newstyle classes and __getattribute__

Stefan Sonnenberg-Carstens stefan.sonnenberg at freenet.de
Sat Oct 29 00:01:00 CEST 2005


Stefan Sonnenberg-Carstens schrieb:
> James Stroud schrieb:
> 
>> On Friday 28 October 2005 14:26, Stefan Sonnenberg-Carstens wrote:
>>
>>> Hi there,
>>
>>
>> [..clip..]
>>
>>> Now, I do this:
>>>
>>> class T(object):
>>>     def __init__(self,name='',port=80):
>>>         self.name=name
>>>         self.port=port
>>>     def __getattribute__(self,key):
>>>         if key=='somekey':
>>>             return None
>>
>>
>> [..snip..]
>>
>>> But, then surprise:
>>> >>> t = T(name="test123",port=443)
>>> >>> dir(t)
>>>
>>> []
>>>
>>> What the hell is going wrong here ?
>>
>>
>>
>> __getattribute__ is returning None in all cases and dir() is 
>> converting None to [].
>>
>> Anyway, you should have done this:
>>
>> py> class T(object):
>> ....     def __init__(self,name='',port=80):
>> ....             self.name=name
>> ....     def __getattribute__(self,key):
>> ....             if key=='somekey':
>> ....                     return None
>> ....             else:
>> ....               return object.__getattribute__(self, key)
>> ....
>> py> t = T(name="test123",port=443)
>> py> dir(t)
>> ['__class__', '__delattr__', '__dict__', '__doc__', 
>> '__getattribute__', '__hash__', '__init__', '__module__', '__new__', 
>> '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__', 
>> '__weakref__', 'name']
>>
>> James
>>
> Sorry, but I am right that you explicitly call a "super" 
> __getattribute__ on object and pass it a reference to self and the
> desired key ?
> Only asking for clarification ...
> 
> But why does that work under 2.4.1, and even under ActiveState's 2.4.1 ?
> Was that changed between those 2 releases ?
> Intuitive behaviour of __getattribute__ would be:
> If a key is not handeld in that function, return what you already got.
> 
> Cheers,
> Stefan
> 
Sorry,forget that.
It never worked in those releases,
I made some errors which made me belief that, sorry.



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