How to avoid global variables in command function call

Normally, if you want a button to toggle a variable between one of N values, you would use a set of radiobuttons. When you use a radiobutton you can associate it with a variable so that whenever you click the button, the variable is automatically selected.

For example:

planet = IntVar()planet.set(0)buttonBlue = Radiobutton(wind, text="Blue Planet", variable=planet, value=1)buttonOrange = Radiobutton(wind, text="Orange Planet", variable=planet, value=0)...def choice (event):#Function binded to can, move the selected planet (blue = 1, prange = 0)    if planet.get() == 0:        moveOrange(event)    else :        moveBlue(event)

If you really want to use a regular button, you can do that with a single callback rather than two, and then use lambda or functools.partial to pass in the new value.

For example:

buttonBlue = Button(wind, text = 'Blue Planet', command = lambda: change(1))buttonOrange = Button(wind, text = 'Blue Planet', command = lambda: change(0))def change(newValue):    global a    a = newValue

Unfortunately, you cannot have a lambda expression with a statement (assignment) in it.But you can easily have just one setter function which returns a closure that you can pass to your Button constructor. Here's an example of creating and using closures:

a = 0def set_a (v):    def closure ():        global a        a = v    return closurecommand = set_a(42)command()print a    # prints 42command = set_a(17)command()print a    # prints 17