Tkinter help - Why this behavior ? (py3)

[Dodo]

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?

Dorian

 

[Alf P. Steinbach]

* 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'.


Cheers & hth.,

- Alf

 

[Dodo]

Le 05/06/2010 19:07, Alf P. Steinbach a écrit :

* Dodo, on 05.06.2010 15:46:

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'.


Cheers & hth.,

- Alf

How do I create custom modal dialogs then?

Dorian

 

[Alf P. Steinbach]

* Dodo, on 07.06.2010 12:38:

Le 05/06/2010 19:07, Alf P. Steinbach a écrit :

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

 

[Dodo]

Le 07/06/2010 15:26, Alf P. Steinbach a écrit :

* Dodo, on 07.06.2010 12:38:

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

Thanks,
I don't know why I didn't find effbot.org on the first place. But I
__did__ googled about modal dialogs!

..wait_window() works great

Thanks for your time,
Dorian

 

[rantingrick]

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()

Please don't write code like this, it is very, very, very, very ugly.
Python is an OOP language do use that to your advantage and you will
make your life much easier! Here is a better alternative.


import Tkinter as tk
from Tkconstants import *
import tkSimpleDialog

class MyDialog(tkSimpleDialog.Dialog):
def body(self, master):
prompt = "Hello from my custom dialog!\nAlthough with
something this simple i should have used tkMessageBox."
tk.Label(self, text=prompt).pack()

def validate(self):
print 'I need to put some code here, maybe'
return True

def apply(self):
print 'I need to put some code here, maybe'


class App(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
b=tk.Button(self, text='Show Dialog', command=self.showDialog)
b.pack(padx=5, pady=5)

def showDialog(self):
d = MyDialog(self)

if __name__ == '__main__':
app = App()
app.mainloop()

 

[Dodo]

Le 09/06/2010 18:49, rantingrick a écrit :

Please don't write code like this, it is very, very, very, very ugly.
Python is an OOP language do use that to your advantage and you will
make your life much easier! Here is a better alternative.


import Tkinter as tk
from Tkconstants import *
import tkSimpleDialog

class MyDialog(tkSimpleDialog.Dialog):
def body(self, master):
prompt = "Hello from my custom dialog!\nAlthough with
something this simple i should have used tkMessageBox."
tk.Label(self, text=prompt).pack()

def validate(self):
print 'I need to put some code here, maybe'
return True

def apply(self):
print 'I need to put some code here, maybe'


class App(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
b=tk.Button(self, text='Show Dialog', command=self.showDialog)
b.pack(padx=5, pady=5)

def showDialog(self):
d = MyDialog(self)

if __name__ == '__main__':
app = App()
app.mainloop()

Could you please explain to me what's the big difference?

Dorian

 

[Dodo]

Le 09/06/2010 19:13, Dodo a écrit :

Le 09/06/2010 18:49, rantingrick a écrit :

Could you please explain to me what's the big difference?

Dorian

I think I see it now. Seems good to be

 

[Terry Reedy]

Could you please explain to me what's the big difference?

What Rick wrote is pretty standard and similar to the example in Lib Ref
24.1.2.2. A Simple Hello World Program and others you can find. It get
the right things done in the right place, and just once.