;;; help.el --- help commands for Emacs
;; Copyright (C) 1985, 1986, 1993, 1994, 1998, 1999, 2000, 2001, 2002,
-;; 2003, 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+;; 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.
;; Maintainer: FSF
;; Keywords: help, internal
;; This file is part of GNU Emacs.
-;; GNU Emacs is free software; you can redistribute it and/or modify
+;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation; either version 3, or (at your option)
-;; any later version.
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
-;; along with GNU Emacs; see the file COPYING. If not, write to the
-;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
-;; Boston, MA 02110-1301, USA.
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
(add-hook 'temp-buffer-setup-hook 'help-mode-setup)
(add-hook 'temp-buffer-show-hook 'help-mode-finish)
+;; The variable `help-window' below is used by `help-mode-finish' to
+;; communicate the window displaying help (the "help window") to the
+;; macro `with-help-window'. The latter sets `help-window' to t before
+;; invoking `with-output-to-temp-buffer'. If and only if `help-window'
+;; is eq to t, `help-mode-finish' (called by `temp-buffer-setup-hook')
+;; sets `help-window' to the window selected by `display-buffer'.
+;; Exiting `with-help-window' and calling `help-print-return-message'
+;; reset `help-window' to nil.
+(defvar help-window nil
+ "Window chosen for displaying help.")
+
+;; `help-window-point-marker' is a marker you can move to a valid
+;; position of the buffer shown in the help window in order to override
+;; the standard positioning mechanism (`point-min') chosen by
+;; `with-output-to-temp-buffer'. `with-help-window' has this point
+;; nowhere before exiting. Currently used by `view-lossage' to assert
+;; that the last keystrokes are always visible.
+(defvar help-window-point-marker (make-marker)
+ "Marker to override default `window-point' of `help-window'.")
+
(defvar help-map
(let ((map (make-sparse-keymap)))
(define-key map (char-to-string help-char) 'help-for-help)
(define-key map "\C-a" 'about-emacs)
(define-key map "\C-c" 'describe-copying)
- (define-key map "\C-d" 'describe-distribution)
- (define-key map "\C-e" 'view-emacs-problems)
+ (define-key map "\C-d" 'view-emacs-debugging)
+ (define-key map "\C-e" 'view-external-packages)
(define-key map "\C-f" 'view-emacs-FAQ)
(define-key map "\C-m" 'view-order-manuals)
(define-key map "\C-n" 'view-emacs-news)
- (define-key map "\C-p" 'describe-project)
- (define-key map "\C-t" 'view-todo)
+ (define-key map "\C-o" 'describe-distribution)
+ (define-key map "\C-p" 'view-emacs-problems)
+ (define-key map "\C-t" 'view-emacs-todo)
(define-key map "\C-w" 'describe-no-warranty)
;; This does not fit the pattern, but it is natural given the C-\ command.
(define-key map "d" 'apropos-documentation)
(define-key map "e" 'view-echo-area-messages)
(define-key map "f" 'describe-function)
+ (define-key map "g" 'describe-gnu-project)
(define-key map "h" 'view-hello-file)
(define-key map "i" 'info)
(WINDOW . quit-window) do quit-window, then select WINDOW.
(WINDOW BUF START POINT) display BUF at START, POINT, then select WINDOW.")
-(defun print-help-return-message (&optional function)
+(define-obsolete-function-alias 'print-help-return-message 'help-print-return-message "23.2")
+(defun help-print-return-message (&optional function)
"Display or return message saying how to restore windows after help command.
This function assumes that `standard-output' is the help buffer.
It computes a message, and applies the optional argument FUNCTION to it.
If FUNCTION is nil, it applies `message', thus displaying the message.
In addition, this function sets up `help-return-method', which see, that
specifies what to do when the user exits the help buffer."
+ ;; Reset `help-window' here to avoid confusing `help-mode-finish'.
+ (setq help-window nil)
(and (not (get-buffer-window standard-output))
(let ((first-message
(cond ((or
(defalias 'help-for-help 'help-for-help-internal)
;; It can't find this, but nobody will look.
(make-help-screen help-for-help-internal
- "a b c C e f F i I k C-k l L m p r s t v w C-c C-d C-f C-n C-p C-t C-w . or ? :"
+ (purecopy "Type a help option: [abcCdefFgiIkKlLmnprstvw.] C-[cdefmnoptw] or ?")
