Should we add preprocessor stuff to conditionally use the C++11 "enum class" construct? #if Whatever #define BOOST_HAVE_ENUM_CLASS #endif //... #if BOOST_HAVE_ENUM_CLASS #define BOOST_ENUM_CLASS( Name ) enum class Name #define BOOST_ENUM_CLASS_BASE( Name, Type ) enum class Name : Type #define BOOST_ENUM_CLASS_REFER( Type, Enumerator ) (Type :: Enumerator) #else #define BOOST_ENUM_CLASS( Name ) enum Name #define BOOST_ENUM_CLASS_BASE( Name, Type ) BOOST_ENUM_CLASS( Name ) #define BOOST_ENUM_CLASS_REFER( Type, Enumerator ) (Enumerator) #endif I'm not sure that the second version of BOOST_ENUM_CLASS_BASE is the best alternative. Nor do I know if the parentheses around enumerators are best. You can use BOOST_ENUM_CLASS in an enum definition header and BOOST_ENUM_CLASS_BASE as a header or a forward declaration. Since enumerators can be scoped, BOOST_ENUM_CLASS_REFER encapsulates the need to add the enum type's name.