Hi, I have some trouble about extended_type_info registration using BOOST_CLASS_EXPORT macro with shared library. Indeed an assertion forbides the registration of the same extended_type_info many times. This cases occurs when defining serialization of derivated classes in different libraries for example considers the 2 libraries : * the first one define a class and its serialization scheme * the second one define a class derived from the class in the first libs and its serialization scheme A program using this two libraries to serialize classes raise an assertion at runtime due to double registration of the base class [ file serialization/extended_type_info.cpp line 74 // make sure that attempt at registration is done only once assert(lookup(eti) == m_self->m_map.end()); ] Here the detail implementation of libraries LIB1 * files : Base.hpp ; Base.cpp defining a base class ( no serialization code here) * file : BaseSerilization.hxx which contains the definition of the non intrusive template function serialize ( no macro BOOST_CLASS_EXPORT here ) * file BaseSerilizationInstanciation.cpp which explicit instanciate the previous function with a fixed Archive class, this file also contain the macro BOOST_CLASS_EXPORT(Base) LIB2 * file Derivated.hpp, Derivated.cpp defining derivated class from Base ( no serialization code here) * file : DerivatedSerilization.hxx which contains the definition of the non intrusive template function serialize ( no macro BOOST_CLASS_EXPORT here ) ** #include "lib1/BaseSerilization.hxx" ** in fonction serialize .... use of base_object< lib1::Base > * file DerivatedInstanciation.cpp which explicit instanciate the previous function with a fixed Archive class, this file also contain the macro BOOST_CLASS_EXPORT(Derivated) a program using these 2 libraries raise an assertion file serialization/extended_type_info.cpp line 74. Indeed the macro BOOST_CLASS_EXPORT(Base) register the extended_type_info of Base. the macro BOOST_CLASS_EXPORT(Derivated) register the extended_type_info of Base *and* the void_caster register in serialize(... Derivated ...) register *again* Base class raising the assertion. So I have some questions 1. Is my design correct ? My programme work fine (Linux&Windows) in release mode. 2. why forbides multi-registration of the same extended_type_info ? 3. what is the interest using std::multiset for unique element instead std::set for tkmap::m_map type ? Regards, Vincent Agnus