Boost C++ Libraries

namespace boost {
  namespace nfp {
    template<typename T> struct is_named_params;

    template<typename T, typename unique_id, typename ReferenceType> 
      struct is_named_params<named_parameter< T, unique_id, ReferenceType >>;
    template<typename NP, typename Rest> 
      struct is_named_params<nfp_detail::named_parameter_combine< NP, Rest >>;

    template<typename unique_id, bool required = false> struct keyword;
    template<typename T, typename unique_id, typename ReferenceType = T&> 
      struct named_parameter;
    template<typename Params, typename KeywordType, 
             typename DefaultType = void> 
      struct param_type;

    template<typename T, typename unique_id, typename ReferenceType, 
             bool required, typename DefaultType> 
      struct param_type<named_parameter< T, unique_id, ReferenceType >, keyword< unique_id, required >, DefaultType>;
    template<typename T, typename unique_id, typename ReferenceType, 
             typename Rest, bool required, typename DefaultType> 
      struct param_type<nfp_detail::named_parameter_combine< named_parameter< T, unique_id, ReferenceType >, Rest >, keyword< unique_id, required >, DefaultType>;
    template<typename NP, typename Rest, typename Keyword, 
             typename DefaultType> 
      struct param_type<nfp_detail::named_parameter_combine< NP, Rest >, Keyword, DefaultType>;

    template<typename T, typename unique_id, bool required = false> 
      struct typed_keyword;

    template<typename unique_id> struct typed_keyword<bool, unique_id, false>;
    template<typename T> void optionally_assign(T &, unspecified);
    template<typename T, typename Source> 
      void optionally_assign(T & target, Source const & src);
    template<typename T, typename Params, typename Keyword> 
      void optionally_assign(T & target, Params const & p, Keyword k);
  }
}