Using nano bind::ref<TimeSeriesReference>

[hhenson]

Hi,

I am trying to move to nanobind from pybind11. I used to make use of shared_ptr holders, but like the idea of the intrusive_base and using ref to wrap return values.

I created a have a make static method (similar to the one in the unit test) and return a newly constructed value as a ref, but when calling in Python I get an error saying it is not possible to convert the ref type to a Python object.

When I change to returning a TimeSeriesReference *, it works fine.

Is there any special magic I am missing?

My code is here:
ref.cpp

// This is included in one module
#include <nanobind/intrusive/counter.inl>

// This is added
nb::intrusive_init(
        [](PyObject *o) noexcept {
            nb::gil_scoped_acquire guard;
            Py_INCREF(o);
        },
        [](PyObject *o) noexcept {
            nb::gil_scoped_acquire guard;
            Py_DECREF(o);
        });

nb::class_<nb::intrusive_base>(
    m, "intrusive_base",
    nb::intrusive_ptr<nb::intrusive_base>(
        [](nb::intrusive_base *o, PyObject *po) noexcept { o->set_self_py(po); }));

using ptr = nb::ref<TimeSeriesReference>;

// And finally the class is registered.
void TimeSeriesReference::register_with_nanobind(nb::module_ &m) {
        nb::class_<TimeSeriesReference, nb::intrusive_base>(m, "TimeSeriesReference")
            .def("__str__", &TimeSeriesReference::to_string)
            .def("__ref__", &TimeSeriesReference::to_string)
            .def("bind_input", &TimeSeriesReference::bind_input)
            .def_prop_ro("has_output", &TimeSeriesReference::has_output)
            .def_prop_ro("is_empty", &TimeSeriesReference::is_empty)
            .def_prop_ro("is_valid", &TimeSeriesReference::is_valid)
            .def_static("make", static_cast<ptr (*)()>(&TimeSeriesReference::make))
            .def_static("make", static_cast<ptr (*)(TimeSeriesOutput::ptr)>(&TimeSeriesReference::make))
            .def_static("make", static_cast<ptr (*)(std::vector<ptr>)>(&TimeSeriesReference::make));

From what I can see I think I have done all the things done in the unit test in nanobind.

[hhenson]

OK, after a bit more investigation, I think I figured out what I was doing wrong.
I had a few places where I had included ref.h without first importing nanobind.h.
Once doing this it resolves the problem.

I guess I would update the documentation to say "ALWAYS include nanobind.h before ref.h".