Function _array_fromobject_generic

numpy/core/src/multiarray/multiarraymodule.c:1647–1788

static inline PyObject *
_array_fromobject_generic(
        PyObject *op, PyArray_Descr *in_descr, PyArray_DTypeMeta *in_DType,
        _PyArray_CopyMode copy, NPY_ORDER order, npy_bool subok, int ndmin)
{
    PyArrayObject *oparr = NULL, *ret = NULL;
    PyArray_Descr *oldtype = NULL;
    int nd, flags = 0;

    /* Hold on to `in_descr` as `dtype`, since we may also set it below. */
    Py_XINCREF(in_descr);
    PyArray_Descr *dtype = in_descr;

    if (ndmin > NPY_MAXDIMS) {
        PyErr_Format(PyExc_ValueError,
                "ndmin bigger than allowable number of dimensions "
                "NPY_MAXDIMS (=%d)", NPY_MAXDIMS);
        goto finish;
    }
    /* fast exit if simple call */
    if (PyArray_CheckExact(op) || (subok && PyArray_Check(op))) {
        oparr = (PyArrayObject *)op;

        if (dtype == NULL && in_DType == NULL) {
            /*
             * User did not ask for a specific dtype instance or class. So
             * we can return either self or a copy.
             */
            if (copy != NPY_COPY_ALWAYS && STRIDING_OK(oparr, order)) {
                ret = oparr;
                Py_INCREF(ret);
                goto finish;
            }
            else {
                if (copy == NPY_COPY_NEVER) {
                    PyErr_SetString(PyExc_ValueError,
                            "Unable to avoid copy while creating a new array.");
                    goto finish;
                }
                ret = (PyArrayObject *)PyArray_NewCopy(oparr, order);
                goto finish;
            }
        }
        else if (dtype == NULL) {
            /*
             * If the user passed a DType class but not a dtype instance,
             * we must use `PyArray_AdaptDescriptorToArray` to find the
             * correct dtype instance.
             * Even if the fast-path doesn't work we will use this.
             */
            dtype = PyArray_AdaptDescriptorToArray(oparr, in_DType, NULL);
            if (dtype == NULL) {
                goto finish;
            }
        }

        /* One more chance for faster exit if user specified the dtype. */
        oldtype = PyArray_DESCR(oparr);