Python3: Class inheritance and private fields

Python doesn't really have private variables, there are two conventions:

• Variables prefixed with underscore (_var) are used to let you and other people know that it's intended to be private
• Variables prefixed with two undersores (__var) are also mangled by python interpreter and also are prefixed by class name, but they are still accessible like self._Superclass__var in your example

See also the documentation.

There is one more issue in your code - you are using class variables, not instance variables (this is what usually called static class variables in other languages).

Check this example:

class Superclass:
    var = 1

    def getVar(self):
        print(self.var)

my_object = Superclass()
my_object2 = Superclass()
my_object.getVar()  # outputs 1
my_object2.getVar()  # outputs 1

Superclass.var = 321  # this value is share across all instances
my_object.getVar()  # outputs 321
my_object2.getVar()  # outputs 321

And when you are doing self.var = xxx assignments in your methods, you just hide the class-level variable and add the new instance-level variable with same name.

See also the documentation: https://docs.python.org/3.6/tutorial/classes.html#class-and-instance-variables