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326 lines
11 KiB
EmacsLisp
326 lines
11 KiB
EmacsLisp
;;; ehelp.el --- bindings for electric-help mode
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;; Copyright (C) 1986 Free Software Foundation, Inc.
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;; Maintainer: FSF
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;; Keywords: help, extensions
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;; This file is part of GNU Emacs.
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;; GNU Emacs is free software; you can redistribute it and/or modify
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;; it under the terms of the GNU General Public License as published by
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;; the Free Software Foundation; either version 2, or (at your option)
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;; any later version.
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;; GNU Emacs is distributed in the hope that it will be useful,
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;; but WITHOUT ANY WARRANTY; without even the implied warranty of
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;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;; GNU General Public License for more details.
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;; You should have received a copy of the GNU General Public License
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;; along with GNU Emacs; see the file COPYING. If not, write to
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;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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;;; Commentary:
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;; This package provides a pre-packaged `Electric Help Mode' for
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;; browsing on-line help screens. There is one entry point,
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;; `with-electric-help'; All you have to give it is a no-argument
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;; function that generates the actual text of the help into the current
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;; buffer.
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;;; Code:
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(require 'electric)
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(defvar electric-help-map ()
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"Keymap defining commands available in `electric-help-mode'.")
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(put 'electric-help-undefined 'suppress-keymap t)
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(if electric-help-map
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()
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(let ((map (make-keymap)))
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(fillarray (car (cdr map)) 'electric-help-undefined)
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(define-key map (char-to-string meta-prefix-char) (copy-keymap map))
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(define-key map (char-to-string help-char) 'electric-help-help)
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(define-key map "?" 'electric-help-help)
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(define-key map " " 'scroll-up)
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(define-key map "\^?" 'scroll-down)
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(define-key map "." 'beginning-of-buffer)
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(define-key map "<" 'beginning-of-buffer)
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(define-key map ">" 'end-of-buffer)
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;(define-key map "\C-g" 'electric-help-exit)
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(define-key map "q" 'electric-help-exit)
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(define-key map "Q" 'electric-help-exit)
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;;a better key than this?
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(define-key map "r" 'electric-help-retain)
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(setq electric-help-map map)))
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(defun electric-help-mode ()
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"`with-electric-help' temporarily places its buffer in this mode.
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\(On exit from `with-electric-help', the buffer is put in `default-major-mode'.)"
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(setq buffer-read-only t)
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(setq mode-name "Help")
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(setq major-mode 'help)
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(setq mode-line-buffer-identification '(" Help: %b"))
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(use-local-map electric-help-map)
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;; this is done below in with-electric-help
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;(run-hooks 'electric-help-mode-hook)
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)
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(defun with-electric-help (thunk &optional buffer noerase)
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"Arguments are THUNK &optional BUFFER NOERASE. BUFFER defaults to \"*Help*\"
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THUNK is a function of no arguments which is called to initialize
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the contents of BUFFER. BUFFER will be erased before THUNK is called unless
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NOERASE is non-nil. THUNK will be called with `standard-output' bound to
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the buffer specified by BUFFER
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After THUNK has been called, this function \"electrically\" pops up a window
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in which BUFFER is displayed and allows the user to scroll through that buffer
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in electric-help-mode.
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When the user exits (with `electric-help-exit', or otherwise) the help
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buffer's window disappears (i.e., we use `save-window-excursion')
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BUFFER is put into `default-major-mode' (or `fundamental-mode') when we exit"
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(setq buffer (get-buffer-create (or buffer "*Help*")))
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(let ((one (one-window-p t))
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(config (current-window-configuration))
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(bury nil))
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(unwind-protect
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(save-excursion
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(if one (goto-char (window-start (selected-window))))
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(let ((pop-up-windows t))
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(pop-to-buffer buffer))
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(save-excursion
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(set-buffer buffer)
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(electric-help-mode)
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(setq buffer-read-only nil)
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(or noerase (erase-buffer)))
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(let ((standard-output buffer))
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(if (not (funcall thunk))
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(progn
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(set-buffer buffer)
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(set-buffer-modified-p nil)
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(goto-char (point-min))
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(if one (shrink-window-if-larger-than-buffer (selected-window))))))
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(set-buffer buffer)
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(run-hooks 'electric-help-mode-hook)
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(if (eq (car-safe (electric-help-command-loop))
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'retain)
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(setq config (current-window-configuration))
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(setq bury t)))
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(message "")
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(set-buffer buffer)
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(setq buffer-read-only nil)
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(condition-case ()
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(funcall (or default-major-mode 'fundamental-mode))
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(error nil))
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(set-window-configuration config)
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(if bury
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(progn
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;;>> Perhaps this shouldn't be done.
