Exceptions in threads

[Martin von Loewis]

Dale Strickland-Clark <dale at riverhall.NOTHANKS.co.uk> writes:

> I was kind of hoping for some undocumented onException() or onEnd()
> methods that I could override. A bit of a long shot, I grant you.

How would that work? A thread is called "thread" because it is a
single thread of control; it always does its thing, and the outside
world cannot force it to do anything else. 

If you have thread objects, nothing stops you from doing

class NotiableThread(threading.Thread):

  def onException(self):
    print "onexception called"

  def start_new_thread(self, *args):
    t = NotifyingThread(self, *args):
    r.start()
    return t

def NotifyingThread(threading.Thread):
  def __init__(self, parent, *args):
    self.parent = parent
    threading.Thread.__init__(self, *args)

  def run(self):
    try:
      threading.Thread.run(self)
    except:
      self.parent.onException()

With this architecture, a thread that terminates with an exception
will invoke a onException operation on the parent thread. However,
this invocation will occur in the content of the *child* thread, not
in the context of the parent thread. Having the parent thread execute
something else just makes no sense.

Regards,
Martin