issue_comments: 403076034

Some additional explanations

I was consulted by an onwer of a project that is using xarray inside it, the way to load xarray objects that is pickled with older-version xarray.

They does not recommend to use pickle, but some users actually do this and have troubles to restore old pickled files.

In partiular, xarray renamed Coordinate to IndexVariable in some point between v0.7 to v0.8. There might be another module/class name changes too, and these result in the (uninformed) error python UnpicklingError: NEWOBJ class argument isn't a type object

What I would like to propose here is to provide a workaround to unpickle old xarray objects. The function would look like ```python def unpickle_legacy(filename): """ Unpickle old xarray objects. """ class RenamingUnpickler(pickle.Unpickler): def find_class(self, module, name): if name == 'Coordinate': name = 'IndexVariable' return super().find_class(module, name)

with open(filename, 'rb') as f:
    return RenamingUnpickler(f).load()

``` for all the previous releases.

Continuously supporting such a function might be an additional task, but it will emphasize the robustness of our project.

Any comments are welcome.