~certify-web-dev/twisted/certify-trunk

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" lang="en"><head><title>Twisted Documentation: The Twisted FAQ</title><link href="../howto/stylesheet.css" type="text/css" rel="stylesheet" /></head><body bgcolor="white"><h1 class="title">The Twisted FAQ</h1><div class="toc"><ol><li><a href="#auto0">General</a></li><ul><li><a href="#auto1">What is Twisted?</a></li><li><a href="#auto2">Why should I use Twisted?</a></li><li><a href="#auto3">I have a problem getting Twisted.</a></li><li><a href="#auto4">Why is Twisted so big?</a></li><li><a href="#auto5">But won't Twisted bloat my program, since it's so big?</a></li></ul><li><a href="#auto6">Stability</a></li><ul><li><a href="#auto7">Does the 1.0 release mean that all of Twisted's APIs are stable?</a></li><li><a href="#auto8">Which parts of Twisted are stable?</a></li></ul><li><a href="#auto9">Installation</a></li><ul><li><a href="#auto10">I run mktap (from site-packages/twisted/scripts/mktap.py)

and nothing happens!</a></li><li><a href="#auto11">Why do the Debian packages for Alphas and Release Candidates have weird versions containing old version numbers?</a></li></ul><li><a href="#auto12">Core Twisted</a></li><ul><li><a href="#auto13">How can I access self.factory from my Protocol's __init__?</a></li><li><a href="#auto14">Where can I find out how to write Twisted servers?</a></li><li><a href="#auto15">When I try to install my reactor, I get errors about a reactor

already being installed. What gives?</a></li><li><a href="#auto16">twistd won't load my .tap file! What's this

Ephemeral nonsense?</a></li><li><a href="#auto17">I get Interrupted system call errors when I use os.popen2. How do I read results from a sub-process in

Twisted?</a></li><li><a href="#auto18">Why don't my spawnProcess programs see my environment variables?</a></li><li><a href="#auto19">My Deferred or DeferredList never fires, so my program just mysteriously

hangs! What's wrong?</a></li><li><a href="#auto20">My exceptions and tracebacks aren't getting printed!</a></li><li><a href="#auto21">How do I use Deferreds to make my blocking code non-blocking?</a></li><li><a href="#auto22">I get exceptions.ValueError: signal only works in main thread when I

try to run my Twisted program! What's wrong?</a></li><li><a href="#auto23">I'm trying to stop my program with sys.exit(), but Twisted

seems to catch it! How do I exit my program?</a></li><li><a href="#auto24">How do I find out the IP address of the other end of my connection?</a></li></ul><li><a href="#auto25">Web</a></li><ul><li><a href="#auto26">Is the Twisted web server a toy?</a></li><li><a href="#auto27">But can Twisted Web do PHP?</a></li><li><a href="#auto28">And can Twisted Web do virtual hosting?</a></li><li><a href="#auto29">How do I use twisted.web to do complex things?</a></li><li><a href="#auto30">I've been using Woven since before it was called Woven. I just upgraded

and now I'm getting a confusing traceback talking about INodeMutator. What

gives?</a></li><li><a href="#auto31">My Woven pages are sent to the browser with a trailing slash appended to the

URL, which breaks all of the relative links. How do I get rid of the trailing

slash?</a></li><li><a href="#auto32">Argh! When using Woven, my newlines get mangled inside a <pre></a></li><li><a href="#auto33">When trying to use Guard, I get infinite redirects to URLs with long

hexadecimal numbers. What's the deal?</a></li></ul><li><a href="#auto34">Perspective Broker</a></li><ul><li><a href="#auto35">How can I get the reference to a client from a Perspective?</a></li></ul><li><a href="#auto36">Requests and Contributing</a></li><ul><li><a href="#auto37">Twisted is cool, but I need to add more functionality.</a></li><li><a href="#auto38">I have a patch. How do I maximize the chances the Twisted developers

will include it?</a></li><li><a href="#auto39">And to whom do I send it?</a></li><li><a href="#auto40">My company would love to use Twisted, but it's missing feature X, can you implement it?</a></li></ul><li><a href="#auto41">Documentation</a></li><ul><li><a href="#auto42">Twisted really needs documentation for X, Y or Z - how come it's not documented?.</a></li><li><a href="#auto43">Wow the Twisted documentation is nice! I want my docs to look like that

too!</a></li></ul><li><a href="#auto44">Communicating with us</a></li><ul><li><a href="#auto45">There's a bug in Twisted. Where do I report it?</a></li><li><a href="#auto46">Where do I go for help?</a></li><li><a href="#auto47">How do I e-mail a Twisted developer?</a></li></ul></ol></div><div class="content"><span></span><h2>General<a name="auto0"></a></h2><h3>What is <q>Twisted</q>?<a name="auto1"></a></h3><p>Please see