+ ;; Don't purecopy this one, because it's not evaluated (it's
+ ;; directly used as a docstring in a function definition, so it'll
+ ;; be moved to the DOC file anyway: no need for purecopying it).
"You have typed %THIS-KEY%, the help character. Type a Help option:
\(Use SPC or DEL to scroll through this text. Type \\<help-map>\\[help-quit] to exit the Help command.)
-a command-apropos. Type a list of words or a regexp; it shows a list of
- commands whose names match. See also the apropos command.
-b describe-bindings. Display a table of all key bindings.
-c describe-key-briefly. Type a key sequence;
- it displays the command name run by that key sequence.
-C describe-coding-system. Type the name of the coding system to describe,
- or just RET to describe the ones currently in use.
-d apropos-documentation. Type a pattern (a list of words or a regexp), and
- it shows a list of functions, variables, and other items whose
- documentation matches that pattern. See also the apropos command.
-e view-echo-area-messages. Go to the buffer that logs echo-area messages.
-f describe-function. Type a function name and you see its documentation.
-F Info-goto-emacs-command-node. Type a command name;
- it goes to the on-line manual's section that describes the command.
-h Display the HELLO file which illustrates various scripts.
-i info. The Info documentation reader: read on-line manuals.
-I describe-input-method. Describe a specific input method (if you type
- its name) or the current input method (if you type just RET).
-k describe-key. Type a key sequence;
- it displays the full documentation for that key sequence.
-K Info-goto-emacs-key-command-node. Type a key sequence;
- it goes to the on-line manual's section that describes
- the command bound to that key.
-l view-lossage. Show last 100 characters you typed.
-L describe-language-environment. This describes either a
- specific language environment (if you type its name)
- or the current language environment (if you type just RET).
-m describe-mode. Display documentation of current minor modes,
- and the current major mode, including their special commands.
-n view-emacs-news. Display news of recent Emacs changes.
-p finder-by-keyword. Find packages matching a given topic keyword.
-r info-emacs-manual. Display the Emacs manual in Info mode.
-s describe-syntax. Display contents of syntax table, plus explanations.
-S info-lookup-symbol. Type a symbol; it goes to that symbol in the
- on-line manual for the programming language used in this buffer.
-t help-with-tutorial. Select the Emacs learn-by-doing tutorial.
-v describe-variable. Type name of a variable;
- it displays the variable's documentation and value.
-w where-is. Type a command name; it displays which keystrokes
- invoke that command.
-. display-local-help. Display any available local help at point
- in the echo area.
-
-C-a Display information about Emacs.
-C-c Display Emacs copying permission (GNU General Public License).
-C-d Display Emacs ordering information.
-C-e Display info about Emacs problems.
-C-f Display the Emacs FAQ.
-C-m Display how to order printed Emacs manuals.
-C-n Display news of recent Emacs changes.
-C-p Display information about the GNU project.
-C-t Display the Emacs TODO list.
-C-w Display information on absence of warranty for GNU Emacs."
+a PATTERN Show commands whose name matches the PATTERN (a list of words
+ or a regexp). See also the `apropos' command.
+b Display all key bindings.
+c KEYS Display the command name run by the given key sequence.
+C CODING Describe the given coding system, or RET for current ones.
+d PATTERN Show a list of functions, variables, and other items whose
+ documentation matches the PATTERN (a list of words or a regexp).
+e Go to the *Messages* buffer which logs echo-area messages.
+f FUNCTION Display documentation for the given function.
+F COMMAND Show the on-line manual's section that describes the command.
+g Display information about the GNU project.
+h Display the HELLO file which illustrates various scripts.
+i Start the Info documentation reader: read on-line manuals.
+I METHOD Describe a specific input method, or RET for current.
+k KEYS Display the full documentation for the key sequence.
+K KEYS Show the on-line manual's section for the command bound to KEYS.
+l Show last 300 input keystrokes (lossage).
+L LANG-ENV Describes a specific language environment, or RET for current.
+m Display documentation of current minor modes and current major mode,
+ including their special commands.
+n Display news of recent Emacs changes.
