Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!hoptoad!tim
From: tim@hoptoad.uucp (Tim Maroney)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Scratch8, Scratch20 lmg's
Message-ID: <10848@hoptoad.uucp>
Date: 18 Mar 90 09:51:24 GMT
References: <14420@reed.UUCP>
Reply-To: tim@hoptoad.UUCP (Tim Maroney)
Organization: Eclectic Software, San Francisco
Lines: 25

In article <14420@reed.UUCP> bowman@reed.UUCP (Eric Bowman) writes:
>Just wondering:  how safe are Scratch8 and Scratch20 in terms of future
>compatibility?  (I realize this is kind of unanswerable, but if I can get
>a feel for how many people _use_ them, I'll probably have a good feel for
>how safe they are.)

They're low-memory globals, and therefore unsafe.  Of the low-memory
globals, I would expect Apple to consider these among the most
dispensable.

Low-memory globals may go away at some point in the future for purposes
of simplifying and improving multitasking.  Or they may not -- Apple
couldn't get rid of any large set of them without breaking a huge
amount of the binary software available now.

The recommended solution for most Scratch-using software is to use
code space and PC-relative reads and writes for global data that can't
be reached with a globals register.
-- 
Tim Maroney, Mac Software Consultant, sun!hoptoad!tim, tim@toad.com

"What's bad? What's the use of turning?
 In Hell I'll be there a-burning!
 Meanwhile, think of what I'm earning!
 All on account of my name." - Bill Sykes, "Oliver"