;;; help-macro.el --- Makes command line help such as help-for-help
;; Copyright (C) 1993, 1994, 1997 Free Software Foundation, Inc.
;; Author: Lynn Slater <email@example.com>
;; Maintainer: FSF
;; Created: : Mon Oct 1 11:42:39 1990
;; Adapted-By: ESR
;; This file is part of XEmacs.
;; XEmacs 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 2, or (at your option)
;; any later version.
;; XEmacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
;; along with XEmacs; see the file COPYING. If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.
;;; Synched up with: FSF 20.2.
;; This file supplies the macro make-help-screen which constructs
;; single character dispatching with browsable help such as that provided
;; by help-for-help. This can be used to make many modes easier to use; for
;; example, the Gnu Emacs Empire Tool uses this for every "nested" mode map
;; called from the main mode map.
;; The name of this package was changed from help-screen.el to
;; help-macro.el in order to fit in a 14-character limit.
;;-> *********************** Example of use *********************************
;;-> "c:civ m:mil p:population f:food ?"
;;-> "You have discovered the GEET redistribution commands
;;-> From here, you can use the following options:
;;->c Redistribute civs from overfull sectors into connected underfull ones
;;-> The functions typically named by empire-ideal-civ-fcn control
;;-> based in part on empire-sector-civ-threshold
;;->m Redistribute military using levels given by empire-ideal-mil-fcn
;;->p Redistribute excess population to highways for max pop growth
;;-> Excess is any sector so full babies will not be born.
;;->f Even out food on highways to highway min and leave levels
;;-> This is good to pump max food to all warehouses/dist pts
;;->Use \\[help-for-empire-redistribute-map] for help on redistribution.
;;->Use \\[help-for-empire-extract-map] for help on data extraction.
;;->Please use \\[describe-key] to find out more about any of the other keys."
;;-> (define-key c-mp "\C-h" 'help-for-empire-redistribute-map)
;;-> (define-key c-mp help-character 'help-for-empire-redistribute-map)
(defcustom three-step-help t
"*Non-nil means give more info about Help command in three steps.
The three steps are simple prompt, prompt with all options,
and window listing and describing the options.
A value of nil means skip the middle step, so that
\\[help-command] \\[help-command] gives the window that lists the options."
(defmacro make-help-screen (fname help-line help-text helped-map)
"Construct help-menu function name FNAME.
When invoked, FNAME shows HELP-LINE and reads a command using HELPED-MAP.
If the command is the help character, FNAME displays HELP-TEXT
and continues trying to read a command using HELPED-MAP.
When FNAME finally does get a command, it executes that command
and then returns."
`(defun ,fname ()
(flet ((help-read-key (prompt)
;; This is in `flet' to avoid problems with autoloading.
;; #### The function is ill-conceived -- there should be
;; a way to do it without all the hassle!
(while (not (key-press-event-p
(aref (setq events (read-key-sequence prompt)) 0)))
;; Mouse clicks are not part of the help feature, so
;; reexecute them in the standard environment.
(mapc 'dispatch-event events))
(let ((key (nconc (event-modifiers (aref events 0))
(list (event-key (aref events 0))))))
;; Make the HELP key translate to C-h.
(when (lookup-key function-key-map key)
(setq key (lookup-key function-key-map key)))
(if (eq (length key) 1)
(message "%s" line-prompt))
(let* ((help-screen (documentation (quote ,fname)))
;; We bind overriding-local-map for very small
;; sections, *excluding* where we switch buffers and
;; where we execute the chosen help command.
config new-frame key)
(set-keymap-parents local-map (list ,helped-map))
(let* ((overriding-local-map local-map))
(setq key (help-read-key nil))))
(setq key ??)))
(when (or (equal key ??)
(equal key (list help-char)))
(setq config (current-window-configuration))
(and (not (eq (window-frame (selected-window))
(setq new-frame (window-frame (selected-window))
(setq buffer-read-only nil)
(while (member key `((,help-char) ?? (control v) space ?\177
delete backspace (meta v)))
(cond ((member key '((control v) space))
((member key '(?\177 delete (meta v) backspace))
(let ((cursor-in-echo-area t)
(setq key (help-read-key
(format "Type one of the options listed%s: "
"" " or Space to scroll")))))))
;; We don't need the prompt any more.
(let ((defn (lookup-key local-map key)))
(setq config nil))
(setq new-frame nil))
(and (get-buffer "*Help*")
(and new-frame (iconify-frame new-frame))