return an object of a different class

aitilang aitilang at 163.com
Wed Feb 16 03:32:57 CET 2011


er................
I think you need a NumberFactory that makes SmallNumber and BigNumber 
according to the initial value.

于 2011-2-16 10:23, spam at uce.gov 写道:
> How can I do something like this in python:
>
> #!/usr/bin/python3.1
>
> class MyNumbers:
>   def __init__(self, n):
>     self.original_value = n
>     if n <= 100:
>       self = SmallNumers(self)
>     else:
>       self = BigNumbers(self)
>
> class SmallNumbers:
>   def __init__(self, n):
>     self.size = 'small'
>
> class BigNumbers:
>   def __init__(self, n):
>     self.size = 'big'
>
> t = MyNumbers(200)
>
>
> When I do type(t) it says MyNumbers, while I'd want it to be 
> BigNumbers, because BigNumbers and SmallNumbers will have different 
> methods etc...
>
> Do I need to use metaclasses?
>
> Thanks.




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