Configuration Files and Tkinter--Possible?

[Gabriel Genellina]

En Wed, 04 Mar 2009 12:12:50 -0200, W. eWatson <notvalid2 at sbcglobal.net>  
escribió:

> That's fine, but I think my problem boils down to one question. There  
> seem to be two ways to communicate with a dialog (I mean a collection of  
> widgets assembled in a window that requires the user enter various  
> parameters, integers, strings, yes/no button, etc.): 1. a callback and  
> 2. control variables. Which one should be used?

The simplest way that probably works. The one you feel most comfortable  
with. The one best fits your application. There is no single answer.

> To be more explicit, look at this code from your source above  
> <http://effbot.org/tkinterbook/entry.htm>. (This is about the simplest  
> "dialog" one can have.) :
[...code...]
> Note that above this example, the author mentions:
> "You can also bind the entry widget to a StringVar instance, and set or  
> get the entry text via that variable:
> Why have two ways of doing this?

You may have some related widgets, and want to keep them syncronized. By  
example, a slider 0-100 and a text entry for some percentage. Moving the  
slider changes the number displayed, and editing the number moves the  
slider accordingly. There are other ways of doing the same: you may react  
to some events in one widget, and alter the other accordingly. But:
- that requires that you know *which* events actually modify the value
- increases coupling between all your widgets (consider what happens when  
you want to add an image showing the effect of moving the slider)

So, in some cases, it is more convenient to use bound variables. You may  
consider this as a micro-application of the Model-View-Controller pattern.

That said, I seldom use bound variables (but I seldom write GUIs using  
Tkinter either).

-- 
Gabriel Genellina