python getattr and name

Question

I'm using "new style" classes in Python 2.6 and am having trouble with __getattr__ in a subclass.

If the subclass implements like such...

def __getattr__(self, name):
    if self.__folderDict.has_key(name):
        if name == 'created':
            return doSomethingSpecial(self.__folderDict[name])
        return self.__folderDict[name]
    else:
        raise AttributeError()

It's not clear to me why my attribute exception gets thrown for a reference to __name__ ?

My understand is that __getattr__ should not even get called and that __name__ should be fullfilled by __getattribute__ since I'm using new style?

Here's a more complete example...

class Base(object):
    @staticmethod
    def printMsg(msg, var):
        print msg + str(var)
        return

    def printName(self):
        Base.printMsg('#', self.__name__)
        return

class Derived(Base):
    def __getattr__(self, name):
        if self.__testDict.has_key(name):
            return self.__testDict[name]
        else:
            raise AttributeError()

    __testDict = {'userid': 4098}


d = Derived()
print d.userid
d.printName()

The result is...

4098
Traceback (most recent call last):
File "D:/.../Scratch/scratch01.py", line 24, in <module>
d.printName()
File "D:/.../Scratch/scratch01.py", line 17, in __getattr__
raise AttributeError()
AttributeError

Agree with the former comment, your information is not very detailed and clear, people may feel confused when they want to write answers. But according to your understanding of __getattr__ and __getattribute__, [this post](http://stackoverflow.com/questions/3278077/difference-between-getattr-vs-getattribute-in-python) seems useful to you. — Reorx, Mar 17 '12 at 16:06

score 1 · Accepted Answer · answered Mar 17 '12 at 16:51

__name__ is predefined for class objects, not instances, and you don't define __name__ anywhere before trying to read it. So _getattr__ is called (since __name__ can't be found via normal lookup) and results in an exception. I suspect that what you actually want is:

...
def printName(self):
    Base.printMsg('#', self.__class__.__name__)
    return
...

python getattr and name

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python __getattr__ and __name__

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python getattr and name