...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::numeric::one
// In header: <boost/accumulators/numeric/functional.hpp> template<typename T> struct one { // types typedef one type; typedef T value_type; // public member functions operator T const &() const; static T const value; };