Returning None | ndarray from cpp to python

[kj4tmp]

Is it possible to return None or ndarray from cpp to python?

I am returning an view of an array that may be a null pointer.

Can I return None when this array is null pointer?

[kj4tmp]

.def("get_iomap", [](SOEM_wrapper &wrapper, uint16_t slave) -> std::tuple<BytesArray, BytesArray> {
            if (slave > wrapper.maxslave) {
                throw std::invalid_argument("requested slave is larger than maxslave.");
            }
            // when viewing master iomap (slave=0). bytecount will be accurate
            if (slave == 0){
                size_t shape_inputs[1] = {wrapper.slavelist[slave].Ibytes};
                size_t shape_outputs[1] = {wrapper.slavelist[slave].Obytes};
                return std::make_tuple(
                    BytesArray(wrapper.slavelist[slave].inputs, 1, shape_inputs, nb::handle()),
                    BytesArray(wrapper.slavelist[slave].outputs, 1, shape_outputs, nb::handle()));
            }
            // for slave iomaps, since bytecount can be zero for bitcount < 8, 
            // we will only trust bitcount
            size_t shape_inputs[1] = {wrapper.slavelist[slave].Ibits / 8 + (wrapper.slavelist[slave].Ibits % 8 != 0)};
            size_t shape_outputs[1] = {wrapper.slavelist[slave].Obits / 8 + (wrapper.slavelist[slave].Obits % 8 != 0)};
            return std::make_tuple(
                    BytesArray(wrapper.slavelist[slave].inputs, 1, shape_inputs, nb::handle()),
                    BytesArray(wrapper.slavelist[slave].outputs, 1, shape_outputs, nb::handle()));
        });

well it appears that I can return an empty array by settings shape = 0 and it doesnt matter that the pointer is null pointer