...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::type_erasure::ostreamable
// In header: <boost/type_erasure/operators.hpp> template<typename Os = std::ostream, typename T = _self> struct ostreamable { // public static functions static void apply(Os &, const T &); };