...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::icl::identity_based_inplace_combine
// In header: <boost/icl/functors.hpp> template<typename Type> struct identity_based_inplace_combine : public std::binary_function< Type &, const Type &, void > { // public static functions static Type identity_element(); };