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copied!<p>My previous answer didn't provide sufficient detail, and the solution is really not so simple. This is a complete snippet showing how to do it:</p> <pre><code>#include <boost/flyweight/factory_tag.hpp> #include <boost/flyweight/hashed_factory_fwd.hpp> #include <boost/multi_index_container.hpp> #include <boost/multi_index/identity.hpp> #include <boost/multi_index/hashed_index.hpp> #include <boost/mpl/aux_/lambda_support.hpp> #include <boost/mpl/if.hpp> class bucket_query { public: typedef std::size_t size_type; virtual size_type bucket_count()const=0; virtual size_type max_bucket_count()const=0; virtual size_type bucket_size(size_type n)const=0; }; static bucket_query* bucket_query_ptr=0; template< typename Entry,typename Key, typename Hash=boost::mpl::na,typename Pred=boost::mpl::na, typename Allocator=boost::mpl::na > class accessible_hashed_factory_class: public boost::flyweights::factory_marker, public bucket_query { struct index_list: boost::mpl::vector1< boost::multi_index::hashed_unique< boost::multi_index::identity<Entry>, typename boost::mpl::if_< boost::mpl::is_na<Hash>, boost::hash<Key>, Hash >::type, typename boost::mpl::if_< boost::mpl::is_na<Pred>, std::equal_to<Key>, Pred >::type > > {}; typedef boost::multi_index::multi_index_container< Entry, index_list, typename boost::mpl::if_< boost::mpl::is_na<Allocator>, std::allocator<Entry>, Allocator >::type > container_type; public: typedef const Entry* handle_type; accessible_hashed_factory_class(){bucket_query_ptr=this;} handle_type insert(const Entry& x) { return &*cont.insert(x).first; } void erase(handle_type h) { cont.erase(cont.iterator_to(*h)); } static const Entry& entry(handle_type h){return *h;} typedef std::size_t size_type; virtual size_type bucket_count()const{return cont.bucket_count();} virtual size_type max_bucket_count()const{return cont.max_bucket_count();} virtual size_type bucket_size(size_type n)const{return cont.bucket_size(n);} private: container_type cont; public: typedef accessible_hashed_factory_class type; BOOST_MPL_AUX_LAMBDA_SUPPORT( 5,accessible_hashed_factory_class,(Entry,Key,Hash,Pred,Allocator)) }; template< typename Hash=boost::mpl::na,typename Pred=boost::mpl::na, typename Allocator=boost::mpl::na BOOST_FLYWEIGHT_NOT_A_PLACEHOLDER_EXPRESSION > struct accessible_hashed_factory:boost::flyweights::factory_marker { template<typename Entry,typename Key> struct apply: boost::mpl::apply2< accessible_hashed_factory_class< boost::mpl::_1,boost::mpl::_2,Hash,Pred,Allocator >, Entry,Key > {}; }; /* testing */ #include <boost/flyweight.hpp> #include <iostream> #include <string> int main() { typedef boost::flyweight<std::string,accessible_hashed_factory<> > string_fw; string_fw s1("hello"),s2("hello"),s3("bye"); std::cout<<"number of buckets: "<<bucket_query_ptr->bucket_count()<<std::endl; } </code></pre> <p>The idea is: <code>accessible_hashed_factory_class</code> autoregisters itself via <code>bucket_query_ptr</code> exposing an interface for consulting bucket count etc. (<code>bucket_query</code>) that you can adapt and extend according to your needs. The solution is far from elegant but might solve your problem.</p>

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