Bug? If not, how to work around it?

[Bengt Richter]

On Wed, 06 Aug 2003 20:40:25 +0100, Gonçalo Rodrigues <op73418 at mail.telepac.pt> wrote:

>Hi,
>
>Consider the following class:
>
>>>> class Test(object):
>... 	def __init__(self, obj):
>... 		self.__obj = obj
>... 	def __getattr__(self, name):
>... 		return getattr(self.__obj, name)
>... 	
>
>Now:
>
>>>> a = Test([])
>>>> a.__iter__
><method-wrapper object at 0x0112CF30>
>>>> iter(a)
>Traceback (most recent call last):
>  File "<interactive input>", line 1, in ?
>TypeError: iteration over non-sequence
>>>> 
>
>Is this a bug? If not, how to code Test such that iter sees the
>__iter__ of the underlying object?
>
Perhaps this way?

 >>> class Test(object):
 ...     def __init__(self, obj):
 ...         self.__obj = obj
 ...     def __getattribute__(self, name):
 ...         return getattr(object.__getattribute__(self, '_Test__obj'), name)
 ...     def __iter__(self):
 ...         return iter(object.__getattribute__(self, '_Test__obj'))
 ...
 >>> a = Test([11, 22])
 >>> a.__iter__
 <method-wrapper object at 0x00902DB0>
 >>> iter(a)
 <listiterator object at 0x00902C50>
 >>> for i in a: print i,
 ...
 11 22
 >>> b = Test('abc')
 >>> for c in b: print `c`,
 ...
 'a' 'b' 'c'
 >>> c = Test(123)
 >>> for x in c: print x
 ...
 Traceback (most recent call last):
   File "<stdin>", line 1, in ?
   File "<stdin>", line 7, in __iter__
 TypeError: iteration over non-sequence
 >>>

Regards,
Bengt Richter