RE: Setter Gettor method style

[Bissell, Tim]

> From: Pascal Bourguignon [mailto:pjb@informatimago.com]
[...]
> > From: Martin =?iso-8859-1?Q?H=E4cker?= <mhaecker@mac.com>
> > Date: Mon, 5 Aug 2002 00:32:27 +0200
> > 
> > >The '({' stuff is a gcc extension; 'do {...} while(0)' is portable.
> > 
[...]
> In this particular  case, it's just syntactic sugar  that don't change
> anything  to the  generated  code.  So  I  would say,  stick with  the
> compatible do{...}while(0).

This is not strictly speaking true; ({... }) is a gcc extension which
allows you to wrap a code fragment which returns a value, inside a C
expression.
do { ... } while (0) is not a C expression, it is a C statement,
so they are not equivalent.
Specifically, if I define:

#define FOO(X) ({ int result = (X); \
                  if (result > 32 || result < 16) result = 9; result; })

I can go:

{
   int x = ....;
   if (FOO(x) == 12) { .... do something .... }
}

but a definition of:

#define FOO(X) do { int result = (X); \
                  if (result > 32 || result < 16) result = 9; result; }
while (0);

will generate syntax errors in the compiler...



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