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import sys
import weakref
def set_up():
observable = Observable()
observer = Observer()
observable.add_observer(observer)
return observable
class Observable(object):
def __init__(self):
self.observers = []
def add_observer(self, observer):
sys.stdout.write( 'observer %s\n' % (observer,))
ref = weakref.ref(observer)
self.observers.append(ref)
sys.stdout.write('weakref: %s\n' % (ref(),))
def Notify(self):
for o in self.observers:
o = o()
try:
import gc
except ImportError:
o = None #some jython does not have gc, so, there's no sense testing this in it
else:
try:
gc.get_referrers(o)
except:
o = None #jython and ironpython do not have get_referrers
if o is not None:
sys.stdout.write('still observing %s\n' % (o,))
sys.stdout.write('number of referrers: %s\n' % len(gc.get_referrers(o)))
frame = gc.get_referrers(o)[0]
frame_referrers = gc.get_referrers(frame)
sys.stdout.write('frame referrer %s\n' % (frame_referrers,))
referrers1 = gc.get_referrers(frame_referrers[1])
sys.stdout.write('%s\n' % (referrers1,))
sys.stderr.write('TEST FAILED: The observer should have died, even when running in debug\n')
else:
sys.stdout.write('TEST SUCEEDED: observer died\n')
sys.stdout.flush()
sys.stderr.flush()
class Observer(object):
pass
def main():
observable = set_up()
observable.Notify()
if __name__ == '__main__':
main()
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