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From: lsr@apple.UUCP (Larry Rosenstein)
Newsgroups: net.micro.mac
Subject: Re: Reviews wanted please
Message-ID: <23179@apple.UUCP>
Date: Thu, 20-Feb-86 20:53:04 EST
Article-I.D.: apple.23179
Posted: Thu Feb 20 20:53:04 1986
Date-Received: Mon, 24-Feb-86 07:30:29 EST
References: <396@3comvax.UUCP> <1430@wucs.UUCP> <1305@cbdkc1.UUCP>
Reply-To: lsr@apple.UUCP (Larry Rosenstein)
Distribution: net
Organization: Advanced Development Group, Apple Computer
Lines: 20

In article <1305@cbdkc1.UUCP> gwe@dkc1.UUCP ( George Erhart x4021 CB 3D288 RNB ) writes:
>The keyword here is *handle*. Inside Mac makes a big deal about explaining
>the difference between handles and simple pointers. They state very clearly
>that if you are going to reference an item pointed to with handles, AND
>you are going to do anything that allocates memory ... lock the handle
>before using it or the memory manager may rearrange things on you. To be
>on the safe side ... lock all handles before using and unlock them when
>you are done. 

The Software Supplement also contains a list of the ROM calls that allocate
or move objects on the heap.  For example, you don't have to worry about a
call to SetRect but you have to worry about DrawString (calls the Font
Manager, which may swap in the font).

-- 
Larry Rosenstein
Apple Computer

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