Temporarily revert star annotation in call signatures - remove all internal xarray imports

[Zeitsperre]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR fixes 'xarray.core' has no attribute 'merge' when running with dask 2025.3.0 #2120
  • This PR fixes 'xarray.core' has no attribute 'ops' in xarray 2025.03.0 #2113
• Tests for the changes have been added (for bug fixes / features)
  • (If applicable) Documentation has been added / updated (for bug fixes / features)
• CHANGELOG.rst has been updated (with summary of main changes)
  • Link to issue (:issue:number) and pull request (:pull:number) has been added

What kind of change does this PR introduce?

• Reverts star-annotated call signatures (not supported for Python 3.10)
  *xclim now uses directly operator instead of using xarray's derived get_op function. A refactoring in xarray had changed the position of get_op which caused a bug.
  • All other uses of xarray's internal API were also removed (:pull:2116).
• Updates the pre-commit hooks.

Does this PR introduce a breaking change?

No.

[Zeitsperre]

This PR needs the changes from #2114

[github-actions]

Note

This Pull Request modifies the SDBA module.
The changes made here have been approved. Be sure to port any relevant changes to xsdba.
[!NOTE]
This Pull Request modifies the SDBA module.
The changes made here have been approved. Be sure to port any relevant changes to xsdba.
[!NOTE]
This Pull Request modifies the SDBA module.
The changes made here have been approved. Be sure to port any relevant changes to xsdba.
[!NOTE]
This Pull Request modifies the SDBA module.
The changes made here have been approved. Be sure to port any relevant changes to xsdba.
[!NOTE]
This Pull Request modifies the SDBA module.
The changes made here have been approved. Be sure to port any relevant changes to xsdba.
[!NOTE]
This Pull Request modifies the SDBA module.
The changes made here have been approved. Be sure to port any relevant changes to xsdba.

[aulemahal]

@Zeitsperre My last commit removed all xarray imports that were not from their "public" API, hoping that avoids all further problemes like we add with xarray 2025.3.

To do so, I had to copy a few lines from xarray for the merge_attrs_drop_conflicts and get_temp_dimname functions. @coxipi you might want to the the same as I did for xsdba, even though this is not a bug right now, just futurproofing.

I also had to remove DataArrayResample and DatasetResample from the signature of xc.core.calendar.time_bnds. They are still mentionned in the docstring... Not the best, but I don't see how I can have them in the signature without importing them at runtime....

I also fixed an issue with setting options that are deep dictionaries. And fixed the issue with the missing methods. Flox is now enabled by default for resampling with first and last, but the way xarray calls flox is broken for datetime data in some cases. I simply used another resampling method as the line in expected_count only cares about the output coordinates. (This call is done because the alternative was to dig into private xarray objects)

[Zeitsperre]

I also fixed an issue with setting options that are deep dictionaries. And fixed the issue with the missing methods. Flox is now enabled by default for resampling with first and last, but the way xarray calls flox is broken for datetime data in some cases. I simply used another resampling method as the line in expected_count only cares about the output coordinates. (This call is done because the alternative was to dig into private xarray objects)

Thanks for the fixes! Think you could mention this in the Changelog as a (potentially) breaking change?

[coveralls]

coverage: 89.96% (-0.04%) from 90.004%
when pulling 668f83d on revert-star-annotation
into bade70a on main.

[aulemahal]

as a (potentially) breaking change?

I don't think the user is impacted at all! This change does not change anything in the function's outputs.

I found more xarray internals and removed them. I had to reimplement a version of days_in_year to do so, but the version I copied from xarray is pretty short.

The last xarray internal calls I see, but couldn't/wouldn't remove are:

• xr.core.common._contains_cftime_datetimes and xr.conventions.encode_cf_variable in xclim.sdba.map_blocks : I think the whole block of code can be removed, but I will do so in a PR to xsdba instead.
• xr.coding.cftime_offsets.to_offset in a few places : we need the returned Offset object, which itself isn't public API anyway. No way I am reimplementing this whole machinery in xclim.

Finally, I also had to remove the annotations from xclim.sdba.Grouper.group. I think returning a GroupBy object is ok, but it isn't itself public API, only its methods are... It could be moved around in the module without warning.