----- Mensaje original ----- De: hongleij@126.com Fecha: Miércoles, Junio 27, 2007 10:16 am Asunto: [Boost-users] [multi-index] how to use in herit member as index Para: boost-users@lists.boost.org
//boost #include <boost/multi_index_container.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/multi_index/member.hpp> using namespace ::boost; using namespace ::boost::multi_index;
#include <string>
struct Peer { std::string userid; }; struct CPeer:public Peer { int index; }; struct userid{};
typedef multi_index_container< CPeer, indexed_by<
hashed_unique<tag<userid>,member<CPeer,std::string,&CPeer::userid> >
CPeersType;
//how could i use userid as an index in CPeer ,not in Peer,
Hello, If you're using Boost 1.34, then you can simply use hashed_unique< tag<userid>, member<Peer,std::string,&Peer::userid> > (note we're writing Peer here rather than CPeer.) If you can't afford upgrading to Boost 1.34, you must use a custom key extractor: struct UseridExtractor { typedef std::string result_type; const std::string& operator()(const CPeer& cp)const { return cp.userid; } }; typedef multi_index_container< CPeer, indexed_by< hashed_unique<tag<userid>,UseridExtractor> >
CPeersType;
(more on custom key extractors at http://tinyurl.com/39shzv ). Thank you for using Boost.MultiIndex, Joaquín M López Muñoz Telefónica, Investigación y Desarrollo