Point users to where in their code they should make mods for Dataset.dims

[hmaarrfk]

Its somewhat annoying to get warnings that point to a line within a library where the warning is issued. It really makes it unclear what one needs to change.

This points to the user's access of the dims attribute.

• Closes #xxxx
• Tests added
• User visible changes (including notable bug fixes) are documented in whats-new.rst
• New functions/methods are listed in api.rst

[dcherian]

mind switching it to

xarray/xarray/core/utils.py

Line 1256 in 9acc411

def emit_user_level_warning(message, category=None):

please?

[hmaarrfk]

sure. i mean, i feel like stack inspection is so overkill though. the call the warning is mean to be fast. any kind of stack inspection in my mind is going to be slower.

The other advantage of emitting stacklevel=3 is that you can actually find internal instances of this within xarray.

However, as you wish. Please feel free to modify this as you see fit and merge, it is really meant to be a simple one liner and merged with ease.

[max-sixty]

Yes, fair — it is definitely a perf tradeoff.

"Ideally" the warnings aren't firing in hot paths / folks rework their code to prevent them. But it is a bit fuzzy.

If we can find a case where it doesn't work well, we could def change the policy...

[max-sixty]

Am going to force merge because the errors are unrelated. But they don't seem transient — I think there's an issue with the dependencies unfortunately.

(I'm guessing moving to a poetry-based installation would be too much of a lift? Upgrading dependencies deliberately with something like dependabot would eliminate 95%+ of our failures on main...)

[hmaarrfk]

Also, i'm not sure if you care, but:

$ grep \\\.warn\(  . -R
./xarray/tests/test_assertions.py:            warnings.warn("warning in test")
./xarray/tests/test_assertions.py:            warnings.warn("warning in test")
./xarray/tests/test_assertions.py:            warnings.warn("test")
./xarray/core/dataset.py:                warnings.warn(
./xarray/core/dataset.py:        warnings.warn(
./xarray/core/dataset.py:            warnings.warn(
./xarray/core/dataset.py:                warnings.warn(
./xarray/core/dataset.py:            warnings.warn(
./xarray/core/dataset.py:            warnings.warn(
./xarray/core/dataset.py:        warnings.warn(
./xarray/core/dataset.py:            warnings.warn(
./xarray/core/dataset.py:            warnings.warn(
./xarray/core/dataset.py:            warnings.warn(
./xarray/core/resample.py:        warnings.warn(
./xarray/core/resample.py:        warnings.warn(
./xarray/core/common.py:            warnings.warn(
./xarray/core/common.py:            warnings.warn(
./xarray/core/common.py:            warnings.warn(
./xarray/core/accessor_dt.py:        warnings.warn(
./xarray/core/computation.py:            warnings.warn(
./xarray/core/computation.py:            warnings.warn(
./xarray/core/groupby.py:        warnings.warn(
./xarray/core/groupby.py:        warnings.warn(
./xarray/core/dataarray.py:        warnings.warn(
./xarray/core/dataarray.py:            warnings.warn(
./xarray/core/options.py:    warnings.warn(
./xarray/core/rolling.py:            warnings.warn(
./xarray/core/variable.py:        warnings.warn(
./xarray/core/variable.py:            warnings.warn(
./xarray/core/variable.py:            warnings.warn(
./xarray/core/variable.py:            warnings.warn(
./xarray/core/nputils.py:        warnings.warn("Polyfit may be poorly conditioned", RankWarning, stacklevel=2)
./xarray/core/duck_array_ops.py:            warnings.warn(
./xarray/core/extensions.py:            warnings.warn(
./xarray/core/utils.py:    warnings.warn(
./xarray/core/utils.py:        warnings.warn(
./xarray/core/utils.py:            warnings.warn(
./xarray/core/utils.py:            warnings.warn(
./xarray/core/utils.py:    warnings.warn(message, category=category, stacklevel=stacklevel)
./xarray/backends/plugins.py:            warnings.warn(
./xarray/backends/plugins.py:            warnings.warn(f"Engine {name!r} loading failed:\n{ex}", RuntimeWarning)
./xarray/backends/plugins.py:            warnings.warn(f"{engine!r} fails while guessing", RuntimeWarning)
./xarray/backends/plugins.py:            warnings.warn(f"{engine!r} fails while guessing", RuntimeWarning)
./xarray/backends/pynio_.py:        warnings.warn(
./xarray/backends/file_manager.py:                warnings.warn(
./xarray/backends/zarr.py:                    warnings.warn(
./xarray/util/deprecation_helpers.py:                warnings.warn(
./xarray/plot/facetgrid.py:                warnings.warn("Ignoring col_wrap since both col and row were passed")
./xarray/plot/facetgrid.py:        warnings.warn(
./xarray/plot/facetgrid.py:        warnings.warn(
./xarray/plot/dataarray_plot.py:                warnings.warn(msg, DeprecationWarning, stacklevel=2)
./xarray/plot/dataarray_plot.py:            warnings.warn(
./xarray/plot/dataarray_plot.py:                warnings.warn(msg, DeprecationWarning, stacklevel=2)
./xarray/plot/dataset_plot.py:                warnings.warn(msg, DeprecationWarning, stacklevel=2)
./xarray/plot/utils.py:        warnings.warn(
./xarray/plot/utils.py:            warnings.warn(
./xarray/coding/cftimeindex.py:            warnings.warn(
./xarray/coding/variables.py:                warnings.warn(
./xarray/coding/variables.py:                warnings.warn(
./xarray/coding/variables.py:                        warnings.warn(
./xarray/coding/times.py:    warnings.warn(warning_msg, SerializationWarning)
./xarray/coding/times.py:                    warnings.warn(
./xarray/namedarray/core.py:            warnings.warn(

[hmaarrfk]

I've been using a custom linting script with ripgrep to enforce easy rules for style like this.

[hmaarrfk]

Thanks again for merging!

[max-sixty]

Thanks again for merging!

Thank you @hmaarrfk !

[max-sixty]

I've been using a custom linting script with ripgrep to enforce easy rules for style like this.

Yes, I've had some success with pre-commit for this!

[hmaarrfk]

it doesn't even have to be so fancy. just

# put it in a run_lint.sh script

matches=$(rg --line-number "^from warnings import warn")
if [ $? == "0" ]; then
    echo To point the user to the correct line of code
    echo We prefer to use `from xarray.core.utils import emit_user_level_warning`
    echo "${matches}"
    exit 1
fi

matches=$(rg --line-number "warnings\.warn")
if [ $? == "0" ]; then
    echo To point the user to the correct line of code
    echo We prefer to use `from xarray.core.utils import emit_user_level_warning`
    echo "${matches}"
    exit 1
fi

[max-sixty]

Yeah, the nice thing about pre-commit is that it runs on every commit already, and runs locally on every platform, and isn't new to most folks. But the script totally fine too!