Date: Sun, 22 Jun 2003 21:29:15 -0400 From: Garance A Drosihn <drosih@rpi.edu> To: "Poul-Henning Kamp" <phk@phk.freebsd.dk>, "Sam Leffler" <sam@errno.com> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/vm vm_mmap.c Message-ID: <p0521063cbb1c0360e6bb@[128.113.24.47]> In-Reply-To: <1197.1056217385@critter.freebsd.dk> References: <1197.1056217385@critter.freebsd.dk>
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At 7:43 PM +0200 6/21/03, Poul-Henning Kamp wrote:
> >> Log:
> >> Use a do {...} while (0); and a couple of breaks to reduce
> >> the level of indentation a bit.
>>>
>>> Revision Changes Path
>>> 1.161 +80 -78 src/sys/vm/vm_mmap.c
> >> http://cvsweb.FreeBSD.org/src/sys/vm/vm_mmap.c.diff?r1=1.160&r2=1.161
>>
>>I find this change truly repulsive and gratuitous.
>
>It is a precusor to moving devices out of vnodes. In order to
>get the patch which _does_ something to be manageable, I will
>sort out some minor issues first, this is one of them.
>
>If your complaint is about the use of do { ... break; ... break; }
>while (0); then launch an campaign to have it banned in style 9.
>
>IMO it is superior to goto, and ever deepening if-else constructs.
For this specific example, I don't see that it really buys you
all that much. However, I would say that there are times that
the 'do { ... break; ... break; } while (0);'
strategy can be much easier to read than ever-deepening if-else's.
I would not be happy to see it banned in style(9).
When I use it, I do tend to put a comment on the either the
first or the file line, eg:
do { /* just a target for 'break's */
} while (0); /* just a target for 'break's */
This is just my own opinion, of course. I'm not going to get all
wild-eyed and pound the table over it. The other tactic I use is:
if (...) {
if (other)
goto skipstuff;
if (yetmore)
goto skipstuff;
...stuff...
skipstuff:
alwaydo()
}
which works about the same when it comes to indent-levels.
--
Garance Alistair Drosehn = gad@gilead.netel.rpi.edu
Senior Systems Programmer or gad@freebsd.org
Rensselaer Polytechnic Institute or drosih@rpi.edu
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