Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ncar!husc6!xait!dee
From: dee@XAIT.Xerox.COM (Donald Eastlake)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Need some MF help
Message-ID: <43620@XAIT.Xerox.COM>
Date: 9 Apr 89 00:07:23 GMT
References: <1562@neoucom.UUCP> <28399@apple.Apple.COM> <43464@XAIT.Xerox.COM> <1227@internal.Apple.COM> <43549@XAIT.Xerox.COM> <28586@apple.Apple.COM>
Reply-To: dee@XAIT.Xerox.COM (Donald Eastlake)
Distribution: na
Organization: Transfinite Systems Company, Inc., Cambridge, MA
Lines: 43

In article <28586@apple.Apple.COM> lsr@Apple.COM (Larry Rosenstein) writes:
>As always, the price you pay for now listening to the "thought police" is a
>risk that your program won't work as you might desire on future systems.  If
>you are willing to take that risk and/or provide "unexpected" updates to
>your program then you should go ahead and add the feature.  

I suppose that following the rules decreases the probability of unexpected
updates but history shows that conscienctiously following all the rules is
no guarantee of avoiding them.

>One of Tech Support's jobs is to warn developers of upcoming changes.  Often
>they cannot talk about the exact new feature that's coming, and can only
>warn not to do something right now.  It is usually worthwhile to listen to
>what they say, and decide if you want to ignore the warning.

Checking a cross reference for my program, I find yet a third place
where I check for "MultiFinder".  My program is security oriented and
one of its features is to clear out a Mac as much as possible including
parameter RAM and memory.  Unfortunately, under MultiFinder low memory
lies and you have to do a special call to find out about physical memory
limits (unless you want to poke around yourself which seems really hairy
with all the different flavors of memory mapping/folding on different
Macs).  (By the way, my program dispatches on the processor type to do
things to clear different processor internal registers so it may need an
update for the 68040, etc., anyway.)

To summarize, if I were to follow Apple's advice and not test for
MultiFinder, user would find my program obscuring icons by putting
windows over the right side of the screen, they would get confusing
error message saying they could not eject a volume because it was busy
when they try various operations on an MFS disk (for some things my
program unmounts the disk and then remounts it), and my program would
be unable to achieve one of its operational requirements because it
could not clear memory.

The advice not to check for MultiFinder but rather to check for specific
capabilities is excellent.  Too bad its inapplicable because no way was
provided to check for a number of said capabilities.

-- 
	+1 617-969-9570		Donald E. Eastlake, III
	ARPA: dee@XAIT.Xerox.COM    usenet:  {cbosg,decvax,linus}!cca!dee
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