Python在嵌套循环内继续，进入正确的嵌套层次

Question

我正在做一些事情，需要通过几个层次的检查方式来检查是否满足条件，然后再全部退出或设置某些变量，然后开始循环。 我的问题围绕着如何从内部for循环跳回主while循环。

while True:
    message = stomp.get
    message = simplejson.loads(message.body)

    if message[0]['fieldname1'] == False:
      global ShutdownState
      ShutdownState = True
      break # Should leave the While loop all together

    else:

      for item in message[0]['fieldname2'][0]['fieldname2-1']

        if item['fieldname2-1-1'] == True:
           list1_new[len(list_new):] = [item['fieldname2-1-2']
           list1-state = set(list1) == set(list1_new)

           if list1-state == True:
               continue # should reset the while loop

        else:
           list1 = list1_new # should print the new list1 and then reset the while loop
           print list1
           continue

Answer 1

尚不清楚示例代码是要代表整个循环还是只是循环的开始。 如果这是全部，那么有很多方法可以对其进行重组。 这是第一个选项（请注意，代码中有一些错别字（例如list1-state而不是list1_state等），因此我不得不进行一些调整。您需要检查它是否仍然匹配（使用您的原始代码。（有关在列表中查找第一个元素的实现的更多信息以及一些替代方法，请查看Python：在列表中查找 ）。

while True:
    message = stomp.get
    message = simplejson.loads(message.body)

    # If the message doesn't match this criterion,
    # we need to abort everything.
    if not message[0]['fieldname1']:
        global ShutdownState
        ShutdownState = True
        break

    try:
        # get the first item in message[0]['fieldname2'][0]['fieldname2-1']
        # such item['fieldname2-1-1'] is true.  Whether we
        # find one and do this code, or don't and catch the
        # StopIteration, we wrap back to the while loop.
        item = next(x
                    for x in message[0]['fieldname2'][0]['fieldname2-1']
                    if item['fieldname2-1-1'])
        list1_new[len(list_new),:] = item['fieldname2-1-2']
        list1_state = (set(list1) == set(list1_new))

        if not list1_state:
            list1 = list1_new # should print the new list1 and then reset the while loop
            print list1
    except StopIteration:
        # There was no such item.
        pass

您也可以通过使其成为do-while循环来进行清理，但这不是主要因素。 基于在Python中模拟do-while循环？ ，您可以执行以下操作：

def get_message():
    message = stomp.get
    return simplejson.loads(message.body)

message = get_message()
while message[0]['fieldname1']:
    try:
        # get the first item in message[0]['fieldname2'][0]['fieldname2-1']
        # such item['fieldname2-1-1'] is true.  Whether we
        # find one and do this code, or don't and catch the
        # StopIteration, we wrap back to the while loop.
        item = next(x
                    for x in message[0]['fieldname2'][0]['fieldname2-1']
                    if item['fieldname2-1-1'])
        list1_new[len(list_new),:] = item['fieldname2-1-2']
        list1_state = (set(list1) == set(list1_new))

        if not list1_state:
            list1 = list1_new # should print the new list1 and then reset the while loop
            print list1
    except StopIteration:
        # There was no such item.
        pass
    message = get_message()

global ShutdownState
ShutdownState = True