Mailman 3 June 2010 - Twisted

[Twisted-Python] deferred as a Protocol class attribute, Protocol as class attribute of a Factory ...
by Jean Daniel 16 Jun '10

16 Jun '10

Hello, Reading the SMTP client tutorial[1], I do not see the impact of the factory having a protocol defined as a class attribute. Especially when here is a big fat warning [2] that I should actually understand the inplications. My guess is that in this first case the protocol methods do not need access to the protocol instance, maybe it is a clear indication that the protocol is stateless, and there is a gain ressource-wise since there is no instance created and maintained. But I am not sure. What are the implications of the protocol being a class attribute of the factory? Almost the same question: in the imapclient example [3], there is a LineReceiver subclass hooked to stdio. The lineReceived callback willl fire a callback added to an _class attribute_ deferred filled with a user function. I think this design prevents two instances of the LineReceiver subclass which would race on the class attribute deferred. What are the advantages of having defined the deferred at the class level instead of at the instance level? Thanks for your help, [1]: http://twistedmatrix.com/documents/current/mail/tutorial/smtpclient/smtpcli… [2]: """Another minor change to note is that the protocol attribute is now defined in the class definition, rather than tacked onto an instance after one is created. This means it is a class attribute, rather than an instance attribute, now, which makes no difference as far as this example is concerned. There are circumstances in which the difference is important: be sure you understand the implications of each approach when creating your own factories. """ [3]: twisted/doc/mail/examples/imapclient.py in the sources and http://twistedmatrix.com/documents/current/mail/examples/imap4client.py on the web

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[Twisted-Python] Twisted Web, Unicode & request.write()
by Jason J. W. Williams 16 Jun '10

16 Jun '10

Hi Y'all, What's the correct way to write out Unicode data to the client in Twisted Web? request.write() throws a "Data must not be unicode". Content-Type header is set with "; charset=utf-8" appended to the content type. -J

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[Twisted-Python] twisted.web questions
by Allen Bierbaum 14 Jun '10

14 Jun '10

We have a large client-server based application based on twisted. The application has grown to the point where we would like to add a REST-based API to the server side to allow for interfacing with a wider variety of client applications. Over the weekend I started looking into twisted.web and had a couple of basic questions: 1) Is there any method to stream a large request (ex: PUT or POST with file upload) into the system or does the entire body have to be loaded into memory as part of the request? 2) Has anyone used an existing URL Routing system (ex: Routes [1], Selector [2]) and adapted it for use with Twisted? (I know I could use the twisted preferred method of parent child hierarchies, but our application has a better fit with the route-based method used by Pylons, Django, Rails, etc) 3) Is there a document anywhere that describes all the environment variables the user can get from the request and how to get to them? (something like the environ section of the WSGI PEP [3]) 4) Are their any wrappers people have developed to make it a bit easier to use deferreds (in particular inlinecallbacks) in the handlers for twisted.web? (I am considering just writing a wrapper myself that provides an interface similar to google app engine webapp [4] but wanted to check first so I don't reinvent something) Thanks, Allen [1] http://routes.groovie.org/index.html [2] http://lukearno.com/projects/selector/ [3] http://www.python.org/dev/peps/pep-0333/#environ-variables [4] http://code.google.com/appengine/docs/python/tools/webapp/

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[Twisted-Python] trial + test-case-mode
by Laurens Van Houtven 14 Jun '10

14 Jun '10

Hey, Does anyone have some magic Elisp to integrate Since I know a bunch of you are happy emacs users and TTD afficionados, I'm checking here just in case someone has already hacked something up to add trial as a backend for test-case-mode. If nobody has, I'll give it a shot. test-case-mode: http://www.emacswiki.org/cgi-bin/emacs-en/TestCaseMode test-case-mode integrated to work with nose's test runner, from Georg Brandl's excellent dotemacs dir: http://bitbucket.org/birkenfeld/dotemacs/src (in extensions.el, grep for test-case-nose-backend and test-case in general) tia lvh

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com 13 Jun '10

13 Jun '10

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[Twisted-Python] Dropping Python 2.4 support on Windows after 10.1
by exarkun＠twistedmatrix.com 09 Jun '10