+p TOPIC Find packages matching a given topic keyword.
+r Display the Emacs manual in Info mode.
+s Display contents of current syntax table, plus explanations.
+S SYMBOL Show the section for the given symbol in the on-line manual
+ for the programming language used in this buffer.
+t Start the Emacs learn-by-doing tutorial.
+v VARIABLE Display the given variable's documentation and value.
+w COMMAND Display which keystrokes invoke the given command (where-is).
+. Display any available local help at point in the echo area.
+
+C-a Information about Emacs.
+C-c Emacs copying permission (GNU General Public License).
+C-d Instructions for debugging GNU Emacs.
+C-e External packages and information about Emacs.
+C-f Emacs FAQ.
+C-m How to order printed Emacs manuals.
+C-n News of recent Emacs changes.
+C-o Emacs ordering and distribution information.
+C-p Info about known Emacs problems.
+C-t Emacs TODO list.
+C-w Information on absence of warranty for GNU Emacs."
help-map)
\f
(defun function-called-at-point ()
"Return a function around point or else called by the list containing point.
If that doesn't give a function, return nil."
- (or (with-syntax-table emacs-lisp-mode-syntax-table
- (or (condition-case ()
- (save-excursion
- (or (not (zerop (skip-syntax-backward "_w")))
- (eq (char-syntax (following-char)) ?w)
- (eq (char-syntax (following-char)) ?_)
- (forward-sexp -1))
- (skip-chars-forward "'")
- (let ((obj (read (current-buffer))))
- (and (symbolp obj) (fboundp obj) obj)))
- (error nil))
- (condition-case ()
- (save-excursion
- (save-restriction
- (narrow-to-region (max (point-min)
- (- (point) 1000)) (point-max))
- ;; Move up to surrounding paren, then after the open.
- (backward-up-list 1)
- (forward-char 1)
- ;; If there is space here, this is probably something
- ;; other than a real Lisp function call, so ignore it.
- (if (looking-at "[ \t]")
- (error "Probably not a Lisp function call"))
- (let ((obj (read (current-buffer))))
- (and (symbolp obj) (fboundp obj) obj))))
- (error nil))))
- (let* ((str (find-tag-default))
- (sym (if str (intern-soft str))))
- (if (and sym (fboundp sym))
- sym
- (save-match-data
- (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
- (setq sym (intern-soft (match-string 1 str)))
- (and (fboundp sym) sym)))))))
+ (with-syntax-table emacs-lisp-mode-syntax-table
+ (or (condition-case ()
+ (save-excursion
+ (or (not (zerop (skip-syntax-backward "_w")))
+ (eq (char-syntax (following-char)) ?w)
+ (eq (char-syntax (following-char)) ?_)
+ (forward-sexp -1))
+ (skip-chars-forward "'")
+ (let ((obj (read (current-buffer))))
+ (and (symbolp obj) (fboundp obj) obj)))
+ (error nil))
+ (condition-case ()
+ (save-excursion
+ (save-restriction
+ (narrow-to-region (max (point-min)
+ (- (point) 1000)) (point-max))
+ ;; Move up to surrounding paren, then after the open.
+ (backward-up-list 1)
+ (forward-char 1)
+ ;; If there is space here, this is probably something
+ ;; other than a real Lisp function call, so ignore it.
+ (if (looking-at "[ \t]")
+ (error "Probably not a Lisp function call"))
+ (let ((obj (read (current-buffer))))
+ (and (symbolp obj) (fboundp obj) obj))))
+ (error nil))
+ (let* ((str (find-tag-default))
+ (sym (if str (intern-soft str))))
+ (if (and sym (fboundp sym))
+ sym
+ (save-match-data
+ (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
+ (setq sym (intern-soft (match-string 1 str)))
+ (and (fboundp sym) sym))))))))
\f
;;; `User' help functions
+(defun view-help-file (file &optional dir)
+ (view-file (expand-file-name file (or dir data-directory)))
+ (goto-address-mode 1)
+ (goto-char (point-min)))
+
(defun describe-distribution ()
"Display info on how to obtain the latest version of GNU Emacs."
(interactive)
- (view-file (expand-file-name "DISTRIB" data-directory)))
+ (view-help-file "DISTRIB"))
(defun describe-copying ()
"Display info on how you may redistribute copies of GNU Emacs."
