Paul Moore wrote:
2009/6/29 MRAB <pyt...@mrabarnett.plus.com>:
superpollo wrote:
hi folks.
the follwing shoud print 'stuff' for 3 seconds and then stop. why it does
not work? (prints stuff forever)
1 #!/usr/bin/python
2
3 import threading
4 import sys
5
6 t = threading.Timer(3.0, sys.exit)
7 t.start()
8 while True:
9 print "stuff ",
The Timer runs the function in another thread. Perhaps sys.exit is just
exiting that thread and not the main thread.
sys.exit raises a SystemExit exception, which will get handled in the
new thread (where it won't do anything). Conceded, this isn't
particularly intuitive.
For a non-toy example, you'd probably create an Event object, use your
timer to set the event, and your while loop would do while
event.is_set(), so the problem wouldn't arise.
Paul.
so why this does not work?
1 #!/usr/bin/python
2
3 import threading
4
5 e = threading.Event()
6 t = threading.Timer(3.0, e.set())
7 t.start()
8 while not e.isSet():
9 print "stuff ",
it does *NOT* print (but it should, shouldn't it?), then exits after 3
sec but with error:
Exception in thread Thread-1:Traceback (most recent call last):
File "/usr/lib/python2.3/threading.py", line 442, in __bootstrap
self.run()
File "/usr/lib/python2.3/threading.py", line 575, in run
self.function(*self.args, **self.kwargs)
TypeError: 'NoneType' object is not callable
what gives?
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