BUG: Regression in v2.2.x Pandas DataFrame Raises a __deepcopy__ error when class placed in `attrs` about pandas HOT 6 OPEN

To follow up, this PR #55314 is the breaking change.

from pandas.

As outlined in the PR, deepcopy was introduced to prevent unwanted side effects when attrs are used and propagated.

The failure mode of using a class without __deepcopy__ is transparent, just like the fix required (implement deepcopy) to be able to use attrs with the custom class.

On the other hand, side effects from not deepcopy'ing attrs in the background are intransparent to the end user. So in the end using deepcopy is probably preferable.

from pandas.

@achapkowski Maybe try df.attrs["metadata"] = {**InsensitiveDict(data)}.

from pandas.

@achapkowski Since you are making a custom implementation of a dictionary, you can implement a __deepcopy__ like this:

    def __deepcopy__(self, memo):
        result = InsensitiveDict(deepcopy({**self}))
        memo[id(self)] = result
        return result

from pandas.

I know I can implement deepcopy, but the issue is if I use any 3rd party library, like this class from requests, I have to monkey patch it.

from pandas.

How is it problematic? From what I read it's a problem with geopandas not pandas. This is a major regression because most classes and packages do not implement deepcopy.

from pandas.