09 Jun '10

Hey all, I would like to propose that after Twisted 10.1 is released, we cease to claim support for Python 2.4 on any version of Windows. This seems reasonable to me considering that Python 2.5 was first released in September of 2006 and that either Windows Python installations can be upgraded easily or very likely no upgrades are possible at all (specifically, no upgrades of Twisted). The motivation for this is that we do not have the hardware resources to continue to test Twisted on Python 2.4 on Windows, particularly considering we will shortly want to begin testing on Python 2.7 on Windows. If Windows/Python 2.4 support is important enough to anyone that they can offer to host the build slaves necessary to continue testing, then I'll withdraw the suggestion. Lastly, I am not proposing dropping Python 2.4 support on any other platform (ie, Debian and Fedora). Jean-Paul

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[Twisted-Python] Stackless.py and Twisted
by Andrew Francis 09 Jun '10

09 Jun '10

Hi Folks: My talk "Prototyping Go's Select for Stackless with Stackless.py" recently got accepted to EuroPython. In the talk, I modified stackless.py to support the Go language's Select statement. I support Select as a method rather than a Python language feature. Implementing Select turns out to be relatively. However my original interest in stackless.py was about subclassing the Twisted Reactor and making it stackless's scheduler. As opposed to running Twisted in a separate tasklet so an application does not deadlock under certain edge cases. In part I wanted to experiment with changing the stackless scheduler in such a way as to improve the performance of IO driven applications. I am wondering if I would see a speed up if compiled into pypy-c (unfortunately right now I don't believe the JIT and Stackless are integrated)? Is this too wild an idea? Cheers, Andrew

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[Twisted-Python] The 10.1 release -- what's happening
by Jonathan Lange 08 Jun '10

08 Jun '10

Hello, Many of you have been asking, "what happened to the 10.1 release?" Essentially, glyph and I both had horrible weekends for different reasons. Instead of releasing, I waited around for glyph and fixed a bunch of release-related tickets. I'm going to try to do a pre-release this week. Sorry for the delay. jml

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[Twisted-Python] handling SIGCHLD
by Michael P. Soulier 08 Jun '10

08 Jun '10

Hi, I have a twisted service that needs to fork child processes to do tasks, after which they will exit. I wrote a signal handler for SIGCHLD but it didn't seem to be called. I read something about twisted installing its own signal handlers that may conflict. Is this true? How would you recommend handling a SIGCHLD in twisted? Many thanks, Mike -- Michael P. Soulier <msoulier(a)digitaltorque.ca> "Any intelligent fool can make things bigger and more complex... It takes a touch of genius - and a lot of courage to move in the opposite direction." --Albert Einstein

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[Twisted-Python] Setting a different logger for Twistd
by Landreville 08 Jun '10

08 Jun '10

Hello, I saw a few tickets and some mailing list messages similar to this question, but never saw a definitive answer. How do I go about using a different logger when I am using twistd? I have a file that defines the application object and I tried the following code in hopes that I could make the logger have max rotated logs set to a smaller number: logfile = LogFile(LOG_FILE, LOG_DIRECTORY, LOG_SIZE, maxRotatedFiles=MAX_LOGS) application.setComponent(ILogObserver, FileLogObserver(logfile)) but I get an assertion error coming up: Traceback (most recent call last): File "/usr/bin/twistd", line 21, in <module> run() File "/Library/Python/2.6/site-packages/Twisted-9.0.0-py2.6-macosx-10.6-universal.egg/twisted/scripts/twistd.py", line 27, in run app.run(runApp, ServerOptions) File "/Library/Python/2.6/site-packages/Twisted-9.0.0-py2.6-macosx-10.6-universal.egg/twisted/application/app.py", line 693, in run runApp(config) File "/Library/Python/2.6/site-packages/Twisted-9.0.0-py2.6-macosx-10.6-universal.egg/twisted/scripts/twistd.py", line 23, in runApp _SomeApplicationRunner(config).run() File "/Library/Python/2.6/site-packages/Twisted-9.0.0-py2.6-macosx-10.6-universal.egg/twisted/application/app.py", line 421, in run self.logger.start(self.application) File "/Library/Python/2.6/site-packages/Twisted-9.0.0-py2.6-macosx-10.6-universal.egg/twisted/application/app.py", line 249, in start log.startLoggingWithObserver(self._observer) File "/Library/Python/2.6/site-packages/Twisted-9.0.0-py2.6-macosx-10.6-universal.egg/twisted/python/log.py", line 592, in startLoggingWithObserver addObserver(observer) File "/Library/Python/2.6/site-packages/Twisted-9.0.0-py2.6-macosx-10.6-universal.egg/twisted/python/log.py", line 253, in addObserver assert callable(other) AssertionError

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