Rewriting __getattr__

[Jean-Michel Pichavant]

kost BebiX wrote:
> You're absolutely right! Now try to do except Keyerror: raise AttributeError and it will also fail. But why?
>
> 07.01.2011, 15:45, "Jean-Michel Pichavant" <jeanmichel at sequans.com>:
>   
>> kost BebiX wrote:
>>
>>     
>>>  Hi everyone!
>>>  I just saw a bug (?) in bson.dbref:DBRef.__getattr__
>>>
>>>  Here's they're code:
>>>      def __getattr__(self, key):
>>>          return self.__kwargs[key]
>>>
>>>  And when you do copy.deepcopy on that object it will raise you KeyError. So here's a small piece of code that reproduces the problem:
>>>       
>> from http://docs.python.org/reference/datamodel.html
>>
>> About __getattr__
>> "This method should return the (computed) attribute value or raise an
>> AttributeError
>> <http://docs.python.org/library/exceptions.html#exceptions.AttributeError>
>> exception."
>>
>> The code you provided raises a KeyError thus methods such as 'getattr'
>> will fail as they expect an AttributeError exception.
>>
>> JM
>>
>> --
>> http://mail.python.org/mailman/listinfo/python-list
>>     
>
>   
please don't top post :)

It fails because you simply did not returned any value (with your class 
A example).

class A(object):
    def __init__(self):
        self.d = {}
    def __getattr__(self, key):
        try:
            *return* self.d[key]
        except KeyError:
            raise AttributeError


works fine with deepcopy

JM