Boost
C++ Libraries
...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::transform::result<This(Expr)>
template<typename This, typename Expr> struct result<This(Expr)> { // types typedef typename PrimitiveTransform::template impl< Expr, int, int >::result_type type; };