[Tutor] trying to put Tkinter widget handlers in a module

[John Fouhy]

2008/9/29  <dwbarne at earthlink.net>:
> I am writing a large Python/Tkinter/Pmw program. It has become so big that I would like to move some of the widget handlers to a module for import. The following small program illustrates:
>
> # --- begin code ---
[...]
>        c = Checkbutton(
>            master,
>            text='Check if yes',
>            variable=self.var,
>            command=self.handlerCheckButton,
>            )
[...]
>    def handlerCheckButton(self):
>        self.doNotSend=self.var.get()
>        if self.doNotSend:
>            print "\nChecked"
>        else:
>            print "\nNot checked"
>
> Is there no way to put handlers in a module and import them? Is 'self' getting in the way?

Short answer -- yes.  Well, I guess so -- if you posted the error
message you're getting, I'd be able to say for sure.  Essentially,
you're trying to take the event handlers out of the class, but this is
a problem because they refer to attributes of the class.

To get around it, you need to supply your handlers with a reference to
the Frame object.  I guess you could try something like this:

### handlers.py ###
def handleCheckButton(obj):
    def handler():
        obj.doNotSend = obj.var.get()
        if obj.doNotSend:
            print '\nChecked'
        else:
            print '\nNot checked'
    return handler

### main code ###
c = Checkbutton(
            master,
            text='Check if yes',
            variable=self.var,
            command=handlers.handleCheckButton(self)
            )
###

I think this would work, though I have not checked it.  Whether it is
a good idea, though, is another question.  I think moving some of your
class functionality out to another module could easily confuse
people..

-- 
John.