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
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