在不创建新属性的情况下减少值的简单方法？

Question

我在做一个程序，你发射一个“爆炸机”，我有5枚弹药。我要炸死一个有5个生命的外星人。最后，我实例化播放器，让他爆炸6次，以检查程序是否正常工作。但我做的方式使它的数额不会减少。有一个简单的解决办法，还是我只需要做一个新的属性弹药和健康？以下是我所拥有的：

class Player(object):
""" A player in a shooter game. """
def blast(self, enemy, ammo=5):
    if ammo>=1:
        ammo-=1
        print "You have blasted the alien."
        print "You have", ammo, "ammunition left."
        enemy.die(5)
    else:
        print "You are out of ammunition!"


class Alien(object):
    """ An alien in a shooter game. """
    def die(self, health=5):
        if health>=1:
            health-=1
            print "The alien is wounded. He now has", health, "health left."
        elif health==0:
            health-=1
            print "The alien gasps and says, 'Oh, this is it.  This is the big one. \n" \
                  "Yes, it's getting dark now.  Tell my 1.6 million larvae that I loved them... \n" \
                  "Good-bye, cruel universe.'"
        else:
            print "The alien's corpse sits up momentarily and says, 'No need to blast me, I'm dead already!"

# main
print "\t\tDeath of an Alien\n"

hero = Player()
invader = Alien()
hero.blast(invader)
hero.blast(invader)
hero.blast(invader)
hero.blast(invader)
hero.blast(invader)
hero.blast(invader)

raw_input("\n\nPress the enter key to exit.")

Answer 1

我只是修改了上面的程序，使两个属性命名为ammo和health。 我觉得他们让程序很简单。通过改变属性的初始值来尝试不同的结果。

class Player(object):
""" A player in a shooter game. """ 
def __init__(self, ammo):
    self.ammo = ammo

def blast(self, enemy):
    if enemy.health > 0:
        if self.ammo > 0:
            print "The player has blasted the alien.\n"
            print "The player has", self.ammo, "ammunition left."
            enemy.die()  
        elif self.ammo == 0:
            print "The player can't blast the alien because he is out of ammunition.\n"
        self.ammo -= 1

class Alien(object):
""" An alien in a shooter game. """ 
def __init__(self, health):
    self.health = health

def die(self):
    if self.health > 0:
        self.health -= 1
        print "The alien is wounded. He now has", self.health, "health left.\n"
    if self.health == 0:
        self.health -= 1
        print "The alien gasps and says, 'Oh, this is it. This is the big one. \n"\
          "Yes, it's getting dark now. Tell my 1.6 million larvae that I "\
          "loved them...\nGood-bye, cruel universe.'\n"
    elif self.health < 0:
        print "The alien's corpse sits up momentarily and says, 'No need to blast me, I'm dead already!"

print "\t\tDeath of an Alien\n"
hero = Player(6)
invader = Alien(3)
blast = int(raw_input("How many times do you want to blast the alien? "))
for cnt in range(blast - 1):
    hero.blast(invader)