Tkinter: is there a way to check checkboxes by default?

Question

I have this piece of code that will create a simple checkbox :

from Tkinter import *

CheckVar = IntVar()
self.checkbutton = Checkbutton(self.root, text = "Test", variable = CheckVar)

However this checkbox in unchecked by default and I'm searching for a way to check it.

So far I have tried to insert

CheckVar.set(1)

right after CheckVar but it didn't work.

Thanks for your help

Edit : here is my full piece of code. When I run it, the box is still unchecked

from Tkinter import *

class App():
    def __init__(self, root):   
        self.root = root
        CheckVar = IntVar()
        CheckVar.set(1)
        self.checkbutton = Checkbutton(self.root, text = "Test", variable = CheckVar)
        self.checkbutton.grid(row=0, column=0,)


root = Tk()
app = App(root)
root.mainloop()

Answer 1

Your CheckVar is a local variable. It's getting garbage collected. Save it as an object attribute. Also, you can create the variable and initialize it all in one step:

self.CheckVar = IntVar(value=1)
self.checkbutton = Checkbutton(..., variable = self.CheckVar)

You can also use the select function of the checkbutton:

self.checkbutton.select()

Answer 2

I think the function you are looking for is .select()

This function selects the checkbutton (as can be assumed from the function name)

Try calling this function after your widget is defined:

from Tkinter import *

CheckVar = IntVar()
self.checkbutton = Checkbutton(self.root, text = "Test", variable = CheckVar)
self.checkbutton.select()

By calling the function right after the widget is created, it looks as though it's selected by default.