On Jan 28, 8:36 pm, Jean-Paul Calderone <exar...@divmod.com> wrote: > On Wed, 28 Jan 2009 06:30:32 -0800 (PST), koranthala <koranth...@gmail.com> > wrote: > >On Jan 28, 7:10 pm, Jean-Paul Calderone <exar...@divmod.com> wrote: > >> On Wed, 28 Jan 2009 02:02:57 -0800 (PST), koranthala > >> <koranth...@gmail.com> wrote: > >> >On Jan 27, 9:27 pm, koranthala <koranth...@gmail.com> wrote: > >> >> On Jan 27, 6:57 pm, Jean-Paul Calderone <exar...@divmod.com> wrote: > >> > [snip] > > >> >> Thank you Jean-Paul. > >> >> My code is more complex than what I have mentioned. When I mentioned > >> >> msg.send, the msg object actually gets the data from DB etc to send. > >> >> And there are many other items being done. > >> >> I will try to see whether I can change the code to incorporate what > >> >> you mentioned. > > >> >> I rewrote most of my code after learning just raw deferreds - I had > >> >> planned to study inlineCallbacks - but then it slipped my mind - now > >> >> it has come to bit me. :-( > > >> >Hi, > >> > I tried to update the code as per the suggestion, but to no avail. > >> > My system uses Python2.4.3 (cannot move to 2.5) - so I tried to > >> >rewrite with deferredGenerators - since I thought inlineCallbacks are > >> >similar to deferredGenerators. > > >> > But I cannot seem to rewrite it in a format where the functional > >> >encapsulation is not broken. > >> > i.e. as I mentioned in the first example - I have to pass SELF to > >> >child objects for them to modify it. > > >> Why? You don't do this in the original version of your code. Why do > >> it after switching to Twisted (particularly since you seem to want *not* > >> to)? > > >> Jean-Paul > > >Without that, I am unable to increment success and failure counters > >which are part of the message handler object. > >In the original version, if send fails the return value of > >protocol.send is propogated back to msg.send and to msg handler.send. > >But in twisted, it is not so. So, I have to pass in SELF through to > >increment success and failure counter. > >Is it possible otherwise in twisted? > > Why isn't the return value of protocol.send propagated back to msg.send? > It sounds like it should be. > > Jean-Paul
Thank you very much again Jean-Paul for helping me out. I am unable to understand how I will be able to propogate the return value of protocol.send to msg.send. Maybe I am being foolish - but my understanding is as follows. In a non-reactor pattern scenario: msg_handler.send_message calls msg.send which inturn calls protocol.send. So, the reply to protocol.send actually goes up the stack till msg_handler.send_message wherein I can increment/decrement success/ failure counter. In reactor pattern: msg_handler.send_message calls msg.send which call protocol.send which causes a deferred to be created. Now, when the deferred finishes its work, reactor calls the callback associated - but the original context (stack etc) is lost. Now, the only mechanism of interaction is via the parameters passed in the callback. This means that msg_handler has to pass in its object to msg.send which inturn has to send either msg_handler or self to protocol.send so that it is stored in the parameter to the callback. When callback is hit, I use this parameter to call methods in each object. This is what I was trying to say in my first mail that - Twisted, being twisted in its behavior is causing quite a lot of confusion in design decisions - because now I have to break functional encapsulation - by asking lower layer objects to handler upper layer objects behaviors. As I said earlier, maybe I am being completely stupid - there might be a very easy and obvious solution. But I cannot seem to get it at all. -- http://mail.python.org/mailman/listinfo/python-list
