[Tutor] "Print" behaviour inside a loop?

[Chinook]

On Sat, 11 Jun 2005 19:42:27 -0400, Simon Gerber wrote
(in article <42AB76E3.90107 at gmail.com>):

> Hullo,
> 
> Firstly, thanks to everyone who helped me find my own IP address. That 
> was a big help. That bit is working now, and working very nicely. I am 
> now stuck on something purely aesthetic - printing a few dots across the 
> screen to provide a bit of feedback while the VPN tunnel is being 
> established.
> 
> def vpn_connect(choice):
>     import time
>     ip_addr = ""
>     tries = 0
>     retries = 10
>     print "Connecting to %s" % (choice),
>     os.system("pon %s" % (choice))
>     while ip_addr == "" and tries < retries:
>         print "...",                 # This is the line causing problems
>         time.sleep(0.5)
>         ip_addr = get_addr()
>         if ip_addr != '':
>               #create the route!         
>               pass
>         else:
>               tries += 1
>     sys.exit()
> 
> It works. The problem is, nothing is displayed on screen until after the 
> connection occurs - at which point we see:
> 
> "Connecting to Prodigi ... ... ... ... ... ... ... "
> 
> If I remove the comma at the end of the marked line, the ellipses  print 
> every .5 seconds as desired, except they print down the screen of course!
> 
> After googling around a little, I found a post that seemed to say  
> Python won't draw the results of 'print' statements until it hits a 
> newline. I tried using sys.stout.write('...'), but had the same problem 
> there, too. I've also found a few progress bar classes around the web, 
> but I not exactly want a progress bar. I just want to print '...' every 
> few seconds until connected.
> 
> Any hints? I looked up the python reference manual, but couldn't find 
> any way to force print statements to draw. Should I be looking into 
> threads, perhaps?
> 
> Regards,
> 
> 
> _______________________________________________
> Tutor maillist  -  Tutor at python.org
> http://mail.python.org/mailman/listinfo/tutor
> 

Just use sys.stdout.writelines(' ... ')

Example:
  >>> import sys
  >>> sys.stdout.writelines ('... '); sys.stdout.writelines ('... ')
  ... ... >>>

That what your looking for?
Lee C