+ typedef typename add_lvalue_reference<From>::type lvalue_type;
+ typedef typename add_rvalue_reference<From>::type rvalue_type;
+ static lvalue_type _m_from;
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES) && ((__GNUC__ > 4) || ((__GNUC__ == 4) && (__GNUC_MINOR__ > 6)))
+ static bool const value =
+ sizeof( boost::detail::checker<To>::_m_check(static_cast<rvalue_type>(_m_from), 0) )
+ == sizeof(::boost::type_traits::yes_type);
+#else
+ static bool const value =
+ sizeof( boost::detail::checker<To>::_m_check(_m_from, 0) )