python 多线程用于继续循环直到用户输入。帮助理解所要求的示例

Question

我正在实现一个循环，该循环应该继续下去，直到用户按照 this page 上的说明按下 Return 键。我让它工作:

def _input_thread_2( L ):
    raw_input()
    L.append( None )

#### test _input_thread()
L = []
thread.start_new_thread(_input_thread_2, (L, ))
while True: 
    time.sleep(1)
    print "\nstill going..."
    if L: 
        break

我的问题是为什么下面这个看似简单的适配却行不通？它不会在按下某个键时退出循环，而是继续循环:

def _input_thread_3( keep_going ):
    """ 
    Input: doesn't matter
    Description - When user clicks the return key, this changes the input to the False bool. 
    """
    raw_input()
    keep_going = False

#### test _input_thread()
keep_going = True
thread.start_new_thread(_input_thread_3, (keep_going, ) )
while True: 
    time.sleep(1)
    print "\nstill going..."
    if not keep_going: 
        break

你能帮我理解它们之间的区别吗？

Answer 1

In Python, why can a function modify some arguments as perceived by the caller, but not others?

这就是原因。你的keep_alive是不可变的，而列表是可变的。