Re: [boost] Re: some more questions on MPL and Borland

From: Joel de Guzman (djowel_at_[hidden])
Date: 2003-02-04 08:17:09

----- Original Message ----- 
From: "Vladimir Prus" <ghost_at_[hidden]>

> Joel de Guzman wrote:
> > Hi,
> > 
> > Borland cannot handle this code:
> > 
> > #include <boost/type_traits.hpp>
> > #include <boost/mpl/if.hpp>
> > 
> > using namespace boost;
> > using namespace boost::mpl;
> > 
> > struct A {};
> > struct B {};
> > 
> > template <typename T>
> > struct C : if_<is_empty<T>, A, B>::type {};
> > 
> > struct D { int i; };
> > struct E {};
> > 
> > struct F : C<D> {};
> > struct G : C<E> {};
> 
> Just tried. Works pretty fine. My CVS tree might be a week old, or so.
> Also, maybe 'if_c<::boost::is_empty<T>::value, A, B>' will work. Did
> the same with 'is_same' recently.

template <typename T>
struct C : if_c< ::boost::is_empty<T>::value, A, B>::type {};

Nope, does not work.

Joel de Guzman
joel_at_[hidden]
http://www.boost-consulting.com