Issue with TKinter widet binding

Question

I am a new learner to TKinter, and I'm testing the Radio Widget. I am using this simple program to test that I can use it correctly.

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showinfo
from tkinter import Tk, Text

# root window
root = tk.Tk()
root.geometry('300x220')
root.resizable(False, False)
root.title('Radio Button Demo')

#Display result
def display_radio():
    showinfo(
        title = "Result",
             message = selectable_numbers.get()
    )

#Selectable options
selectable_numbers = tk.StringVar()
numbers = (('1', 'One'),
           ('2', 'Two'),
           ('3', 'Three'),
           ('4', 'Four'))

#Label
simple_label = ttk.Label(text = "Select a number")
simple_label.pack(fill='x', padx=5, pady=5)

#Creating the radio buttons with iteration
for number in numbers:
    r = ttk.Radiobutton(root,
                        text = number[0],
                        value = number[1],
                        variable = selectable_numbers
    )
    r.pack(fill='x', padx = 5, pady = 5)

#Button to display
display_button = ttk.Button(root,
                            text = "Display Number")
display_button.pack(fill='x', padx=5, pady=5)

display_button.bind('<Any-Button>', display_radio(), add='+')

root.mainloop()

When I run this program, the message box appears immediently with nothing in it, then the button does not work any more. I am comparing this code with an example code that does work, and as far as I can tell they are functionally identical.

import tkinter as tk
from tkinter import ttk
from tkinter.messagebox import showinfo

# root window
root = tk.Tk()
root.geometry('300x220')
root.resizable(False, False)
root.title('Radio Button Demo')


def show_selected_size():
    showinfo(
        title='Result',
        message=selected_size.get()
    )


selected_size = tk.StringVar()
sizes = (('Small', 'S'),
         ('Medium', 'M'),
         ('Large', 'L'),
         ('Extra Large', 'XL'),
         ('Extra Extra Large', 'XXL'))

# label
label = ttk.Label(text="What's your t-shirt size?")
label.pack(fill='x', padx=5, pady=5)

# radio buttons
for size in sizes:
    r = ttk.Radiobutton(
        root,
        text=size[0],
        value=size[1],
        variable=selected_size
    )
    r.pack(fill='x', padx=5, pady=5)

# button
button = ttk.Button(
    root,
    text="Get Selected Size",
    command=show_selected_size)

button.pack(fill='x', padx=5, pady=5)


root.mainloop()

Any reason why the button becomes functionless in my code? I have tested my code with both command binding and event binding, and they both have the same results.

Instead of `display_button.bind(..., display_radio())` use: `display_button.bind(..., display_radio)` — TheLizzard, Jul 26 '21 at 10:25

score 0 · Answer 1 · answered Jul 26 '21 at 11:09

In your first program you are binding <Any-Button> to display_radio.

The function display_radio receives an event from the binding so change

def display_radio( ): to def display_radio( event ): and change

display_button.bind('<Any-Button>', display_radio(), add='+')

to

display_button.bind('<Any-Button>', display_radio, add='+')

This will fix it.

I found nothing wrong with your second program, worked as expected!

Issue with TKinter widet binding

1 Answers1