On Wed, May 29, 2013 at 11:46 AM, Croepha <croe...@gmail.com> wrote:
> Is there anything like this in the standard library?
>
> class AnyFactory(object):
> def __init__(self, anything):
> self.product = anything
> def __call__(self):
> return self.product
> def __repr__(self):
> return "%s.%s(%r)" % (self.__class__.__module__, self.__class__.__name__,
> self.product)
In other words, the function (lambda: x) with a repr that tells you
what x is? Not that I'm aware of, but you could just do something
like:
def return_x(): return x
And then the repr will include the name "return_x", which will give
you a hint as to what it does.
Also, "AnyFactory" is a misleading name because the class above is not
a factory.
> my use case is:
> collections.defaultdict(AnyFactory(collections.defaultdict(AnyFactory(None))))
>
> And I think lambda expressions are not preferable...
What you have above is actually buggy. Your "AnyFactory" will always
return the *same instance* of the passed in defaultdict, which means
that no matter what key you give to the outer defaultdict, you always
get the same inner defaultdict.
Anyway, I think it's clearer with lambdas:
defaultdict(lambda: defaultdict(lambda: None))
But I can see your point about the repr. You could do something like this:
class NoneDefaultDict(dict):
def __missing__(self, key):
return None
def __repr__(self):
return "NoneDefaultDict(%s)" % super(NoneDefaultDict, self).__repr__()
some_dict = defaultdict(NoneDefaultDict)
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