class Attribute:    # Attribute in the gaming sense of the word, rather than of an object
    def __init__ (self, game):
        self.game = game	                # Done in a central place now
        self.game.attributes.append (self)  # Insert each attribute into a list held by the game
 
class Sprite (Attribute):   # Here, a sprite is an rectangularly shaped attribute that can move
    def __init__ (self, game, width, height):
        self.width = width
        self.height = height
        Attribute.__init__ (self, game)		# Call parent constructor to set game attribute
        
class Paddle (Sprite):
    width = 10		# Constants are defined per class, rather than per individual object
    height = 100	# since they are the same for all objects of that class
					# They are defined BEFORE the __init__, not INSIDE it
    def __init__ (self, game, index):
        self.index = index  # Paddle knows its player index, 0 == left, 1 == right
        Sprite.__init__ (self, game, self.width, self.height)
        
class Ball (Sprite):
    side = 8
    
    def __init__ (self, game):
        Sprite.__init__ (self, game, self.side, self.side)

class Scoreboard (Attribute):	# The scoreboard doesn't move, so it's an attribute but not a sprite
	pass
 
class Game:
    def __init__ (self):
        self.attributes = []    # All attributes will insert themselves into this polymorphic list
        self.paddles = [Paddle (self, index) for index in range (2)]    # Pass game as parameter self
        self.ball = Ball (self)
        self.scoreboard = Scoreboard (self)
        
game = Game ()  # Create and run game