void_cast_register should be necessary only in the most unusual cases. It should happen automatically as part of the "base_object" wrappers call. Also it is used void_cast_register<Derived, Base> which is the opposite you've of what you've done below. So I would remove it from your example. The export should make up for this. There are number of code paths related to borland 5.64 and borland 5.51. I don't know anything about borland 6. void_cast/export/template instantiation are areas which many compilers have exhibited unexpected behavior. So its quite possible that the code as is can't accomodate BC 6. As far as I know - we've never seen borland 6 or tested it. So if you want to use any part of boost with a new compiler whose ancestor has a history of special requirements, you should be prepared to run the test suite for that compiler. Please do this and post the results. Robert Ramey Richard Jennings wrote:

I am using Boost 1.32.0 with Borland C++ Builder 6 and attempting to serialize an object via a pointer to a base class but I am getting a runtime exception of "unregistered void cast".

Having read the page in the documentation on Runtime Casting, I thought I should be able to use boost::serialization::void_cast_register<Base, Derived>(0,0); to associate the base and derived classes, but I can't get it to work. If I use the alternate method (to serialize the base class and provide a do-nothing serialize method in the base class) then it works fine. Any ideas what's wrong?

The program below demonstrates the problem. Class A uses the serialize base class method and that's ok while class B uses the void_cast_register method and an exception is thrown when it's serialized: ----- #include <iostream> #include <boost/filesystem/fstream.hpp> #include <boost/filesystem/path.hpp> #include <boost/archive/xml_oarchive.hpp> #include <boost/serialization/export.hpp> #include <boost/serialization/base_object.hpp>

#if defined(_DEBUG) # pragma link "libboost_serialization-bcb-mt-d-1_32.lib" #else # pragma link "libboost_serialization-bcb-mt-1_32.lib" #endif

class Base_c { public: virtual void SomeMethod() = 0; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) {} }; BOOST_IS_ABSTRACT(Base_c)

class A : public Base_c { public: A() : m_Id("A"){}; void SomeMethod(){}; private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { /* boost::serialization::void_cast_register<Base_c, A>(0,0); */ ar & boost::serialization::make_nvp("Base", boost::serialization::base_object<Base_c>(*this)); ar & BOOST_SERIALIZATION_NVP(m_Id); } std::string const m_Id; }; BOOST_CLASS_EXPORT(A);

class B : public Base_c { public: B() : m_Id("B"){}; void SomeMethod(){};

private: friend class boost::serialization::access; template<class Archive> void serialize(Archive & ar, const unsigned int version) { boost::serialization::void_cast_register<Base_c, B>(0,0); /* ar & boost::serialization::make_nvp("Base", boost::serialization::base_object<Base_c>(*this)); */ ar & BOOST_SERIALIZATION_NVP(m_Id); } std::string const m_Id; }; BOOST_CLASS_EXPORT(B)

main(int, char**) {

boost::filesystem::ofstream OfStream(boost::filesystem::path("D:\\Temp\\SerialisationText.xml", boost::filesystem::native)); boost::archive::xml_oarchive Archive(OfStream);

try { Base_c *pBase, *pBase2; pBase = new A(); pBase2 = new B();

Archive & boost::serialization::make_nvp("AByBasePointer", pBase); std::cout << "Serialised A ok\n"; Archive & boost::serialization::make_nvp("BByBasePointer", pBase2); std::cout << "Serialised B ok\n"; } catch (std::exception& E) { std::cout << "Exception: " << E.what(); } } ----- The output is: Serialised A ok Exception: unregistered void cast