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danielhfrank/arg_default_dict.py

Created January 22, 2013 21:59
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Extend `collections.defaultdict` to actually be useful and call its `default_factory` with the missing key as an argument. Essentially just a concise way of memoizing the `default_factory` function.
Raw
arg_default_dict.py
from collections import defaultdict
class ArgDefaultDict(defaultdict):
def __missing__(self, key):
self[key] = self.default_factory(key)
return self[key]
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