Stateless objects without __init__()

The following is an example of a degenerate class that doesn't need an __init__() method. It's a common design pattern for Strategy objects. A Strategy object is plugged into a Master object to implement an algorithm or decision. It may rely on data in the master object; the Strategy object may not have any data of its own. We often design strategy classes to follow the Flyweight design pattern: we avoid internal storage in the Strategy object. All values are provided to Strategy as method argument values. The Strategy object itself can be stateless. It's more a collection of method functions than anything else.

In this case, we're providing the game play decisions for a Player instance. The following is an example of a (dumb) strategy to pick cards and decline the other bets:

class GameStrategy:
    def insurance( self, hand ):
        return False
    def split( self, hand ):
        return False
    def double( self, hand ):
        return False
    def hit( self, hand ):
        return sum(c.hard for c in hand.cards) <= 17

Each method requires the current Hand as an argument value. The decisions are based on the available information; that is, on the dealer's cards and the player's cards.

We can build a single instance of this strategy for use by various Player instances as shown in the following code snippet:

dumb = GameStrategy()

We can imagine creating a family of related strategy classes, each one using different rules for the various decisions a player is offered in blackjack.