Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!mailrus!csd4.milw.wisc.edu!bionet!agate!saturn!helios!mongo
From: mongo@helios (Mongo Package)
Newsgroups: comp.windows.x
Subject: Re: XNextEvent vs. select(2)
Summary: This is neat, but system-dependent
Keywords: Command-driven programs
Message-ID: <5832@saturn.ucsc.edu>
Date: 22 Dec 88 16:20:56 GMT
References: <2214@daisy.UUCP>
Sender: usenet@saturn.ucsc.edu
Reply-To: mongo@helios.ucsc.edu (Mongo Package)
Organization: University of California, Santa Cruz;  UCO/Lick Observatory
Lines: 29

In article <2214@daisy.UUCP> klee@daisy.UUCP (Ken Lee) writes:
>I asked about combining XNextEvent() with select().  [stuff deleted]
>The solution is simple:
>    Get the X connection file descriptor with ConnectionNumber(dpy) or
>    XConnectionNumber(dpy) (Xlib manual section 2.2.1).
>    Do a select on this and any other interesting fd's (including sockets).
>    If the X connection fd fires, read it with XNextEvent.  Read your
>    other fd's as you would normally.

This is exactly the way that I have begun to follow up my earlier 
questions on porting a large, clunky, old, command-driven program to use
X11 for its display.  Instead of doing fgets() to get a line from the
user at the terminal, I call a function which does the above.  When X
events come in they are handled, until a command line is completed.
Then the program continues past this new function doing the old, clunky,
command-driven code.  While this old code is running, no X events are
handled.  Not handling X events would be irritating, but fortunately, the
old code occasionally checks to see if it has been interrupted, and I just
add some X event handling to the interrupt checkpoints.

Now my only trouble with this is that my code is supposed to run on other
systems than Unix (i.e., VMS).  I haven't looked into how a select() would
be done in VMS, but I suppose it could be faked using QIOs to set flags
saying input is ready.  If anybody has any pointers about this, I'd still
like to hear them.  

Steve Allen
sla@helios.ucsc.edu
sla@ucscloa.bitnet
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