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Date: Sun, 23 Mar 2003 00:27:11 -0800 (PST)
From: Linus Torvalds <torvalds@transmeta.com>
To: Adrian Bunk <bunk@fs.tum.de>
cc: Alan Cox <alan@lxorguk.ukuu.org.uk>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] parallel port
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On Sun, 23 Mar 2003, Adrian Bunk wrote:
> > 
> > for me. I think I complained about that once before already. Tssk, tssk.
> 
> It's perhaps a silly question:
> Why did you use a "do ... while  (0)" in your fix?

I always do that (well, almost always), just because it protects macros 
from being mis-used.

For example, if you have

	#define macro(x) ((x) = 3)

that _looks_ safe, but it allows people to write

	x++ = macro(x);

or similar nonsense. So if you want a macro that always behaves like a 
statement (and can't be used as an expression), the "do { } while (0)" 
will do that.

[ The real answer is that it's so built in to my spine, that I just can't 
  stop myself. Even if it doesn't really matter. ]

			Linus

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