Mailman 3 August 2003 - Twisted

[Twisted-Python] Unruly Callback Code
by Justin Johnson Aug. 6, 2003

Aug. 6, 2003

I have some code that is getting a bit unruly due to the number of callbacks I am doing. I've defined all of this in a single method because it is part of a command line tool with multiple sub-commands, each with its own options, and I made the entire program (i.e. the command line tool) the class, and the sub-commands are methods on that class. However, I'm beginning to think I need to rearrange this so it is more maintainable, like putting each sub-command in its own class so the callbacks … [View More]can be methods on the class instead of inline functions. Would someone mind looking at the code below and suggesting ways to clean this up? Thanks. -Justin # Subcommand: mkvob def cmd_mkvob(self): """Usage: mkvob -v vob-tag[,vob-tag,...] -o site [-g group] [-s site,site,...] """ options = self.config.subOptions original_site = options["original"] group = options["group"] vobs = options["vobs"].split(",") sites = [] if options["sites"] != None: sites = options["sites"].split(",") def gotObject(object): self.perspectives[original_site] = object print "Successfully connected to %s (%s)." % (original_site, config.siteToServer[original_site]) print "Calling remote mkvob ..." d = object.callRemote("mkvob", vobs, group) return d def gotNoObject(object): print "Failed to connect:", object return object def renameReplica(results, vobs, original_site): # Do I have to connect again to do this? obj = self.perspectives[original_site] obj.callRemote("renameReplica", vobs, "original", original_site) return obj def mkRepExport(results, vobs, sites, original_site): obj = self.perspectives[original_site] d = obj.callRemote("mkReplicaExport", vobs, sites) return d def _stop(*args): print "The mkvob operation completed successfully" reactor.stop() return args def mkRepImport(results, vobs, sites): if len(vobs) > 0 and len(sites) > 0: deferreds = [] for site in sites: def onSuccess(object, site): self.perspectives[site] = object d = object.callRemote("mkReplicaImport", vobs) return d def applyTriggers(results, vobs, site): obj = self.perspectives[site] d = obj.callRemote("applyTriggers", vobs) return d d = self.connectToServer(config.siteToServer[site]) d.addCallback(onSuccess, site).addErrback(log.err) d.addCallback(applyTriggers, vobs, site).addErrback(log.err) deferreds.append(d) return defer.DeferredList(deferreds) return results d = self.connectToServer(config.siteToServer[original_site]) d.addCallbacks(gotObject, gotNoObject) d.addCallback(renameReplica, vobs, original_site).addErrback(log.err) d.addCallback(mkRepExport, vobs, sites, original_site).addErrback(log.err) d.addCallback(mkRepImport, vobs, sites).addErrback(log.err) d.addBoth(_stop) #log.startLogging(sys.stdout) reactor.run() [View Less]

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[Twisted-Python] callback conventions
by Matthew R. Scott Aug. 6, 2003

Aug. 6, 2003

Where I work, we have been using a convention of specifying callbacks that do not need to be used outside of a certain scope, by defining functions within functions. So far, it has helped us keep our code cleaner-looking and easier to browse and maintain. Example snipped from working code: class Daemon(pb.Referenceable): # ... def pingServer(self): def success(result): self.reactor.callLater(1, self.pingServer) def failure(reason): self.… [View More]

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[Twisted-Python] SSL and Perspective Broker
by Edmund Dengler Aug. 5, 2003

Aug. 5, 2003

Greetings! Grabbed a copy of 1.0.7alpha2. Tried out a simple echo server using "getObjectAtSSL", and it seems to work. Looking over the docs and API, I cannot seem to find anyplace that would allow the specification of client certificates. Is this supported (or planned to be supported)? Regards, Ed

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[Twisted-Python] Jelly assertion error when running client and server in the same process
by Patrik Blommaskog Aug. 5, 2003

Aug. 5, 2003

I have a client and a server application communicating using Twisted and PB. They run fine as separate programs. When adding some unit tests, I try to run both the server and a client in the same application, but I get an assertion error as shown below. I don't really understand enough of what's happening under the Twisted hood to tell from the message and looking at flavors.py what's causing the problem. The applications are growing, so I made an attempt to make a minimal example from … [View More]scratch to demonstrate the problem. However, I failed to reproduce it this way. Since stripping down the applications to a bare minimum can take some time, I would first like to ask the list if anyone can give me an indication of what could be the problem? Even with my bad etiquette of not providing an example, someone is likely to have written that assert statement for a reason. Traceback (most recent call last): File "C:\Python22\Lib\site-packages\twisted\internet\base.py", line 368, in runUntilCurrent call.func(*call.args, **call.kw) File "E:\p\storskogen\src\skogen\common\Core.py", line 132, in onActorEntered handler(actor) File "E:\p\storskogen\src\skogen\server\PlayerPerspective.py", line 65, in onActorEntered self.remote.callRemote("addActor", actor) File "C:\Python22\Lib\site-packages\twisted\spread\pb.py", line 323, in callRemote return self.broker._sendMessage('',self.perspective, self.luid, name, args, kw) --- <exception caught here> --- File "C:\Python22\Lib\site-packages\twisted\spread\pb.py", line 788, in _sendMessage netArgs = self.serialize(args, perspective=perspective, method=message) File "C:\Python22\Lib\site-packages\twisted\spread\pb.py", line 742, in serialize return jelly(object, self.security, None, self) File "C:\Python22\Lib\site-packages\twisted\spread\jelly.py", line 845, in jelly return _Jellier(taster, persistentStore, invoker).jelly(object) File "C:\Python22\Lib\site-packages\twisted\spread\jelly.py", line 451, in jelly sxp.append(self.jelly(item)) File "C:\Python22\Lib\site-packages\twisted\spread\jelly.py", line 407, in jelly return obj.jellyFor(self) File "C:\Python22\Lib\site-packages\twisted\spread\flavors.py", line 434, in jellyFor assert jellier.invoker is self.broker, "You cannot exchange cached proxies between brokers." exceptions.AssertionError: You cannot exchange cached proxies between brokers. FWIW, I can say that the "self.remote.callRemote("addActor", actor)" line belongs to the listener (server) side. Both peers make remote calls to each other. The listener side has a number of Cacheable's and Cacheable's containing Cacheable's, while the connecting side only exposes one Referenceable. - Patrik [View Less]

