Text widget updates only after calling method exits (threadingissue?)

[mariox19]

Are Tkinter widgets running on their own thread?

If I try to make a simple application that will print the letters A to
Z to a Tkinter Text widget, and I space the printing of each letter by
1 second, it seems no text will appear in the Text widget until the
method exits.

Take a look at this snippet:

# Assume I have created no threads other than the one that comes
with Main

def printToTkinterTextWidget(text):
"""
Prints A-Z to the Text widget, 1 letter per second.
"""
# Problem: no text appears in the widget until 26 seconds has
elapsed
for aNumber in range(65, 91):
self.textWidget.insert(END, text)
time.sleep(1)

If I am supposed to send messages to Tkinter objects only from the
main thread, how can I get the letters to appear 1 per second?

Thanks,

Mario

[Marc 'BlackJack' Rintsch]

On Tue, 11 Dec 2007 17:58:37 -0800, mariox19 wrote:

If I am supposed to send messages to Tkinter objects only from the
main thread, how can I get the letters to appear 1 per second?

Take a look at the `after()` method on widgets.

Ciao,
Marc 'BlackJack' Rintsch

[Eric Brunel]

On Wed, 12 Dec 2007 02:58:37 +0100, mariox19 <ma********@gmail.comwrote:

Are Tkinter widgets running on their own thread?

No. And usually, GUI toolkits and threads don't mix well...

If I try to make a simple application that will print the letters A to
Z to a Tkinter Text widget, and I space the printing of each letter by
1 second, it seems no text will appear in the Text widget until the
method exits.

Take a look at this snippet:

# Assume I have created no threads other than the one that comes
with Main

def printToTkinterTextWidget(text):
"""
Prints A-Z to the Text widget, 1 letter per second.
"""
# Problem: no text appears in the widget until 26 seconds has
elapsed
for aNumber in range(65, 91):
self.textWidget.insert(END, text)
time.sleep(1)

time.sleep will not give back the control to the Tkinter mainloop, so your
text widget won't be refreshed on screen. Try:
self.textWidget.update_idletasks()
before the sleep.

HTH
--
python -c "print ''.join([chr(154 - ord(c)) for c in
'U(17zX(%,5.zmz5(17l8(%,5.Z*(93-965$l7+-'])"

[mariox19]

*** SOLVED ***

Thanks, Eric. I've had luck with code along these lines:

# 1. Assume Text widget as instance variable: textView
# 2. Assume button with method, 'start', bound to it

def start(self, event=None):
"""
Starts the demo.
"""
# Print A-Z to widget, pausing 1/10 second between each letter
for aNumber in range(65, 91):
self.textView.insert(END, chr(aNumber))
self.textView.update_idletasks()
time.sleep(0.1)

The code does just what I want it to.

Mario

On Dec 12, 3:43 am, "Eric Brunel" <[e-mail]:

On Wed, 12 Dec 2007 02:58:37 +0100, mariox19 <[e-mail]:

Are Tkinter widgets running on their own thread?

No. And usually, GUI toolkits and threads don't mix well...

If I try to make a simple application that will print the letters A to
Z to a Tkinter Text widget, and I space the printing of each letter by
1 second, it seems no text will appear in the Text widget until the
method exits.

Take a look at this snippet:

# Assume I have created no threads other than the one that comes
with Main

def printToTkinterTextWidget(text):
"""
Prints A-Z to the Text widget, 1 letter per second.
"""
# Problem: no text appears in the widget until 26 seconds has
elapsed
for aNumber in range(65, 91):
self.textWidget.insert(END, text)
time.sleep(1)

time.sleep will not give back the control to the Tkinter mainloop, so your
text widget won't be refreshed on screen. Try:
self.textWidget.update_idletasks()
before the sleep.

HTH
--
python -c "print ''.join([chr(154 - ord(c)) for c in
'U(17zX(%,5.zmz5(17l8(%,5.Z*(93-965$l7+-'])"