Re: [Boost-users] [multi-index] how to use in herit member as index

----- 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 #include #include 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 >

...

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 > (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 >

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