Dict inside defaultdict being shared across keys

Question

I have a dictionary inside a defaultdict. I noticed that the dictionary is being shared across keys and therefore it takes the values of the last write. How can I isolate th

Answer 1

Your values all contain references to the same object from defaults: you rebuild the outer dict, but not the inner one. Just make a function that creates a new, separate object:

def builder():
    return {'a': 1, 'b': {}}
dd = defaultdict(builder)