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From: cunniff@hpfcdc.HP.COM (Ross Cunniff)
Newsgroups: comp.sys.amiga.tech
Subject: How to peek at queued Intution msgs?
Message-ID: <11640015@hpfcdc.HP.COM>
Date: 14 Apr 89 20:04:36 GMT
Organization: HP Ft. Collins, Co.
Lines: 49

What is the best way to look for a SPECIFIC message
on a window's UserPort?   For example, say I have an
application that has the standard event loop:

EventLoop()
{
    while( !Done ) {
	Wait( 1 << MyWindow->UserPort.mp_SigBit );
	while( Msg = GetMsg( MyWindow->UserPort ) ) {
	    if( Class = WHATEVER )
		DoSomeLongAndComplicatedThing();
	    else
		DoSomethingElse();
	    ReplyMsg( Msg );
	}
    }
}

Further, assume DoSomeLongAndComplicatedThing() wants
to allow the user to abort the action by, say, pressing
the ESC key or something.  Now, I can have the simple-
minded approach:

CheckForEscapeKey()
{
    while( Msg = GetMsg( MyWindow->UserPort ) ) {
	if( (Msg->Class == VANILLAKEY) && Msg->Code == '\033' ) {
	    /* Aha! */
	    ReplyMsg( Msg );
	    return 1;
	}
	ReplyMsg( Msg );
    }
    return 0;
}

However, this eats ALL pending events that happen before the abort,
including potentially important ones such as NEWSIZE.

The question is, therefore: is there a supported way of peeking at the
UserPort queue and finding a specific IDCMP message without deleting
all messages before it?  Or am I stuck doing significantly smarter
processing in CheckForEscapeKey() in order not to miss the *REALLY*
important messages?

				Ross Cunniff
				Hewlett-Packard Colorado Languages Lab
				...{ucbvax,hplabs}!hpfcla!cunniff
				cunniff%hpfcrt@hplabs.HP.COM