Hello,   I have a base class and a large number of derived classes that are all adapted as fusion sequences. The intention is to serialize through the base pointer.  struct Base; struct D_1 : public Base;struct D_2 : public Base;...  All the D_i are adapted as fusion sequences. Besides, there is an mpl vector of all the D_i called DVECTOR.   In a normal setting, I would have written this:    template <typename Archive>void serialize(Archive& ar, Base& b, unsigned int ){  ar & b.member1;}    template <typename Archive>void serialize(Archive& ar, D1& d, unsigned int ){  ar & boost::serialization::base_object<Base>(d);  ar & d.memberd1;}BOOST_CLASS_EXPORT_KEY(D1)   and the same for all D_i. Then I would need BOOST_CLASS_EXPORT_IMPLEMENT for all the D_i as well in the relevant translation units.   The base_object part of serialize() is the same for all D_i The D_i specific part of serialize(), I have the ability to generate with fusion meta functions.   This leads to a template function with 2 template arguments:   template void serialize(Archive& ar, Derived& d, unsigned int ){  ar & boost::serialization::base_object<Base>(d);  // fusion code to work on the Derived fusion sequence to generate a  " ar & ... " line for each member of Derived}  Robert, My question is about the BOOST_CLASS_EXPORT_KEY() and BOOST_CLASS_EXPORT_IMPLEMENT() macros. Am I able to generate all of them from DVECTOR?   regards,