如何修复IF语句，使我无法从lis中删除和追加项

Question

我目前正在写一个简单的程序来管理一个租车公司的停车场，我已经到了最后没有真正的问题，直到现在。为了说明我的意思，我将发布我的代码，然后发布我的问题。在

# class for Car_Yard
class CarYard():

    def __init__(self, listOfCars):
        self.availableCars = listOfCars

    def carYardCarsAvailable(self):
        print("Available Cars: ")
        for car in self.availableCars:
            print(car)

    def carYardRentCar(self, rentCar):
        if rentCar in self.availableCars:
            print("Congratulations on renting your new car, here\'s the keys")
            self.availableCars.remove(rentCar)
        else:
            print("We currently don't have that car in our yard")

    def carYardReturnCar(self, rentCarReturn):
        self.availableCars.append(rentCarReturn)
        print("You have returned the car. Thank You!")


# class for Buyer and his/hers actions
class Buyer():

    def buyerRentCar(self):
        print("Which car would you like to rent out?" )
        self.car = input()
        return self.car

    def buyerReturnCar(self):
        print("Which car would you like to return? ")
        self.car = input()
        return self.car


# create objects from class and pass a list of cars to the car yard
carYard = CarYard (['Mazda','Holden','Ford','Porsche','Honda','VW','Toyota','Kia'])
buyer = Buyer

# infinite loop
while True:
    print()
    print("Enter 1 to see our wide range of cars")
    print("Enter 2 to rent a car")
    print("Enter 3 to return a car")
    print("Enter 4 to leave the rental yard")
    print()

    userInput = int(input())

    if userInput is 1:
        carYard.carYardCarsAvailable()
    elif userInput is 2:
        rentCar = buyer.buyerReturnCar
        carYard.carYardRentCar(rentCar)
    elif userInput is 3:
        rentCarReturn = buyer.buyerReturnCar
        carYard.carYardReturnCar(rentCarReturn)
    elif userInput is 4:
        quit()

我遇到的问题是，当我运行代码并输入2时，它会自动跳转到“我们目前没有那辆车在我们的院子里”，当我输入3时，是说“你已经还车了”。谢谢你！“。在

我试图弄清楚为什么我的代码没有被调用为Buyer类来请求输入。对我可能遗漏的东西有什么建议吗？在

Answer 1

你不应该那样使用is。is运算符测试两个对象是否相同，这与测试它们的值是否相等不同。你真正想要的是一个等式测试（例如userInput == 1）。在

不管怎样，问题的根源是，你传递的是方法，而不是那些方法返回的值。例如，这可能会更好：

buyer = Buyer()
...
elif userInput == 2:
    rentCar = buyer.buyerReturnCar()
    carYard.carYardRentCar(rentCar)

通过传递buyer.buyerRentCar你就是在向carYardRentCar传递一个方法，自然它无法将该方法与汽车列表中的任何内容相匹配。您需要传递一个由carYardRentCar()返回的字符串。这将导致调用该方法，请求用户输入，然后结果将被传递，这正是您想要的