NodeIndices does not implement sequence protocol

[polwel]

Information

• rustworkx version: rustworkx-0.12.0-cp39-cp39-win_amd64.whl from PyPI
• Python version: 3.9.12
• Rust version: n/a
• Operating system: Windows 10

What is the current behavior?

Minimal example:

>>> import rustworkx as rx
>>> graph = rx.generators.directed_path_graph(5)
>>> reversed(rx.topological_sort(graph))
Traceback (most recent call last):
  File "C:\Users\polw\venv-dev\lib\site-packages\IPython\core\interactiveshell.py", line 3378, in run_code
    exec(code_obj, self.user_global_ns, self.user_ns)
  File "<ipython-input-4-c1f474a6ec26>", line 1, in <module>
    reversed(rx.topological_sort(graph))
TypeError: rustworkx.NodeIndices is not a sequence

From Python, I can use both len() and indexing on rustworkx.NodeIndices. So that works.

What is the expected behavior?

No error :)

reversed consumes sequences, and NodeIndices is documented to implement the sequence protocol.

Steps to reproduce the problem

See above.

[polwel]

FWIW, on python 3.7 it fails with a different message: TypeError: object of type 'rustworkx.NodeIndices' has no len(). Haven't tested other versions.

On both systems retworkx 0.11 worked fine.

[mtreinish]

Sigh I thought pyo3 fixed all these compatibility issues (we hit similar things earlier in the cycle after upgrading our pyo3 version). Thanks for reporting this I'll see if we're missing something on the newer pyo3 version and get it to act like a sequence properly again, and in the worst case we can just downgrade pyo3 to a version that is doing the correct thing.

[IvanIsCoding]

We need to add tests to cover some behaviors and expected use cases of the custom return types, it's similar to #614 that we took some PyO3 "magic" for granted and they changed the API