443 lines
17 KiB
EmacsLisp
443 lines
17 KiB
EmacsLisp
;;; ehelp.el --- bindings for electric-help mode -*- lexical-binding: t -*-
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;; Copyright (C) 1986, 1995, 2000-2024 Free Software Foundation, Inc.
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;; Author: Richard Mlynarik
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;; (according to ack.texi and authors.el)
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;; Maintainer: emacs-devel@gnu.org
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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 3 of the License, or
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;; (at your option) 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. If not, see <https://www.gnu.org/licenses/>.
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;;; Commentary:
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;; This package provides a pre-packaged `Electric Help Mode' for
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;; browsing Emacs 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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;; To make this the default, you must do
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;; (define-key global-map "\C-h" 'ehelp-command)
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;; (define-key global-map [help] 'ehelp-command)
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;; (define-key global-map [f1] 'ehelp-command)
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;;; Code:
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(require 'electric)
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(defvar electric-help-form-to-execute nil)
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(defgroup electric-help ()
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"Electric help facility."
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:version "21.1"
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:group 'help)
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(defcustom electric-help-shrink-window t
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"If set, adjust help window sizes to buffer sizes when displaying help."
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:type 'boolean
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:group 'electric-help)
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(defcustom electric-help-mode-hook nil
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"Hook run by `with-electric-help' after initializing the buffer."
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:type 'hook
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:group 'electric-help)
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(put 'electric-help-undefined 'suppress-keymap t)
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(defvar electric-help-map
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(let ((map (make-keymap)))
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;; FIXME fragile. Should derive from help-mode-map in a smarter way.
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(set-keymap-parent map button-buffer-map)
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;; allow all non-self-inserting keys - search, scroll, etc, but
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;; let M-x and C-x exit ehelp mode and retain buffer:
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(suppress-keymap map)
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(define-key map "\C-u" 'electric-help-undefined)
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(define-key map [?\C-0] 'electric-help-undefined)
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(define-key map [?\C-1] 'electric-help-undefined)
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(define-key map [?\C-2] 'electric-help-undefined)
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(define-key map [?\C-3] 'electric-help-undefined)
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(define-key map [?\C-4] 'electric-help-undefined)
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(define-key map [?\C-5] 'electric-help-undefined)
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(define-key map [?\C-6] 'electric-help-undefined)
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(define-key map [?\C-7] 'electric-help-undefined)
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(define-key map [?\C-8] 'electric-help-undefined)
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(define-key map [?\C-9] 'electric-help-undefined)
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(define-key map (if (characterp help-char)
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(char-to-string help-char)
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(vector help-char))
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'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 [?\S-\ ] 'scroll-down)
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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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(define-key map "r" 'electric-help-retain)
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(define-key map "\ex" 'electric-help-execute-extended)
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(define-key map "\C-x" 'electric-help-ctrl-x-prefix)
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map)
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"Keymap defining commands available in `electric-help-mode'.")
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(defvar-local electric-help-orig-major-mode nil)
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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 original `major-mode' is restored.)"
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(setq buffer-read-only t)
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(setq electric-help-orig-major-mode major-mode)
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(setq mode-name "Help")
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(setq major-mode 'help-mode)
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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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(add-hook 'mouse-leave-buffer-hook 'electric-help-retain)
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(view-mode -1)
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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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;;;###autoload
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(defun with-electric-help (thunk &optional buffer noerase minheight)
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"Pop up an \"electric\" help buffer.
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THUNK is a function of no arguments which is called to initialize the
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contents of BUFFER. BUFFER defaults to `*Help*'. BUFFER will be
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erased before THUNK is called unless NOERASE is non-nil. THUNK will
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be called while BUFFER is current and with `standard-output' bound to
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the buffer specified by BUFFER.
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If THUNK returns nil, we display BUFFER starting at the top, and shrink
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the window to fit. If THUNK returns non-nil, we don't do those things.
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After THUNK has been called, this function \"electrically\" pops up a
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window in which BUFFER is displayed and allows the user to scroll
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through that buffer in `electric-help-mode'. The window's height will
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be at least MINHEIGHT if this value is non-nil.
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If THUNK returns nil, we display BUFFER starting at the top, and
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shrink the window to fit if `electric-help-shrink-window' is non-nil.
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If THUNK returns non-nil, we don't do those things.
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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'), and
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BUFFER is put back into its original major mode."
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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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(electric-help-form-to-execute nil))
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(unwind-protect
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(save-excursion
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(when one
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(goto-char (window-start)))
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(let ((pop-up-windows t))
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(pop-to-buffer buffer))
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(with-current-buffer buffer
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(when (and minheight (< (window-height) minheight))
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(enlarge-window (- minheight (window-height))))
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(electric-help-mode)
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(setq buffer-read-only nil)
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(unless noerase
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(erase-buffer)))
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(let ((standard-output buffer))
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(unless (funcall thunk)
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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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(when (and one electric-help-shrink-window)
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(shrink-window-if-larger-than-buffer))))
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(set-buffer buffer)
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(run-hooks 'electric-help-mode-hook)
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(setq buffer-read-only t)
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(if (eq (car-safe (electric-help-command-loop)) 'retain)
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(setq config (current-window-configuration))
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(setq bury t))
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;; Remove the hook.
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(when (memq 'electric-help-retain mouse-leave-buffer-hook)
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(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)))
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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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;; Restore the original major mode saved by `electric-help-mode'.
