How to get events in new windows to function correctly with tkinter Python?

Question

been having a problem with this program since this morning, it seems to just be placement of code rather than the code itself, I am trying to run a calculator in a new tkinter window separate from the root window and have been juggling the code around to try and get it to function to no avail, the errors that keep popping up seem to be based on "typeSpace" or "calcWindow" not being defined but they clearly are, does anybody know how to correctly place this code so it recognizes these variables correctly at run time?

from tkinter import *
import tkinter as tk
#def onButton_Plus():
#        global one_Num#Declares global variable
#        number_One = typeSpace.get()#Gets number typed on calculator by user
#        one_Num = int(number_One)
#        typeSpace.delete(0, END)
def calcClick():

    calcWindow = Toplevel()##opens a new window for Calculator mode
    ##Creates a empty field in the calculator page for numbers to be displayed
    typeSpace = Entry(calcWindow, width=35, borderwidth=5)
    typeSpace.grid(row=0, column=0, columnspan=3, padx=10, pady=10)
    ##Names the new window
    calcWindow.title("Calculator Mode")

    ##Defines calculator buttons and places them in grid setting on screen
    button_1 = Button(calcWindow, text="1", padx=40, pady=20, command=lambda: onButton_Click(1)).grid(row=3, column=0)
    button_2 = Button(calcWindow, text="2", padx=40, pady=20, command=lambda: onButton_Click(2)).grid(row=3, column=1)
    button_3 = Button(calcWindow, text="3", padx=40, pady=20, command=lambda: onButton_Click(3)).grid(row=3, column=2)
    button_4 = Button(calcWindow, text="4", padx=40, pady=20, command=lambda: onButton_Click(4)).grid(row=2, column=0)
    button_5 = Button(calcWindow, text="5", padx=40, pady=20, command=lambda: onButton_Click(5)).grid(row=2, column=1)
    button_6 = Button(calcWindow, text="6", padx=40, pady=20, command=lambda: onButton_Click(6)).grid(row=2, column=2)
    button_7 = Button(calcWindow, text="7", padx=40, pady=20, command=lambda: onButton_Click(7)).grid(row=1, column=0)
    button_8 = Button(calcWindow, text="8", padx=40, pady=20, command=lambda: onButton_Click(8)).grid(row=1, column=1)
    button_9 = Button(calcWindow, text="9", padx=40, pady=20, command=lambda: onButton_Click(9)).grid(row=1, column=2)
    button_0 = Button(calcWindow, text="0", padx=40, pady=20, command=lambda: onButton_Click(0)).grid(row=4, column=0)
    button_plus = Button(calcWindow, text="+", padx=39, pady=20, command=lambda: onButton_Click()).grid(row=5, column=0)
    button_equal = Button(calcWindow, text="=", padx=91, pady=20, command=lambda: onButton_Click()).grid(row=5, column=1,columnspan=2)
    button_clear = Button(calcWindow, text="Clear", padx=79, pady=20, command= onButton_Clear()).grid(row=4, column=1, columnspan=2)
def tiClick():
     tInputWindow = Toplevel()##opens a new window for the text input mode
     tInputWindow.title("Text Input Mode")##Names the new window


def onButton_Click(number):

    onNo = typeSpace.get()##gets the number pressed by the user
    typeSpace.delete(0, END)##deletes previous numbers typed
    typeSpace.insert(0, str(onNo) + str(number))##Inserts the number clicked into the field
def onButton_Clear():##Defines what the clear button does when clicked

    typeSpace.delete(0, END)##deletes all previous numbers typed

root = Tk()#Creates root widget
root.title("Welcome Screen")#Names the welcome screen
welcomeLabel = Label (root, text="Hello user, welcome to the text input and calculator program")#Creates label widget
welcomeLabel.grid(row=0, column=0)#Casts label to screen in specified position

textInputButton = Button(root, text="Text Input Mode", command=tiClick, fg='red')#adds button
textInputButton.grid(row=1, column=10)#Positions button

calc = Button(root, text="Calculator Mode", command=calcClick, fg='red')#adds button
calc.grid(row=2, column=10)#Positions button

root.mainloop()

Your code is very messy. For starters, you shouldn't use `from tkinter import *` and `import tkinter as tk`. That is very bad practice. — 10 Rep, May 14 '20 at 20:25
Read up on [Tutorial - 9.2. Python Scopes and Namespaces](https://docs.python.org/3/tutorial/classes.html#python-scopes-and-namespaces) and [AttributeError: NoneType object has no attribute](https://stackoverflow.com/a/1101765/7414759) — stovfl, May 14 '20 at 21:23

score 3 · Accepted Answer · answered May 14 '20 at 21:03

When you define a variable inside a function its use is limited only to that function. Here you have defined typeSpace and calcWindow in the calcClick() function ,so typeSpace is a local variable and thus when you make any changes to typeSpace in a function other than calcClick() function, the program returns the error of typeSpace not being defined.

