Hi, I'm trying to create my own struct that is compatible with boost::mpl::or_ as well as boost::enable_if. I find that using boost::mpl::or_ requires that my structure have a 'type' member, and enable_if looks for 'value'. Must I define both? What is the proper way to handle this? Below is my structure: template< typename t_type > struct is_sink { typedef typename boost::mpl::or_< vfx::io::is_device<t_type>, boost::is_same<t_type, vfx::io::Sink> > type; }; The above structure works perfectly fine with boost::mpl::or_, but does not work for boost::enable_if because it is looking for a 'value' member. I feel what it should be looking for is is_sink::type::value. An example of how I use the above structure is below: template< typename t_source, typename t_data > typename boost::enable_if< boost::mpl::and_<*is_source<t_source>*, boost::is_pod<t_data> >, t_source
::type& operator>> ( t_source& source, t_data& data ) { source.Read( reinterpret_cast<boost::uint8_t*>( &data ), sizeof( t_data ) ); return source; }