...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<< — The operator attaches an attribute value to the log record.
// In header: <boost/log/utility/manipulators/add_value.hpp> template<typename CharT, typename RefT> basic_record_ostream< CharT > & operator<<(basic_record_ostream< CharT > & strm, add_value_manip< RefT > const & manip);