[Twisted-Python] Shutdown empty reactor?

[Phillip J. Eby]

Hi.  I've recently had an inquiry from a PEAK user who wants their reactor 
loop to shut down automatically when there are no selectables or pending 
calls.  There doesn't appear to be any way to do this without breaking 
reactor encapsulation, as there is no (for example) 'getSelectables()' method.

Is this something that could be added, or is there any general interest in 
having idle reactors shut down?  In principle, there is no way for a 
running-on-empty reactor to do any further useful work, and no way for it 
to be shut down, either.  (If one is using threads, then there is always a 
"waker" selectable present, which means that by definition a reactor using 
threads is never "running on empty".)

Thanks.