issue_comments

@TomNicholas, since the latest commit reverted the completion of the .update deprecation cycle, I think it should be fine to merge this and issue the release.

this would essentially mean that we are extending the deprecation (since code and docs should be in sync)... we did consider the wrapper object in #4932, but I think back then we decided that warning in-code was too much trouble. I'll undo the removal and push the version to 0.21, which should give us some time to discuss what to do.

I would still return something from Dataset.update() for now.

I agree that it would be great to remove it, but to do that perhaps we could make some of Dataset subclass that issues a warning when any method is called on it? Perhaps something like: ```python import xarray import warnings

class DeprecatedDatasetFromUpdate(xarray.Dataset): slots = ['_accessed']

def init(self, args, kwargs): self._accessed = False super().init(args, **kwargs)

def getattribute(self, key): if not super().getattribute('_accessed'): warnings.warn( "This xarray.Dataset was created as the return value of " "xarray.Dataset.update(), but update() will return None in the " "future", category=FutureWarning) self._accessed = True return super().getattribute(key) ```

But could be a little tricky to get right, so perhaps let's save this for a later PR.

As far as I'm concerned this should be ready for a final review. We didn't yet decide what to do about the Dataset.update return value, though.

thanks for the whats-new.rst entries, @TomNicholas

Thanks @keewis for the keep_attrs deprecations (and for the other as well, of course).

This is great - there is one more to remove in combine.py isn't there? line 638

EDIT: I pushed a commit to this branch removing that one too.

Excellent, thanks a lot @keewis !

Maybe it's worth merging from the command line to retain the distinct commits on main (though maybe GH saves them?)