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# from http://mail.python.org/pipermail/python-dev/2001-June/015239.html
# if you keep changing a dictionary while looking up a key, you can
# provoke an infinite recursion in C
# At the time neither Tim nor Michael could be bothered to think of a
# way to fix it.
class Yuck:
def __init__(self):
self.i = 0
def make_dangerous(self):
self.i = 1
def __hash__(self):
# direct to slot 4 in table of size 8; slot 12 when size 16
return 4 + 8
def __eq__(self, other):
if self.i == 0:
# leave dict alone
pass
elif self.i == 1:
# fiddle to 16 slots
self.__fill_dict(6)
self.i = 2
else:
# fiddle to 8 slots
self.__fill_dict(4)
self.i = 1
return 1
def __fill_dict(self, n):
self.i = 0
dict.clear()
for i in range(n):
dict[i] = i
dict[self] = "OK!"
y = Yuck()
dict = {y: "OK!"}
z = Yuck()
y.make_dangerous()
print(dict[z])
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