spike.c

#include <Python.h>

static int spike_exec(PyObject *module);
static PyObject *nb_add(PyObject *self, PyObject *args);

typedef struct { int ID; } mod_state_t;
static PyModuleDef_Slot spike_slots[] = {
    {Py_mod_exec, spike_exec},
    {0, NULL}
};
static PyMethodDef Methods[] = { {NULL, NULL, 0, NULL} };
static struct PyModuleDef spike = {
    PyModuleDef_HEAD_INIT,
    NULL,
    NULL,
    sizeof(mod_state_t),
    Methods,
    spike_slots
};

static PyType_Slot slots1[] = {
    {Py_nb_add, nb_add},
    {0, 0},
};
static PyType_Spec Type1_spec = {
    "MyType1", 0, 0,
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
    slots1,
};

static PyType_Slot slots2[] = { {0, 0} };
static PyType_Spec Type2_spec = {
    "MyType2", 0, 0,
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
    slots2,
};

static PyObject *nb_add(PyObject *self, PyObject *args) {
    PyObject *module = PyType_GetModuleByDef(Py_TYPE(self), &spike);
    mod_state_t *state = (mod_state_t*) PyModule_GetState(module);
    return PyLong_FromLong(state->ID);
}

static int spike_exec(PyObject *module) {
    PyObject *py_name = PyObject_GetAttrString(module, "__name__");
    const char *name_s = PyUnicode_AsUTF8AndSize(py_name, NULL);
    mod_state_t *state = (mod_state_t*) PyModule_GetState(module);
    PyObject *type;
    if (strcmp(name_s, "spike") == 0) {
        type = PyType_FromModuleAndSpec(module, &Type1_spec, NULL);
        PyModule_AddObject(module, "MyType1", type);
        state->ID = 1;
    } else {
        // imported as something else like: import subspike.spike
        type = PyType_FromModuleAndSpec(module, &Type2_spec, NULL);
        PyModule_AddObject(module, "MyType2", type);
        state->ID = 2;
    }
    Py_DECREF(type);
    return 0;
}

PyMODINIT_FUNC PyInit_spike(void) {
    return PyModuleDef_Init(&spike);
}

/* Test:
import spike
import subspike.spike # simlink to spike.{tags}.so

class C(spike.MyType1):
   pass

print("class C(spike.MyType1)")
print(f"{C() + C()=}")

class C(spike.MyType1, subspike.spike.MyType2):
   pass

print("class C(spike.MyType1, subspike.spike.MyType2)")
print(f"{C() + C()=}")

class C(subspike.spike.MyType2, spike.MyType1):
   pass

print("class C(subspike.spike.MyType2, spike.MyType1)")
print(f"{C() + C()=}")

# Output:
class C(spike.MyType1)
C() + C()=1
class C(spike.MyType1, subspike.spike.MyType2)
C() + C()=1
class C(subspike.spike.MyType2, spike.MyType1)
C() + C()=2

*/