[Twisted-Python] Learning Twisted
exarkun at divmod.com
Sun May 16 18:13:55 EDT 2004
Jason Diamond wrote:
> Sorry for the length of this post but I learn best by trying to
> explain what I'm learning (even if nobody's listening). Twisted seems
> very cool but also *huge* and unlike any framework I've used before so
> I thought I'd post my first experiences with it in the hopes that I
> could be corrected where needed (and maybe even help people other new
> like me).
I'd like to repeat what Glyph said. This is great feedback, I'd love to =
see more of it :)
> This is what I came up with:
> from twisted.internet import reactor, protocol
> from twisted.protocols import imap4
> class MyIMAP4Client(imap4.IMAP4Client):
> def connectionMade(self):
> print "connectionMade"
The above works (as you noticed ;) but isn't quite as good as hooking =
into the "serverGreeting" method, which is called after the IMAP4 server =
sends its initial message (I realize this isn't well documented).
> Note that this is *not* a method of the MyIMAP4Client class. But it
> worked! I got this printed to the console:
> loginCallback: (, 'OK LOGIN Ok.')
> I don't know, however, what the tuple represents. What's that empty
> list? In a perfect world, would this be explained in the IMAP4Client
> documentation? (I'm assuming that every callback would be different.)
The callback value here is something of an implementation detail. =
Deferreds (somewhat informally) often fall into one of two categories: =
those which will eventually be called back with an interesting value =
which is necessary for further computations, and those which will =
eventually be called back with a not-so-interesting value which only =
serves to indicate that the desired operation has completed. login() =
falls into the second category.
> Am I correct in assuming that the IMAP4Client documentation needs some
> buffing up? (Maybe I can help with that.) I didn't look at any source
> code (other than in the HOWTOs) in implementing this so I think that's
> a good sign. But as I mentioned above, I'm not clear on how I know
> what the signature for my callbacks should be or what the parameters
> to those callbacks mean in some cases.
Yep. More documentation would be great. The actual signature for =
callbacks is easy. It's always a callable that takes one argument (by =
the way, this is why your code worked with both free functions and =
methods - it doesn't matter what kind of callable you use, as long as it =
takes one argument). Further documentation about the specifics of what =
that one parameter means is definitely needed, though.
> Thanks for reading this far!
Thanks for writing!
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