Question

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 = {}

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

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

UnboundLocalError: local variable 'bool' referenced before assignment

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

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

---

EDIT: 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()

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.

So this prints:

{}
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

---

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

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

Answer 1

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.

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.

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.