Clean Code - Ch. 6 Object Shape

object-shape.py

class Shape:
    def area(self):
        raise Exception

class Square(Shape):
    def __init__(self, side):
        self._side = side

    def area(self):
        return self._side ** 2

class Rectangle(Shape):
    def __init__(self, width, height):
        self._width = width
        self._height = height

    def area(self):
        return self._width * self._height

class Circle(Shape):
    def __init__(self, radius):
        self.PI = 3.14159
        self._radius = radius

    def area(self):
        return self.PI * (self._radius ** 2)

def main():
    s = Square(5)
    print s.area()

    r = Rectangle(3, 8)
    print r.area()

    c = Circle(4)
    print c.area()

if __name__ == '__main__':
    main()