This is a C++ syntax issue. The first example explicitly instantiates the serialize declaration without specifying its implementation which leads to an undefined symbol. just use: template<class Archive> void PaloClient::serialize( Archive &ar, const unsigned int version ) { ar & m_PaloClientImpl; } and the appropriate code wil be instantiated if and only if it is actually invoked. Robert Ramey "Oliver Kania" <kania.oliver@googlemail.com> wrote in message news:1262c4ee0711290739x12408875u39e54bbe9effb093@mail.gmail.com... Hello ! When linking a program that consists only of main.cpp with a library that serializes a class "Palo Cllient" I get the following message (sry for the mess): ================================================== error LNK2019: unresolved external symbol "private: void __thiscall jedox::palo::PaloClient::serialize<class boost::archive::text_oarchive>(class boost::archive::text_oarchive &,unsigned int)" (??$serialize@ Vtext_oarchive@archive@boost@@@PaloClient@palo@jedox@@AAEXAAVtext_oarchive@archive@boost@@I@Z) referenced in function "public: static void __cdecl boost::serialization::access::serialize<class boost::archive::text_oarchive,class jedox::palo::PaloClient>(class boost::archive::text_oarchive &,class jedox::palo::PaloClient &,unsigned int)" (??$serialize@ Vtext_oarchive@archive@boost@@VPaloClient@palo@jedox@@@access@serialization@boost@@SAXAAVtext_oarchive@archive@2@AAVPaloClient@palo@jedox@@I@Z) ================================================== This happens even though I do NOT explicitly serialize anything. Main.cpp includes: #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> For the class PaloClient, I do use the Pimpl idiom and serialize as it is recommended in the documentation: PaloClient.cpp: -------------------------------------------------------------- #include <boost/archive/text_oarchive.hpp> #include <boost/archive/text_iarchive.hpp> #include <boost/serialization/scoped_ptr.hpp> .... template<class Archive> void PaloClient::serialize( Archive &ar, const unsigned int version ) { ar & m_PaloClientImpl; } template void PaloClient::serialize<boost::archive::text_iarchive>( boost::archive::text_iarchive & ar, const unsigned int file_version ); template void PaloClient::serialize<boost::archive::text_oarchive>( boost::archive::text_oarchive & ar, const unsigned int file_version ); ------------------------------------------------------------------------ Now, when I change this to void PaloClient::serialize(boost::archive::text_iarchive & ar, const unsigned int file_version) { ar & m_PaloClientImpl; } void PaloClient::serialize (boost::archive::text_oarchive & ar, const unsigned int file_version) { ar & m_PaloClientImpl; } The linkage error disappears. I guess this is a Visual C++ compiler problem but I wanted to post this in case someone else has similar problems. Kind regards, Oliver PS: Thanks for this great serialization library, it saved me many weeks of programming. ------------------------------------------------------------------------------ _______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users