<a href="http://twistedmatrix.com/products/twisted">Twisted</a></p><h3>Why should I use Twisted?<a name="auto2"></a></h3><p>See <a href="http://twistedmatrix.com/services/twisted-advantage">The

Twisted Advantage</a></p><h3>I have a problem <q>getting</q> Twisted.<a name="auto3"></a></h3><p>Did you check the HOWTO collection? There are so many documents there

that they might overwhelm you... try starting from the index, reading through

the overviews and seeing if there seems to be a chapter which explains what

you need to. You can try reading the PostScript or PDF formatted books,

inside the distribution. And, remember, the source will be with

you... always.</p><h3>Why is Twisted so big?<a name="auto4"></a></h3><p>Twisted is a lot of things, rolled into one big package. We're not sure if

it'll stay this way, yet, but for now, if you have only specific needs, we

recommend grabbing the big Twisted tarball, and if you want, you can run the

'setup.py' script with a modified config file to generate a package with only

certain Twisted sub-packages. Twisted as a whole makes it into many operating

system distributions (FreeBSD, Debian and Gentoo, at least) so size shouldn't

be an issue for the end developer or user. In addition, packaging Twisted

as a whole makes sure the end users do not have to worry about versioning

parts of Twisted and inter-version compatibility.</p><p>If you are distributing Twisted to end-users, you can base your distribution

on the <q>Nodocs</q> packages, which are signficantly smaller.</p><h3>But won't Twisted bloat my program, since it's so big?<a name="auto5"></a></h3><p>No. You only need to import the sub-packages which you want to use, meaning

only those will be loaded into memory. So if you write a low-level network

protocol, you'd only import twisted.internet, leaving out extraneous things

like twisted.web, etc. Twisted itself is very careful with internal

dependancies, so importing one subpackage is not likely to import the whole

twisted package.</p><h2>Stability<a name="auto6"></a></h2><h3>Does the 1.0 release mean that all of Twisted's APIs are stable?<a name="auto7"></a></h3><p>No, only specific parts of Twisted are stable, i.e. we only promise

backwards compatibility for some parts of Twisted. While these APIs may be

extended, they will not change in ways that break existing code that uses

them. </p><p>While other parts of Twisted are not stable, we will however do

our best to make sure that there is backwards compatibility for these parts

as well. In general, the more the module or package are used, and the closer they

are to being feature complete, the more we will concentrate on providing backwards

compatibility when API changes take place.</p><h3>Which parts of Twisted are stable?<a name="auto8"></a></h3><p>Only modules explictily marked as such can be considered stable. Semi-stable

modules may change, but not in a large way and some sort of backwards-compatibily

will probably be provided. If no comment about API stability is present, assume

the module is unstable.</p><p>In Twisted 1.1, <em>most of twisted.internet, .cred and

.application are completely stable</em> (excepting of course code

marked as deprecated).</p><p>But as always, the only accurate way of knowing a module's stability is reading

the module's docstrings.</p><h2>Installation<a name="auto9"></a></h2><h3>I run mktap (from site-packages/twisted/scripts/mktap.py)

and nothing happens!<a name="auto10"></a></h3><p>Don't run scripts out of <code>site-packages</code>. The Windows

installer should install executable scripts to someplace like

<code>C:\Python22\scripts\</code>, *nix installers put them in

<code>$PREFIX/bin</code>, which should be in your $PATH.</p><h3>Why do the Debian packages for Alphas and Release Candidates have weird versions containing old version numbers?<a name="auto11"></a></h3><p>

An example: 1.0.6+1.0.7rc1-1

</p><p>

In Debian versioning, 1.0.7rc1 is <em>greater than</em> 1.0.7. This

means that if you install a package with Version: 1.0.7rc1, and then

that package gets a new version 1.0.7, apt will not upgrade it for

you, because 1.0.7 looks like an older version. So, we prefix the

previous version to the actual version. 1.0.6+1.0.7rc1 is <em>less

than</em> 1.0.7.

