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From: josh@mit-vax.LCS.MIT.EDU (Joshua Marantz)
Newsgroups: comp.emacs
Subject: Re: A proposal for a standardized key handling method
Message-ID: <2525@mit-vax.LCS.MIT.EDU>
Date: Tue, 4-Aug-87 10:35:05 EDT
Article-I.D.: mit-vax.2525
Posted: Tue Aug  4 10:35:05 1987
Date-Received: Thu, 6-Aug-87 01:33:51 EDT
References: <250@cogent.UUCP>
Distribution: world
Organization: MIT LCS, Cambridge, MA
Lines: 41
In-reply-to: mark@cogent.UUCP's message of 4 Aug 87 08:07:17 GMT

Posting-Front-End: GNU Emacs 18.33.1 of Tue Dec 16 1986 on mit-vax (berkeley-unix)


Gosling EMACS (and possibly GNU Emacs) had what I consider a cleaner
solution, though it didn't use termcap or terminfo.  The form of the
bind command is:

(bind-to-key "function-name" "character-sequence")

If "character-sequence" is more than one character long, the first character
gets bound to an "auto-generated" keymap, and the second character is the
binding within the auto-generated keymap.  This recursion can go on
indefinitely, allowing for the binding of arbitrarily long escape sequences.

For example:

(bind-to-key "forward-character" "\^F")
(bind-to-key "forward-word" "\ef")
(bind-to-key "forward-character" "\e[C")
(bind-to-key "backward-character" "\e[D")

Would cause the following binding state to exist:

Global Map:	Control-F	-->	function "forward-character"
Global Map:	Escape		-->	keymap "auto-keymap-1"
Auto-keymap-1:	f		-->	function "forward-word"
Auto-keymap-1:	[		-->	keymap "auto-keymap-2"
Auto-keymap-2:	C		-->	function "forward-character"
Auto-keymap-2:	D		-->	function "backward-character"

To avoid "auto-keymap-*", you can first do
(define-keymap "ESC-map")
(bind-to-key "ESC-map" "\e")
(define-keymap "ANSI-prefix-map")
(bind-to-key "ANSI-prefix-map" "\e[")

This is a good approach because no keyboard information has to be hardwired
into the editor.  You have to evaluate the tradeoff of whether you want
to take advantage of the Unix terminfo/termcap facility, which may not
have all you need, and probably won't be supported on other platforms.
I vote for the portable, flexible approach described here.

-Joshua Marantz
Emacs Enthusiast