-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hi!
Most of you might remember that I was working on a twisted generic positioning (GPS and things like it) framework, and here's a preliminary status report. First of all, we've moved from twisted.protocols.positioning to twisted.positioning. Yay! Seriously though: work is mostly coming along nicely, and a serious patch for separate review is probably only a few days' work away. For those interested, the ticket is here: http://twistedmatrix.com/trac/ticket/3926 And you can check out work in progress from launchpad: https://code.launchpad.net/~lvh/twisted/positioning As you might remember, we (thanks to the adhoc code reviews from glyph, tazle, dash andexarkun) decided on an implementation slightly different from the original one, using: - an NMEAReceiver class, which *only* does the receiving bit and is perfectly stateless: this does things like unpacking the sentence and checking the checksum - an IPositioningReceiver (now renamed IPositioningProvider, but I'm not sure that's the right name yet) interface that has a bunch of *sane* callbacks -- ones you actually want instead of ones that are directly a consequence of NMEA being a steaming pile of dung - an NMEAAdapter that would adapt the receiver and keep as much state as necessary internally to produce the meaningful callbacks as defined in the interface I'm having a bit of trouble implementing this this way, and I'd love to hear your comments or suggestions on the topic. Here's the code right now: http://bit.ly/1azA5q The interface lives in this file: http://bit.ly/3wWL2c I originally thought that the NMEAAdapter (which adapts an NMEAReceiver to the IPositioningReceiver interface) was really an adapter in the twisted.python.components sense of the word, so that you could do something like PositioningReceiver(NMEAReceiver()) and you'd get and NMEAAdapter object, as described in the Twisted components howto. The problem is attaching the method stubs in NMEAReceiver (nmea_GPGGA, nmea_GPRMC, nmea_GPGSV) to the methods in the NMEAAdapter that actually interpret these sentences. Ordinarily, you'd subclass that class to override those stubs. How do you feel this should be done while keeping the adapter? Should we keep the adapter at all? Of course, I could do ugly things in the adapters' __init__ like: def __init__(self, receiver): receiver.nmea_GPGGA = self.nmea_GPGGA receiver.nmea_GPRMC = self.nmea_GPRMC receiver.nmea_GPGSV = self.nmea_GPGSV But that looks like a really bad idea: it's like I'm subverting inheritance. Instead, I'm currently doing this by subclassing the receiver (thanks to exarkun for this suggestion): class NMEAAdapter(NMEAReceiver): This fixes the method stubs being correctly assigned (I suppose the correct term would be overriding, through plain old inheritance). The problem is that neither the interface nor components/adapters are involved in any way, so I feel like I'm missing something important. Thanks for reading Laurens -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Use GnuPG with Firefox : http://getfiregpg.org (Version: 0.7.7) iEYEARECAAYFAkpwyB4ACgkQT5v5zGkvKT5zPwCbB9IXwaUhP4mr33961ifG7Q92 exMAoLMh5pMXgBT0Q6kvkppCQCWJ26eZ =9Rfs -----END PGP SIGNATURE----- _______________________________________________ Twisted-Python mailing list Twisted-Python@twistedmatrix.com http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python