(interactive)
- (view-file (expand-file-name "COPYING" data-directory))
- (goto-char (point-min)))
+ (view-help-file "COPYING"))
-(defun describe-project ()
+(defun describe-gnu-project ()
"Display info on the GNU project."
(interactive)
- (view-file (expand-file-name "THE-GNU-PROJECT" data-directory))
- (goto-char (point-min)))
+ (view-help-file "THE-GNU-PROJECT"))
+
+(define-obsolete-function-alias 'describe-project 'describe-gnu-project "22.2")
(defun describe-no-warranty ()
"Display info on all the kinds of warranty Emacs does NOT have."
(interactive)
(describe-copying)
(let (case-fold-search)
- (search-forward "NO WARRANTY")
+ (search-forward "Disclaimer of Warranty")
+ (forward-line 0)
(recenter 0)))
(defun describe-prefix-bindings ()
(when (consp version)
(let* ((all-versions
(let (res)
- (mapcar
+ (mapc
(lambda (file)
(with-temp-buffer
(insert-file-contents
(beginning-of-line)
(point)))))))
-
-(defun view-todo (&optional arg)
+(defun view-emacs-todo (&optional arg)
"Display the Emacs TODO list."
(interactive "P")
- (view-file (expand-file-name "TODO" data-directory)))
+ (view-help-file "TODO"))
+
+(define-obsolete-function-alias 'view-todo 'view-emacs-todo "22.2")
+
(defun view-echo-area-messages ()
"View the log of recent echo-area messages: the `*Messages*' buffer.
(defun view-order-manuals ()
"Display the Emacs ORDERS file."
(interactive)
- (view-file (expand-file-name "ORDERS" data-directory))
- (goto-address))
+ (view-help-file "ORDERS"))
(defun view-emacs-FAQ ()
"Display the Emacs Frequently Asked Questions (FAQ) file."
(defun view-emacs-problems ()
"Display info on known problems with Emacs and possible workarounds."
(interactive)
- (view-file (expand-file-name "PROBLEMS" data-directory)))
+ (view-help-file "PROBLEMS"))
+
+(defun view-emacs-debugging ()
+ "Display info on how to debug Emacs problems."
+ (interactive)
+ (view-help-file "DEBUG"))
+
+(defun view-external-packages ()
+ "Display external packages and information about Emacs."
+ (interactive)
+ (view-help-file "MORE.STUFF"))
(defun view-lossage ()
- "Display last 100 input keystrokes.
+ "Display last 300 input keystrokes.
To record all your input on a file, use `open-dribble-file'."
(interactive)
- (help-setup-xref (list #'view-lossage) (interactive-p))
- (with-output-to-temp-buffer (help-buffer)
+ (help-setup-xref (list #'view-lossage)
+ (called-interactively-p 'interactive))
+ (with-help-window (help-buffer)
(princ (mapconcat (lambda (key)
(if (or (integerp key) (symbolp key) (listp key))
(single-key-description key)
(while (progn (move-to-column 50) (not (eobp)))
(when (search-forward " " nil t)
(delete-char -1))
- (insert "\n")))
- (print-help-return-message)))
+ (insert "\n"))
+ ;; jidanni wants to see the last keystrokes immediately.
+ (set-marker help-window-point-marker (point)))))
\f
;; Key bindings
or a buffer name."
(interactive)
(or buffer (setq buffer (current-buffer)))
- (help-setup-xref (list #'describe-bindings prefix buffer) (interactive-p))
+ (help-setup-xref (list #'describe-bindings prefix buffer)
+ (called-interactively-p 'interactive))
(with-current-buffer buffer
(describe-bindings-internal nil prefix)))
\(Ordinarily these are omitted from the output.)
The optional argument PREFIX, if non-nil, should be a key sequence;
then we display only bindings that start with that prefix."
- (interactive)
(let ((buf (current-buffer)))
- (with-output-to-temp-buffer "*Help*"
+ (with-help-window "*Help*"
(with-current-buffer standard-output
(describe-buffer-bindings buf prefix menus)))))
(if (or (null defn) (integerp defn) (equal defn 'undefined))
(message "%s%s is undefined"
(help-key-description key untranslated) mouse-msg)
- (help-setup-xref (list #'describe-function defn) (interactive-p))
+ (help-setup-xref (list #'describe-function defn)
+ (called-interactively-p 'interactive))
;; Don't bother user with strings from (e.g.) the select-paste menu.
