[Tkinter-discuss] Can't do proper event binding in a for loop

[thea_t]

Thank you guys! I know what's wrong now! :)



Michael Lange wrote:
> 
> Hi,
> 
> Thus spoketh Firat Ozgul <ozgulfirat at gmail.com> 
> unto us on Tue, 19 Oct 2010 13:19:03 +0300:
> 
>> Hello,
>> 
>> for loop doesn't work, because in a for loop all events will be bound
>> all at once, and you will only see the effect of the last binding. You
>> need something that binds events one by one.
>> 
>> If I were you, I would use the next() method of Python iterators:
> 
> I think the OP suffered from a different problem in her code, namely the
> IndexError that will be raised when i+1 or i-1 become >2 or <0 .
> I guess what she wanted to achieve can be done, but not with this simple
> lambda, she needs to catch the IndexError with something like:
> 
> def up_and_down(*buttons):
> 
>     def callback(event):
>         index = list(buttons).index(event.widget)
>         try:
>             if event.keysym == 'Up':
>                 buttons[index - 1].focus_set()
>             elif event.keysym == 'Down':
>                 buttons[index + 1].focus_set()
>         except IndexError:
>             pass
> 
>     for i in range(len(buttons)-1):
>         buttons[i].bind("<Down>", callback)
> 
>     for i in range(1, len(buttons)):
>         buttons[i].bind("<Up>", callback)
> 
> I hope this helps
> 
> Michael
> 
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