[Python-Dev] Active Objects in Python

[Christopher Armstrong]

On 9/28/05, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> Nick Coghlan wrote:
>
> > PEP 342's yield expressions can probably be used to help address that problem,
> > though:
> >
> >    class SomeAO(ActiveObject):
> >      def processSomeMessage(self):
> >        msg = yield
> >        # Do something with the message
> >        next_msg = yield makeSomeBlockingCall(self)
> >        # Do something with the next message
>
> I don't see how that helps, since makeSomeBlockingCall()
> is evaluated (and therefore blocks) *before* the yield
> happens.

Sounds like makeSomeBlockingCall is just misnamed (probably depending
who you ask).

I wrote a small library recently that wraps Twisted's Deferreds and
asynchronous Failure objects such that you can do stuff like

try:
 x = yield remoteObject.getSomething()
except Foo:
 print "Oh no!"

This is just a 2.5-ification of defgen, which is at
twisted.internet.defer.{deferredGenerator,waitForDeferred}. So anyway,
if your actor messages always return Deferreds, then this works quite
nicely.


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