Robert P. J. Day wrote:
On Mon, 1 Jan 2007, Christoph Hellwig wrote:
On Sun, Dec 31, 2006 at 02:32:25PM -0500, Robert P. J. Day wrote:
+ (a) Enclose those statements in a do - while block:
+
+ #define macrofun(a, b, c) \
+ do { \
+ if (a == 5) \
+ do_this(b, c); \
+ } while (0)
nitpick, please don't add an indentaion level for the do {. Do this
should look like:
#define macrofun(a, b, c) \
do { \
if (a == 5) \
do_this(b, c); \
} while (0)
the former is the way it's presented in CodingStyle currently, it
wasn't my personal opinion on the subject. i was just reproducing
what was already there.
+ (b) Use the gcc extension that a compound statement enclosed in
+ parentheses represents an expression:
+
+ #define macrofun(a, b, c) ({ \
if (a == 5) \
do_this(b, c); \
- } while (0)
+ })
I'd rather document to not use this - it makes the code far less
redable. And it's a non-standard extension, something we only
use if it provides us a benefit which it doesn't here.
it might be a bit late to put a cork in *that* bottle:
$ grep -r "#define.*({" *
We aren't trying to prevent its past use. We just aren't encouraging
the use of gcc extensions if there are reasonable & better ways to
do something.
--
~Randy
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