Inheritance Example

The following example creates a class named Shape with an attribute named sides and a method named perimeter. Three subclasses are created named Triangle, Rectangle, and Square. An instance of each subclass is created, and the attribute value and method result are printed for each shape.

class Shape(object):
    sides = None

    def __init__(self, sides):
        self.sides = sides

    def perimeter(self):
        perimeter = 0
        for side in self.sides:
            perimeter += side
        return perimeter

class Triangle(Shape):
    def __init__(self, side1, side2, side3):
        self.sides = [side1, side2, side3]

class Rectangle(Shape):
    def __init__(self, length, width):
        self.sides = [length, width, length, width]

class Square(Shape):
    def __init__(self, side):
        self.sides = [side, side, side, side]

triangle = Triangle(3, 4, 5)
print("triangle sides:", triangle.sides)
print("triangle perimeter:", triangle.perimeter())

rectangle = Rectangle(4, 2)
print("rectangle sides:", rectangle.sides)
print("rectangle perimeter:", rectangle.perimeter())

square = Square(2)
print("square sides:", square.sides)
print("square perimeter:", square.perimeter())


Output:

triangle sides: [3, 4, 5]
triangle perimeter: 12
rectangle sides: [4, 2, 4, 2]
rectangle perimeter: 12
square sides: [2, 2, 2, 2]
square perimeter: 8