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```class KeyedEqualityMixin(object):
def __eq__(self, other):
return self.__key__() == other.__key__()
def __ne__(self, other):
return self.__key__() != other.__key__()

class KeyedComparisonMixin(KeyedEqualityMixin):
def __lt__(self, other):
return self.__key__() < other.__key__()
def __le__(self, other):
return self.__key__() <= other.__key__()
def __gt__(self, other):
return self.__key__() > other.__key__()
def __ge__(self, other):
return self.__key__() >= other.__key__()

class KeyedHashingMixin(KeyedEqualityMixin):
def __hash__(self):
return hash(self.__key__())

# =============================
# And at the interactive prompt
# =============================

>>> class C(object):
...     def __init__(self, x):
...         self.x = x
...
>>> x, y, z = C(1), C(1), C(2)
>>> x == y, y < z, hash(x) == hash(y)
(False, False, False)
>>> class C(KeyedEqualityMixin):
...     def __init__(self, x):
...         self.x = x
...     def __key__(self):
...         return self.x
...
>>> x, y, z = C(1), C(1), C(2)
>>> x == y, y < z, hash(x) == hash(y)
(True, False, False)
>>> class C(KeyedComparisonMixin):
...     def __init__(self, x):
...         self.x = x
...     def __key__(self):
...         return self.x
...
>>> x, y, z = C(1), C(1), C(2)
>>> x == y, y < z, hash(x) == hash(y)
(True, True, False)
>>> class C(KeyedHashingMixin):
...     def __init__(self, x):
...         self.x = x
...     def __key__(self):
...         return self.x
...
>>> x, y, z = C(1), C(1), C(2)
>>> x == y, y < z, hash(x) == hash(y)
(True, False, True)
```

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• revision 2 (14 years ago)
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