为什么全球化布尔值不起作用而全球化字典能起作用 [英] Why does globalising a boolean not work but globalising a dictionary does

问题描述

这只是一个问题，想知道为什么这行不通.我想出了一个更好的方法，但是我不知道为什么以前它不起作用.

This is just a question wondering why this doesn't work. I have figured out a better way, but I don't know why previously it wasn't working.

global mydict
mydict = {}

这似乎很好用，并使mydict词典成为全局词典.我什至打印出mydict，它的工作原理.但是，这样做:

This seems to work fine, and has made the mydict dictionary global. I even print mydict and it works. However, doing this:

global bool
bool = False

似乎无效.如果尝试在我的代码中打印布尔值，我会得到:

Does not seem to work. If trying to print bool in my code, I get:

UnboundLocalError: local variable 'bool' referenced before assignment

那为什么它对字典而不是布尔型有效?

So why does it work for the dictionary and not the boolean?

哦，如果有人想知道如何找到更好的方法，我会初始化一个类，并通过以下操作使bool在该类中成为全局变量:self.bool = False起作用了.我是从以下问题中得到的:将所有变量设置为全局

Oh, also, if anyone was wondering how I figured out a better way, I initialised a class and made bool global in the class by doing: self.bool = False which worked. I got it from this question: Making all variables global

根据要求，我将发布必要的代码:

As requested, I'll post the necessary code:

import chatbot
global mydict
mydict = {}
global haveamessage
haveamessage = False

class MyBot(chatbot.ChatBot):
    def __init__(self, username, password, site):
        chatbot.ChatBot.__init__(self,username,password,site)

    def on_message(self, c, e):
        print mydict
        print haveamessage

if __name__ == '__main__':
    bot = MyBot("MyUsername", "MyPassword", "MySite")
    bot.start()

我将尝试解释此代码. chatbot模块几乎允许用户在Wikia上的Wiki中创建bot，该公司允许创建任何人都可以编辑的wiki. Wiki上有一个聊天扩展，用户可以与之聊天.该脚本允许机器人加入聊天并执行命令.当有人在聊天中发布内容时，on_message()熄灭.

I'll try explain this code. Pretty much the chatbot module is to allow users to create bots in wikis on Wikia, a company that allows wikis to be created which anyone can edit. On a wiki there is a chat extension where users can talk to. This script allows a bot to join the chat and do commands. on_message() goes off when someone posts something in the Chat.

因此打印:

{}
Traceback (most recent call last):
  File "file.py", line 146, in <module>
    bot.start()
  File "/Library/Python/2.7/site-packages/chatbot.py", line 371, in start
    self.on_message(self.c, e)
  File "file.py", line 12, in on_message
    print haveamessage
UnboundLocalError: local variable 'haveamessage' referenced before assignment

---

我想澄清的是，这不会对所有人产生错误，是因为您不在Wikia聊天中.函数on_message()仅在有人在聊天室中发布内容时运行.例如，我可能有:

---

I'd like to clarify that the reason this isn't producing an error for all of you is because you are not in a Wikia chat. the function on_message() only runs when someone posts something in the Chat. For example, I may have:

def on_message(self, c, e):
    if e.text == 'hello': # e.text is what a user posts in the chat. e = event
        c.send('Hello!') # c.send simply sends back a message in the chat. c = connection

因此，当有人在聊天中打招呼时，Bot会回发Hello！

So when someone posts in chat hello, the Bot posts back Hello!

推荐答案

您发布的代码不会产生您声称的错误.但是，在函数外部使用global关键字无效，因此，它不能按预期工作也就不足为奇了.

The code you've posted does not produce the error you claim it does. However using the global keyword outside of a function has no effect, so it's not surprising that it doesn't work like you expect.

我假设在您的真实代码中，您实际上是在尝试分配给on_message内部的haveamessage.如果是这样，则在该方法内需要一个global语句.

I assume that in your real code, you're actually trying to assign to haveamessage inside on_message. If so, you need a global statement inside that method.

基本规则是:如果尝试从函数中分配全局变量，则需要在该函数中使用global关键字.否则，您根本不需要global关键字.变量是否为布尔值没有区别.

Basically the rule is: If you try to assign a global variable from within a function, you need to use the global keyword within that function. Otherwise you don't need the global keyword at all. Whether or not the variable is a boolean makes no difference.

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