(when (stringp (aref key (1- (length key))))
(aset key (1- (length key)) "(any string)"))
(setq sequence (vector up-event))
(aset sequence 0 'mouse-1)
(setq defn-up-tricky (key-binding sequence nil nil (event-start up-event))))))
- (with-output-to-temp-buffer (help-buffer)
+ (with-help-window (help-buffer)
(princ (help-key-description key untranslated))
(princ (format "\
-%s runs the command %S
- which is "
+%s runs the command %S, which is "
mouse-msg defn))
(describe-function-1 defn)
(when up-event
----------------- up-event %s----------------
-<%S>%s%s runs the command %S
- which is "
+%s%s%s runs the command %S, which is "
(if mouse-1-tricky "(short click) " "")
- ev-type mouse-msg
+ (key-description (vector up-event))
+ mouse-msg
(if mouse-1-remapped
- " is remapped to <mouse-2>\nwhich" "")
+ " is remapped to <mouse-2>, which" "")
defn-up))
(describe-function-1 defn-up))
(unless (or (null defn-up-tricky)
----------------- up-event (long click) ----------------
Pressing <%S>%s for longer than %d milli-seconds
-runs the command %S
- which is "
+runs the command %S, which is "
ev-type mouse-msg
mouse-1-click-follows-link
defn-up-tricky))
- (describe-function-1 defn-up-tricky)))
- (print-help-return-message)))))
+ (describe-function-1 defn-up-tricky)))))))
\f
(defun describe-mode (&optional buffer)
"Display documentation of current major mode and minor modes.
(interactive "@")
(unless buffer (setq buffer (current-buffer)))
(help-setup-xref (list #'describe-mode buffer)
- (interactive-p))
+ (called-interactively-p 'interactive))
;; For the sake of help-do-xref and help-xref-go-back,
;; don't switch buffers before calling `help-buffer'.
- (with-output-to-temp-buffer (help-buffer)
+ (with-help-window (help-buffer)
(with-current-buffer buffer
(let (minor-modes)
;; Older packages do not register in minor-mode-list but only in
(let ((mode mode-name))
(with-current-buffer standard-output
(let ((start (point)))
- (insert (format-mode-line mode))
+ (insert (format-mode-line mode nil nil buffer))
(add-text-properties start (point) '(face bold)))))
(princ " mode:\n")
- (princ (documentation major-mode)))
- (print-help-return-message))))
+ (princ (documentation major-mode)))))
+ ;; For the sake of IELM and maybe others
+ nil)
(defun describe-minor-mode (minor-mode)
temp-buffer-max-height))))
\f
+;;; help-window
+
+(defcustom help-window-select 'other
+ "Non-nil means select help window for viewing.
+Choices are:
+ never (nil) Select help window only if there is no other window
+ on its frame.
+ other Select help window unless the selected window is the
+ only other window on its frame.
+ always (t) Always select the help window.
+
+This option has effect if and only if the help window was created
+by `with-help-window'"
+ :type '(choice (const :tag "never (nil)" nil)
+ (const :tag "other" other)
+ (const :tag "always (t)" t))
+ :group 'help
+ :version "23.1")
+
+(defun help-window-display-message (quit-part window &optional other)
+ "Display message telling how to quit and scroll help window.
+QUIT-PART is a string telling how to quit the help window WINDOW.
+Optional argument OTHER non-nil means return text telling how to
+scroll the \"other\" window."
+ (let ((scroll-part
+ (cond
+ ((pos-visible-in-window-p
+ (with-current-buffer (window-buffer window)
+ (point-max)) window)
+ ;; Buffer end is visible.
+ ".")
+ (other ", \\[scroll-other-window] to scroll help.")
+ (t ", \\[scroll-up] to scroll help."))))
+ (message "%s"
+ (substitute-command-keys (concat quit-part scroll-part)))))
+
+(defun help-window-setup-finish (window &optional reuse keep-frame)
+ "Finish setting up help window WINDOW.
+Select WINDOW according to the value of `help-window-select'.
