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hidden attributes

Bengt Richter bokr at oz.net
Tue Dec 17 19:51:26 EST 2002 
On 18 Dec 2002 00:09:49 GMT, bokr at oz.net (Bengt Richter) wrote:

>On 17 Dec 2002 11:04:30 -0800, mis6 at pitt.edu (Michele Simionato) wrote:
>
>>I've just discovered that the attribute __name__ is hidden i.e.
>>not shown by dir:
>>
>>>>> class C: pass
>>...
>>>>> C.__name__
>>'C'
>>>>> dir(C)
>>['__doc__', '__module__'] # __name__ is not shown 
>>>>> help(dir)
>>Help on built-in function dir:
>>
>>dir(...)
>>    dir([object]) -> list of strings
>>
>>    Return an alphabetized list of names comprising (some of) the attributes
>>                                                     ^^^^^^^
>>    of the given object, and of attributes reachable from it:
>>
>>    No argument:  the names in the current scope.
>>    Module object:  the module attributes.
>>    Type or class object:  its attributes, and recursively the attributes of
>>        its bases.
>>    Otherwise:  its attributes, its class's attributes, and recursively the
>>        attributes of its class's base classes.
>>
>>Why __name__ is hidden and how do I discover if there other hidden
>>attributes I don't know about ?
>>
>My guess would be that somehow the attribute access for '__name__'
>finds its way internally to the value via something like
>
> >>> import types
> >>> class C: pass
> ...
> >>> types.ClassType.__getattribute__(C, '__name__')
> 'C'
>
This seems to work more generally, so maybe it's a better guess:

 >>> class C: pass
 ...
 >>> class D(object): pass
 ...
 >>> class E(type): pass
 ...
 >>> [type(x).__getattribute__(x,'__name__') for x in (C,D,E)]
 ['C', 'D', 'E']

>but that's a guess. One could check the code, I suppose. I wonder how hard it
>would be to write a little Python tool to grep the C sources for hardcoded
>attribute names. It might make an interesting listing. Maybe such a script exists?
>

Regards,
Bengt Richter
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