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Python Object-Oriented Python Inheritance Multiple Superclasses

Need To understand the super method with no inheritance

in the listed Example in the video there was two classes (Agile and Sneaky) inside attribute.py how used super inside them despite that they did not inherited from any above classes like previous Videos Examples

2 Answers

Jeff Muday
MOD
Jeff Muday
Treehouse Moderator 26,896 Points

I agree with you that this video is not so clear.

Kenneth is demonstrating "Loosely Coupled Code" to call our attention to what is going on with the __super__ method and how if it is not included, you might have unexpected results associated with MRO (method resolution order) with multiple inheritances. If these are left out, args and kwargs might not be in the instantiated object unless these are passed up the "chain" with the __super__ method.

I am not a fan of his example as I think it demonstrates what can go wrong with Object-Oriented Programming. Conceptually, Character is a class, I agree with that. But the idea that Agile and Sneaky are classes, I would not agree -- semantically speaking, Agile and Sneaky are modifiers of the Character object.

Here's a simpler example of __super__. Think about Squares and Rectangles. A Square is a Rectangle with equal length and width.

If we didn't use inheritance, we would duplicate lots of code!

class Rectangle:
    def __init__(self, length, width):
        self.length = length
        self.width = width

    def area(self):
        return self.length * self.width

    def perimeter(self):
        return 2 * self.length + 2 * self.width

class Square:
    def __init__(self, length):
        self.length = length

    def area(self):
        return self.length * self.length

    def perimeter(self):
        return 4 * self.length

If we use inheritance and __super__ we can save lots of code (and testing).

class Rectangle:
    def __init__(self, length, width):
        self.length = length
        self.width = width

    def area(self):
        return self.length * self.width

    def perimeter(self):
        return 2 * self.length + 2 * self.width

# Here we declare that the Square class inherits from the Rectangle class
class Square(Rectangle):
    def __init__(self, length):
        super().__init__(length, length) # note the super is sending these up to the parent class

Thanks a lot now i have got the point :)