Path: utzoo!utdoe!generic!pnet91!ericmcg
From: ericmcg@pnet91.cts.com (Eric Mcgillicuddy)
Newsgroups: comp.sys.apple2
Subject: Re: Handles  Re: Handle Dereferencing (was Re: Q: Orca/C and SFMultiGet2)
Message-ID: <314@generic.UUCP>
Date: 23 Dec 90 00:50:06 GMT
Sender: root@generic.UUCP
Organization: People-Net [pnet91], Etobicoke, ON
Lines: 17

Handles allow you to put the actual code anywhere in memory. The Handle also
tracks various attributes of the memory to which it holds the pointer, i.e.
who owns, what can be done to it, if it can be moved, etc. This allows a
certain amount of memory protection without the expense of hardware memory
management equipment, which is typical of Apple's design philosophy (not just
the Apple II either). 

Dereferencing a Handle in assembly is a bit ugly, but in C it is a piece of
cake. Don't worry about it too much, just pick "Programmer's Introduction to
the Apple IIGS". This book explains much of what you need to know about
programming.

BTW handles also allow you to move the actual code around in memory (if it can
be moved that is).

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