Clean Code - Ch. 6 Data Shape

data-shape.py

class Square:
    def __init__(self):
        self.side = 0

class Rectangle:
    def __init__(self):
        self.width = 0
        self.height = 0

class Circle:
    def __init__(self):
        self.radius = 0

class Geometry:
    def __init__(self):
        self.PI = 3.14159

    def area(self, shape):
        if isinstance(shape, Square):
            return shape.side ** 2
        elif isinstance(shape, Rectangle):
            return shape.width * shape.height
        elif isinstance(shape, Circle):
            return self.PI * (shape.radius ** 2)
        else:
            raise Exception

def main():
    g = Geometry()

    s = Square()
    s.side = 5
    print g.area(s)

    r = Rectangle()
    r.width = 3
    r.height = 8
    print g.area(r)

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

if __name__ == '__main__':
    main()