Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!hplabs!nsc!voder!apple!dan
From: dan@Apple.COM (Dan Allen)
Newsgroups: comp.sys.mac.programmer
Subject: Global Data Disclaimer
Keywords: Global data
Message-ID: <11091@apple.Apple.Com>
Date: 27 May 88 01:24:52 GMT
References: <8534@dartvax.Dartmouth.EDU> <10896@apple.Apple.Com> <6645@cit-vax.Caltech.Edu>
Reply-To: dan@apple.UUCP (Dan Allen)
Organization: Apple Computer Inc, Cupertino, CA
Lines: 27

There is a limit to the amount of global data that can be referenced in
the current Mac OS.  I realize that this is a problem.

I have mentioned before that USUALLY when people need to work with lots
of real numbers, as in large global numeric arrays, there are very slick
ways of allocating the data and getting around the conformant array
problem.  I have previously mentioned that a very good solution for the
C programming language can be found in "Numerical Receipes in C",
Cambridge Press.

I agree that in the best of all possible worlds there would not be any 
global data limit.  But there is a limit currently.  I am simply saying
that to change it right now would cause a lot of incompatibility
problems, and that there are useful and easy workarounds to the problem.
I also said that the average large Mac application does not have a
problem, and I quoted the following data:

HyperCard 1.2   312732 bytes of code,  25872 bytes of global data = 8%
MPW Shell 2.0+  179874 bytes of code,  20674 bytes of global data = 11%

Let's all live with the limit, knowing that in some future Mac OS we
will certainly try to have the problem fixed.  Let's spend our time in
the meantime trying to write good code and not moan about this problem
so much...

Dan Allen
Software Explorer
Apple Computer