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;; so that when we say "Press space to bury" we mean it
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(replace-buffer-in-windows buffer)
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;; must do this outside of save-window-excursion
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(bury-buffer buffer))))))
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(defun electric-help-command-loop ()
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(catch 'exit
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(if (pos-visible-in-window-p (point-max))
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(progn (message "<<< Press Space to bury the help buffer >>>")
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(if (equal (setq unread-command-events (list (read-event)))
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'(?\ ))
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(progn (setq unread-command-events nil)
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(throw 'exit t)))))
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(let (up down both neither
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(standard (and (eq (key-binding " ")
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'scroll-up)
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(eq (key-binding "\^?")
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'scroll-down)
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(eq (key-binding "Q")
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'electric-help-exit)
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(eq (key-binding "q")
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'electric-help-exit))))
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(Electric-command-loop
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'exit
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(function (lambda ()
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(let ((min (pos-visible-in-window-p (point-min)))
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(max (pos-visible-in-window-p (point-max))))
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(cond ((and min max)
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(cond (standard "Press Q to exit ")
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(neither)
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(t (setq neither (substitute-command-keys "Press \\[scroll-up] to exit ")))))
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(min
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(cond (standard "Press SPC to scroll, Q to exit ")
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(up)
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(t (setq up (substitute-command-keys "Press \\[scroll-up] to scroll; \\[electric-help-exit] to exit ")))))
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(max
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(cond (standard "Press DEL to scroll back, Q to exit ")
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(down)
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(t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[scroll-up] to exit ")))))
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(t
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(cond (standard "Press SPC to scroll, DEL to scroll back, Q to exit ")
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(both)
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(t (setq both (substitute-command-keys "Press \\[scroll-up] to scroll, \\[scroll-down] to scroll back, \\[electric-help-exit] to exit ")))))))))
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t))))
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;(defun electric-help-scroll-up (arg)
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; ">>>Doc"
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; (interactive "P")
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; (if (and (null arg) (pos-visible-in-window-p (point-max)))
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; (electric-help-exit)
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; (scroll-up arg)))
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(defun electric-help-exit ()
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">>>Doc"
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(interactive)
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(throw 'exit t))
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(defun electric-help-retain ()
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"Exit `electric-help', retaining the current window/buffer configuration.
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\(The *Help* buffer will not be selected, but \\[switch-to-buffer-other-window] RET
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will select it.)"
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(interactive)
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(throw 'exit '(retain)))
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(defun electric-help-undefined ()
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(interactive)
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(error "%s is undefined -- Press %s to exit"
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(mapconcat 'single-key-description (this-command-keys) " ")
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(if (eq (key-binding "Q") 'electric-help-exit)
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"Q"
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(substitute-command-keys "\\[electric-help-exit]"))))
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;>>> this needs to be hairified (recursive help, anybody?)
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(defun electric-help-help ()
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(interactive)
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(if (and (eq (key-binding "Q") 'electric-help-exit)
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(eq (key-binding " ") 'scroll-up)
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(eq (key-binding "\^?") 'scroll-down))
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(message "SPC scrolls forward, DEL scrolls back, Q exits and burys help buffer")
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;; to give something for user to look at while slow substitute-cmd-keys
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;; grinds away
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(message "Help...")
