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From: gandalf@apple.com (Martin Gannholm)
Newsgroups: comp.sys.mac.hypercard
Subject: Re: HyperCard application memry requirements.
Message-ID: <11924@goofy.Apple.COM>
Date: 31 Jan 91 00:21:47 GMT
Sender: usenet@Apple.COM
Organization: Apple Computer, Inc.
Lines: 44
References:<11910@goofy.Apple.COM> <1991Jan30.192213.2863@waikato.ac.nz>

In article <1991Jan30.192213.2863@waikato.ac.nz> ldo@waikato.ac.nz 
(Lawrence D'Oliveiro, Waikato University) writes:
> What do you suggest an application do if it has ongoing 
> (i e not transitory) memory requirements that can 
> vary *extremely* widely, depending on the data that it is called
> on to handle?

Well, firstly if the system software were perfect and fit every need, they 
wouldn't be working on a System 7.0, would they?
There are applications out there that do caching of data onto disk when 
there isn't enough memory available. I believe that some of the color 
image manipulation programs do this. HyperCard also does this for objects 
such as cards and backgrounds of a stack. You don't ask it to, it just 
does it automatically.
  When it comes to the buffers that HyperCard uses you couldn't really be 
paging those onto the disk all the time (manual VM), since you want 
real-time response when the user clicks and drags on the card. QuickDraw 
also can't use disk memory as the buffer for a grafport.

D'Oliveiro continues:
> By the way, under 7.0, is MultiFinder temporary memory automatically
> deallocated for the application when it quits? If it isn't, then I
> can't see much difference between the MultiFinder temporary heap
> and the system heap.

I believe so, but I may be wrong. Also, multifinder has the option to put 
the memory you ask for in any place it pleases, thereby minimizing some of 
the effects of application fragmentation (you know, largest unused block 
in "About the Finder").

As programs and the use of them changes over time we'll see need for 
changes in the operating system to provide a better model. One of the 
amazing things is that a lot of changes have been made to the Mac over the 
years, but with relatively few incompatibilities. Those of us that are 
programmers need to be ready to change some of the ways we do things every 
now and then. Programming the Mac is always going to be a moving target, 
and nobody ever said that it was easy.


Martin Gannholm
Apple Computer

Exclaimer!!!   I never said it...Nobody heard me say it...You can't prove 
anything!