Messages in this thread | | | Date | Mon, 1 Jan 2007 14:20:20 +0000 | From | Christoph Hellwig <> | Subject | Re: [PATCH] Documentation: Explain a second alternative for multi-line macros. |
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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)
> + (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.
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