twisted.words.xish.utility.addOnetimeObserver can register a permanent xml stream observer

[jgill]

twisted.words.xish.utility.addOnetimeObserver() adds an observer to an XPath event on an xml stream. Under some situations the method will defer appending the callback to the callback queue, e.g. if is in the middle of a dispatch call. The queued command, however, calls addObserver() rather than _addObserver(), and therefore drops the 'onetime' flag.

A simple fix might be to change the lambda call near the start of _addObserver() from

lambda:self.addObserver(event, observerfn, priority, *args, **kwargs)

to:

lambda:self._addObserver(onetime, event, observerfn, priority, *args, **kwargs)

[jgill]

Part of words package.

[ralphm]

Reading that piece of code, this indeed seems to be the case. Do you have a test case that shows this behavior?

[ralphm]

(In [23387]) Branching to 'xish-nested-dispatch-3066'

[ralphm]

I made up the test case myself and fixed the one for the non-onetime observer to actually test that.

Please review.

[therve]

2 tests are failing:

[ERROR]: twisted.words.test.test_xishutil.EventDispatcherTest.testStuff

Traceback (most recent call last):
  File "/home/therve/Projets/Twisted/trunk/twisted/words/test/test_xishutil.py", line 80, in testStuff
    self.assertEquals(cb1.object, msg)
exceptions.AttributeError: CallbackTracker instance has no attribute 'object'
===============================================================================
[ERROR]: twisted.words.test.test_xishutil.EventDispatcherTest.test_addObserverTwice

Traceback (most recent call last):
  File "/home/therve/Projets/Twisted/trunk/twisted/words/test/test_xishutil.py", line 113, in test_addObserverTwice
    self.assertEquals(cb1.object, d)
exceptions.AttributeError: CallbackTracker instance has no attribute 'object'

[ralphm]

:-( Sorry about that. Fixed now.

[therve]

Great, please merge.

[ralphm]

(In [23418]) Fix adding one-time observers while in dispatch.

Author: jgill, ralphm Reviewer: therve Fixes #3066.

[trac]

Milestone Words 8.0.0 + 1 deleted