maint: deprecation warning for traitlets

[mattijn]

In the Github Actions is appearing the following warning message:

=============================== warnings summary ===============================
tests/test_jupyter_chart.py: 30 warnings
  /opt/hostedtoolcache/Python/3.11.6/x64/lib/python3.11/site-packages/traitlets/traitlets.py:869: 
  DeprecationWarning: Deprecated in traitlets 4.1, use the instance .metadata dictionary directly, 
  like x.metadata[key] or x.metadata.get(key, default)

We use traitlets within the altair.JupyterChart() class, I did a quick scan of jupyter_chart.py in comparison with traitlets migration docs for 4.1, but I cannot see something that require changing. Not sure where this warning is coming from. You have any idea @jonmmease?

[jonmmease]

Huh, I'm not sure what's triggering that. From the traitlets code, it looks like the deprecation warning is raised when calling the instance.get_metadata() method: https://github.com/ipython/traitlets/blob/fc130b2d44338c8716bab5d409ce7487674f4d15/traitlets/traitlets.py#L860

But we're not doing this directly. I'll try to step through with a debugger to see where this is happening.

[flekschas]

@jonmmease did you ever find out what's triggering these warnings? I'm seeing them in one of my projects too and we're also not using get_metadata().

[jonmmease]

No, I don't think I followed through on digging into it

[dangotbanned]

I'm pretty sure I added filters to the tests that produce this (to ignore) but had no idea this issue existed

If this is the same thing, I couldn't find the source either.

I'll have a look tomorrow and report back

[dangotbanned]

@flekschas @jonmmease

Hopefully these help:

• test: add pytest.mark.filterwarnings for tests that cannot avoid them

  I have been unable to track down what specific calls are triggering the traitlets warnings.
  There seems to be multiple levels of indirection, but the stacklevel reported is external to altair.

• Very slow loading diff (#3431) - It will jump to the right file eventually
• https://github.com/vega/altair/blame/main/tests/test_jupyter_chart.py

If you can find where the Warning is emitted, try changing stacklevel=2 -> stacklevel=3 or higher (directly in the traitlets code) to debug.

See warnings.warn for more info on stacklevel.

---

Update

So far it seems to be triggered by any attribute access of an altair.jupyter_chart.(Selections|Params) instance.

Changing stacklevel=2 -> stacklevel=3 here led me to ipywidgets.Widget.add_traits(), which does call trait.get_metadata('sync').

• stacklevel=3
• stacklevel=4
• stacklevel=5
• stacklevel=6 is where you call alt.JupyterChart()

mro leads to Widget

• altair.JupyterChart
• anywidget.AnyWidget
• ipywidgets.DOMWidget
• ipywidgets.Widget

[dangotbanned]

@mattijn you could consider this fixed, if all you wanted was to avoid the warning in GitHub Actions/pytest.
I imagine you might have wanted to fix the source though.

Unless what I suggested in #3234 (comment) is able to identify the trigger, we're a bit stuck due to how the warning was written in traitlets.

Update

• fix: get_metadata deprecated since traitlets 4.1 jupyter-widgets/ipywidgets#3894

This PR uses the exact fix I came up with, but is failing the ipywidgets CI.
It doesn't break the altair test suite and removes the warnings

Update 2

• HTMLManager: Support both ipywidgets 7 and 8 models jupyter-widgets/ipywidgets#3932

Linking this PR, as it is likely the other PR won't be merged before that