Issue with subclasses, slots and mangled attributes #506

Activity

1. seperman

   self-assigned this

   on Dec 15, 2024
2. seperman commented on Dec 15, 2024

   

   seperman

   on Dec 15, 2024

   Member

   More actions

   Hi @chriswyatt
   Thanks for reporting the issue and the steps to reproduce. It does seem like an edge case. Looking into it!
3. seperman commented on Dec 15, 2024

   

   seperman

   on Dec 15, 2024

   Member

   More actions

   I don't have MongoDB. When I pass the following code, it works correctly. Am I missing something here?

       def test_custom_objects_slot_in_group_change(self):
           class ClassA:
               __slots__ = ('x', 'y')
   
               def __init__(self, x, y):
                   self.x = x
                   self.y = y
   
           class ClassB(ClassA):
               pass
   
           t1 = ClassA(1, 1)
           t2 = ClassB(1, 1)
           ddiff = DeepDiff(t1, t2, ignore_type_in_groups=[(ClassA, ClassB)])
           result = {}
           assert result == ddiff
4. chriswyatt commented on Dec 16, 2024

   

   chriswyatt

   on Dec 16, 2024

   Last edited by chriswyatt

   Author

   More actions

   Hi @seperman . Thanks for taking a look. The slots need to contain a mangled attribute, i.e. an attribute with 2 leading underscores.

   You can also see it in the ObjectId source code:
   https://github.com/mongodb/mongo-python-driver/blob/master/bson/objectid.py
5. seperman

   added 2 commits that reference this issue on Aug 4, 2026

   Fix mangled __slots__ attribute lost for subclass instances

   ...

   This issue will close once commit 8c3377b is merged into the 'master' branch.

   8c3377b

   Merge pull request #609 from uttam12331/fix/slots-mangled-subclass-506

   ...

   This issue will close once commit 55be560 is merged into the 'master' branch.

   55be560