Re: [Tutor] "Print" behaviour inside a loop?
Simon Gerber wrote:
> I got it working with
>
> while ip_addr == "":
> sys.stdout.writelines("...")
> sys.stdout.flush()
> time.sleep(0.5)
> ip_addr = get_addr()
> if ip_addr != '':
> ...
You should use sys.stdout.write(), not writelines(). writelines() expects a
sequence of strings so what you wrote is roughly equivalent to
sys.stdout.write(".")
sys.stdout.write(".")
sys.stdout.write(".")
Kent
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Re: [Tutor] "Print" behaviour inside a loop?
>Just use sys.stdout.writelines(' ... ')
>
>Example:
> >>> import sys
> >>> sys.stdout.writelines ('... '); sys.stdout.writelines ('... ')
> ... ... >>>
>
>
Thank you for the suggestion Lee, but I'm afraid that doesn't work
either. Same problems as described before. Max Noel hit the nail right
on the head, though. I got it working with
while ip_addr == "":
sys.stdout.writelines("...")
sys.stdout.flush()
time.sleep(0.5)
ip_addr = get_addr()
if ip_addr != '':
...
Script works like a charm now! Still rife with bugs and problems that
would make it more or less useless for anyone except me - but a
perfectly good, pptp config program already exists. I just made my own
for education reasons.
Anyone curious can view the whole thing here:
http://members.optusnet.com.au/~sger/pytp
I'd welcome any constructive criticism. Also, I'm storing a lot of
passwords in plain text files. I hope I got all the permissions stuff
right, but again, if anyone happens to spot any obvious flaws please do
share.
Regards,
--
"Come back to the workshop and dance cosmological models with me?"
- Peer, "Permutation City", by Greg Egan.
Simon Gerber
[EMAIL PROTECTED]
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Re: [Tutor] "Print" behaviour inside a loop?
On Sat, 11 Jun 2005 19:42:27 -0400, Simon Gerber wrote
(in article <[EMAIL PROTECTED]>):
> 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,
>
>
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>
Just use sys.stdout.writelines(' ... ')
Example:
>>> import sys
>>> sys.stdout.writelines ('... '); sys.stdout.writelines ('... ')
... ... >>>
That what your looking for?
Lee C
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Re: [Tutor] "Print" behaviour inside a loop?
On Jun 12, 2005, at 00:42, Simon Gerber wrote:
> 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?
I/O in Python is buffered -- that is, it uses RAM whenever
possible to delay the actual reading/writing operations, which in
turn speeds them up. For example, when you read a character from a
file, a larger part of the file is stored in a RAM buffer so as to
speed up subsequent calls.
In the same way, whenever you write to stdout (or to a file),
everything is stored in a buffer until a newline is reached or the
buffer is manually flushed. The latter is what you're looking for,
it's done by calling the file object's (in your case, stdout --
remember, on UNIX everything is a file) flush method.
Here's a small example:
#!/usr/bin/env python
import time, sys
for i in xrange(20):
sys.stdout.write(".")
sys.stdout.flush()
time.sleep(0.2)
-- Max
maxnoel_fr at yahoo dot fr -- ICQ #85274019
"Look at you hacker... A pathetic creature of meat and bone, panting
and sweating as you run through my corridors... How can you challenge
a perfect, immortal machine?"
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[Tutor] "Print" behaviour inside a loop?
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,
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