[boost] Re: Problem with BOOST_STATIC_ASSERT

From: Craig Henderson (cdm.henderson_at_[hidden])
Date: 2002-09-09 02:30:37

Thanks David. I guess if I'm gonna ask stupid questions like this, it should
go to the boost.user list :-)

"David Abrahams" <dave_at_[hidden]> wrote in message
news:012d01c2575d$cdf27830$6401a8c0_at_boostconsulting.com...
> From: "Craig Henderson" <cdm.henderson_at_[hidden]>
>
>
> > I have a problem with the BOOST_STATIC_ASSERT macros on VC++.Net. My
> class
>
>     ...
>
> > Please could someone explain this behaviour? Am I missing something or
> there
> > something wrong with the macro or vc++ compatibility?
>
> Expressions passed to BOOST_STATIC_ASSERT can only be compile-time
> expressions (thus the word STATIC in the name), but typeid() is a runtime
> expression. If you want a runtime assert, use <cassert>. If you want to
> assert that types are the same at compile-time, try:
>
>   #include <boost/type_traits.hpp>
>
>   ...
>
>     BOOST_STATIC_ASSERT((
>         boost::is_same<typename Res::value_type,
diff_result<T>*>::value));
>
> or if you want equivalent behavior to your typeid() expression:
>
>     BOOST_STATIC_ASSERT((
>         boost::is_same<
>             typename boost::remove_cv<
>                 typename boost::remove_reference<
>                     typename Res::value_type
>                 >::type
>             >::type
>             , diff_result<T>*
>         >::value
>     ));
>
>
> HTH,
> Dave
> -----------------------------------------------------------
>            David Abrahams * Boost Consulting
> dave_at_[hidden] * http://www.boost-consulting.com
>
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