使用Python 3列表

Question

Python (3)列表有一些问题。

def initLocations():
    locName = ["The Town","The Blacksmith Hut"]
    locDesc = ["A small but beautiful town. You've lived here all your life.",     "There are many shops here, but the Blacksmith Hut is the most intricate."]

这是脚本的顶部。稍后，它将由以下名称调用：

initLocations()

然后大约4行之后：

while currentLoc<20:
    initLocations()
    print("Type 'Help' for advice on what to do next.")
    passedCommand = input("?: ")
    mainProcess(passedCommand)

更多信息在这里：http://pastebin.com/5ib6CJ4g

继续得到错误

print("Left: " + locName[currentLoc-1])
NameError: name 'locName' is not defined

任何帮助都很感激。

Answer 1

函数中定义的变量是该函数的本地变量。它们不会泄漏到调用范围(这是一件好事)。如果您想要函数提供可用的东西，则需要返回它们。例如：

def initLocations():
    locName = […]
    locDesc = […]
    return locName, locDesc

这将使函数返回一个包含名称列表和描述列表的二元组。在调用函数时，您将需要捕获这些值并再次将它们保存到变量中。例如：

locName, locDesc = initLocations()

Answer 2

仅仅调用一个函数并不会在外部范围内创建变量。您将不得不使他们global，但这是一个非常糟糕的方式做一些事情。您需要从函数中return它。在initLocations()中，您需要有一个语句return locName，当您调用它时，您需要使用locName = initLocations()。如果您有两个变量，则需要将它们作为元组发送。

演示

def initLocations():
    locName = ["The Town","The Blacksmith Hut"]
    locDesc = ["A small but beautiful town. You've lived here all your life.",     "There are many shops here, but the Blacksmith Hut is the most intricate."
    return (locName,locDesc)

然后

while currentLoc<20:
    locName,locDesc = initLocations()
    print("Type 'Help' for advice on what to do next.")
    passedCommand = input("?: ")
    mainProcess(passedCommand)

这被称为元组包装序列解压。

小票

正如Padraic在comment中提到的，拥有一个函数来声明这两个列表是非常无用的(除非你必须这样做)。

你可以这样做，

locName = ["The Town","The Blacksmith Hut"]
locDesc = ["A small but beautiful town. You've lived here all your life.",     "There are many shops here, but the Blacksmith Hut is the most intricate."
while currentLoc<20:        
    print("Type 'Help' for advice on what to do next.")
    passedCommand = input("?: ")
    mainProcess(passedCommand)

这是一个更好的方法

Answer 3

initLocations内部的作用域不是全局的。除非变量声明为global或函数作为值返回，否则在该函数的作用域外部(包含范围级别)中将无法使用在该函数范围内创建的值。

第二种办法非常可取：

def initLocations():
    locName = ["The Town","The Blacksmith Hut"]
    locDesc = ["A small but beautiful town. You've lived here all your life.",     
               "There are many shops here, but the Blacksmith Hut is the most intricate."]
    return locName, locDesc

然后，在稍后调用该函数时：

locName, locDesc = initLocations()