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;; We should really get a usable *Help* buffer when retaining
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;; the electric one with `r'. The problem is that a simple
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;; call to `help-mode' won't cut it; e.g. RET is bound wrong
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;; afterwards (`View-scroll-line-forward' instead of `help-follow').
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;; That's because Help mode should be set with `with-help-window'
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;; instead of the direct call to `help-mode'. But at least
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;; RET works correctly on links after using `help-mode'.
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;; This is satisfactory enough.
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(condition-case ()
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(funcall (or electric-help-orig-major-mode 'fundamental-mode))
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(error nil))
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(set-window-configuration config)
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(when bury
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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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(if (functionp electric-help-form-to-execute)
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(funcall electric-help-form-to-execute)
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(eval electric-help-form-to-execute)))))
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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 "%s" (substitute-command-keys "<<< Press Space to bury the help buffer, Press \\[electric-help-retain] to retain it >>>"))
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(let ((ev (read-event)))
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(if (equal ev ?\s)
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(throw 'exit t)
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(push ev unread-command-events)))))
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(let (up down both neither
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(standard (and (eq (key-binding " " nil t)
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'scroll-up)
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(eq (key-binding "\^?" nil t)
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'scroll-down)
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(eq (key-binding "q" nil t)
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'electric-help-exit)
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(eq (key-binding "r" nil t)
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'electric-help-retain))))
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(Electric-command-loop
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'exit
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(lambda ()
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(sit-for 0) ;necessary if last command was end-of-buffer or
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;beginning-of-buffer - otherwise pos-visible-in-window-p
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;will yield a wrong result.
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(let ((min (pos-visible-in-window-p (point-min)))
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(max (pos-visible-in-window-p (1- (point-max)))))
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(cond (isearch-mode 'noprompt)
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((and min max)
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(cond (standard "Press q to exit, r to retain ")
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(neither)
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(t (setq neither (substitute-command-keys "Press \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
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(min
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(cond (standard "Press SPC to scroll, q to exit, r to retain ")
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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, \\[electric-help-retain] to retain ")))))
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(max
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(cond (standard "Press DEL to scroll back, q to exit, r to retain ")
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(down)
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(t (setq down (substitute-command-keys "Press \\[scroll-down] to scroll back, \\[electric-help-exit] to exit, \\[electric-help-retain] to retain ")))))
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(t
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(cond (standard "Press SPC to scroll, DEL to scroll back, q to exit, r to retain ")
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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, \\[electric-help-retain] to retain "))))))))
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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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"Exit `with-electric-help', restoring the previous window/buffer configuration.
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\(The *Help* buffer will be buried.)"
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(interactive)
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;; Make sure that we don't throw twice, even if two events cause
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;; calling this function:
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(if (memq 'electric-help-retain mouse-leave-buffer-hook)
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(progn
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(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
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(throw 'exit t))))
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(defun electric-help-retain ()
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"Exit `with-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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;; Make sure that we don't throw twice, even if two events cause
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;; calling this function:
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(if (memq 'electric-help-retain mouse-leave-buffer-hook)
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(progn
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(remove-hook 'mouse-leave-buffer-hook 'electric-help-retain)
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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" nil t) '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" nil t) 'electric-help-exit)
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(eq (key-binding " " nil t) 'scroll-up)
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(eq (key-binding "\^?" nil t) 'scroll-down)
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(eq (key-binding "r" nil t) 'electric-help-retain))
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(message "SPC scrolls up, DEL scrolls down, q exits burying help buffer, r exits")
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(message "%s" (substitute-command-keys "\\[scroll-up] scrolls up, \\[scroll-down] scrolls down, \\[electric-help-exit] exits burying help buffer, \\[electric-help-retain] exits")))
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(sit-for 2))
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;;;###autoload
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(defun electric-helpify (fun &optional name)
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(let ((name (or 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 'help-print-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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(with-current-buffer b
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(set-buffer-modified-p t)))
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(fset 'help-print-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 'help-print-return-message p)
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(and b (buffer-name b)
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(with-current-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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;; This is to be bound to M-x in ehelp mode. Retains ehelp buffer and then
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;; continues with execute-extended-command.
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(defun electric-help-execute-extended (_prefixarg)
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(interactive "p")
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(setq electric-help-form-to-execute
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(lambda ()
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(with-suppressed-warnings ((interactive-only
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execute-extended-command))
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(execute-extended-command nil))))
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(electric-help-retain))
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;; This is to be buond to C-x in ehelp mode. Retains ehelp buffer and then
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;; continues with ctrl-x prefix.
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(defun electric-help-ctrl-x-prefix (_prefixarg)
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(interactive "p")
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(setq electric-help-form-to-execute
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(lambda ()
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(message nil)
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(setq unread-command-events
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(append unread-command-events '(?\C-x)))))
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(electric-help-retain))
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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 "*Apropos*"))
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;(define-key help-map "a" 'electric-command-apropos)
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(defun electric-apropos ()
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(interactive)
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(electric-helpify 'apropos))
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;;;; ehelp-map
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(defvar ehelp-map
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(let ((map (copy-keymap help-map)))
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(substitute-key-definition 'apropos 'electric-apropos map)
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(substitute-key-definition 'command-apropos 'electric-command-apropos 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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map))
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;;;###(autoload 'ehelp-command "ehelp" "Prefix command for ehelp." t 'keymap)
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(defalias 'ehelp-command ehelp-map)
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(put 'ehelp-command 'documentation "Prefix command for ehelp.")
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(provide 'ehelp)
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;;; ehelp.el ends here
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