Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mcsun!unido!fauern!opal!fub!geminix.in-berlin.de!robot!karl
From: karl@robot.in-berlin.de (Karl-P. Huestegge)
Newsgroups: comp.unix.programmer
Subject: Re: How do you read the arrow keys?
Message-ID: <1991Jan2.154109.922@robot.in-berlin.de>
Date: 2 Jan 91 15:41:09 GMT
References: <3080@dali> <1990Dec28.195518.26577@ivy.uucp> <4927:Dec2920:17:4790@kramden.acf.nyu.edu>
Organization: K.-P. Huestegge, Sytemanalyse und Beratung, Berlin
Lines: 27

brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:

>iverson@ivy.uucp (Tim Iverson) writes:
>  [ on the problem of interpreting <esc> given escape sequences ]
>> This is a failing of every package I've seen that purports to handle arrow
>> keys in a device independent manner, although, it's such a basic problem
>> that I assume someone somewhere is offering a package that does do it right.

>It's really the terminal's fault, not the programmer's fault. Codes
>coming from the terminal should be uniquely decodable as untimed byte
>streams. In the best situation, no code is a prefix of another.

>A terminal could, for example, produce two <esc>s when you hit the
>escape key. This solves the problem trivially.
>Using timeouts isn't ``doing it right.'' It's an unfortunate kludge to
>deal with the failings of current hardware.

You're right, but a lot of terminals are able to send 8bit iso-8859 
Control codes (CSI instead of 'ESC [' and DCS instead of 'ESC P' etc).

DEC's VT220/VT320 can handle this for example. But I don't know if the
termcap/terminfo libs can handle it...  I havn't tried yet.


-- 
Karl-Peter Huestegge                       karl@robot.in-berlin.de
Berlin Friedenau                           ..unido!fub!geminix!robot!karl