Cameron: This was the exact issue, and I had initially suspected as much, but had no idea how to fix it. I had tried to use the global variable directive, but as it turned out I had misused it.
Anyway, everything is working as it should. Thanks Rance On Mon, Jan 5, 2015 at 12:39 AM, Cameron Simpson <c...@zip.com.au> wrote: > On 04Jan2015 23:19, Rance Hall <ran...@gmail.com> wrote: > >> Thanks to the advice from Joseph and Alan, I hacked a quick python script >> which demonstrates my problem more accurately. >> Its not board specific as was my last code. This sample works the same on >> my pcduino as it does on my desktop. [...] >> >> [...] >> exitFlag = 0 >> > > Ok. > > def threadloop(): >> while not exitFlag: >> print "exitFlag value: ", exitFlag >> delay(2000) >> >> def cleanup(): >> exitFlag = 1 >> print "Exit flag value: ", exitFlag >> for t in threads: >> t.join() >> sys.exit() >> > > These two hold your issue. > > threadloop() _does_ consult the global "exitFlag". But only because you > never assign to it in this function. So when you consult the name > "exitFlag", it looks for a local variable and does not find one, so it > looks in the global scope and finds it there. > > cleanup() uses exitFlag as a _local_ variable (like most variables in > python). This is because it assigns to it. Python will always use a local > variable for something you assign to unless you tell it not to; that (by > default) keeps the effects of a function within the function. Because of > this, cleanup does not affect the global variable. > > Here, it would be best to add the line: > > global exitFlag > > at the top of _both_ functions, to be clear that you are accessing the > global in both cases. So: > > def threadloop(): > global exitFlag > while not exitFlag: > print "exitFlag value: ", exitFlag > delay(2000) > def cleanup(): > global exitFlag > exitFlag = 1 > print "Exit flag value: ", exitFlag > for t in threads: > t.join() > sys.exit() > > Cheers, > Cameron Simpson <c...@zip.com.au> > > Out of memory. > We wish to hold the whole sky, > But we never will. > - Haiku Error Messages http://www.salonmagazine.com/ > 21st/chal/1998/02/10chal2.html > > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
