AMDG

David Abrahams wrote:

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;
   

      ^
missing "::type" here? Otherwise, the "typename" above is probably illegal
 

typename is legal because the or_ is qualified.  It doesn't matter
that boost::mpl is a namespace.  (Don't you just love these intuitive rules)