Prevent creating new attributes outside __init__

Question

I want to be able to create a class (in Python) that once initialized with __init__, does not accept new attributes, but accepts modifications of existing attri

Answer 1

What about this:

class A():
    __allowed_attr=('_x', '_y')

    def __init__(self,x=0,y=0):
        self._x=x
        self._y=y

    def __setattr__(self,attribute,value):
        if not attribute in self.__class__.__allowed_attr:
            raise AttributeError
        else:
            super().__setattr__(attribute,value)