I couldn't think of a good subject..
Basically, say I have a class
class Spam:
def __init__(self, x):
self.x = x
then if I create two instances:
a = Spam('foo')
b = Spam('foo')
a == b # False
What I *really* want is to keep a collection of all the Spam instances,
and if i try to create a new Spam instance with the same contructor
parameters, then return the existing Spam instance. I thought new-style
classes would do it:
class Spam(object):
cache = {}
def __new__(cls, x):
if cls.cache.has_key(x):
return cls.cache[x]
def __init__(self, x):
self.x = x
self.cache[x] = self
a = Spam('foo')
b = Spam('foo')
Well, in this case a and b are identical... to None! I assume this is
because the test in __new__ fails so it returns None, I need to then
create a new Spam.. but how do I do that without calling __new__ again?
I can't call __init__ because there's no self...
So what is the best/preferred way to do this?
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