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From: dgold@apple.UUCP
Newsgroups: comp.sys.mac
Subject: Re: MacWrite 4.5 BOMB
Message-ID: <578@apple.UUCP>
Date: Mon, 30-Mar-87 16:34:13 EST
Article-I.D.: apple.578
Posted: Mon Mar 30 16:34:13 1987
Date-Received: Wed, 1-Apr-87 05:21:11 EST
References: <8703232111.AA11200@osupyr.UUCP>
Reply-To: dgold@apple.UUCP (David Goldsmith)
Organization: Apple Computer Inc., Cupertino, USA
Lines: 25

In article <8703232111.AA11200@osupyr.UUCP> pgn@osupyr.UUCP (Paul G. Nevai) writes:
>My simple FKEY doing nothing but ExitToShell explodes on MacWrite, Word and
>Excel. Do you think that they could all be guilty and I am innocent? Just
>try that FKey, takes 5 minutes to write it on LSP.
I believe all of these programs patch Mac ROM traps.  If you simply
ExitToShell, the program does not get a chance to clean up and the patches
are left in (there are more serious problems with MacWrite, as it will leave
all of its work files open).  Since the patches are still there, and point
at nonexistent application code (since you've left the application), anyone
who calls those traps (like the Finder) will jump off into garbage, with
predictable results.  In general, it is NOT SAFE to call ExitToShell behind
an application's back, and there is no guarantee that it will work.

Some applications which patch traps also patch ExitToShell, so that during
debugging, if a crash occurs, you can ExitToShell in Macsbug.  The ExitToShell
patch cleans up the other patches, then exits.
-- 
David Goldsmith
Apple Computer, Inc.
MacApp Group

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