[Boost-users] how to detect if a type is among a know list inside enable_if

Hi, I need to enable only if a type T is among a specific known list. I tried to build an operator is_one_of< T, list of known types > condition that could be used within an enable_if (like others type_traits operators), like this: or< is_same< T, type1 >, or< is_same< T, type2>, ... > so I searched for an or< condition1, condition2> construct and didn't find anything... Thanks for your suggestions! Claude