Function arraydescr_reduce

numpy/core/src/multiarray/descriptor.c:2603–2716

* return a tuple of (callable object, args, state). * * TODO: This method needs to change so that unpickling doesn't * use __setstate__. This is required for the dtype * to be an immutable object. */

 *       to be an immutable object.
 */
static PyObject *
arraydescr_reduce(PyArray_Descr *self, PyObject *NPY_UNUSED(args))
{
    /*
     * version number of this pickle type. Increment if we need to
     * change the format. Be sure to handle the old versions in
     * arraydescr_setstate.
    */
    const int version = 4;
    PyObject *ret, *mod, *obj;
    PyObject *state;
    char endian;
    int elsize, alignment;

    ret = PyTuple_New(3);
    if (ret == NULL) {
        return NULL;
    }
    mod = PyImport_ImportModule("numpy.core._multiarray_umath");
    if (mod == NULL) {
        Py_DECREF(ret);
        return NULL;
    }
    obj = PyObject_GetAttrString(mod, "dtype");
    Py_DECREF(mod);
    if (obj == NULL) {
        Py_DECREF(ret);
        return NULL;
    }
    PyTuple_SET_ITEM(ret, 0, obj);
    if (PyTypeNum_ISUSERDEF(self->type_num)
            || ((self->type_num == NPY_VOID
                    && self->typeobj != &PyVoidArrType_Type))) {
        obj = (PyObject *)self->typeobj;
        Py_INCREF(obj);
    }
    else {
        elsize = self->elsize;
        if (self->type_num == NPY_UNICODE) {
            elsize >>= 2;
        }
        obj = PyUnicode_FromFormat("%c%d",self->kind, elsize);
    }
    PyTuple_SET_ITEM(ret, 1, Py_BuildValue("(NOO)", obj, Py_False, Py_True));

    /*
     * Now return the state which is at least byteorder,
     * subarray, and fields
     */
    endian = self->byteorder;
    if (endian == '=') {
        endian = '<';
        if (!PyArray_IsNativeByteOrder(endian)) {
            endian = '>';
        }
    }
    if (PyDataType_ISDATETIME(self)) {
        PyObject *newobj;