Re: [Boost-users] [TypeTraits] Is it possible to detect that type is not exist and use default type?

AMDG Sakharuk, Vlad (GMI Development) wrote:

Here is example: class one { public: typedef someclass internal; };

class two { // No internal class };

class default_internal{ };

I would like to be able to write something if it possible:

template class proc { };

So I can use proc with both

proc<one> One; proc<two> Two;

without specifying derived type?

Use BOOST_MPL_HAS_XXX_TRAIT_DEF with boost::mpl::eval_if. #include #include BOOST_MPL_HAX_XXX_TRAIT_DEF(internal) template<class T> struct get_internal { typedef typename T::internal type; }; template< class T, class B = typename boost::mpl::eval_if >::type

class proc; In Christ, Steven Watanabe