In order to use a local variable outside the funtion it is defined in you just need to give it the status of a global variable :

global calcWindow
calcWindow = Toplevel()

global typeSpace
typeSpace = Entry(calcWindow, width=35, borderwidth=5)
typeSpace.grid(row=0, column=0, columnspan=3, padx=10, pady=10)

Buttons button_plus, button_equal and button_clear will not work. The function onButton_Click(number) will not accept empty entries. Also if you insert a value other than a number (like +,= or clear)

.
.
    button_plus = Button(calcWindow, text="+", padx=39, pady=20, command=lambda: onButton_Click(+)).grid(row=5, column=0)
    button_equal = Button(calcWindow, text="=", padx=91, pady=20, command=lambda: onButton_Click("=")).grid(row=5, column=1,columnspan=2)
    button_clear = Button(calcWindow, text="Clear", padx=79, pady=20, command= onButton_Clear("Clear")).grid(row=4, column=1, columnspan=2)
.
.

The program will return error

Refer to this if you get in any trouble again

from tkinter import *
import tkinter as tk




#TEXT INPUT MODE
def tiClick():
     tInputWindow = Toplevel()##opens a new window for the text input mode
     tInputWindow.title("Text Input Mode")##Names the new window





#CALCULATOR MODE
def onButton_Plus():
    global one_Num #Declares global variable
    number_One = typeSpace.get()#Gets number typed on calculator by user
    one_Num = int(number_One)
    typeSpace.delete(0, END)
def calcClick():
    calcWindow = Toplevel()##opens a new window for Calculator mode
    ##Creates a empty field in the calculator page for numbers to be displayed
    global typeSpace
    typeSpace = Entry(calcWindow, width=35, borderwidth=5)
    typeSpace.grid(row=0, column=0, columnspan=3, padx=10, pady=10)
    ##Names the new window
    calcWindow.title("Calculator Mode")

    ##Defines calculator buttons and places them in grid setting on screen
    button_1 = Button(calcWindow, text="1", padx=40, pady=20, command=lambda: onButton_Click(1)).grid(row=3, column=0)
    button_2 = Button(calcWindow, text="2", padx=40, pady=20, command=lambda: onButton_Click(2)).grid(row=3, column=1)
    button_3 = Button(calcWindow, text="3", padx=40, pady=20, command=lambda: onButton_Click(3)).grid(row=3, column=2)
    button_4 = Button(calcWindow, text="4", padx=40, pady=20, command=lambda: onButton_Click(4)).grid(row=2, column=0)
    button_5 = Button(calcWindow, text="5", padx=40, pady=20, command=lambda: onButton_Click(5)).grid(row=2, column=1)
    button_6 = Button(calcWindow, text="6", padx=40, pady=20, command=lambda: onButton_Click(6)).grid(row=2, column=2)
    button_7 = Button(calcWindow, text="7", padx=40, pady=20, command=lambda: onButton_Click(7)).grid(row=1, column=0)
    button_8 = Button(calcWindow, text="8", padx=40, pady=20, command=lambda: onButton_Click(8)).grid(row=1, column=1)
    button_9 = Button(calcWindow, text="9", padx=40, pady=20, command=lambda: onButton_Click(9)).grid(row=1, column=2)
    button_0 = Button(calcWindow, text="0", padx=40, pady=20, command=lambda: onButton_Click(0)).grid(row=4, column=0)
    button_plus = Button(calcWindow, text="+", padx=39, pady=20, command=onButton_Plus).grid(row=5, column=0)
    button_equal = Button(calcWindow, text="=", padx=91, pady=20, command=onButton_Equals).grid(row=5, column=1,columnspan=2)
    button_clear = Button(calcWindow, text="Clear", padx=79, pady=20, command= onButton_Clear).grid(row=4, column=1, columnspan=2)

def onButton_Click(number):
    onNo = typeSpace.get()##gets the number pressed by the user
    typeSpace.delete(0, END)##deletes previous numbers typed
    typeSpace.insert(0, str(onNo) + str(number))##Inserts the number clicked into the field

def onButton_Clear():##Defines what the clear button does when clicked
    typeSpace.delete(0, END)##deletes all previous numbers typed

def onButton_Equals():
    sec_Num = typeSpace.get()
    typeSpace.delete(0, END)
    sec_Num = int(sec_Num)
    ANSWER = one_Num+sec_Num
    typeSpace.insert(0, ANSWER)

root = Tk()#Creates root widget
root.title("Welcome Screen")#Names the welcome screen
welcomeLabel = Label (root, text="Hello user, welcome to the text input and calculator program")#Creates label widget
welcomeLabel.grid(row=0, column=0)#Casts label to screen in specified position

textInputButton = Button(root, text="Text Input Mode", command=tiClick, fg='red')#adds button
textInputButton.grid(row=1, column=10)#Positions button

calc = Button(root, text="Calculator Mode", command=calcClick, fg='red')#adds button
calc.grid(row=2, column=10)#Positions button

root.mainloop()

Hope it was helpful...

