Boost
C++ Libraries
...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
This is an older version of Boost and was released in 2023. The current version is 1.90.0.
boost::log::sources::severity::apply
// In header: <boost/log/sources/severity_feature.hpp> template<typename BaseT> struct apply { // types typedef basic_severity_logger< BaseT, LevelT > type; };