Re: [boost] Boost.Preprocessor: Alternatives to defined(x)

From: Vesa Karvonen (vesa_karvonen_at_[hidden])
Date: 2003-01-05 17:28:50

From: "Paul Mensonides" <pmenso57_at_[hidden]>
>Vesa, I can get it to work on VC and Metrowerks if I alter the semantics
>slightly.  Namely by doing this:
>
>#define IS_ZERO(x) IS_ZERO_I( CHECK x () )
>// ...
>
>#define CHECK() 1
>
>The semantic change is that 'x' must not be a function-like macro.  What do
>you think?

I think that the predicate should still be useful even with the limitation. 
That may well be the best that can be done with some preprocessors at the 
moment. In time, it might be possible to lift the limitation.

...

By the way, I just found the following article (after I posted my proposed 
IS_EMPTY()):

http://groups.google.com/groups?q=is_empty+paul+mensonides&hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=2HB49.54872%24D36.57225%40rwcrnsc53&rnum=1

Interesting stuff.

-Vesa Karvonen

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