Mastering Object-oriented Python

Complex composite objects

The following is an example of a blackjack Hand description that might be suitable for emulating play strategies:

class Hand:
    def __init__( self, dealer_card ):
        self.dealer_card= dealer_card
        self.cards= []
    def hard_total(self ):
        return sum(c.hard for c in self.cards)
    def soft_total(self ):
        return sum(c.soft for c in self.cards)

In this example, we have an instance variable self.dealer_card based on a parameter of the __init__() method. The self.cards instance variable, however, is not based on any parameter. This kind of initialization creates an empty collection.

To create an instance of Hand, we can use the following code:

d = Deck()
h = Hand( d.pop() )
h.cards.append( d.pop() )
h.cards.append( d.pop() )

This has the disadvantage ...