python - :TypeError: argument of type 'function' is not iterable", 但在单独测试时有效

Question

我是 Python 2 的新手。我正在尝试构建一个“购物车”Python 程序，但卡在了“放入购物车前检查库存”步骤。

首先，我在这里阅读了很多相同问题的线程，但它们似乎与我的原因不同。

其次，我已经将每个函数和测试分开放在不同的文件中。他们单独工作得很好。但是当加入 check_stock(y) 函数时，它给出了错误。

我认为问题出在“in”命令上。

    def check_stock(y):             #// Problem in this function // 
        if y in list:
            print "%s is available" % y
            add_to_cart(y)
        else:
            print "Sorry, but %s is not available." % y

    def check_finish():
        y = raw_input(">")
        if y == "checkcart":        
            print cart              #check inside shopping cart
        elif y == " ":
            check_finish()          #loop back for blank
        elif y == "list":
            list()                  #present the list
        else:
            while y != "ok":        #"ok" = finished shopping
                check_stock(y)
            else:
                print "Checking out..."
                sorted(cart)
                print "Your item(s) are %s." % cart
                exit(0)

下面是剩余的代码，如果有帮助的话:

cart = []
list = ['apple', 'banana', 'cat', 'dog', 'elephant', 'flamingo', 'goofy', 'ham']
a = 0

def list():
    print list                  #present the list
def representInt(s):            #check if value is integer
    try:
        int(s)
        return True
    except ValueError:
        return False
def annoyedAtError(a):          #interaction for repeated mistakes
    if a < 2:
        print "Numbers only please"
    elif 2 < a < 4:
        print "Man, just do as I say, please. I have another shift tonight."
    elif a == 5 :
        print "Hey, seriously?"
    else:
        print "..."
def check_stock(y):             #// PROBLEM HERE // cross-check with list if item is available
    if y in list:
        print "%s is available" % y
        add_to_cart(y)
    else:
        print "Sorry, but %s is not available." % y

def add_to_cart(y):
    amount = (raw_input("How many do you want to add? > "))
    if representInt(amount) == False:
        annoyedAtError(a)
        global a 
        a = a + 1
        add_to_cart(y)
    else: 
        y = y + " " + amount
        print "%s is added to cart" % (y)
        cart.append(y)
        check_finish()
def check_finish():
    y = raw_input(">")
    if y == "checkcart":        
        print cart              #check inside shopping cart
    elif y == " ":
        check_finish()          #loop back for blank
    elif y == "list":
        list()                  #present the list
    else:
        while y != "ok":        #"ok" = finished shopping
            check_stock(y)
        else:
            print "Checking out..."
            sorted(cart)
            print "Your item(s) are %s." % cart
            exit(0)
def welcome():      
    print """\nWelcome to cyber shopping.\n 
    Please enter things you want to buy.
    Check your cart by typing: checkcart
    type "ok" when finished.
    type "list" for things available for buying"""
def start():
    welcome()
    check_finish()

start()

Answer 1

您创建了一个名为 list 的列表(您不应该这样做，因为它已经是内置名称)，但是您还创建了一个名为 list 的函数(再次强调，不要这样做)。 list 现在指的是函数，而不是你的列表。因此，当您检查 y in list 时，它会尝试检查该项目是否在函数中。您不能在函数上使用 in，因此会出现错误。解决方案很简单:为事物使用更清晰的名称!!