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From: minow@mountn.dec.com (Martin Minow)
Newsgroups: comp.sys.mac.programmer
Subject: Re: THINK C Suggestions
Message-ID: <1966@mountn.dec.com>
Date: 12 Oct 90 22:57:18 GMT
References: <90283.224058CXT105@psuvm.psu.edu> <16704@thorin.cs.unc.edu>
Reply-To: minow@bolt.enet.dec.com (Martin Minow)
Organization: Digital Equipment Corporation
Lines: 34

In article <16704@thorin.cs.unc.edu> morse@currituck.cs.unc.edu
(Bryan Morse) writes:

>The general question is: how do you efficiently (using C notation) 
>double-dereference handles and access structure members, especially 
>when chaining handle dereferences?  

Define your handle-based structures as follows:

	typedef struct Mumble {
	    int		mumble;
	} MumbleRec, *MumblePtr, **MumbleHdl;
	/*
	 * The MumbleRec is always accessed using the
	 * mumbleHandle local variable.  Thus, any
	 * element in the structure may be accessed
	 * using the following macro.
	 */
	#define MBL	(**mumbleHandle)

Now, your subroutine is just

	void
	IncrementMumble(
		register MumbleHdl mumbleHandle
	    )
	{
		++MBL.mumble;
	}

It's that simple.

Martin Minow
minow@bolt.enet.dec.com