Peter Dimov wrote:

You can add

virtual void load( boost::archive::text_iarchive& ar, unsigned v ) = 0; virtual void save( boost::archive::text_oarchive& ar, unsigned v ) = 0;

to base and call them in A::serialize, but this obviously only works for a specific archive type.

I specifically need to be able to support different archives, so this won't work - but I think something similar to what you have suggested will. Robert Ramey wrote:

How about the following:

template<class Archive> void save(Archive& ar, const unsigned int version) const { ar << _m; cout << "serialise A, _m = " << (unsigned long)_m << endl;}

void save(Archive& ar, const unsigned int version) const { base * t; ar >> t; // deserialize to a temporary // modify _m according to t cout << "serialise A, _m = " << (unsigned long)_m << endl; delete t;

}

Yeh something like this would do the trick. So actually, what I am thinking of is a kind of a mix of Robert's and Peter's suggestions (see code below). It is not the prettiest, but I think I should only have to do this for one class hierarchy in particular, so it isn't too bad. Thanks for your help. The serialization library is going to make my life a lot easier! Darryl Lawson #include <iostream> #include <fstream> #include <cassert> #include #include #include using namespace std; struct base { virtual ~base() {} template<class Archive> void serialize(Archive& ar, const unsigned int version) {} virtual void load(const base* rhs) {} }; struct derived : public base { derived() : base(), _value(0) {} template<class Archive> void serialize(Archive& ar, const unsigned int version) { boost::serialization::void_cast_register(); ar & _value; } virtual void load(const base* rhs) { const derived* t = dynamic_cast(rhs); assert(t); if (!t) return; _value = t->_value; } int _value; }; BOOST_CLASS_EXPORT(derived); struct A { A() { _m = new derived; cout << "construct A, _m = " << (unsigned long)_m << endl; } template<class Archive> void save(Archive & ar, const unsigned int version) const { ar << _m; cout << "save A, _m = " << (unsigned long)_m << endl; } template<class Archive> void load(Archive & ar, const unsigned int version) { base* t; ar >> t; _m->load(t); delete t; cout << "load A, _m = " << (unsigned long)_m << endl; } BOOST_SERIALIZATION_SPLIT_MEMBER(); private: base* _m; }; void save(const A& a, const char* filename) { std::ofstream ofs(filename); boost::archive::text_oarchive oa(ofs); oa << a; } void load(A& a, const char* filename) { std::ifstream ifs(filename); boost::archive::text_iarchive ia(ifs); ia >> a; } int main(int argc, char* argv[]) { A a; save(a, "archive.txt"); A new_a; load(new_a, "archive.txt"); return 0; }