-current-buffer standard-output
834 (describe-vector table 'internal-describe-syntax-value)
835 (while (setq table (char-table-parent table))
836 (insert "\nThe parent syntax table is:")
837 (describe-vector table 'internal-describe-syntax-value))))))
839 (defun help-describe-category-set (value)
841 ((null value) "default")
842 ((char-table-p value) "deeper char-table ...")
843 (t (condition-case err
844 (category-set-mnemonics value)
845 (error "invalid"))))))
848 (defun describe-categories (&optional buffer)
849 "Describe the category specifications in the current category table.
850 The descriptions are inserted in a buffer, which is then displayed.
851 If BUFFER is non-nil, then describe BUFFER's category table instead.
852 BUFFER should be a buffer or a buffer name."
854 (setq buffer (or buffer (current-buffer)))
855 (help-setup-xref (list #'describe-categories buffer)
856 (called-interactively-p 'interactive))
857 (with-help-window (help-buffer)
858 (let* ((table (with-current-buffer buffer (category-table)))
859 (docs (char-table-extra-slot table 0)))
860 (if (or (not (vectorp docs)) (/= (length docs) 95))
861 (error "Invalid first extra slot in this category table\n"))
862 (with-current-buffer standard-output
863 (insert "Legend of category mnemonics (see the tail for the longer description)\n")
864 (let ((pos (point)) (items 0) lines n)
866 (if (aref docs i) (setq items (1+ items))))
867 (setq lines (1+ (/ (1- items) 4)))
870 (let ((elt (aref docs i)))
872 (string-match ".*" elt)
873 (setq elt (match-string 0 elt))
874 (if (>= (length elt) 17)
875 (setq elt (concat (substring elt 0 14) "...")))
876 (if (< (point) (point-max))
877 (move-to-column (* 20 (/ n lines)) t))
878 (insert (+ i ?\s) ?: elt)
879 (if (< (point) (point-max))
883 (if (= (% n lines) 0)
885 (goto-char (point-max))
887 "character(s)\tcategory mnemonics\n"
888 "------------\t------------------")
889 (describe-vector table 'help-describe-category-set)
890 (insert "Legend of category mnemonics:\n")
892 (let ((elt (aref docs i)))
894 (if (string-match "\n" elt)
895 (setq elt (substring elt (match-end 0))))
896 (insert (+ i ?\s) ": " elt "\n"))))
897 (while (setq table (char-table-parent table))
898 (insert "\nThe parent category table is:")
899 (describe-vector table 'help-describe-category-set))))))
903 ;; arch-tag: 9e10331c-ae81-4d13-965d-c4819aaab0b3
904 ;;; help-fns.el ends here