...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::proto::default_domain — The domain expressions have by default, if
proto::extends<>
has not been used
to associate a domain with an expression.
// In header: <boost/proto/domain.hpp> struct default_domain : proto::domain<> { };