intobject.c

long
PyInt_AsLong(register PyObject *op)
{
    PyNumberMethods *nb;
    PyIntObject *io;
    long val;

    if (op && PyInt_Check(op))
        return PyInt_AS_LONG((PyIntObject*) op);

    if (op == NULL || (nb = Py_TYPE(op)->tp_as_number) == NULL ||
        nb->nb_int == NULL) {
        PyErr_SetString(PyExc_TypeError, "an integer is required");
        return -1;
    }

    io = (PyIntObject*) (*nb->nb_int) (op);
    if (io == NULL)
        return -1;
    if (!PyInt_Check(io)) {
        if (PyLong_Check(io)) {
            /* got a long? => retry int conversion */
            val = PyLong_AsLong((PyObject *)io);
            Py_DECREF(io);
            if ((val == -1) && PyErr_Occurred())
                return -1;
            return val;
        }
        else
        {
            Py_DECREF(io);
            PyErr_SetString(PyExc_TypeError,
                        "__int__ method should return an integer");
            return -1;
        }
    }

    val = PyInt_AS_LONG(io);
    Py_DECREF(io);

    return val;
}