Hi all. I'm playing with the boost::serialization library, but having a compile issue, with a very obscure error message. It is as follows: Compiler: VC7.1 on Windows XP I get the following compile errors: Compiling... TestClass.cpp c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(142) : error C2027: use of undefined type 'boost::serialization::extended_type_info_null<T>' with [ T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(142) : see reference to class template instantiation 'boost::serialization::extended_type_info_null<T>' being compiled with [ T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(138) : while compiling class-template member function 'bool boost::archive::detail::iserializer<Archive,T>::is_polymorphic(void) const' with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(375) : see reference to class template instantiation 'boost::archive::detail::iserializer<Archive,T>' being compiled with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(369) : while compiling class-template member function 'void boost::archive::detail::load_non_pointer_type<Archive,T>::load_standard: :invoke(Archive &,T &)' with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(425) : see reference to class template instantiation 'boost::archive::detail::load_non_pointer_type<Archive,T>::load_standard ' being compiled with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(418) : while compiling class-template member function 'void boost::archive::detail::load_non_pointer_type<Archive,T>::invoke(Archive &,T &)' with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(572) : see refe rence to class template instantiation 'boost::archive::detail::load_non_pointer_type<Archive,T>' being compiled with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\basic_text_iarchi ve.hpp(64) : see reference to function template instantiation 'void boost::archive::load<Archive,T>(Archive &,T &)' being compiled with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\text_wiarchive.hp p(68) : see reference to function template instantiation 'void boost::archive::basic_text_iarchive<Archive>::load_override<T>(T &,int)' being compiled with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\interface_ iarchive.hpp(76) : see reference to function template instantiation 'void boost::archive::text_wiarchive_impl<Archive>::load_override<T>(T &,int)' being compiled with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Work\Sandbox\CppThroughCOM\CppThroughCOM\TestClass.cpp(67) : see reference to function template instantiation 'Archive &boost::archive::detail::interface_iarchive<Archive>::operator

...

<CppTestClass>(T &)' being compiled

with [ Archive=boost::archive::text_wiarchive, T=CppTestClass ] c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(142) : error C2146: syntax error : missing ';' before identifier 'typex' c:\Dev.Releasev7.2.CR4556\3rdparty\boost\boost\archive\detail\iserialize r.hpp(142) : error C2065: 'typex' : undeclared identifier Here's my code: CppTestClass.hpp: #pragma once #include <boost/serialization/serialization.hpp> #include <boost/serialization/base_object.hpp> #include <boost/serialization/version.hpp> class CppTestClass { private: int m_x; public: CppTestClass(void); virtual ~CppTestClass(void); private: friend class boost::serialization::access; template<class Archive> void load(Archive & ar, const unsigned int version) { ar & version; ar & m_x; } template<class Archive> void save(Archive & ar, const unsigned int version) const { ar & version; ar & m_x; } public: friend std::wostream& operator<<(std::wostream& p_stream, const CppTestClass& p_testClass) { p_stream << p_testClass.m_x; return p_stream; } friend std::wistream& operator>>(std::wistream& p_stream, CppTestClass& p_testClass) { p_stream >> p_testClass.m_x; return p_stream; } BOOST_SERIALIZATION_SPLIT_MEMBER() public: void setX(int p_x) { m_x = p_x; } int getX() const { return m_x; } }; BOOST_CLASS_VERSION(CppTestClass, 1) In TestClass.cpp: This gives no compile errors: std::wstringstream ofs; boost::archive::text_woarchive oa(ofs); // write class instance to archive ofs << m_cppTestClass; ofs >> serData; However, this does: // create and open an archive for input std::wstringstream ifs; ifs << serData; boost::archive::text_wiarchive ia(ifs); // read class state from archive ia >> m_cppTestClass; //!!! errant line? Any ideas what's going on? Thanks in advance, Lawrence