[boost] variant - is there an easy way to tell if an object is a variant at compile time?

From: Brock Peabody (brock.peabody_at_[hidden])
Date: 2004-02-05 19:28:27

Is there an easy way to write:

   template <typename T> struct is_variant {

      typedef ??? type;
   };

So far the best I can come up with is:

1) T has a member type "types" and 
2) T is convertible to make_variant_over<T::types>::type and
3) make_variant_over<T::types>::type is convertible to T

Does anyone have a better idea?

Thanks!