...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::is_dimensionless_quantity — check that a type is a dimensionless quantity
template<typename T> struct is_dimensionless_quantity : public boost::units::is_quantity_of_dimension< T, Dim > { };