Asyncore and Generators
November 30, 2001 | Fredrik Lundh
I’ve been playing with asyncore and 2.2’s new generator model. Here’s the idea:
Instead of passing events to callbacks, pass information to a single handle function (a generator) via instance attributes. When the handler needs more data from the network, use yield to pass control back to the asyncore dispatcher.
Does it work? You bet.
from YieldAsyncore import * class httpClient(YieldDispatcherWithSend): def __init__(self, host, port, path): self.host = host self.path = path YieldDispatcherWithSend.__init__(self, host, port) def handle(self): # send request self.send( "GET %s HTTP/1.0\r\nHost: %s\r\n\r\n" % (self.path, self.host) ) yield OK # look for response header while self.data: try: i = string.index(self.data, "\r\n\r\n") except ValueError: yield MORE # need more data else: print self, repr(self.data[:i]) self.data = self.data[i+4:] if not self.data: yield OK break # process response body while self.data: print self, len(self.data) yield OK print self, "done"
It’s not co-routines, but it’s pretty damn close!
(In case it’s not obvious, the trick here is that you can create any number of httpClient instances, and let them all run in parallel.)