[Python-Dev] What exception should Thread.start() raise? (original) (raw)

Steven Bethard steven.bethard at gmail.com
Mon Jun 4 21:50:39 CEST 2007

On 6/4/07, BJörn Lindqvist <bjourne at gmail.com> wrote:

The threading module contains buggy code:

class Thread(Verbose): ... def start(self): _assert self.initialized, "Thread.init() not called" _assert not self.started, "thread already started" ... If you run such code with python -O, weird stuff may happen when you call mythread.start() multiple times. -O removes assert statements so the code won't fail with an AssertionError which would be expected. So what real exception should Thread.start() raise? I have suggested adding an IllegalStateError modelled after java's IllegalStateException, but that idea was rejected. So what exception should be raised here, is it a RuntimeError?

If you want to be fully backwards compatible, you could just write this like::

def start(self):
    if not self.__initialized:
        raise AssertionError("Thread.__init__() not called")
    if self.__started:
        raise AssertionError("thread already started")

But I doubt anyone is actually catching the AssertionError, so changing the error type would probably be okay.

STeVe

I'm not in-sane. Indeed, I am so far out of sane that you appear a tiny blip on the distant coast of sanity. --- Bucky Katt, Get Fuzzy

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