Tkinter Buttons lose functionality when I invoke it from another python file

Question

I am new to Tkinter and I want to do this for my college project. I was going to do a simple app launcher with calculator, clock and a notes app from a main.py. I looked online and found various methods to import other python files. I used init.py to do it.

init.py

from .clock_app import open_clock
from .notes_app import open_notes
from .calc_app import open_calc

This is the code for my main file (app launcher).

from tkinter import Tk,Button, PhotoImage
import Apps

def main():
    root = Tk()
    #Icons
    root_icon = PhotoImage(file="Assets/app_launcher_icon.png")
    #main root properties
    
    
    root.title("App Launcher")
    root.geometry("700x500")
    root.resizable(False,False)
    root.configure(bg="#49de71")
    root.iconphoto(False,root_icon)
    
    #Functions for each app added
    

    #Icons
    
    
    #Buttons to open each app

    calendar_button = Button(root, text="Clock",command = Apps.open_clock)
    calendar_button.place(x=239,y=5)
    calendar_button.config(height=20,width=30)

    calculator_button = Button(root,text="Calculator",command = Apps.open_calc)
    calculator_button.config(height=20,width=30)
    calculator_button.place(x=472,y=5)

    root.mainloop()
    
if __name__ == "__main__":
    main()

And this is the code to the calculator,

from tkinter import *

class calc_app:
    def __init__(self, root):
        self.root = root
        self.root.title("Calculator")
        root.destroy()
        # Create widgets for the second window
        # from here
        global expression
        expression=""
        
        #to update expression in text box
        def press(num):
            global expression
            expression = expression + str(num)
            equation.set(expression)
            
        def equalpress():
            try:
                global expression
                total = str(eval(expression))
                equation.set(total)
                expression=""
                
            except:
                equation.set(" error ")
                expression=""
        
        def clear():
            global expression
            expression = ""
            equation.set("")
            
        calculator=Tk()
        calculator.configure(background="#07398a")
        calculator.geometry("350x300")
        calculator.resizable(False,False)
        
        equation = StringVar()
        expression_field = Entry(calculator,textvariable=equation,width=30,font=('Arial', 20))
        expression_field.place(x=0,y=0)
        
        button7 = Button(calculator, text=' 7 ', fg='black', bg='#4287f5', 
                   command=lambda: press(7), height=2, width=10) 
        button7.place(x=5,y=55)

        button8 = Button(calculator, text=' 8 ', fg='black', bg='#4287f5', 
                   command=lambda: press(8), height=2, width=10) 
        button8.place(x=90,y=55)

        button9 = Button(calculator, text=' 9 ', fg='black', bg='#4287f5', 
                   command=lambda: press(9), height=2, width=10) 
        button9.place(x=175,y=55)
        
        button4 = Button(calculator, text=' 4 ', fg='black', bg='#4287f5', 
                   command=lambda: press(4), height=2, width=10) 
        button4.place(x=5,y=105)

        button5 = Button(calculator, text=' 5 ', fg='black', bg='#4287f5', 
                   command=lambda: press(5), height=2, width=10) 
        button5.place(x=90,y=105)

        button6 = Button(calculator, text=' 6 ', fg='black', bg='#4287f5', 
                   command=lambda: press(6), height=2, width=10) 
        button6.place(x=175,y=105)

        button1 = Button(calculator, text=' 1 ', fg='black', bg='#4287f5', 
                   command=lambda: press(1), height=2, width=10) 
        button1.place(x=5,y=155)

        button2 = Button(calculator, text=' 2 ', fg='black', bg='#4287f5', 
                   command=lambda: press(2), height=2, width=10) 
        button2.place(x=90,y=155)

        button3 = Button(calculator, text=' 3 ', fg='black', bg='#4287f5', 
                   command=lambda: press(3), height=2, width=10)  
        button3.place(x=175,y=155)

        button0 = Button(calculator, text=' 0 ', fg='black', bg='#4287f5', 
                   command=lambda: press(0), height=2, width=10) 
        button0.place(x=90,y=205)

        plus = Button(calculator, text=' + ', fg='black', bg='#4287f5', 
               command=lambda: press("+"), height=5, width=11)  
        plus.place(x=260,y=160)

        minus = Button(calculator, text=' - ', fg='black', bg='#4287f5', 
                       command=lambda: press("-"), height=3, width=11)
        minus.place(x=260,y=100)

        multiply = Button(calculator, text=' * ', fg='black', bg='#4287f5', 
                   command=lambda: press("*"), height=2, width=22) 
        multiply.place(x=5,y=255)

        divide = Button(calculator, text=' / ', fg='black', bg='#4287f5', 
                   command=lambda: press("/"), height=2, width=23) 
        #divide.grid(row=5, column=3) 
        divide.place(x=175,y=255)

        equal = Button(calculator, text=' = ', fg='black', bg='#4287f5', 
               command=equalpress, height=2, width=10) 
        #equal.grid(row=5, column=2) 
        equal.place(x=175,y=205)

        clear = Button(calculator, text='Clear', fg='black', bg='#4287f5', 
               command=clear, height=2, width=11) 
        #clear.grid(row=5, column='1')
        clear.place(x=260,y=55)

        Decimal= Button(calculator, text='.', fg='black', bg='#4287f5', 
                   command=lambda: press('.'), height=2, width=10) 
        #Decimal.grid(row=6, column=0) 
        Decimal.place(x=5,y=205)
        
        
        

       

def open_calc():
    calc = Toplevel()
    app = calc_app(calc)


if __name__ == "__main__":
    root = Tk()
    app = calc_app(root)
    root.mainloop()

The Clock app works fine. The calculator app also works fine when i run it alone, but when i try to run it from the main file, the buttons don't seem to work.

I figured it was some sort of importing problem, but I didn't see anything that catered to what I was having. I followed the same step of the clock app i created that seems to work from the app launcher, but that didn't really seem to work out for the calculator.

Answer 1

First you create a toplevel window calc inside open_calc() and pass it into calc_app(). This toplevel window is then destroyed (root.destroy()) inside calc_app.__init__(). Then you create another instance of Tk() (calculator). The issue is caused by multiple instances of Tk().

You should not destroy the toplevel window and create another instance of Tk(), just use the toplevel window:

class calc_app:
    def __init__(self, root):
        calculator = root
        calculator.title("Calculator")
        # don't destroy the toplevel
        #root.destroy()
        ...
        # don't create another instance of Tk()
        #calculator=Tk()
        ...

Note also that you should use instance variable self.expression instead of global variable expression.