global variable not recognized; says its local variable

Question

Its not recognizing the global variable. I experienced this issue before and thought the global variable would prevent the error but no matter what i try it always returns this: local variable 'P1o' referenced before assignment

 #import pwinput
import PySimpleGUI as sg
P1o = ("")
P2o = ("")
MAX_ROWS = MAX_COL = 10
 def Battleship1():
    layout = [
                [sg.Text('Player1 please enter your ship positions'), sg.InputText('', size=(10,1), key='input_\P1o')],
                [sg.Submit(), sg.Cancel()]
                          ]
    window = sg.Window('player1 values', layout)
   
    while True:
        event, values = window.read()
        if event == sg.WIN_CLOSED:
            break
        elif event == 'Submit':
            
            P1o = P1o.append(int(values['input_\P1o']))
            window.close()
        elif event == 'cancel':
            window.close()
            break
    layout = [
                [sg.Text('Player2 please enter your ship positions'), sg.InputText('', size=(10,1), key='input_\P2o')],
                [sg.Submit(), sg.Cancel()]
                          ]
    window = sg.Window('player2 values', layout)
    
    while True:
        event, values = window.read() 
        if event == sg.WIN_CLOSED:
            break
        if event == 'Submit':
            P1o = P1o.append(int(values['input_\P1o']))
            turn()
            turn_()
        if event == 'cancel':
            window.close()
            break

   """ i set up the multiplayer function"""
layout = [  [sg.Text("Welcome to battleship!!\nObject of the game is to sink all five of your enemy's ships!!!\nlabel your ship positions with a number (0-9)\n and another number (0-9)\n and separate each position with spaces e.g 1,2 2,3 3,4")],
            [sg.Button('Single Player'), sg.Button('Multiplayer')] ]
window = sg.Window('Menu', layout)

while True:
    event, values = window.read()
    
    if event == sg.WIN_CLOSED:
        break
    if event == 'Multiplayer':
        window.close()
        Battleship1()
        break

Additionally: `P1o = P1o.append(int(values['input_\P1o']))` makes no sense when `P1o` is a string. And if you make `P1o` a list this still doesn't make sense, because `append` always returns `None`. — Matthias, Jan 22 '23 at 13:36

score 0 · Accepted Answer · answered Jan 22 '23 at 12:17

I would suggest you to use P1o and P2o as your local variables, as they are only needed in your battleship function.

You can use them as your global or as your local variables. I'll leave the choice to you.

CASE 1: Using it as local variable:

def Battleship1():
    P1o = ""
    P2o = ""

Here, it just creates two local variables for the function and would prevent the referenced before assignment error.

CASE 2: Using it as global variable:

def Battleship1():
    global P1o, P2o

global keyword is used to reference the globals() dictionary where all the global variables are mentioned. So, it would tell the function that P1o and P2o is a global variable.

global variable not recognized; says its local variable

1 Answers1