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 2014. The current version is 1.89.0.
boost::proto::context::null_context::eval
// In header: <boost/proto/context/null.hpp> template<typename Expr, typename ThisContext = null_context const> struct eval : proto::context::null_eval< Expr, ThisContext > { };