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From: anson@spray.CalComp.COM (Ed Anson)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Multifinder: how do I patch GetNextEvent?
Message-ID: <2453@spray.CalComp.COM>
Date: 10 Oct 88 21:25:41 GMT
References: <747@ttrdf.UUCP> <10050022@eecs.nwu.edu>
Reply-To: anson@spray.UUCP (Ed Anson)
Organization: CalComp, A Lockheed Company, Hudson, NH, USA
Lines: 27

In article <10050022@eecs.nwu.edu> bob@eecs.nwu.edu (Bob Hablutzel) writes:
>>   What is the proper way to patch the GetNextEvent() trap for
>> compatibility with MultiFinder?.  I have created an INIT that
>    [ bunch of stuff deleted ]
>
>The problem here is that you have written a "tail patch". This is a critter
>that does it's work _after_ the original ROM routine. These are verboten, since
>some of Apple's patches to the OS rely on the return address of the call.

I know that tail patches are officially forbidden, but I have written a
successful one for GetNextEvent.

Yes, I know Apple promises they'll maybe break it some day. But today it
works. I'm afraid I missed the original posting, so I don't know what the
the poster's particular problem is.

What I'm still trying to figure out is this: Why does Apple persist in
forbidding a very useful type of patch? Just so they can continue to use
a kludge in their own patches? The necessity of such a proscription has 
still not been explained to my satisfaction.

The opinions expressed above are my own, and not those of my employer. (But
you knew that!)
-- 
=====================================================================
   Ed Anson,    Calcomp Display Products Division,    Hudson NH 03051
   (603) 885-8712,      anson@elrond.CalComp.COM