How to access outer class from an inner class?

The methods of a nested class cannot directly access the instance attributes of the outer class.

Note that it is not necessarily the case that an instance of the outer class exists even when you have created an instance of the inner class.

In fact, it is often recommended against using nested classes, since the nesting does not imply any particular relationship between the inner and outer classes.

You're trying to access Outer's class instance, from inner class instance. So just use factory-method to build Inner instance and pass Outer instance to it.

class Outer(object):

    def createInner(self):
        return Outer.Inner(self)

    class Inner(object):
        def __init__(self, outer_instance):
            self.outer_instance = outer_instance
            self.outer_instance.somemethod()

        def inner_method(self):
            self.outer_instance.anothermethod()