Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!pasteur!ames!haven!purdue!decwrl!sun!pitstop!sundc!seismo!uunet!munnari!jkjl
From: jkjl@munnari.oz (John Lim)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Re: A plea for help (double-clicking disabled in Finder...)
Message-ID: <2672@munnari.oz>
Date: 6 Feb 89 02:25:47 GMT
References: <379@lclark.UUCP> <2580011@hpausla.HP.COM> <25305@apple.Apple.COM>
Reply-To: jkjl@munnari.UUCP (John Lim)
Organization: Comp Sci, Melbourne Uni, Australia
Lines: 41

>	Something that I don't believe is very explicitly spelled out
>in Inside Mac, although it is mentioned several times is that you really
>do want to restore the previous lock state.  Most times your code should
>look like:
>
>	short		state = HGetState(handle);
>
>	HLock(handle);
>	...
>	HSetState(handle, state);
>
>That way you get to make sure it's locked and at the same time don't destroy
>anybody else's notion that it's locked.
>
>David W. Berry
>apple!dwb@sun.com	dwb@apple.com	973-5168@408.MaBell

You only need to do something like this for shared resources like those
from the System File or when you have IPC. Otherwise checking the 
Resource Bits is not really necessary.

The normal HLock-HUnlock pair of traps is satisfactory for most circumstances.

	john lim

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