...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
boost::property_tree::path_of — If you want to use a custom key type, specialize this struct for it and give it a 'type' typedef that specifies your path type. The path type must conform to the Path concept described in the documentation. This is already specialized for std::basic_string.
// In header: <boost/property_tree/ptree_fwd.hpp> template<typename Key> struct path_of { };