Francesco Bochicchio wrote:
> It should be added here that in Python you have several ways get around
> this Tkinter limitation and pass an user argument to the callback. Once
> upon a time , back in Python 1.x, I used to do something like this:
>
> class CallIt:
> def __init__(self, f, *args):
> self.f = f
> self.args = args
> def __call__(self):
> return apply(self.f, self.args)
>
> and then, to do what the OP wanted to do:
> command = CallIt(self.Display, 1)
>
> but nowadays, you can achieve the same effect with:
> command = functtools.partial(self.Display,1)
or, much clearer for non-guru programmers, and a lot easier to extend
when you realize that you have to do more than just calling a single
method, use a local callback function:
def do_display():
self.Display(1)
w = Button(callback=do_display)
local functions are cheap in Python; creating a new one for each button
is very inexpensive.
for very simple callbacks, you can use the lambda syntax as well:
w = Button(callback=lambda: self.Display(1))
</F>
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