Get rid of recursive call __getattr__

[Steve Holden]

Peter Otten wrote:
> Pelmen wrote:
> 
> 
>>>>>class Test:
>>
>>          def __getattr__(self, attr):
>>            print attr
>>
>>          def foo(x):
>>            print x
>>
>>
>>>>>t = Test()
>>>>>print t
>>
>>__str__
>>
>>Traceback (most recent call last):
>>  File "<pyshell#23>", line 1, in -toplevel-
>>    print t
>>TypeError: 'NoneType' object is not callable
>>
>>what i have to do? define __str__ explicitly?
> 
> 
> By seemingly not returning anything your __getattr__() method actually
> returns None. Instead you should raise an AttributeError when your
> __getattr__() encounters the name of an attribute it doesn't handle.
> Let's assume Test.__getattr__() should implement an attribute 'alpha' and
> nothing else:
> 
> 
>>>>class Test:
> 
> ...     def __getattr__(self, name):
> ...             print "looking up", name
> ...             if name == "alpha":
> ...                     return 42
> ...             print "lookup failed for", name
> ...             raise AttributeError

or, rather better IMHO,

                   raise AttributeError("lookup failed for %s" % name)
> ...
> 
regards
  Steve
-- 
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