Mailman 3 March 2010 - Twisted

[Twisted-Python] AmpList: length limitations
by Vlad Shevchenko 31 Mar '10

31 Mar '10

Hi all! Stuck with AmpList again :( Im trying to send/retrieve data much larger then 64K and choose AmpList cause it "Convert a list of dictionaries into a list of AMP boxes". My original data looks like a long list of dicts [ {1}, {2}, ..., {x} ]. I convert it to [ {'data': 'json encoded 1,2 dicts'}, {'data': 'json encoded 3,4 dicts}', ... ] hoping EACH element in converted list will be converted to AmpBox and retriever on wire. However, still got TooLong exception on AmpBox.serialize(). AmpBox trying to serialize all my converted list but not each dict in it separately. Does this behavior ok, or this is a bug? -- WBR, Vlad

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Re: [Twisted-Python] [Twisted] #4378: Error handling in NetstringReceiver broken
by Albert Brandl 30 Mar '10

30 Mar '10

On Tue, Mar 30, 2010 at 12:27:54PM -0000, Twisted wrote: > 1. I'm pretty sure this patch, in its current form, will break in the > (still supported) Python 2.4, since it uses the 2.5 generator feature > where you pass in data. Yep - I'll fix this. > 2. Why not initialize the parser in the Protocol's __init__? Less code in > a frequently called path. Good idea, since there's no need anymore to check in every call of dataReceived. > 3. ``stringReceived`` in docstring violates coding standard, should be a > L{} or C{} or something, I forget which. So does received_string variable > name. Oops - this looks like ReST markup :-(. > 4. In dataReceived, when would we expect to get StopIteration to be > raised? Quick read of the generator doesn't show anywhere it actually > returns, it seems to be in infinite loop. When the generator is left by raising an exception, it will raise a StopIteration the next time someone sends data. But this is irrelevant now, since Python 2.4 does not support sending data to a generator. > 5. Using long() is unnecessary, you can just use int(). Ok. > 6. Hooray for more and better tests! I am uncomfortable about use of > transport.disconnecting, but we've already gone down the path of using it > elsewhere, and not sure what else you could do, so it's probably fine. I might introduce a new exception (see discussion on the mailing list) - this would allow to get rid of the check for transport.disconnecting. > 7. In test_receiveTwoNetstrings(self), perhaps the second string should be > different than the first, e.g. "a" and "woo", to catch theoretical bugs > where parser repeatedly spits out first thing it parsed. Good idea. Thanks & best regards, Albert -- DI Albert Brandl Weiermayer Solutions GmbH | http://www.weiermayer.com 4813 Altmünster | Abteistraße 12 | Austria Fon: +43(0)720 70 30 14 | Fax: +43 (0) 7612 88081

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[Twisted-Python] twisted vs wsgi
by Chris Withers 30 Mar '10

30 Mar '10

Hi All, I've managed to cobble this together as a way of starting a BFG app under Twisted's wsgi server: """ from twisted.web.wsgi import WSGIResource from twisted.web.server import Site from twisted.internet import reactor from webob import Response from repoze.bfg.configuration import Configurator def hello_world(request): return Response('Hello world!') if __name__ == '__main__': config = Configurator() config.begin() config.add_view(hello_world) config.end() resource = WSGIResource(reactor, reactor.getThreadPool(), config.make_wsgi_app()) factory = Site(resource, 'server.log') reactor.listenTCP(8080, factory) reactor.run() """ I struggled to find good narrative docs on using Twisted as a WSGI server. Where should I have been looking and have I dropped any clangers in the above? cheers, Chris

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Re: [Twisted-Python] [twisted-python] a problem about reactor
by Bo Shi 30 Mar '10

30 Mar '10

Joson, this doesn't have anything to do with the reactor (aside from perhaps it forcing you to ctrl-c to stop the program). You never 1. close() the file or 2. flush() the contents of the file to disk. Sent from my mobile phone. Please excuse any typos. On Mar 29, 2010, at 11:04, Joson Mandaro <joson.prog(a)gmail.com> wrote: > Hi all, > > I'm puzzled by this code: > > # -*- coding: utf-8 -*- > from twisted.web.client import reactor > > f = open("test1.txt","w") > f.write("html") > reactor.run() > > Then it won't write anything into test1.txt. When I deleted > "reactor.run()", it will write contents. It is interesting but I > don't know why the reactor blocks file writing. > > Best regards, > > Joson > _______________________________________________ > Twisted-Python mailing list > Twisted-Python(a)twistedmatrix.com > http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python

