...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::proto::functional::make_expr::result<This(A...)>
// In header: <boost/proto/make_expr.hpp> template<typename This, typename... A> struct result<This(A...)> : proto::result_of::make_expr< Tag, Domain, A... > { };