test.pyx

test.pyx

# distutils: language = c++
cdef cppclass A:
    void c_test():
        print ("hello from A")

cdef cppclass B(A):
    void SetObject(A* ptr):
        print ("dummy method, hello from B")

cdef class pyA:
    cdef A* thisptr
    def __cinit__(self):
        self.thisptr = new A()

    def __dealloc__(self):
        if self.thisptr is not NULL:
            del self.thisptr

cdef class pyB (pyA):
    def __cinit__(self):
        if self.thisptr:
            del self.thisptr
        self.thisptr = new B()

    def __dealloc__(self):
        if self.thisptr is not NULL:
            del self.thisptr

    def set_object(self, obj):
        """
        >>> from test import pyA, pyB
        >>> pya = pyA()
        >>> pyb = pyB()
        >>> pyb_2 = pyB()
        >>> pyb_2.set_object(pya)
        dummy method, hello from B
        >>> pyb_2.set_object(pyb)        
        dummy method, hello from B
        """
        cdef pyA tmpobj = <pyA> obj
        # still need to cast to B class to use SetObject
        (<B*> self.thisptr).SetObject(<A*> tmpobj.thisptr)