On Jul 14, 3:07 am, marco <ma...@minasithil.org> wrote: > Hello gals and guys, > > I'm an experienced Python user and I'd like to begin playing with > Twisted. > I started RTFM the tutorial advised on the official site and I found it > really useful and well done. > > Now I'd like to practice a bit by coding a little program that reads > strings from a serial device and redirects them remotely via TCP. For > that sake I'm trying to use deferred. >
Deferreds probably aren't a good solution for this problem. They're useful for one-time events, but you have an event that repeats over and over again with different data. > In the tutorial, a deferred class is instantiated at factory level, then > used and destroyed. > > And here things get harder for me. > Now, in my test program I need to manage data which comes in a "random" > manner, and I thought about doing it in a few possible ways: > > 1. create a deferred at factory level and every time I read something > from the serial port add some callbacks: > > class SerToTcpProtocol(Protocol): > > def dataReceived(self, data): > # deferred is already instantiated and launched > # self.factory.sendToTcp sends data to the TCP client > self.factory.deferred.addCallback(self.factory.sendToTcp, data) > Or you could do self.factory.sendToTcp(data) > 2. or, either, create a deferred at protocol level every time I receive > something, then let the deferred do what I need and destroy it: > > class SerToTcpProtocol(Protocol): > > def dataReceived(self, data): > d = defer.Deferred() > d.addCallback(self.factory.sendToTcp, data) > d.callback(data) > Same here. :) > 3. or again, use a deferred list: > > class SerToTcpProtocol(Protocol): > > def dataReceived(self, data): > d = defer.Deferred() > d.addCallback(self.factory.sendToTcp, data) > self.factory.listDeferred.addCallback(lambda d) > d.callback(data) > I'm not sure what the listDeferred is there for. Deferreds are a good abstraction for "do one thing and then tell me what the result was". You have a different sort of thing here, where there isn't much of a result (sending to tcp probably always works until you lose your connection). A method call works well for that. Jean-Paul -- http://mail.python.org/mailman/listinfo/python-list
