This will allow pandas objects to be collected on the first generation of the gc rather than wait for it to break cycles. Practically I am not sure this will have much of a user change.

dask/distributed#956 (comment)

The idea is to change this code here

from

class _NDFrameIndexer(object): _valid_types = None _exception = KeyError axis = None def __init__(self, obj, name): self.obj = obj self.ndim = obj.ndim self.name = name 

to

class _NDFrameIndexer(object): _valid_types = None _exception = KeyError axis = None def __init__(self, obj, name): self.obj = weakref.ref(obj) self.ndim = obj.ndim self.name = name 

and corresponding self.obj to self.obj()

it 'works' in that gc collection happens immedately upon object deletion (IOW del df). but a few fails on caching / chaining. In particular tests like: https://github.com/pandas-dev/pandas/blob/master/pandas/tests/indexing/test_chaining_and_caching.py#L31 I think were relying upon the reference NOT being collected (so that they can check it).

So this would require some internal reworking to remove / fix this. I suspect we will still achieve the same user effects (meaning of detection of chaining etc).