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(message "%s" (substitute-command-keys "\\[scroll-up] scrolls forward, \\[scroll-down] scrolls back, \\[electric-help-exit] exits.")))
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(sit-for 2))
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(defun electric-helpify (fun)
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(let ((name "*Help*"))
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(if (save-window-excursion
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;; kludge-o-rama
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(let* ((p (symbol-function 'print-help-return-message))
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(b (get-buffer name))
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(m (buffer-modified-p b)))
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(and b (not (get-buffer-window b))
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(setq b nil))
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(unwind-protect
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(progn
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(message "%s..." (capitalize (symbol-name fun)))
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;; with-output-to-temp-buffer marks the buffer as unmodified.
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;; kludging excessively and relying on that as some sort
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;; of indication leads to the following abomination...
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;;>> This would be doable without such icky kludges if either
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;;>> (a) there were a function to read the interactive
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;;>> args for a command and return a list of those args.
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;;>> (To which one would then just apply the command)
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;;>> (The only problem with this is that interactive-p
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;;>> would break, but that is such a misfeature in
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;;>> any case that I don't care)
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;;>> It is easy to do this for emacs-lisp functions;
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;;>> the only problem is getting the interactive spec
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;;>> for subrs
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;;>> (b) there were a function which returned a
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;;>> modification-tick for a buffer. One could tell
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;;>> whether a buffer had changed by whether the
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;;>> modification-tick were different.
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;;>> (Presumably there would have to be a way to either
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;;>> restore the tick to some previous value, or to
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;;>> suspend updating of the tick in order to allow
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;;>> things like momentary-string-display)
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(and b
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(save-excursion
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(set-buffer b)
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(set-buffer-modified-p t)))
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(fset 'print-help-return-message 'ignore)
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(call-interactively fun)
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(and (get-buffer name)
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(get-buffer-window (get-buffer name))
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(or (not b)
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(not (eq b (get-buffer name)))
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(not (buffer-modified-p b)))))
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(fset 'print-help-return-message p)
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(and b (buffer-name b)
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(save-excursion
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(set-buffer b)
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(set-buffer-modified-p m))))))
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(with-electric-help 'ignore name t))))
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(defun electric-describe-key ()
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(interactive)
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(electric-helpify 'describe-key))
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(defun electric-describe-mode ()
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(interactive)
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(electric-helpify 'describe-mode))
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(defun electric-view-lossage ()
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(interactive)
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(electric-helpify 'view-lossage))
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;(defun electric-help-for-help ()
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; "See help-for-help"
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; (interactive)
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; )
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(defun electric-describe-function ()
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(interactive)
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(electric-helpify 'describe-function))
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(defun electric-describe-variable ()
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(interactive)
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(electric-helpify 'describe-variable))
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(defun electric-describe-bindings ()
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(interactive)
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(electric-helpify 'describe-bindings))
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(defun electric-describe-syntax ()
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(interactive)
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(electric-helpify 'describe-syntax))
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(defun electric-command-apropos ()
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(interactive)
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(electric-helpify 'command-apropos))
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;(define-key help-map "a" 'electric-command-apropos)
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;;;; ehelp-map
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(defvar ehelp-map ())
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(if ehelp-map
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nil
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(let ((map (copy-keymap help-map)))
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(substitute-key-definition 'describe-key 'electric-describe-key map)
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(substitute-key-definition 'describe-mode 'electric-describe-mode map)
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(substitute-key-definition 'view-lossage 'electric-view-lossage map)
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(substitute-key-definition 'describe-function 'electric-describe-function map)
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(substitute-key-definition 'describe-variable 'electric-describe-variable map)
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(substitute-key-definition 'describe-bindings 'electric-describe-bindings map)
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(substitute-key-definition 'describe-syntax 'electric-describe-syntax map)
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(setq ehelp-map map)
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(fset 'ehelp-command map)))
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;; Do (define-key global-map "\C-h" 'ehelp-command) if you want to win
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(provide 'ehelp)
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;;; ehelp.el ends here
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