</p><h2>Core Twisted<a name="auto12"></a></h2><h3>How can I access self.factory from my Protocol's __init__?<a name="auto13"></a></h3><p>You can't. A Protocol doesn't have a Factory when it is created. Instead,

you should probably be doing that in your Protocol's

<code>connectionMade</code> method.</p><p>Similarly you shouldn't be doing <q>real</q> work, like connecting to

databases, in a Factory's <code>__init__</code> either. Instead, do that in

<code>startFactory</code>.</p><p>See <a href="servers.html">Writing Servers</a> and

<a href="clients.html">Writing Clients</a> for more details.</p><h3>Where can I find out how to write Twisted servers?<a name="auto14"></a></h3><p>Try <a href="servers.html">Writing Servers</a>.</p><h3>When I try to install my reactor, I get errors about a reactor

already being installed. What gives?<a name="auto15"></a></h3><p>Here's the rule - installing a reactor should always be the

<strong>first</strong> thing you do, and I do mean first. Importing other stuff

before you install the reactor can break your code.</p><p>Tkinter and wxPython support, as they do not install a new reactor, can be

done at any point, IIRC.</p><h3><code>twistd</code> won't load my <code>.tap</code> file! What's this

Ephemeral nonsense?<a name="auto16"></a></h3><p>When the pickled application state cannot be loaded for some reason, it

is common to get a rather opaque error like so:</p><pre class="shell">

% twistd -f test2.tap

Failed to load application: global name 'initRun' is not defined

</pre><p>The rest of the error will try to explain how to solve this problem,

but a short comment first: this error is indeed terse -- but there is

probably more data available elsewhere -- namely, the <code>twistd.log</code>

file. Open it up to see the full exception.</p><p>The error might also look like this:</p><pre class="shell">

Failed to load application: <twisted.persisted.styles.Ephemeral instance at

0x82450a4> is not safe for unpickling

</pre><p>To load a <code>.tap</code> file, as with any unpickling operation, all

the classes used by all the objects inside it must be accessible at the time

of the reload. This may require the PYTHONPATH variable to have the same

directories as were available when the application was first pickled.</p><p>A common problem occurs in single-file programs which define a few

classes, then create instances of those classes for use in a server of some

sort. If the class is used directly, the name of the class will be recorded

in the <code>.tap</code> file as something like

<code>__main__.MyProtocol</code>. When the application is reloaded, it will

look for the class definition in <code>__main__</code>, which probably won't

have it. The unpickling routines need to know the module name, and therefore

the source file, from which the class definition can be loaded.</p><p>The way to fix this is to import the class from the same source file that

defines it: if your source file is called <code>myprogram.py</code> and

defines a class called <code>MyProtocol</code>, you will need to do a

<code>from myprogram import MyProtocol</code> before (and in the same

100

namespace as) the code that references the MyProtocol class. This makes it

101

important to write the module cleanly: doing an <code>import

102

myprogram</code> should only define classes, and should not cause any other

103

subroutines to get run. All the code that builds the Application and saves

104

it out to a <code>.tap</code> file must be inside an <code>if __name__ ==

105

'__main__'</code> clause to make sure it is not run twice (or more).</p><p>When you import the class from the module using an <q>external</q> name,

106

that name will be recorded in the pickled <code>.tap</code> file. When the

107

<code>.tap</code> is reloaded by <code>twistd</code>, it will look for

108

<code>myprogram.py</code> to provide the definition of

109

<code>MyProtocol</code>.</p><p>Here is a short example of this technique:</p><pre class="python">

110

<span class="py-src-comment"># file dummy.py

111

</span><span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span><span class="py-src-op">.</span><span class="py-src-variable">internet</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">protocol</span><span class="py-src-newline">

112

</span><span class="py-src-keyword">class</span> <span class="py-src-identifier">Dummy</span><span class="py-src-op">(</span><span class="py-src-parameter">protocol</span><span class="py-src-op">.</span><span class="py-src-parameter">Protocol</span><span class="py-src-op">)</span><span class="py-src-op">:</span> <span class="py-src-keyword">pass</span><span class="py-src-newline">

113

</span><span class="py-src-keyword">if</span> <span class="py-src-variable">__name__</span> <span class="py-src-op">==</span> <span class="py-src-string">'__main__'</span><span class="py-src-op">:</span><span class="py-src-newline">

114

</span><span class="py-src-indent"> </span><span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span><span class="py-src-op">.</span><span class="py-src-variable">application</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">service</span><span class="py-src-op">,</span> <span class="py-src-variable">internet</span><span class="py-src-newline">

