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class Delegator:
def __init__(self, delegate=None):
self.delegate = delegate
self.__cache = set()
# Cache is used to only remove added attributes
# when changing the delegate.
def __getattr__(self, name):
attr = getattr(self.delegate, name) # May raise AttributeError
setattr(self, name, attr)
self.__cache.add(name)
return attr
def resetcache(self):
"Removes added attributes while leaving original attributes."
# Function is really about resetting delegator dict
# to original state. Cache is just a means
for key in self.__cache:
try:
delattr(self, key)
except AttributeError:
pass
self.__cache.clear()
def setdelegate(self, delegate):
"Reset attributes and change delegate."
self.resetcache()
self.delegate = delegate
if __name__ == '__main__':
from unittest import main
main('idlelib.idle_test.test_delegator', verbosity=2)
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