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[Twisted-Python] How to use AmpList?
by Vlad Shevchenko 29 Mar '10

29 Mar '10

Hi, can't find any reference of how to use AmpList. What should be passed to callRemote? In command: arguments = Amp.List(...) or arguments = [('param', AmpList(...))]? Responder params? Please, advice some refs or examples. -- WBR, Vlad

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[Twisted-Python] Supported Python versions for Twisted 10.0
by Albert Brandl 29 Mar '10

29 Mar '10

Hi! By chance, I recently found the following comment by Glyph on Stack Overflow (dated Oct 18 '08): > Right now, Twisted supports python 2.3 to 2.5. Currently, we're working on 2.6 support > (which we'll obviously have to finish before 3.0!). What are the supported Python versions for the Twisted 10 development? I think it might be a good idea to document these prerequisites in the developer section of the Wiki (or make them more prominent, if they are already there)? I know, I should have made sure _before_ submitting a patch that _sends_ data to a generator... ;-). Regards, Albert -- DI Albert Brandl Weiermayer Solutions GmbH | http://www.weiermayer.com 4813 Altmünster | Abteistraße 12 | Austria | Fon: +43(0)720 70 30 14 | Fax: +43 (0) 7612 88081

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[Twisted-Python] NetstringReceiver
by Albert Brandl 29 Mar '10

29 Mar '10

Hi! The NetstringReceiver class does not exactly do what I'd expect - see issue http://twistedmatrix.com/trac/ticket/4378. Since we plan to use netstrings, I am trying to fix it. I am not quite sure how to handle certain problems, though, and that's where I'd appreciate help. If this is the wrong place to ask this kind of questions, please redirect me ;-). 1.) In the current implementation, a NetstringParseError results in a call to self.transport.loseConnection(). Furthermore the variable brokenPeer is set to 1. But this variable is ignored. Would it be better to check it before receiving data? If yes: what is the correct way for a protocol to handle a broken transport? There is a ConnectionLost exception, but I'm not sure if / when a Protocol is allowed to raise it. 2.) The current implementation uses the method dataReceived to assemble the content of the netstring. When it is complete, the method stringReceived (which raises a NotImplementedError by default) is called. But netstrings can be long - would it be better to create a Deferred instance and call its callback instead? What would be the right place to create this Deferred? 3.) I started testing the NetstringReceiver by creating a class comment with doctests. When I later grepped the sources, I found some doctests, but there no mention of the doctest module in the test policy document. Would it be better to use the unittest framework for testing the code? Thanks and best regards, -- Albert Brandl Weiermayer Solutions GmbH 4813 Altmünster | Abteistraße 12 | Austria Fon: +43(0)720 70 30 14 | Fax: +43 (0) 7612 88081

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[Twisted-Python] [twisted-python] a problem about reactor
by Joson Mandaro 29 Mar '10

29 Mar '10

Hi all, I'm puzzled by this code: # -*- coding: utf-8 -*- from twisted.web.client import reactor f = open("test1.txt","w") f.write("html") reactor.run() Then it won't write anything into test1.txt. When I deleted "reactor.run()", it will write contents. It is interesting but I don't know why the reactor blocks file writing. Best regards, Joson

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[Twisted-Python] Weekly Bug Summary
by exarkun＠twistedmatrix.com 28 Mar '10

28 Mar '10

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Re: [Twisted-Python] [sqlalchemy] Re: SQLAlchemy, Twisted, and sAsync
by Chris Withers 26 Mar '10

26 Mar '10

King Simon-NFHD78 wrote: > The solution to this is either to eager-load all the attributes you > think you are going to need before handing the instance off to another > thread (difficult), or (probably better) to detach (expunge) the > instance from thread A's session. Are there any recommended code examples around for doing this? Once detatched, are these objects (I'm guessing for most people they'll be instances of declaratively mapped models) pickleable? > Thread B should then merge the object > into its own session (using the load=False flag so that it doesn't > needlessly requery the database). Good code examples of this around too? cheers Chris -- Simplistix - Content Management, Batch Processing & Python Consulting - http://www.simplistix.co.uk

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