[Twisted-Python] using a reactor in a loop

[Tom Brown]

On Thursday 01 March 2007 09:32, Jean-Paul Calderone wrote:
> On Thu, 1 Mar 2007 09:21:50 -0800, Tom Brown <brown at esteem.com> wrote:
> >Hello,
> >
> >I am trying to use a reactor in a loop. The application will go through
> > the loop twice then hang when trying to stop the protocol. Here's my
> > loop:
> >
> > [snip]
> >
> >I see the 'reactor stopped' get printed out twice through the loop but I
> > don't see 'running server' get printed out a third time. So,
> > reactor.run() is not returning. I must be missing something or going at
> > this completely wrong. Any suggestions?
>
> The simple thing you're missing is that reactors can't be restarted. :) 
> One way you can restructure your program to avoid needing to do this is to
> put the body of your loop (minus reactor.run()) into a function which
> returns a Deferred and to replace the call to reactor.stop() with code
> which fires that Deferred.  You can set up callbacks on this Deferred to
> execute the whole thing again if necessary.

I read through the deferreds documentation and I'm thoroughly confused on how 
to set this up. I tried to simplify the problem with a simple function:

In [60]: def foo():
   ....:     print 'foo'
   ....:     return Deferred()
   ....:

In [61]: d = foo()
foo

In [62]: d.addCallback(foo)
Out[62]: <Deferred at 0xb786792cL>

So, now I'm lost as to what to do from here. Any suggestions would be 
appreciated.

Thanks,
Tom