On Oct 14, 2009, at 8:26 AM, Tim Allen wrote:
On Wed, Oct 14, 2009 at 07:43:41AM -0400, Steve Steiner (listsin) wrote:
That's the thing about Twisted; sometimes it's hard to know whether the stuff that has been built into standard Python since Twisted 'rolled their own' is a superset, a subset, or a completely different beast. Logging is a good case in point. Since we're using Python's logging everywhere, I wasn't even sure whether there would be an advantage to learning Twisted's similar system. Twisted's trial is another example; we've just been using nose. Seems like there's always some little extra that makes the Twisted stuff worth knowing.
Most of the duplicate stuff in Twisted has the excuse of being written before any alternatives were available, and usually having one or two extra little integration features that current alternatives don't provide.
Yes, that extra little integration feature sometimes makes a huge difference. But, as you said, being as much of Twisted's stuff predates the 'equivalent' stdlib stuff, it's hard to know where the leverage is going to be. For example, Python's standard logging has the advantage of being able to generate many different types of logging outputs (e.g. logging.handlers.SMTPHandler) whereas Twisted's is better integrated with Twisted but is missing many of those types of things. Trial and deferreds vs. nose and its integration with e.g. coverage... It's hard to know when to use which and, as you said, we want to use standard library stuff wherever possible.
Once I was using Trial, which automatically sets up Twisted's logging system to log to a handy file for debugging purposes, I had to decide what to do about logging - try to reroute Twisted's logging into the Python logging system (which would mean doing something complicated for tests), or just give up and use Twisted's logging everywhere. I opted for the latter route as the path of least resistance (and because it would be easier to set up with twistd later).
I'm working out a blended method having a PythonLoggingObserver that relay's Twisted's log messages to Python standard logging, as per Glyph's suggestion. That way we don't have to mangle all of our working logging code, bug special notifications we can reroute to a special "Twisted Messages" file that we know to keep an eye on.
I believe nose does for Python logging what Trial does for Twisted logging these days, and if nose can run Trial's TestCase subclasses, you might just as well stick with what you're already using. There are integration advantages to using all the Twisted goodies together, but it's not nearly the same amazing quantum leap in understanding and capability that Twisted's core provides.
Again, we'll probably end up with a blended approach since we use nose for coverage and profiling integration as well. We are having fun now, right? S