Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!hoptoad!tim
From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Need some MF help
Message-ID: <6959@hoptoad.uucp>
Date: 11 Apr 89 16:21:32 GMT
References: <1562@neoucom.UUCP> <28399@apple.Apple.COM> <43464@XAIT.Xerox.COM> <1227@internal.Apple.COM> <6849@saturn.ucsc.edu>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Distribution: na
Organization: Eclectic Software, San Francisco
Lines: 23

In article <6849@saturn.ucsc.edu> alibaba@ucscb.UCSC.EDU (Alexander M.
Rosenberg) writes:
>>>         ApplicationTrap ( ... ); this trap would be guaranteed to never
>>> be used by Apple but the application would have license to patch it. 
>
>What if one wanted an app to talk to code preloaded by an INIT, hmm?
>
>Can you say cheap IPC? I thought you could.

Wouldn't work under MultiFinder, or under UniFinder if more than one
INIT wanted to use this mechanism.  There are a variety of other tricks
you can use; one that's recommedned by Apple (or used to be) is to
allocate a locked block in the System Heap containing some trademarked
string, then the address of a rendezvous point; you can then search for
the string from the bottom of the system heap and find the rendezvous
point that way.  There are also a variety of almost-guaranteed
appraoches you can do with trap patches.
-- 
Tim Maroney, Consultant, Eclectic Software, sun!hoptoad!tim
"When errors are found in old research, the relevant theories are
 re-examined.  When facts contradict theory, theory gets dumped.  Is
 that why the NLP people are unwilling to research their facts?"
	-- Jerry Hollombe on sci.psychology