lisp/help-macro.el

   1 ;;; help-screen.el --- Makes command line help such as help-for-help
   2
   3 ;; Copyright (C) 1993 Free Software Foundation, Inc.
   4
   5 ;; Author: Lynn Slater <lrs@indetech.com>
   6 ;; Created: : Mon Oct  1 11:42:39 1990
   7 ;; Adapted-By: ESR
   8 ;; Last Modified By: Lynn Slater x2048
   9 ;; Last Modified On: Mon Sep 23 14:40:19 1991
  10
  11 ;; This file is part of GNU Emacs.
  12
  13 ;; GNU Emacs is free software; you can redistribute it and/or modify
  14 ;; it under the terms of the GNU General Public License as published by
  15 ;; the Free Software Foundation; either version 2, or (at your option)
  16 ;; any later version.
  17
  18 ;; GNU Emacs is distributed in the hope that it will be useful,
  19 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  20 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21 ;; GNU General Public License for more details.
  22
  23 ;; You should have received a copy of the GNU General Public License
  24 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  25 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  26
  27 ;;; Commentary:
  28 ;;
  29 ;;      This file supplies the macro make-help-screen which constructs
  30 ;; single character dispatching with browsable help such as that provided
  31 ;; by help-for-help. This can be used to make many modes easier to use; for
  32 ;; example, the Gnu Emacs Empire Tool uses this for every "nested" mode map
  33 ;; called from the main mode map.
  34
  35 ;;-> ***********************  Example of use *********************************
  36
  37 ;;->(make-help-screen help-for-empire-redistribute-map
  38 ;;->              "c:civ m:mil p:population f:food ?"
  39 ;;->              "You have discovered the GEET redistribution commands
  40 ;;->   From here, you can use the following options:
  41 ;;->
  42 ;;->c   Redistribute civs from overfull sectors into connected underfull ones
  43 ;;->      The functions typically named by empire-ideal-civ-fcn control
  44 ;;->          based in part on empire-sector-civ-threshold
  45 ;;->m   Redistribute military using levels given by empire-ideal-mil-fcn
  46 ;;->p   Redistribute excess population to highways for max pop growth
  47 ;;->      Excess is any sector so full babies will not be born.
  48 ;;->f   Even out food on highways to highway min and leave levels
  49 ;;->      This is good to pump max food to all warehouses/dist pts
  50 ;;->
  51 ;;->
  52 ;;->Use \\[help-for-empire-redistribute-map] for help on redistribution.
  53 ;;->Use \\[help-for-empire-extract-map] for help on data extraction.
  54 ;;->Please use \\[describe-key] to find out more about any of the other keys."
  55 ;;->              empire-shell-redistribute-map)
  56
  57 ;;->  (define-key c-mp "\C-h" 'help-for-empire-redistribute-map)
  58 ;;->  (define-key c-mp help-character 'help-for-empire-redistribute-map)
  59
  60 ;;; Change Log:
  61 ;;
  62 ;; 22-Jan-1991          Lynn Slater x2048
  63 ;;    Last Modified: Mon Oct  1 11:43:52 1990 #3 (Lynn Slater)
  64 ;;    documented better
  65
  66 ;;; Code:
  67
  68 (provide 'help-screen)
  69 (require 'backquote)
  70
  71 (defmacro make-help-screen (fname help-line help-text helped-map)
  72   "Constructs function FNAME that when invoked shows HELP-LINE and if a help
  73 character is requested, shows HELP-TEXT. The user is prompted for a character
  74 from the HELPED-MAP and the corresponding interactive function is executed."
  75   (` (defun (, fname) ()
  76            (, help-text)
  77            (interactive)
  78            (let ((line-prompt
  79                   (substitute-command-keys (, help-line))))
  80              (message line-prompt)
  81              (let ((char (read-char)))
  82                (if (or (= char ??) (= char help-char))
  83                    (save-window-excursion
  84                      (switch-to-buffer-other-window "*Help*")
  85                      (erase-buffer)
  86                      (insert (documentation (quote (, fname))))
  87                      (goto-char (point-min))
  88                      (while (memq char (cons help-char '(?? ?\C-v ?\ ?\177 ?\M-v)))
  89                        (if (memq char '(?\C-v ?\ ))
  90                            (scroll-up))
  91                        (if (memq char '(?\177 ?\M-v))
  92                            (scroll-down))
  93                        (message "%s%s: "
  94                                 line-prompt
  95                                 (if (pos-visible-in-window-p (point-max))
  96                                     "" " or Space to scroll"))
  97                        (let ((cursor-in-echo-area t))
  98                          (setq char (read-char))))))
  99                (let ((defn (cdr (assq (downcase char) (, helped-map)))))
 100                  (if defn
 101                      (if (keymapp defn)
 102                          (error "sorry, this command cannot be run from the help screen. Start over.")
 103                        (call-interactively defn))
 104                    (ding))))))
 105      ))
 106
 107 ;;; help-screen.el
 108