Question

I was trying to write code that would auto-close a Toplevel Tk window in Python.

I ended up getting it to work, but ran into a little problem along the way that I wasn’t able to figure out.

The second two buttons work, but the first one doesn’t and I don’t understand why…

Any ideas?

from Tkinter import *  root = Tk() def doDestroy ():     TL.destroy()  TL = Toplevel() TL.b = Button (TL, text='lambda destroy', command=lambda: TL.destroy) TL.b.pack()  TL.b2 = Button (TL, text='callback destroy', command=doDestroy) TL.b2.pack()  de = lambda: TL.destroy() TL.b3 = Button (TL, text='lambda that works', command=de) TL.b3.pack() root.mainloop() 

Answer 1

Because it returns a function and not its result.

You should put:

command=TL.destroy 

or if you used lambda:

command=lambda: TL.destroy()