Addition to the answer: Using global variables is usually bad practice. I would suggest using OOP to build this instead. Read up about it [here](https://realpython.com/python3-object-oriented-programming/). — 10 Rep, May 27 '20 at 17:25

score 1 · Answer 2 · answered May 14 '20 at 20:36

Here. I reworked your code and made it less messy.

Code:

from tkinter import *
#def onButton_Plus():
#        global one_Num#Declares global variable
#        number_One = typeSpace.get()#Gets number typed on calculator by user
#        one_Num = int(number_One)
#        typeSpace.delete(0, END)
def calcClick():

    calcWindow = Toplevel()


    typeSpace = Entry(calcWindow, width=35, borderwidth=5)
    typeSpace.grid(row=0, column=0, columnspan=3, padx=10, pady=10)
    calcWindow.title("Calculator Mode")

    def onButton_Click(number):

        onNo = typeSpace.get()##gets the number pressed by the user
        typeSpace.delete(0, END)##deletes previous numbers typed
        typeSpace.insert(0, str(onNo) + str(number))##Inserts the number clicked into the field

    def equal_clicked():
        print(eval(typeSpace.get()))
    def onButton_Clear():##Defines what the clear button does when clicked
        typeSpace.delete(0, END)


    ##Defines calculator buttons and places them in grid setting on screen
    button_1 = Button(calcWindow, text="1", padx=40, pady=20, command=lambda: onButton_Click(1)).grid(row=3, column=0)
    button_2 = Button(calcWindow, text="2", padx=40, pady=20, command=lambda: onButton_Click(2)).grid(row=3, column=1)
    button_3 = Button(calcWindow, text="3", padx=40, pady=20, command=lambda: onButton_Click(3)).grid(row=3, column=2)
    button_4 = Button(calcWindow, text="4", padx=40, pady=20, command=lambda: onButton_Click(4)).grid(row=2, column=0)
    button_5 = Button(calcWindow, text="5", padx=40, pady=20, command=lambda: onButton_Click(5)).grid(row=2, column=1)
    button_6 = Button(calcWindow, text="6", padx=40, pady=20, command=lambda: onButton_Click(6)).grid(row=2, column=2)
    button_7 = Button(calcWindow, text="7", padx=40, pady=20, command=lambda: onButton_Click(7)).grid(row=1, column=0)
    button_8 = Button(calcWindow, text="8", padx=40, pady=20, command=lambda: onButton_Click(8)).grid(row=1, column=1)
    button_9 = Button(calcWindow, text="9", padx=40, pady=20, command=lambda: onButton_Click(9)).grid(row=1, column=2)
    button_0 = Button(calcWindow, text="0", padx=40, pady=20, command=lambda: onButton_Click(0)).grid(row=4, column=0)
    button_plus = Button(calcWindow, text="+", padx=39, pady=20, command=lambda: onButton_Click('+')).grid(row=5, column=0)
    button_equal = Button(calcWindow, text="=", padx=91, pady=20, command=lambda: equal_clicked()).grid(row=5, column=1,columnspan=2)
    button_clear = Button(calcWindow, text="Clear", padx=79, pady=20, command= lambda: onButton_Clear()).grid(row=4, column=1, columnspan=2)


def tiClick():
     tInputWindow = Toplevel()##opens a new window for the text input mode
     tInputWindow.title("Text Input Mode")##Names the new window



root = Tk()#Creates root widget
root.title("Welcome Screen")#Names the welcome screen
welcomeLabel = Label (root, text="Hello user, welcome to the text input and calculator program")#Creates label widget
welcomeLabel.grid(row=0, column=0)#Casts label to screen in specified position

textInputButton = Button(root, text="Text Input Mode", command=tiClick, fg='red')#adds button
textInputButton.grid(row=1, column=10)#Positions button

calc = Button(root, text="Calculator Mode", command=calcClick, fg='red')#adds button
calc.grid(row=2, column=10)#Positions button

root.mainloop()

When you click the equals button, the result is printed to the shell.

Hope this helps!

Addition to the answer: The reason you did get an error was that the name `typeSpace` was defined inside a function and when the function ended the name was garbage collected. @TheMaker avoids this by having the functions `onButton_Click` etc. inside the `calcClick` function i.e. in the same namespace. — figbeam, May 14 '20 at 20:48

How to get events in new windows to function correctly with tkinter Python?

2 Answers2