Derive from C++ class in Ruby (Xapian)

Question

Hi There,

I want to derive from a c++ class in ruby and then pass an instance back to a c++ call. Specifically I want to derive from Xapian::Weight (http://xapian.org/docs/apidoc/html/classXapian%5F1%5F1Weight.html) and then tell Xapian to use my implemention.

I have Xapian talking correctly with acts_as_xapian, but can't get to accept my object.

Does anyone have any examples or solutions?

Cheers

edit:

Specifically this is what I want to implement:

class CoordWeight : public Xapian::Weight {
    public:
        MyWeight * clone() const {
            return new MyWeight;
        }
        MyWeight() { }
        ~MyWeight() { }
        std::string name() const { return "Coord"; }
        std::string serialise() const { return ""; }
        MyWeight * unserialise(const std::string & /*s*/) const {
            return new MyWeight;
        }
        Xapian::weight get_sumpart(Xapian::termcount /*wdf*/, Xapian::doclength /*len*/) const { return 1; }
        Xapian::weight get_maxpart() const { return 1; }

        Xapian::weight get_sumextra(Xapian::doclength /*len*/) const { return 0; }
        Xapian::weight get_maxextra() const { return 0; }

        bool get_sumpart_needs_doclength() const { return false; }
};