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From: asente@decwrl.dec.com (Paul Asente)
Newsgroups: comp.windows.x
Subject: Re: X & signals
Keywords: xwindows signals
Message-ID: <2888@bacchus.dec.com>
Date: 24 Feb 90 05:23:37 GMT
References: <1154@sdrc.UUCP> <132200@sun.Eng.Sun.COM>
Organization: DEC Western Software Lab
Lines: 27

In article <132200@sun.Eng.Sun.COM> argv@sun.UUCP (Dan Heller) writes:
>The problem is that Xlib has no layer for signal handling.  The
>reason is dubious, but it's in many people's opinion that it's
>due to DEC's strong involvement with X and since DEC really likes
>VMS (brought to the US on one of Columbus' ships circa 1492) and
>VMS does not support signals...

That's a pretty dubious explanation.  Try
1) Xlib version 11 is still rather similar internally to Xlib version 10,
which DEC had nothing to do with, and which didn't support signals either.
2) The developers of X11 had a huge amount of stuff on their plates as
it was, and putting signal handling in Xlib was one of the 143 things they
would have liked to have done but didn't have time for.

Anyway, VMS has asynchronous events that are rather similar to signals,
and the VMS Xlib handles them just fine (its internal layers are different
from the Unix internal layers, not surprisingly).

>1)  Avoid using Xlib as the main interface layer to your application.
>    Use a toolkit of some kind.  Xt provides for a timer that handles
>    SIGALARM, but that's the only signal it provides for.

The Xt timers are not asynchronous; they just manipulate the time values
sent to select().

	-paul asente
	    asente@decwrl.dec.com	decwrl!asente