Since @inlineCallbacks are decorators, odd errors pop up if you misuse them.

@inlineCallback but don't call yield:

You'll see this misleading error at runtime:

2010-01-28 16:32:55-0800 [-] [user_notification]   File "/Users/hubbard/code/ve/dx/lib/python2.6/site-packages/twisted/internet/defer.py", line 746, in _inlineCallbacks
2010-01-28 16:32:55-0800 [-] [user_notification]     result = g.send(result)
2010-01-28 16:32:55-0800 [-] [user_notification] exceptions.AttributeError: 'NoneType' object has no attribute 'send'

and wonder why, since you might not be sending anything. Yep, just remove the decorator or check for a missing yield statement.

yield but no @inlineCallback

Komodo will catch this in the editor, thankfully. Not sure what'd happen at runtime, though I suspect a hang since yield is also used for generators and is a valid Python keyword.

return from an @inlineCallback function

Yep, the decorator hijacks the return statement. You need to use

(Komodo will catch this. I like Komodo. You might like it too.)

returnValue from non-decorated function

Unknown. Komodo misses this error, surprisingly.