Python：检查“字典”是否为空似乎不起作用

Question

我正在尝试检查字典是否为空，但是行为不正常。它只是跳过它并显示 ONLINE（在线） ，除了显示消息外没有任何内容。有什么想法吗？

def isEmpty(self, dictionary):
    for element in dictionary:
        if element:
            return True
        return False

def onMessage(self, socket, message):
    if self.isEmpty(self.users) == False:
        socket.send("Nobody is online, please use REGISTER command" \
                 " in order to register into the server")
    else:
        socket.send("ONLINE " + ' ' .join(self.users.keys()))

Answer 1

空字典在Python中的计算结果为False：

>>> dct = {}
>>> bool(dct)
False
>>> not dct
True
>>>

因此，您的isEmpty功能是不必要的。您需要做的是：

def onMessage(self, socket, message):
    if not self.users:
        socket.send("Nobody is online, please use REGISTER command" \
                    " in order to register into the server")
    else:
        socket.send("ONLINE " + ' ' .join(self.users.keys()))