hello, I have a problem with conversion of python class instances to shared_ptr inside python. I defined an abstract base class in c++ that is used in c++ and in embedded python. Only shared_ptr to the concrete instances should be useable. Thus the concrete classes have hidden ctor's. They must provide a factory method for creating. Copying of an object must be done using a clone method. In detail there are two problems to be done in python: 1. Create a shared_ptr to a new class instance by using a class factory method 2. Clone a python class instance and return a shared_ptr to the new instance The example code: //in c++ class Base { public: virtual ~Base() {} virtual shared_ptr<Base> clone() const = 0; virtual std::string name() const = 0; protected: Base() {} }; void whoiam(shared_ptr<Base> pBase) { std::cout << pBase->name(); } //for better explanation of the context described above an concrete //class in c++ class DerivedA : public Base { public: static shared_ptr<DerivedA> create(int n, bool b) { return shared_ptr<DerivedA>(new DerivedA(n, b)); } virtual shared_ptr<Base> clone() const { return shared_ptr<DerivedA>(new DerivedA(*this)); } virtual std::string name() const { return "derivedA"; } protected: DerivedA(int n, bool b) : _n(n), _b(b) {} DerivedA(const DerivedA& other) : _n(other._n) {} private: int _n; bool _b; }; //wrapping base struct BaseWrapper : public Base, wrapper<Base> { shared_ptr<Base> clone() const {return this->get_override("clone")();} std::string name() const { return this->get_override("name")(); } }; //export BOOST_PYTHON_MODULE(test) { def("whoiam", &whoiam); class_("Base", no_init) .def("clone", pure_virtual(&Base::clone)) .def("name", pure_virtual(&Base::name)) ; } //in python from test import * //an concrete class in python with the problematic create and copy //methods class DerivedB(Base): def __init__(self, data): self.__data = data @staticmethod def create(data): return DerivedB(data) def copy(self): return self def name(self): return 'derivedB' b = DerivedB.create('somestring') whoiam(b) bCopied = b.copy() whoiam(bCopied) Here is the result of the interpreter for both whoiam lines: whoiam(b) Boost.Python.ArgumentError: Python argument types in whoiam(DerivedB) did not match C++ signature: whoiam(class boost::shared_ptr<class Base>) How can i define/register an converter which does such a conversion? (I'm using Boost 1.32.0, MSVC7.1 and Python 2.4) Thanks a lot for any help, andreas