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Tkinter question

Cameron Laird claird at lairds.com
Sun Nov 30 11:54:26 EST 2003 
In article <pan.2003.11.28.19.53.15.767100 at phreaker.nospam>,
Logan  <logan at phreaker.nospam> wrote:
>On Fri, 28 Nov 2003 19:59:23 +0100, Ali El Dada wrote:
>
>> i am using Tkinter in my application, and i have a button
>> that, when clicked, opens a new window as in: 
>> 
>> b1 = Button(someframe, text="bla", command = someFunction)
>> 
>> def someFunction():
>>     newWindow = Toplevel()
>>     '''the new window widgets go here'''
>> 
>> of course, whenever the button is clicked, a new window
>> opens. what do you recommend as a neat way to allow only one
>> window to open??
>
>It depends on what kind of behavior you want: if newWindow is e.g.
>a dialog (like 'find', 'find & replace' etc. in an editor), you
>want the new window to pop up, but any older dialog should get 
>destroyed. 
>
>To achieve this, you can make newWindow a *global variable* and
>use e.g. the following (not very elegant, but it works):
>
># here, the 'find'-dialog is created (e.g. inside some class)
>    try:
>	newWindow.destroy()
>    except:
>        pass
>
>    newWindow = Toplevel()
>    # widgets for the 'find'-dialog
>
># here, the 'find&replace'-dialog is created (e.g. inside some class)
>    try:
>	newWindow.destroy()
>    except:
>        pass
>
>    newWindow = Toplevel()
>    # widgets for the 'find&replace'-dialog
>
>
>If you want, that your window gets created only once (and whenever
>such a window is already open, no new window should be created) you
>could either use an approach similar to the one above (i.e. with
>newWindow being a global variable) or e.g. use a class which 
>keeps track on how many instances of itself were already created
>and which behaves accordingly (Google: python, singleton).
>
>There are other solutions, too. The 'right' solution for you
>depends mainly on the design of your whole program (OO or not etc.).
			.
			.
			.
It's quite common with some toolkits--Tkinter
among them--to re-use widgets.  The body of a
program just uses widgets as needed, and 
little initializers or constructors or helpers
take care of creating (or sometimes deiconify-
ing) the widgets as needed.  They aren't 
destroyed, in general, although they might oc-
casionally be iconified or withdrawn or 
unmanaged or such.
-- 

Cameron Laird <claird at phaseit.net>
Business:  http://www.Phaseit.net
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