...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::log::operator<<
// In header: <boost/log/utility/formatting_ostream.hpp> template<typename CharT, typename TraitsT, typename AllocatorT, typename T> basic_formatting_ostream< CharT, TraitsT, AllocatorT > & operator<<(basic_formatting_ostream< CharT, TraitsT, AllocatorT > & strm, T const & value);