Franck PEREZ wrote:
> Hello all,
>
> Considering the following code :
>
> class C(object):
> ...: observers = []
> ...:
> ...: @classmethod
> ...: def showObservers(cls):
> ...: print cls.observers
>
> class D1(C):
> ...: observers = [] #could it be moved in C ?
>
> class D2(C):
> ...: observers = [] #could it be moved in C ?
>
> I want each child class of C to have it's own "observers" class attribute.
>
> The code I provided works... but I'd like to avoid typing "observers =
> []" in each child class.
>
> Is it possible to define something in C which would basically mean :
> "for each child class, automatically bind a new list attribute called
> observers" ?
>
> Are metaclasses a way ? Is it possible to avoid them ?
> Thanks a lot,
> Franck
By an astounding coincidence, I was just working on a similar problem.
Metaclasses can do this, no problem:
class M(type):
def __init__(cls, name, bases, dict):
cls.observers = []
def showObservers(cls):
print cls.observers
class C(object):
__metaclass__ = M
class D1(C): pass
class D2(C): pass
-Kirk McDonald
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