...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::expressions::contains
// In header: <boost/log/expressions/predicates/contains.hpp> template<typename DescriptorT, template< typename > class ActorT, typename SubstringT> unspecified contains(attribute_keyword< DescriptorT, ActorT > const &, SubstringT const & substring);