Tkinter help - Why this behavior ? (py3)

[Alf P. Steinbach]

* Dodo, on 07.06.2010 12:38:
> Le 05/06/2010 19:07, Alf P. Steinbach a écrit :
>> * Dodo, on 05.06.2010 15:46:
>>> Hi,
>>>
>>> let's consider this exemple :
>>>
>>> from tkinter import *
>>> from tkinter.ttk import *
>>>
>>> class First:
>>> def __init__(self):
>>> self.root = Tk()
>>> B = Button(self.root, command=self.op)
>>> B.pack()
>>>
>>> self.root.mainloop()
>>>
>>> def op(self):
>>> Second(self)
>>> print("print")
>>>
>>>
>>> class Second:
>>> def __init__(self, parent):
>>> root = Toplevel(parent.root)
>>> root.grab_set()
>>>
>>> root.mainloop()
>>>
>>>
>>> First()
>>>
>>>
>>>
>>> when I close the second window, the print is NOT executed. It's done
>>> when I close the first window.
>>> Why do it "freeze" my function?
>>
>> First, sorry about Thunderbird 3.x messing up the quoting of the code.
>>
>> Don't know what they did to introduce all those bugs, but anyway,
>> Thunderbird 3.x is an example that even seasoned programmers introduce
>> an unbelievable number of bugs, I think mostly just by repeating code
>> patterns blindly.
>>
>> In your code above you're doing as the TB programmers presumably did,
>> repeating a code pattern that you've seen has worked, without fully
>> grokking it. The call to 'mainloop' enters a loop. A button press causes
>> your callback to be invoked from within that loop, but your code then
>> enters a new 'mainloop'.
>>
>> Don't.
>>
>> Except for modal dialogs the single top level 'mainloop' suffices (all
>> it does is to dispatch "messages" to "handlers", such as your button
>> press callback). So, just place a single call to 'mainloop' at the end
>> of your program. Remove the calls in 'First' and 'Second'.
>>
>>
>
> How do I create custom modal dialogs then?

I typed

   tkinter modal dialog

in the Firefox address bar, and it landed me on

   http://effbot.org/tkinterbook/tkinter-dialog-windows.htm


Cheers & hth.,

- Alf


-- 
blog at <url: http://alfps.wordpress.com>