Question

I’m trying to call a function in one class from another class. Here is my code:

import os

class GameRoom():

    msgLine1 = ""
    msgLine2 = ""
    msgLine3 = ""
    msgLine4 = ""
    msgLine5 = ""

    def GameStatus(self):
        while True:
            os.system('cls')
            print self.msgLine1
            print self.msgLine2
            print self.msgLine3
            print self.msgLine4
            print self.msgLine5 + "\n"
            print "Do what?\n"
            userDecision = raw_input()
            if userDecision.upper() == "GO":
                Player().Go()
                break
            else:
                self.CycleMessages("That's not a valid choice!")

    def CycleMessages(self,newMsg="error"):
        self.msgLine5 = self.msgLine4
        self.msgLine4 = self.msgLine3
        self.msgLine3 = self.msgLine2
        self.msgLine2 = self.msgLine1
        self.msgLine1 = newMsg

class Player():
    def Go(self):
        GameRoom().CycleMessages("Player goes.")
        GameRoom().GameStatus()

def main():
    GameRoom().GameStatus()

if __name__ == '__main__':
    main()

When I call CycleMessages through itself, the lines fill up with ‘That’s not a valid choice!’ normally, like they should. When I call CycleMessages from the Player class, all of the lines clear instead of displaying ‘Player goes.’. ‘error’ doesn’t display either.

I would like ‘Player goes.’ to show up when I call Player().Go(). How do I do this? I appreciate any help!

Answer 1

This is happening because when you call GameRoom().CycleMessages("Player goes."), you’re calling it on a new instance of GameRoom. Easy fix:

class GameRoom():

    def GameStatus(self):
        ...
            if userDecision.upper() == "GO":
                # Pass `Player` this instance of `GameRoom`
                Player().Go(self)
                break
            else:
                self.CycleMessages("That's not a valid choice!")

class Player():

    def Go(self, game):
        # And here, call `CycleMessages` on the passed instance of `GameRoom`.
        game.CycleMessages("Player goes.")
        game.GameStatus()

Also, this wasn’t your question, but you might want to consider changing your naming conventions (see: PEP8).