CODEWITHSUNDEEP
pythonattributespropertiessubclass
user297250
user297250

Reputation:

How to "hide" superclass methods in a subclass

I basically want to create a subclass that "hides" methods on the superclass so that they don't show up in a dir() or hasattr() call and the users can't call them (at least not through any of the normal channels). I would also like to do this with the least amount of "magic" possible. Thanks.

Upvotes: 8

Views: 3313

Answers (2)

Imran
Imran

Reputation: 90999

Overriding the __dir__ and __getattribute__ method respectively should do the trick. This is the pretty much the canonical way to do this kind of stuff in Python. Although whether you should be actually doing this is entirely a different matter.

See Python docs on Customizing Attribute Access

Use __dir__ to list available attributes (this won't affect actual attribute access)

class A(object):
    def __dir__(self):
        return []

>>> print dir(A())
[]

Use __getattribute__ to control actual attribute access

class A(object):
    def __getattribute__(self, attr):
        """Prevent 'private' attribute access"""
        if attr.startswith('_'):
            raise AttributeError

        return object.__getattribute__(self, attr)


>>> a = A()
>>> a.x = 5
>>> a.x
5
>>> a._x = 3
>>> a._x
AttributeError

This is probably what you are trying to do.

class NoSuper(object):
    def __getattribute__(self, attr):
        """Prevent accessing inherited attributes"""
        for base in self.__bases__:
            if hasattr(base, attr):
                raise AttributeError

        return object.__getattribute__(self, attr)

Upvotes: 7

Keith
Keith

Reputation: 43024

You should not subclass then, you should use composition. Wrap your other class instance in a new class instance and use as necessary.

Upvotes: 6

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