python - 当用户提供某个关键字作为输入时结束函数

Question

当用户在输入中键入特定关键字(例如“off”)时，我如何结束函数而无需在每个输入中添加必要的代码？基本上，当用户在下面的任何输入中的任何地方键入“关闭”一词时，我希望该功能完全停止。我已经创建了一个函数(见代码底部)并尝试在我的代码中放置/调用它，但我不确定将它放在哪里或者我是否可以用一个函数来做到这一点？如果没有，我该如何实现？

  def order_coffee():

    drink = input("What would you like? (espresso/latte/cappuccino): ")

    user_owes = int(0)

    if drink == "espresso":
        user_owes = round(1.5, 2)
    elif drink == "latte":
        user_owes = round(2.5, 2)
    elif drink == "cappuccino":
        user_owes = round(3.0, 2)

    print(f"Please insert coins, you owe ${user_owes}.")
    quarters = (int(input("How many quarters?: ")) * .25)
    dimes = (int(input("How many dimes?: ")) * .1)
    nickels = (int(input("How many nickels?: ")) * .05)
    pennies = (int(input("How many pennies?: ")) * .01)

    user_paid = round(quarters + dimes + nickels + pennies, 2)
    print(f"You have inserted ${user_paid}.")
    change = round(user_paid - user_owes, 2)

    if user_paid >= user_owes:
        print(f"Here is ${change} in change.")
        print(f"Here is your {drink} ☕. Enjoy!")
        order_coffee()
    else:
        print("Sorry that's not enough money. Money refunded.")
        order_coffee()
        
order_coffee()

 def off():
        if input == "off":
            return

Answer 1

创建您自己的 input 函数并添加所需的行为:

def my_input(*args, **kwargs):
    str = input(*args, **kwargs)
    if str == "off":
        exit()
    return str

这将在用户输入“关闭”时从整个应用程序退出，从函数退出只是抛出异常，并在函数调用之外捕获它。例如:

def my_input(*args, **kwargs):
    str = input(*args, **kwargs)
    if str == "off":
        raise ValueError('Time to go')

和:

  def order_coffee():
      try:
          # your code
       except ValueError as err:
          # handle it accordingly
          return

更清晰的方法是创建、抛出和处理自定义的Exception。看看这个SO Thread了解如何实现这些自定义异常。