Python 避免使用/覆盖全局变量（以简单示例）

这是一个简单的程序：

询问用户想要多少张票 计算车票的费用 然后询问是否可以继续购买

我如何才能改变我做事的方式，而不必覆盖requestedTickets和costOfTickets全局变量？ （如果用户回复“n”拒绝购买确认，则在确认功能中会覆盖它们。）

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我正在努力学习最佳实践。

为了避免在这样一个简单的情况下使用全局函数，让函数返回它们生成的所有数据，并将它们需要的所有数据作为参数。这应该是一个简单的重构，下一步就是使用类。面向对象编程。

TICKETPRICE = 10
ticketsRemaining = 100
userName = input("What is your first name?: ")


print("There are " + str(ticketsRemaining) + " tickets remaining.")


def ticketsWanted(userName):
    numOfTicketsWanted = input(
        "Hey {} how many tickets would you like? : ".format(userName))
    return int(numOfTicketsWanted)


requestedTickets = ticketsWanted(userName)


def calculateCost():
    ticketQuantity = requestedTickets
    totalCost = ticketQuantity * TICKETPRICE
    return totalCost


costOfTickets = calculateCost()


def confirm():
    global requestedTickets
    global costOfTickets
    tickets = requestedTickets
    totalCost = calculateCost()
    print("Okay so that will be " + str(tickets) +
          " tickets making your total " + str(totalCost))
    confirmationResponse = input("Is this okay? (Y/N) : ")
    while confirmationResponse == "n":
        requestedTickets = ticketsWanted(userName)
        costOfTickets = calculateCost()
        print("Okay so that will be " + str(requestedTickets) +
         " tickets making your total " + str(costOfTickets))
        confirmationResponse = input("Is this okay? (Y/N) : ")


confirm()


def finalStage():
    print("Your order is being processed.")

finalStage()

TICKETPRICE = 10
ticketsRemaining = 100
userName = input("What is your first name?: ")

print("There are " + str(ticketsRemaining) + " tickets remaining.")


def ticketsWanted(userName):
    numOfTicketsWanted = input(
        "Hey {} how many tickets would you like? : ".format(userName))
    return int(numOfTicketsWanted)


def calculateCost(n_tickets):
    totalCost = n_tickets * TICKETPRICE
    return totalCost


def confirm(userName):
    n_tickets = ticketsWanted(userName)
    totalCost = calculateCost(n_tickets)
    print("Okay so that will be " + str(n_tickets) +
          " tickets making your total " + str(totalCost))
    confirmationResponse = input("Is this okay? (Y/n) : ")
    while confirmationResponse == "n":
        n_tickets = ticketsWanted(userName)
        costOfTickets = calculateCost(n_tickets)
        print("Okay so that will be " + str(n_tickets) +
              " tickets making your total " + str(costOfTickets))
        confirmationResponse = input("Is this okay? (Y/n) : ")


def finalStage():
    print("Your order is being processed.")


confirm(userName)
finalStage()