Simple factories

factory_v3

def shape_factory(type, *args, **kwargs):
    if type == "Circle": return Circle(*args, **kwargs)
    elif type == "Square": return Square(*args, **kwargs)
    else: None


class Shape(object):
    def draw(self):
        raise NotImplementedError()
    def erase(self):
        raise NotImplementedError()


class Circle(Shape):
    def draw(self):
        print("Circle.draw")
    def erase(self):
        print("Circle.erase")


class Square(Shape):
    def draw(self):
        print("Square.draw")
    def erase(self):
        print("Square.erase")


circle = shape_factory('Circle')
circle.draw()