在while循环中使用kwargs-Python 3

Question

在下面的代码中，我试图检查值（b）是否为kwargs中的键，如果是，请执行其余操作。

def shop(**kwargs):
    buy = 1
    print ("Welcome to the shop!")
    for i, v in kwargs.items():
        print ("    ", i, ": ", v)
    while buy == 1:
        b = input ("What would you like to buy? ").lower()
        if b == i.lower():
            if v <= Player.gold:
                Player.gold -= v
                Player.inv_plus(i)
                print ("You bought ", i, "for ", v, "gold!")
                print ("Your gold: ", Player.gold)
                print (Player.show_inv())
                print ()
            else:
                print ("You don't have enough gold!")
                print ()
        elif b == "exit":
            buy = 0
        else:
            print ("We don't sell that item!")
            print ()

shop(Stone=5, Potion=10)

但是，当我尝试运行代码时，它总是只允许一个选项。 我发现很难解释，因此我举一个例子：

Welcome to the shop!
     Stone :  5
     Potion :  10
What would you like to buy? stone
We don't sell that item!

What would you like to buy? potion
You bought  Potion for  10 gold!
Your gold:  0
Inventory: 
     Potion 6
     Stone 2

即使它在字典中，它也不会接受石头，但是它将接受药水。 其他时间则相反。

起初我以为是因为它处于while循环中，但是现在我不太确定，在其他任何地方都找不到任何可以帮助我的东西。

抱歉，这很具体，但这给我带来了很多麻烦。

Answer 1

当您遍历所有项目以打印它们时：

for i, v in kwargs.items():
    print ("    ", i, ": ", v)

i变量最终以kwargs保存最后一项的名称。 这就是为什么它适用于“药水”而不适用于“石头”的原因。

正如Mohammed回答的那样，您需要检查kwargs所有项目，而不仅仅是最后一项。

Answer 2

最好将它try..except子句中：

def shop(**kwargs):
    buy = 1
    print ("Welcome to the shop!")
    for i, v in kwargs.items():
        print ("    ", i, ": ", v)
    while True:
        b = input ("What would you like to buy? ").lower()
        if b == 'exit':
            break
        try:
            v = kwargs[b.capitalize()]
        except KeyError:
            print ("We don't sell that item!")
            print ()
            continue
        if v <= Player.gold:
            Player.gold -= v
            Player.inv_plus(i)
            print ("You bought ", b, "for ", v, "gold!")
            print ("Your gold: ", Player.gold)
            print (Player.show_inv())
            print ()
        else:
            print ("You don't have enough gold!")
            print ()