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[Twisted-Python] Re: Subclassing static.File
by Rick Morrison Aug. 5, 2003

Aug. 5, 2003

Wow, that was fast! Thanks to all for the correction. For the curious, I'm subclassing static.File.render() simply so that I can dump the server.Request headers to see how twisted packages up the data for a HTTP POST request, since I couldn't find that info in the twisted^H^Hy little maze of documentation. If you'd like, when I'm finished with my plunking around, perhaps I'll write up a few paragraphs on this that you can drop into the pertinent doc files. Rick

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[Twisted-Python] Subclassing static.File
by Rick Morrison Aug. 5, 2003

Aug. 5, 2003

Hi All: Warning: newbie alert: Just beginning to look into Twisted, and I'm really impressed with the breadth of the functionality here. But, I'm having a bit of trouble getting my head fully around this thing. Here's what I'm currently having trouble with. Here's a simple program (that doesn't work) that subclasses the static.File class: from twisted.internet import app from twisted.web import static, server class FileLogger(static.File): def __init__(self, path, defaultType="text/… [View More]

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[Twisted-Python] Maturity of twisted.web.woven?
by Steve Freitas Aug. 4, 2003

Aug. 4, 2003

Hi all, In David Mertz's recent DeveloperWorks articles on Twisted, he states the opinion, "Twisted's Web templating framework, woven, while becoming quite sophisticated, is unstable enough that I will only touch on it here."[1] Do the core developers agree with this? The reason I'm asking is that I'm looking at coding a commercial (read: credit-card accepting, livelihood-producing) website in the next several weeks, and I'd like to do it in Twisted if that's the wise choice. But I'd … [View More]

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[Twisted-Python] Goin' with the Flow
by Nicola Larosa Aug. 4, 2003

Aug. 4, 2003

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 A couple of comments about Flow, as seen in 1.0.7alpha3. Example 16 (next to last) in the howto does not work, looks like flow.py misses the line: from twisted.flow.threads import * (Added to the tracker as bug #168.) Also, the howto mentions ThreadedIterator, that is nowhere to be found. (Added to the tracker as bug #169.) Lastly, if Twisted makes one's head spin, Flow makes the whole body enter the Sufi dances. :^) - -- "I'm a Python … [View More]

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[Twisted-Python] Surprises in twisted.web.woven
by Tim Allen Aug. 4, 2003

Aug. 4, 2003

I had a little play with Woven tonight, and I'm pleased to report that I'm (slowly) getting my head around it quite satisfyingly. However, I did come across some things which surprised me - I'm not going to call them bugs, because I don't understand Woven well enough. Firstly, I'm rendering HTML, so my HTML template file starts off with an HTML doctype. Woven appears to eat this doctype, which is rather a shame - including the proper doctype makes Internet Explorer 6 behave much more … [View More]like Mozilla, which in turn makes writing webpages much less stressful. I do wind up with the standard XML header at the top of the output, but as I'm not trying to output XML, I'm afraid this might confuse something. Secondly, I was surprised by the behaviour of view templates. See the sample rpy code below: from twisted.web.woven import page, view class TestContent(view.View): template = """<ul model="sampleList" view="List"> <li pattern="listItem" model="." view="Text"/> <li pattern="emptyList"><i>empty</i></li> </ul>""" class TestPage(page.Page): template = """<html><body> <h1 model="title" view="Text"/> <div view="content"/> </body></html>""" def wvfactory_content(self, request, node, model): return TestContent(model) def wmfactory_title(self, request): return "Test page" def wmfactory_sampleList(self, request): return ["Hello", "world!"] resource = TestPage() What I expected was a list that looked like: * Hello * world! What I got was a list that looked like: * <__builtin__.TestPage instance at 0x554f08> * empty If I wrap the <ul> element in the template in a <div> (or anything else), then the output is correct - but I get the dummy <div> in the output. ...it seems that view.View ignores model= and view= attributes on top-level elements in templates, and I have no idea why. Thirdly, looking again at the above sample code - the TestPage template contains a reference to a model named 'title', and Woven looks for the model 'title' in the TestPage instance. Fair enough. The TestContent template contains a reference to a model named 'sampleList', and Woven looks for the model 'sampleList'... not in the TestContent instance as I would expect, but in the TestPage instance again. Finally, if I have a template that looks like this: <p>Have a look at <a href="cat1.png">these</a> <a href="cat2.png">three</a> <a href="cat3.png">cats</a>.</p> then the output HTML looks like: <p>Have a look at <a href="cat1.png">these</a><a href="cat2.png">three</a><a href="cat3.png">cats</a>.</p> ...spaces aren't preserved. I expect an XML processor is allowed to collapse whitespace, but not remove it entirely. [View Less]

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[Twisted-Python] t.w.w.view.View override getTemplate
by Martin.Moellenbeck＠t-online.de Aug. 4, 2003

Aug. 4, 2003

Hi, I want to generate the template by myself and override the method View.getTemplate, but it seen not work. Can Anybody help me? Martin Möllenbeck

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