Can anyone see what's wrong with this example? #include <stdexcept> #include <boost/shared_ptr.hpp> #include <boost/serialization/split_member.hpp> #include <boost/serialization/nvp.hpp> #include <boost/serialization/shared_ptr.hpp> template<typename value_t> struct overflow_policy_base { overflow_policy_base (value_t _min, value_t _max) : min (_min), max (_max) {} virtual value_t apply (value_t) = 0; // virtual value_t apply (value_t); value_t min, max; friend class boost::serialization::access; template<class Archive> inline void serialize (Archive &ar, const unsigned int) { ar & this->min; ar & this->max; } }; template<typename value_t> struct limit_policy : public overflow_policy_base<value_t> { limit_policy (value_t _min, value_t _max) : overflow_policy_base<value_t> (_min, _max) {} virtual value_t apply (value_t x) { if (x > this->max) return this->max; else if (x < this->min) return this->min; else return x; } template<class Archive> inline void serialize (Archive &ar, const unsigned int) { ar & boost::serialization::base_object<overflow_policy_base<value_t> >(*this); } }; template<typename value_t> struct throw_policy : public overflow_policy_base<value_t> { throw_policy (value_t _min, value_t _max) : overflow_policy_base<value_t> (_min, _max) {} virtual value_t apply (value_t x) { if (x > this->max or x < this->min) throw std::runtime_error ("Histogram value out of range"); else return x; } template<class Archive> inline void serialize (Archive &ar, const unsigned int) { ar & boost::serialization::base_object<overflow_policy_base<value_t> >(*this); } }; #include <boost/serialization/export.hpp> BOOST_SERIALIZATION_SHARED_PTR (limit_policy<double>) BOOST_CLASS_EXPORT_GUID (limit_policy<double>, "limit_policy<double>") g++ -I /usr/local/src/boost.cvs -xc++ -fsyntax-only test.hpp /usr/local/src/boost.cvs/boost/serialization/type_info_implementation.hpp: In instantiation of ‘boost::serialization::type_info_implementation<limit_policy<double> >’: /usr/local/src/boost.cvs/boost/serialization/export.hpp:76: instantiated from ‘boost::archive::detail::guid_initializer<limit_policy<double> >’ test.hpp:64: instantiated from here /usr/local/src/boost.cvs/boost/serialization/type_info_implementation.hpp:50: error: invalid use of undefined type ‘struct boost::serialization::extended_type_info_impl<limit_policy<double> >’ /usr/local/src/boost.cvs/boost/serialization/traits.hpp:42: error: declaration of ‘struct boost::serialization::extended_type_info_impl<limit_policy<double> >’