Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!hoptoad!tim
From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Dialog problems
Keywords: Dialog
Message-ID: <7534@hoptoad.uucp>
Date: 4 Jun 89 22:20:59 GMT
References: <1426@ns.network.com>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Eclectic Software, San Francisco
Lines: 37

It's pretty clear that all the code posted has been correct.  I'd like to
mention a few debugging techniques that can be useful in this kind of
situation:

(1)  Brute force.  Cut out small sections of code that are not
absolutely neccessary to correct execution of the software (e.g.,
number processing) and then try to replicate the problem.  Delete only
one small section each time, or cut out a large section until you find
the area of the problem, then narrow it down from there.

(2)  Check for heap corruption using MacsBug.  Break on ModalDialog and
check at that time, the second time around; also, checking after the
first CloseDialog would make sense.  The command is "HC".  If the heap
is corrupted, using the ATHC command will locate the place in short
order.

(3)  Make a tiny application consisting solely of initializing the
managers and then going into your dialog.  Be sure to use exactly the
same code and resources.  If you can run it more than once in the tiny
application (Just stick it in a loop) then your problem is actually in
another section of code and it only happens to blow away that dialog
through coincidence.

(4)  Use RezDet to check the resource fork of your application.

(5)  Step into the ROM call ModalDialog to find out exactly where the
crash happens.  This can be painful but may be neccessary.

(6)  Run in Heap Scramble mode and see if anything breaks.  If so, go
to your code and figure out why.

Good luck!
-- 
Tim Maroney, Consultant, Eclectic Software, sun!hoptoad!tim
"There's a real world out there, with real people.  Go out and play there for
 a while and give the Usenet sandbox a rest.  It will lower your stress
 levels and make the world a happier place for us all." -- Gene Spafford