Unix Type-ahead problem

[Chris Torek]

In article <8942 at csli.Stanford.EDU> gandalf at csli.Stanford.EDU
(Juergen Wagner) writes:
>If UNIX could echo characters as they are *consumed* by the program
>which reads from a terminal, as opposed to when they are *typed*, you
>would get the desired behavior.

This would be easy to implement.  The question is `desired by whom'---
certainly not me.  Except when it would create real trouble (e.g., in
vi, Emacs, rogue/hack/moria, ...) I prefer to see what I am typing-ahead.

VMS (and a number of other systems) do have an advantage over
traditional Unix tty drivers, however, in the area of fast echo during
edit sessions or other `controlled screen' times.  Here, the
application should be allowed to tell the system which characters
should merely echo and be queued, and which should not echo, but rather
cause the application to wake up and see what has been typed thus far.
This must be accompanied by a maximum input length (to avoid screen
wraparound in some cases).  The matter gets rather complicated because
of the vagaries of various terminals; VMS and many (if not all) of
those other systems cheat by assuming that you have a particular brand
of terminal attached.  But it is possible to do right, and it does
improve interactive response in those special cases where it may be
used.
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163)
Domain:	chris at mimsy.umd.edu	Path:	uunet!mimsy!chris