CPython - How to create and add a method attribute to an object with __dict__?

Question

This can be a tricky question...

In short I am creating and adding a method as follows:

static PyObject *ret_arg(PyBVHTree *self, PyObject *arg)
{
    /* just to demonstrate */
    return arg;
}
static PyMethodDef my_meth = {"ret_arg", (PyCFunction)ret_arg, METH_O, 0};       

...
    PyObject* func = PyCFunction_New(&my_meth, my_object);
    Py_DECREF(my_object);
    PyObject_SetAttrString(my_object, "ret_arg", func);
    Py_DECREF(func);
    return my_object;
}

It works! But having some problems :(

eg.:

• If I del my_object. And use the new method, CRASH.
• When I close the program with python. Error: EXCEPTION_ACCESS_VIOLATION. And this is no problem with refcount

So my question is:

What is the correct way to do this?