Struct template has_env

Struct template has_env_var

boost::proto::result_of::has_env_var — Metafunction for computing the return type of proto::has_env_var().

Synopsis

// In header: <boost/proto/transform/env.hpp>

template<typename Env, typename Key> 
struct has_env_var :
   boost::result_of<proto::functional::has_env_var<Key>(Env)>::type
{
};