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From: matthews@eleazar.dartmouth.edu (Jim Matthews)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Problem with LSP glue for SetClikLoop
Message-ID: <13197@dartvax.Dartmouth.EDU>
Date: 24 Apr 89 15:04:58 GMT
References: <13147@dartvax.Dartmouth.EDU> <13148@dartvax.Dartmouth.EDU> <1681@husc6.harvard.edu>
Sender: news@dartvax.Dartmouth.EDU
Reply-To: matthews@eleazar.dartmouth.edu (Jim Matthews)
Organization: Dartmouth College, Hanover, NH
Lines: 34

In article <1681@husc6.harvard.edu> siegel@endor.UUCP (Rich Siegel) writes:
>	[Problems installing a custom TE Click Loop]
>
>	The "LSP Glue" is supplied to us by Apple, so we're pretty much
>at their mercy. The bug is that, as you point out, the "SetClikLoop"
>glue simply smashes the saved click loop.

I apologize to the Think library programmers, and hope Apple's people
will fix this.  I would suggest that Think leave this glue out the LSP
libraries until Apple fixes it.  It's deceptive to offer a routine that
will fail if you either use it twice or use it with a DA that also
calls it.  The users whose machines are crashing don't care whose fault
it is.

>	I'm not sure if this is bulletproof, but I assigned the 
>address of my custom click loop directly to the TEHandle, and it
>seems to work OK.

This isn't bulletproof.  Unlike most call-back routines, click loops
have to preserve D2 and set D0 to a non-zero value at exit.  Hence the
reason for the glue.  It's possible to work around the problem with
libraries routines that return and set registers.

>	A more thorough solution might maintain a stack of routines
>saved in 14(a5), and a special MySetClikLoop which would push the old
>address, save the new.

I question the wisdom of using the application parameter space for
this kind of kludge.  Furthermore this scheme would only allow one
current click loop -- you should be able to have a different routine for
each text edit record.

Jim Matthews
Dartmouth Software Development