如何在Python中“動態”分配類變量？

Question

我有以下代碼：

class Potion(object):
    def __init__(self,name,var,varamount):
        self.name=name
        self.var=var
        self.varamount=varamount

class Inventory(object):
    def __init__(self):
        self.items={}
    def use_potion(self,potion):
        potion.var+=potion.varamount
        print("Used a ",potion.name," !")

class Player():
    def __init__(self):
        self.health=100
        self.mana=100
        self.stamina=100

inventory=Inventory()
player=Player()
healthpotion=Potion("Health potion",player.health,50)
inventory.use_potion(healthpotion)

在這里，我的健康葯水應該增加50到變量player.health 。 但是player.health保持不變，只有healthpotion.var被更改。 假設我想要不同類型的葯水（耐力，法力值，生命值），如何動態地將player.health ， player.stamina和player.mana分配給potion.var ？

Answer 1

這樣做不起作用的原因是您已經將參數player.health傳遞給了Potion，這與編寫相同：

Potion("Health potion",100,50)

Answer 2

class Potion():
    def __init__(self,name,var,varamount):
        self.name=name
        self.var=var
        self.varamount=varamount

class Inventory():
    def __init__(self):
        self.items={}

    def add_item(self, item):
        if item in self.items.keys():
            self.items[item] += 1
        else:
            self.items[item] = 1
        print ('Added a {} potion!'.format(item.name)

    def remove_item(self, item):
        if item in self.items.keys():
            self.items[item] -= 1
            return True
        else:
            print ('No such {} exists!'.format(item.name))
            return False


class Player():
    def __init__(self):
        self.health=100
        self.mana=100
        self.stamina=100
        self.inventory = Inventory()

    def use_item(self, item):
        if isinstance(item, Potion):
            if self.inventory.remove_item(item):
                if item.var == 'health':
                    self.health += item.varamount
                    print ('Used a {0} and healed {1}!'.format(item.name, item.varamount))

player=Player()
healthpotion=Potion("Health potion", 'health', 50)
player.use_item(healthpotion)
player.inventory.add_item(healthpotion)
player.use_item(healthpotion)

#No such Health potion exists!
#Added a health potion!
#Used a Health potion and healed 50!

您需要仔細考慮對象的工作方式。

庫存是使用葯水還是玩家使用葯水？

在提供的代碼中，我使Player類具有自己的清單。 然后播放器可以使用添加到其自身庫存中的葯水。

Answer 3

您需要發送創建的Player實例，而不僅僅是其屬性值：

class Potion(object):
    def __init__(self,name,var,varamount):
        self.name=name
        self.var=var
        self.varamount=varamount

class Inventory(object):
    def __init__(self):
        self.items={}
    def use_potion(self,potion):
        # Your potion.var contains Player instance. Access players health.
        potion.var.health += potion.varamount
        print("Used a ",potion.name," !")

class Player():
    def __init__(self):
        self.health=100
        self.mana=100
        self.stamina=100

inventory=Inventory()
player=Player()
healthpotion=Potion("Health potion",player,50) # Send player instance.
print(player.health) # 100
inventory.use_potion(healthpotion)
print(player.health) # 150

Answer 4

您正在使用對象。 對象“知道”事物（其服裝的值），並且對象可以通過調用其方法來相互發送消息。

在這種情況下：

• Player知道他們的健康。
• Potion知道它能在多大程度上增進健康
• Inventory知道它是否有葯水。
• Player應該有一個清單
• Player可以選擇使用其庫存中的物品
• Inventory跟蹤是否已使用物料

基於這些事實，我們知道類需要哪些方法和屬性。

葯水需要知道可以恢復多少健康點

class Potion(object):

    def __init__(self,name, varamount):
        self.name=name
        self.varamount=varamount

庫存需要能夠跟蹤其內容。

class Inventory(object):
    def __init__(self):
        self.items={}

    def add_potion(self, potion):
        self.items['potion'] = potion

    def get_potion(self):
         return self.items.get('potion')

    def remove_potion(self):
        self.items.pop('potion', None)

玩家需要能夠追蹤其健康狀況並使用葯水。

class Player():
    def __init__(self, inventory):
        self.health=100
        self.mana=100
        self.stamina=100
        self.inventory = inventory

    def use_potion(self):
        potion = self.inventory.get_potion()
        if potion:
            self.health += potion.varamount
            self.inventory.remove_potion()
        print("Used a ",potion.name," !")

inventory=Inventory()

healthpotion=Potion("Health potion", 50)
inventory.add_potion(healthpotion)

player=Player(inventory)
player.use_potion()