+Display message telling how to scroll and eventually quit WINDOW.
+
+Optional argument REUSE non-nil means WINDOW has been reused by
+`display-buffer'. Optional argument KEEP-FRAME non-nil means
+that quitting should not delete WINDOW's frame."
+ (let ((number-of-windows
+ (length (window-list (window-frame window) 'no-mini window))))
+ (cond
+ ((eq window (selected-window))
+ ;; The help window is the selected window, probably the
+ ;; `pop-up-windows' nil case.
+ (help-window-display-message
+ (if reuse
+ "Type \"q\" to restore this window"
+ ;; This should not be taken.
+ "Type \"q\" to quit") window))
+ ((= number-of-windows 1)
+ ;; The help window is alone on a frame and not the selected
+ ;; window, could be the `pop-up-frames' t case.
+ (help-window-display-message
+ (cond
+ (keep-frame "Type \"q\" to delete this window")
+ (reuse "Type \"q\" to restore this window")
+ (view-remove-frame-by-deleting "Type \"q\" to delete this frame")
+ (t "Type \"q\" to iconify this frame"))
+ window))
+ ((and (= number-of-windows 2)
+ (eq (window-frame window) (window-frame (selected-window))))
+ ;; There are two windows on the help window's frame and the other
+ ;; window is the selected one.
+ (if (memq help-window-select '(nil other))
+ ;; Do not select the help window.
+ (help-window-display-message
+ (if reuse
+ ;; Offer `display-buffer' for consistency with
+ ;; `help-print-return-message'. This is hardly TRT when
+ ;; the other window and the selected window display the
+ ;; same buffer but has been handled this way ever since.
+ "Type \\[display-buffer] RET to restore the other window"
+ ;; The classic "two windows" configuration.
+ "Type \\[delete-other-windows] to delete the help window")
+ window t)
+ ;; Select help window and tell how to quit.
+ (select-window window)
+ (help-window-display-message
+ (if reuse
+ "Type \"q\" to restore this window"
+ "Type \"q\" to delete this window") window)))
+ (help-window-select
+ ;; Issuing a message with 3 or more windows on the same frame
+ ;; without selecting the help window doesn't make any sense.
+ (select-window window)
+ (help-window-display-message
+ (if reuse
+ "Type \"q\" to restore this window"
+ "Type \"q\" to delete this window") window)))))
+
+(defun help-window-setup (list-of-frames list-of-window-tuples)
+ "Set up help window.
+LIST-OF-FRAMES and LIST-OF-WINDOW-TUPLES are the lists of frames
+and window quadruples built by `with-help-window'. The help
+window itself is specified by the variable `help-window'."
+ (let* ((help-buffer (window-buffer help-window))
+ ;; `help-buffer' now denotes the help window's buffer.
+ (view-entry
+ (assq help-window
+ (buffer-local-value 'view-return-to-alist help-buffer)))
+ (help-entry (assq help-window list-of-window-tuples)))
+
+ ;; Handle `help-window-point-marker'.
+ (when (eq (marker-buffer help-window-point-marker) help-buffer)
+ (set-window-point help-window help-window-point-marker)
+ ;; Reset `help-window-point-marker'.
+ (set-marker help-window-point-marker nil))
+
+ (cond
+ (view-entry
+ ;; `view-return-to-alist' has an entry for the help window.
+ (cond
+ ((eq help-window (selected-window))
+ ;; The help window is the selected window, probably because the
+ ;; user followed a backward/forward button or a cross reference.
+ ;; In this case just purge stale entries from
+ ;; `view-return-to-alist' but leave the entry alone and don't
+ ;; display a message.
+ (view-return-to-alist-update help-buffer))
+ ((and help-entry (eq (cadr help-entry) help-buffer))
+ ;; The help window was not selected but displayed the help
+ ;; buffer. In this case reuse existing exit information but try
+ ;; to get back to the selected window when quitting. Don't
+ ;; display a message since the user must have seen one before.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) (cddr view-entry)))))
+ (help-entry
+ ;; The help window was not selected, did display the help buffer
+ ;; earlier, but displayed another buffer when help was invoked.
