Hi, I want to use boost::multi_index_container with a class that have protected constructors, but the compile fails. I think I should make multi_index_container a friend of my class, but I don't know how. #include <iostream> #include #include #include #include #include class Item { public: typedef boost::shared_ptr<Item> P; static P create() { return P(new Item()); } static P create(P item) { return P(new Item(item)); } protected: Item() { } Item(P item) : source(item->get_source()) , target(item->get_target()) { } public: std::string source; std::string target; std::string get_source() const {return source;} std::string get_target() const {return target;} struct key : boost::multi_index::composite_key< P, boost::multi_index::const_mem_fun, boost::multi_index::const_mem_fun >{}; typedef boost::multi_index_container< P, boost::multi_index::indexed_by< boost::multi_index::ordered_non_unique< key, boost::multi_index::composite_key_result_lesskey::result_type > > > index_t; }; int main() { Item::index_t index; Item::P t1 = Item::create(); index.insert(t1); return 0; } Thanks in advance: Imre Horvath