Re: #define vs. const

From: Chris Theis (Christian.Theis_at_nospam.cern.ch)
Date: 09/19/04 

Date: Sun, 19 Sep 2004 21:08:56 +0200

"Ioannis Vranos" <ivr@guesswh.at.grad.com> schrieb im Newsbeitrag
news:cikdiv$1h2o$1@ulysses.noc.ntua.gr...
> Chris Theis wrote:
[SNIP]
>
> In most compilers inclusion guards can be replaced with #pragma
> directives. Like
>
> #pragma once
>

Yes, that's true but still compiler dependent.

>
>
> > or of some more nifty uses
> > like in compile time asserts with more informative error messages. I
simply
> > donŽt know how youŽd achieve it without a macro.
> >
> > template <bool x> struct StaticAssert {
> > StaticAssert(...);
> > };
> > template <> struct StaticAssert<false>{};
> > #define COMPILE_ASSERT( Expr, Msg ) \
> > { \
> > class ERROR_##Msg {}; \
> > (void)sizeof( StaticAssert<(Expr) != 0>(( ERROR_##Msg()))); \
> > }
>
>
> With an array of pointers to functions or objects may be?
>

Hmm, could you please elaborate on that. I don't quite see how to gain
informative error messages from compile-time (!) asserts with pointers to
functions or objects. I'd be really interested how to do this, so I'd
appreciate an example.

Best regards
Chris

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