While loop and time.sleep function

[Eric Brunel]

Hi,

Alves, Carlos Alberto - Coelce wrote:
> Hi all,
> I tray to make a simple clock program ( see the code below ).
> Can someone explain to me why code 01 works while code 02 doesn't
[snip]

Eeer, in fact both codes didn't work... At least on my Linux box. The first 
problem is that there is no mainloop, so Tk never actually starts. The 
second problem is that since the control never returns to Tk (because of 
the "while 1"), Tk never gets a chance to refresh the display. So you must 
explicitely refresh it manually:

-----------------------
from Tkinter import *
import time

class Clock:
  def __init__(self,root):
    self.lb=Label(root,padx=5,pady=5,fg='blue',font=('Times',20))
    self.lb.pack()
    self.ck()
    self.update()
  def ck(self):
    self.lb.configure(text=time.asctime()[11:19])
    # Refresh the display; otherwise, nothing happens...
    self.lb.update_idletasks()
  def update(self):
    while 1:
      self.ck()
      time.sleep(1)

if __name__=='__main__':
  root=Tk()
  root.title('Clock')
  Clock(root)
  # Run Tk main loop
  root.mainloop()
-------------------------------

HTH
 - eric -