python - 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()