rolling keep_attrs & default True (#4510)

* rolling keep_attrs & default True

* WIP

* remove docstr on keep_attrs

* adapt tests

* rolling WIP

* small update

* update docs

* update tests

* undo refactoring

* some more fixes

* more doc fixes

* test the name is conserved

* test global default and kwarg

* more fixes...

* do a deep copy

* Apply suggestions from code review

doc/whats-new.rst

@@ -23,6 +23,11 @@ v0.16.2 (unreleased)
 Breaking changes
 ~~~~~~~~~~~~~~~~
 
+- :py:attr:`DataArray.rolling` and :py:attr:`Dataset.rolling` no longer support passing ``keep_attrs``
+  via its constructor. Pass ``keep_attrs`` via the applied function, i.e. use
+  ``ds.rolling(...).mean(keep_attrs=False)`` instead of ``ds.rolling(..., keep_attrs=False).mean()``
+  Rolling operations now keep their attributes per default (:pull:`4510`).
+  By `Mathias Hauser <https://github.com/mathause>`_.
 
 New Features
 ~~~~~~~~~~~~
@@ -64,6 +69,9 @@ Bug fixes
   By `Mathias Hauser <https://github.com/mathause>`_.
 - :py:func:`combine_by_coords` now raises an informative error when passing coordinates
   with differing calendars (:issue:`4495`). By `Mathias Hauser <https://github.com/mathause>`_.
+- :py:attr:`DataArray.rolling` and :py:attr:`Dataset.rolling` now also keep the attributes and names of of (wrapped)
+  ``DataArray`` objects, previously only the global attributes were retained (:issue:`4497`, :pull:`4510`).
+  By `Mathias Hauser <https://github.com/mathause>`_.
 - Improve performance where reading small slices from huge dimensions was slower than necessary (:pull:`4560`). By `Dion Häfner <https://github.com/dionhaefner>`_.
 
 Documentation

xarray/core/common.py

@@ -811,10 +811,6 @@ def rolling(
             setting min_periods equal to the size of the window.
         center : bool or mapping, default: False
             Set the labels at the center of the window.
-        keep_attrs : bool, optional
-            If True, the object's attributes (`attrs`) will be copied from
-            the original object to the new one.  If False (default), the new
-            object will be returned without attributes.
         **window_kwargs : optional
             The keyword arguments form of ``dim``.
             One of dim or window_kwargs must be provided.
@@ -863,8 +859,6 @@ def rolling(
         core.rolling.DataArrayRolling
         core.rolling.DatasetRolling
         """
-        if keep_attrs is None:
-            keep_attrs = _get_keep_attrs(default=False)
 
         dim = either_dict_or_kwargs(dim, window_kwargs, "rolling")
         return self._rolling_cls(