+ ;; Set up things so that quitting will show that buffer again.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) (cdr help-entry))))
+ (help-window-setup-finish help-window t))
+ (t
+ ;; The help window is new but `view-return-to-alist' had an
+ ;; entry for it. This should never happen.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) 'quit-window)))
+ (help-window-setup-finish help-window t))))
+ (help-entry
+ ;; `view-return-to-alist' does not have an entry for help window
+ ;; but `list-of-window-tuples' does. Hence `display-buffer' must
+ ;; have reused an existing window.
+ (if (eq (cadr help-entry) help-buffer)
+ ;; The help window displayed `help-buffer' before but no
+ ;; `view-return-to-alist' entry was found probably because the
+ ;; user manually switched to the help buffer. Set up things
+ ;; for `quit-window' although `view-exit-action' should be
+ ;; able to handle this case all by itself.
+ (progn
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) 'quit-window)))
+ (help-window-setup-finish help-window t))
+ ;; The help window displayed another buffer before. Set up
+ ;; things in a way that quitting can orderly show that buffer
+ ;; again. The window-start and window-point information from
+ ;; `list-of-window-tuples' provide the necessary information.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) (cdr help-entry))))
+ (help-window-setup-finish help-window t)))
+ ((memq (window-frame help-window) list-of-frames)
+ ;; The help window is a new window on an existing frame. This
+ ;; case must be handled specially by `help-window-setup-finish'
+ ;; and `view-mode-exit' to ascertain that quitting does _not_
+ ;; inadvertently delete the frame.
+ (view-return-to-alist-update
+ help-buffer (cons help-window
+ (cons (selected-window) 'keep-frame)))
+ (help-window-setup-finish help-window nil t))
+ (t
+ ;; The help window is shown on a new frame. In this case quitting
+ ;; shall handle both, the help window _and_ its frame. We changed
+ ;; the default of `view-remove-frame-by-deleting' to t in order to
+ ;; intuitively DTRT here.
+ (view-return-to-alist-update
+ help-buffer (cons help-window (cons (selected-window) t)))
+ (help-window-setup-finish help-window)))))
+
+;; `with-help-window' is a wrapper for `with-output-to-temp-buffer'
+;; providing the following additional twists:
+
+;; (1) Issue more accurate messages telling how to scroll and quit the
+;; help window.
+
+;; (2) Make `view-mode-exit' DTRT in more cases.
+
+;; (3) An option (customizable via `help-window-select') to select the
+;; help window automatically.
+
+;; (4) A marker (`help-window-point-marker') to move point in the help
+;; window to an arbitrary buffer position.
+
+;; Note: It's usually always wrong to use `help-print-return-message' in
+;; the body of `with-help-window'.
+(defmacro with-help-window (buffer-name &rest body)
+ "Display buffer BUFFER-NAME in a help window evaluating BODY.
+Select help window if the actual value of the user option
+`help-window-select' says so. Return last value in BODY."
+ (declare (indent 1) (debug t))
+ ;; Bind list-of-frames to `frame-list' and list-of-window-tuples to a
+ ;; list of one <window window-buffer window-start window-point> tuple
+ ;; for each live window.
+ `(let ((list-of-frames (frame-list))
+ (list-of-window-tuples
+ (let (list)
+ (walk-windows
+ (lambda (window)
+ (push (list window (window-buffer window)
+ (window-start window) (window-point window))
+ list))
+ 'no-mini t)
+ list)))
+ ;; Make `help-window' t to trigger `help-mode-finish' to set
+ ;; `help-window' to the actual help window.
+ (setq help-window t)
+ ;; Make `help-window-point-marker' point nowhere (the only place
+ ;; where this should be set to a buffer position is within BODY).
+ (set-marker help-window-point-marker nil)
+ (prog1
+ ;; Return value returned by `with-output-to-temp-buffer'.
+ (with-output-to-temp-buffer ,buffer-name
+ (progn ,@body))
+ (when (windowp help-window)
+ ;; Set up help window.
+ (help-window-setup list-of-frames list-of-window-tuples))
+ ;; Reset `help-window' to nil to avoid confusing future calls of
+ ;; `help-mode-finish' with plain `with-output-to-temp-buffer'.
+ (setq help-window nil))))
+\f
(provide 'help)
;; arch-tag: cf427352-27e9-49b7-9a6f-741ebab02423