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Date: Wed, 2 Jan 2002 09:34:05 -0800 (PST)
From: Julian Elischer <julian@elischer.org>
To: Stephen McKay <mckay@thehub.com.au>
Cc: John Baldwin <jhb@FreeBSD.org>,
	Poul-Henning Kamp <phk@critter.freebsd.dk>, cvs-all@FreeBSD.org,
	cvs-committers@FreeBSD.org, Julian Elischer <julian@FreeBSD.org>,
	Greg Lehey <grog@FreeBSD.org>
Subject: Re: cvs commit: src/share/man/man3 queue.3 
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how about explicitly detailing that it's NULL at the end?
Doesn't that also work?

On Thu, 3 Jan 2002, Stephen McKay wrote:

> On Tuesday, 1st January 2002, Julian Elischer wrote:
> 
> >> >          TAILQ_FOREACH(p, &list, p_next)
> >
> >So you think that the final value of p should be undefined,
> >and there is no  built in way to see if there were any elements in the
> >list at all or whether we completed the list?
> 
> I'd have to say, "Yes".  I expect p to be undefined when the TAILQ_FOREACH
> completes.  It's an internal implementation detail.  Similarly, I wouldn't
> depend on p == head for CIRCLEQ_FOREACH.  You can roll your own loop if
> you want special behaviour.
> 
> >I'm just documenting what the code does, and how people have used it.
> >if you think that phk is correct we should add an example to the man page 
> >showing:
> 
> Perhaps Marcel's good example instead:
> 
> >        TAILQ_FOREACH(p, &list, p_next) {
> >                if (some_test_on(p)) {
> >                        /* Do something */
> >                        break; /* optional */
> >                }
> >        }
> 
> The man page should explicitly state that p is undefined after the loop
> completes unless the user breaks out.  Oh, and explicitly stating that it
> is OK to break out at all might be nice too. :-)
> 
> Stephen.
> 


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