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.*({" *

rday
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