...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::units::get_system<unit< Dim, System >> — Get the system of a unit.
// In header: <boost/units/get_system.hpp> template<typename Dim, typename System> struct get_system<unit< Dim, System >> { // types typedef System type; };