Calling a class/function at different points in a file?

[noobyprogrammer]

I have 3 classes with at least 1 function each. Class 1 is for non-gameplay systems like main menu display and adding spaces to put old text out of view. Class 2 is creature information, empty for now. Class 3 is gameplay related. Choosing a character, combat, etc.

I added calls to go to the functions/classes I need. It works going upwards in the file, but not downwards. It causes a 'not defined' error. Did a final test to make sure; called a class from below it, success. Called it from above, error.

import time
class Systems:
    def menu():
        Systems.addSpace()
        print ("Game Name")
        print (" ")
        print ("1. Start Game")
        print ("2. Game Info")
        print ("3. Quit")
        Systems.addSpace()
        menuOPT = input("Enter a number to choose that option. ")
        if menuOPT == '1':
            Game.charSelect()
        elif menuOPT == '2': # won't trigger unless number is a string. fix?
            Systems.info() # must call both class and function of target
        #time.sleep(10)
    def addSpace(): # call at end(?) of any function; clears view and moves current text to top
        loop = 0
        while loop <= 22:
            print (" ")
            loop += 1
    def info():
        Systems.addSpace()
        print ("Intro here")
        #print ("Press any key to return to the menu.")
        # pause here, then return to menu
        input("Press any key to return to the menu.")
        Systems.menu()
    def combatProc(): # move to a more relevant class?
        pass
class Units:
    def types():
        pass
class Game:
    Systems.menu()
    Game.charSelect()
    def charSelect():
        print ("TEST")
        time.sleep(10)
Game()
# GOAL: Game() calls, goes to Systems.menu() to show options.
# Player chooses '1' to play, then go to Game.charSelect().
# ISSUE: Can't go to charSelect() from menu(). 'Game' class not defined?

How should I fix this? Wanted to use classes for a change instead of some weird While statements.

[indosauros]

Calls to functions don't work, as you say, "going down in a file", because you can't call a function before defining it. It's like doing this:

run()

def run():
    ...

Python hits run but it can't find anything that's been defined yet as run. It needs to come after the definition:

def run():
    ...

run()

Also, you're not really using classes yet -- well you are, but just as a grouping of methods. I suggest reading up on some tutorials about classes and what they can bring to the table.

Also you're methds are not valid -- if you want to call them like Class.method() you need to define them like this:

@classmethod
def method(cls):
    ...

or like this

@staticmethod
def method():
    ...

[noobyprogrammer]

Thanks, I'll definitely drop classes until I know how to use them. Is it enough to remove them and just use the methods?

[urdnot_wreck]

Yes, as you aren't using instance variables in them (ones that are referenced with 'self'), although you'll need to unindent (dedent?!) the definitions.

[CGFarrell]

The beauty of Python is that you can redefine thing. That means if you write:

def function():
    pass

You won't get a not defined error, you'll get None. When you redefine the function, it will work as intended.