Hi, I need a metafunction to check if a type is wrapped as an argument of a template and "unwrap" it if so. Something like: template <template <typename> class T, typename C> struct unwrap { typedef C type; static const bool is_wrapped = false; }; template <template <typename> class T, typename C> struct unwrap<T, T<C>> { typedef C type; static const bool is_wrapped = true; }; So both unwrap<x, int>::type and unwrap<x, x<int>>::type are int, while unwrap<x, y<int>>::type is y<int>. Of course I can use the code above, but I'm just curious - does Boost.MPL already provide a utility that can be used to achieve the same? Thanks and best regards, Robert