More examples of OOP text-based game classes in Python

oop_game2.py

rom collections import defaultdict

_items = defaultdict(set)
_owner = {}

class CanHaveItems(object):
    @property
    def items(self):
        return iter(_items[self])
    def take(self, item):
        item.change_owner(self)
    def lose(self, item):
        """ local cleanup """

class _nobody(CanHaveItems):
    def __repr__(self):
        return '_nobody'
_nobody = _nobody()

class Destroyed(object):
    def __repr__(self):
        return 'This is an ex-item!'

class Item(object):
    def __new__(cls, *a, **k):
        self = object.__new__(cls)
        _owner[self] = _nobody
        _items[_nobody].add(self)
        self._damage = .0
        return self
    def destroy(self):
        self.change_owner(_nobody)
        self.__class__ = Destroyed
    @property
    def damage(self):
        return self._damage
    @damage.setter
    def damage(self, value):
        self._damage = value
        if self._damage >= 1.:
            self.destroy()
    def change_owner(self, new_owner):
        old_owner = _owner[self]
        old_owner.lose(self)
        _items[old_owner].discard(self)
        _owner[self] = new_owner
        _items[new_owner].add(self)


class Ball(Item):
    def __init__(self, color):
        self.color = color
    def __repr__(self):
        return 'Ball(%s)' % self.color

class Player(CanHaveItems):
    def __init__(self, name):
        self.name = name
    def __repr__(self):
        return 'Player(%s)' % self.name

ball = Ball('red')
ball = Ball('blue')

joe = Player('joe')
jim = Player('jim')

print list(joe.items), ':', list(jim.items)
joe.take(ball)
print list(joe.items), ':', list(jim.items)
jim.take(ball)
print list(joe.items), ':', list(jim.items)

print ball, ':', _owner[ball], ':', list(jim.items)
ball.damage += 2
print ball, ':', _owner[ball], ':', list(jim.items)

print _items, ':', _owner