Path: utzoo!attcan!uunet!mcsun!sunic!kth!draken!d88-jwa
From: d88-jwa@nada.kth.se (Reply via mail or intl. +46 8 258 268...)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Integer Size problem
Message-ID: <1480@draken.nada.kth.se>
Date: 24 Aug 89 12:16:49 GMT
References: <15141@dartvax.Dartmouth.EDU> <11689@cit-vax.Caltech.Edu> <1465@draken.nada.kth.se> <8377@hoptoad.uucp>
Reply-To: d88-jwa@nada.kth.se (Jon W{tte)
Organization: Royal Institute of Technology, Stockholm, Sweden
Lines: 46

In article <8377@hoptoad.uucp   tim@hoptoad.UUCP (Tim Maroney) writes:
  In article <11689@cit-vax.Caltech.Edu   palmer@tybalt.caltech.edu.UUCP
  (David Palmer) writes:
    A better way, clearer and probably faster, however is to just do:
    	**(rect **)myHandle = myRect;
    You don't have to lock anything down, it is a single easy to understand
  
  In article <1465@draken.nada.kth.se   d88-jwa@nada.kth.se (Jon W{tte) writes:
    Wrong. Incorrect. What happens if a interrupt happens between the set
    pointers and the block move instruction ? And this interrupt happens
    to shuffle memory ? LOCK THE HANDLES first ! ALWAYS !

Many people have said things about this. For instance:
  
  Wrong.  Incorrect.  Interrupts are forbidden to shuffle memory.  Lock
  handles only when you need to; you risk fragmenting the heap otherwise.
  
I should have said: "And unlock them again when you don't dereference them,"
but I though that was a clear issue.

What's NOT a clear issue is the following:
May OS interrupts move or purge memory ? Apple may do as it damned well
pleases in many other cases, so what about this ? After all, most of the
handle manipulation is in DoVBLTask in ROM...

      	**myhandle.boundrect = myRect;
      		/* ^ or whatever the element name is */
    
    Both Inside Mac and the TechNotes tell us no to change any fields in
    windows or GrafPorts directly. But since everybody's doing it, they
    won't DARE change anything :-)
  
  So?  He's not changing anything in a window or graphics port, he's
  changing something in a window template resource.  If the difference
  isn't clear to you, I recommend re-reading the Window Manager chapter
  of Inside Mac.

I'm sorry, I saw only boundsRect, which I translated as a struct Window
element in my mind. You're right and I'm wrong in this case.

Happy hacking everyone :-)


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