Run once while loop

[John O'Hagan]

On Tue, 3 Apr 2012 23:00:22 +0200
Anatoli Hristov <tolidtm at gmail.com> wrote:

> On 03 Apr 2012, at 22:45, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> 
> > On Tue, Apr 3, 2012 at 2:36 PM, Anatoli Hristov <tolidtm at gmail.com> wrote:
> >> Hi,
> >>
> >> I'm trying to do a while loop with condition of time if time is
> >> 12:00:00 print text, but for this one second the text is printed at
> >> least 50 times, how can I print only once?
> >
> > Set a flag when you print the text to indicate that you've already
> > printed it, and don't print it again if the flag is set.  When it's no
> > longer 12:00:00, reset the flag.
> >
> > That said, a busy while loop is probably the wrong way to do this,
> > because it will run your CPU at 100%.  Better would be to put the
> > thread to sleep with time.sleep() calls or a real event loop with a
> > timer event.
> >
> > Cheers,
> > Ian
> 
> Thank you Ian,
> 
> what if I wait for other conditions if I use time.sleep for 1 sec? it
> means that all the program is sleeping for a sec.
> 

If I understand correctly, you don't want the whole program to sleep. If
that's the case, you could use threading.Timer, for example:

import threading, time

def twelve():
    print("It's twelve o'clock")

local_secs = (time.time() - time.timezone) % (24 * 60 * 60)
secs_till_12 = 12 * 60 * 60 - (local_secs % (12 * 60 * 60))

wait_till_12 = threading.Timer(secs_till_12, twelve)
wait_till_12.start()


Regards,

John