Annotation equality checks can miss some parent class checks

[zhiltsov-max]

The annotation's __eq__() is primarily supported for testing. It's used here:

datumaro/tests/utils/test_utils.py

Line 142 in 36dc989

return expected == actual

In some annotation classes (e.g. RleMask) this method misses some checks due to class inheritance and base method implementation in attrs-defined classes.

Example:

import datumaro as dm
import numpy as np
from datumaro.util import mask_tools

>>> dm.Mask([0], id=1) == dm.Mask([0], id=1)
True
>>> dm.Mask([0], id=1) == dm.Mask([0], id=2)
False

>>> dm.Mask([[0]], id=1) == dm.RleMask(mask_tools.to_uncompressed_rle(mask_tools.mask_to_rle([[0]]), width=1, height=1), id=1)
True
>>> dm.Mask([[0]], id=1) == dm.RleMask(mask_tools.to_uncompressed_rle(mask_tools.mask_to_rle([[0]]), width=1, height=1), id=2)
True

Calls to the parent __eq__() in derived attrs classes is a deep topic with a lot of discussion: python-attrs/attrs#387. It seems we have nothing better than implementing the base class __eq__ manually, but done this way, it won't be used in the autogenerated __eq__ in subclasses.

@attrs(slots=True, kw_only=True, order=False, eq=False)
class Annotation:
    ...

    def __eq__(self, other: Annotation) -> bool:
        # attrs doesn't allow calling the autogenerated __eq__ for different subclasses,
        # but we need to compare the parent fields in some __eq__ overrides in subclasses.
        if not isinstance(other, __class__):
            return False

        return (
            self.id == other.id and
            self.group == other.group and
            self.object_id == other.object_id and
            self.attributes == other.attributes
        )

Originally posted by @zhiltsov-max in #131 (comment)