Hello, I have a sample hierarchy of polymorphic classes (A from which B inherits). One of them (A1, B1) is managed with boost::shared_ptr, the other one (A2, B2) via std::shared_ptr (I defined the get_pointer template for std::shared_ptr). When I call f1(boost::shared_ptr<A1>) with an object B1 from python, it is correctly upcast to the pointer to its base class and the c++ function is called. When I call f2(std::shared_ptr<A2>) with B2 argument from python, no upcasting takes place and I get Boost.Python.Argument error. The code is here: foo.cpp: #include<boost/shared_ptr.hpp> /// make boost::python understand std::shared_ptr #include<memory> namespace boost { template<class T> T* get_pointer(std::shared_ptr<T> p){ return p.get(); } } // define a hierarchy struct A1{ virtual ~A1(){} }; struct B1: public A1{ virtual ~B1(){} }; void f1(boost::shared_ptr<A1> ptr){ std::cerr<<"f1()"<<std::endl; } struct A2{ virtual ~A2(){} }; struct B2: public A2{ virtual ~B2(){} }; void f2(std::shared_ptr<A2> ptr){ std::cerr<<"f2()"<<std::endl; } #include<boost/python.hpp> using namespace boost::python; BOOST_PYTHON_MODULE(foo){ class_<A1,boost::shared_ptr<A1>>("A1"); class_<B1,boost::shared_ptr<B1>,bases<A1>>("B1"); def("f1",f1); class_<A2,std::shared_ptr<A2>>("A2"); class_<B2,std::shared_ptr<B2>,bases<A2>>("B2"); def("f2",f2); } compiling with (under Linux): g++ -std=c++0x foo.cpp -o foo.so -fPIC -shared -lboost_python `pkg-config python --libs --cflags` Running PYTHONPATH=. python -c "import foo; foo.f1(foo.B1()); foo.f2(foo.B2());" I obtain: f1() Traceback (most recent call last): File "<string>", line 1, in <module> Boost.Python.ArgumentError: Python argument types in foo.f2(B2) did not match C++ signature: f2(std::shared_ptr<A2>) Where is the problem? Cheers, Vaclav