Hi, I am trying to extend existing C++ objects in Python via inheritance. I can do this successfully and run virtual methods overridden in Python. When I however, try to add the python object to a list of pointers of the C++ Base object type(the Base object the python class has overridden), I get a type error: 'Attempting to append an invalid type' I am sure this error is due to there begin no 'implicitly_convertible' functionality from derived* to base*. In C++, this would be defined as so: implicitly_convertible<[Derived_from_base]*,Base*>();. Is it possible to define this in python? How can I achieve this? Here is sample code reproducing this behaviour. *C++* struct Base { virtual ~Base() {} virtual int f() = 0; }; struct A { std::vector<Base*>& GetBaseList() { return m_base_List; } std::vector<Base*> m_base_List; }; struct BaseWrap : Base, wrapper<Base> { int f() { return this->get_override("f")(); } }; BOOST_PYTHON_MODULE(sandbox) { class_<BaseWrap, Base*, boost::noncopyable>("Base", no_init) .def("f", pure_virtual(&Base::f)); class_<A, A*>("A", init<>()) .add_property("baseList", make_function(&A::GetBaseList, return_internal_reference<>())); //implicitly_convertible<[Derived_from_base]*,Base*>(); class_<std::vector<Base*>>("BaseList").def(vector_indexing_suite<std::vector<Base*>>()); } *Python* from sandbox import * class derived(Base): def __init__(self): self.name = "test" def f(self): print("Hello Derived!") d = derived() d.f() # Output: Hello Derived! a = A() a.baseList.append(d) # TypeError: Attempting to append an invalid type Any help or ideas will be greatly appreciated. Regards, Christoff