115

</span> <span class="py-src-variable">a</span> <span class="py-src-op">=</span> <span class="py-src-variable">service</span><span class="py-src-op">.</span><span class="py-src-variable">Application</span><span class="py-src-op">(</span><span class="py-src-string">"dummy"</span><span class="py-src-op">)</span><span class="py-src-newline">

116

</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">dummy</span><span class="py-src-newline">

117

</span> <span class="py-src-variable">f</span> <span class="py-src-op">=</span> <span class="py-src-variable">protocol</span><span class="py-src-op">.</span><span class="py-src-variable">Factory</span><span class="py-src-op">(</span><span class="py-src-op">)</span><span class="py-src-newline">

118

</span> <span class="py-src-variable">f</span><span class="py-src-op">.</span><span class="py-src-variable">protocol</span> <span class="py-src-op">=</span> <span class="py-src-variable">dummy</span><span class="py-src-op">.</span><span class="py-src-variable">Dummy</span> <span class="py-src-comment"># Note! Not "Dummy"</span><span class="py-src-newline">

119

</span> <span class="py-src-variable">internet</span><span class="py-src-op">.</span><span class="py-src-variable">TCPServer</span><span class="py-src-op">(</span><span class="py-src-number">2000</span><span class="py-src-op">,</span> <span class="py-src-variable">f</span><span class="py-src-op">)</span><span class="py-src-op">.</span><span class="py-src-variable">setServiceParent</span><span class="py-src-op">(</span><span class="py-src-variable">service</span><span class="py-src-op">.</span><span class="py-src-variable">IServiceCollect</span><span class="py-src-op">(</span><span class="py-src-variable">a</span><span class="py-src-op">)</span><span class="py-src-op">)</span><span class="py-src-newline">

120

</span> <span class="py-src-variable">a</span><span class="py-src-op">.</span><span class="py-src-variable">save</span><span class="py-src-op">(</span><span class="py-src-op">)</span><span class="py-src-newline">

121

</span><span class="py-src-dedent"></span><span class="py-src-endmarker"></span></pre><h3>I get <q>Interrupted system call</q> errors when I use <code class="python">os.popen2</code>. How do I read results from a sub-process in

122

Twisted?<a name="auto17"></a></h3><p>You should be using <code class="python">reactor.spawnProcess</code> (see

123

<code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.interfaces.IReactorProcess.spawnProcess.html" title="twisted.internet.interfaces.IReactorProcess.spawnProcess">interfaces.IReactorProcess.spawnProcess</a></code>).

124

There's also a convenience function, <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.utils.getProcessOutput.html" title="twisted.internet.utils.getProcessOutput">getProcessOutput</a></code>, in <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.utils.html" title="twisted.internet.utils">twisted.internet.utils</a></code>.</p><h3>Why don't my spawnProcess programs see my environment variables?<a name="auto18"></a></h3><p><code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.interfaces.IReactorProcess.spawnProcess.html" title="twisted.internet.interfaces.IReactorProcess.spawnProcess">spawnProcess</a></code>

125

defaults to clearing the environment of child processes as a security

126

feature. You can either provide a dictionary with exactly the name-value

127

pairs you want the child to use, or you can simply pass in

128

<code>os.environ</code> to inherit the complete environment. </p><h3>My Deferred or DeferredList never fires, so my program just mysteriously

129

hangs! What's wrong?<a name="auto19"></a></h3><p>It really depends on what your program is doing, but the most common cause

130

is this: it <em>is</em> firing -- but it's an error, not a success, and you

131

have forgotten to add an <a href="glossary.html#errback">errback</a>, so

132

nothing happens. Always add errbacks!</p><p>The reason this happens is that unhandled errors in Deferreds get printed

133

when the Deferred is garbage collected. Make sure your Deferred is garbage

134

collected by deleting all references to it when you are done with it, e.g.

135

after <code class="python">callback()</code> is called.</p><h3>My exceptions and tracebacks aren't getting printed!<a name="auto20"></a></h3><p>See previous question.</p><h3>How do I use Deferreds to make my blocking code non-blocking?<a name="auto21"></a></h3><a name="deferreds-aren't-magic"></a><p>You don't. Deferreds don't magically turn a blocking function call into a

136

non-blocking one. A Deferred is just a simple object that represents a

137

<em>deferred result</em>, with methods to allow convenient adding of

138

callbacks. (This is a common misunderstanding; suggestions on how to make this

139

clearer in the <a href="defer.html">Deferred Execution</a> howto are

140

welcome!)</p><p>If you have blocking code that you want to use non-blockingly in Twisted,

141

either rewrite it to be non-blocking, or run it in a thread. There is a

142

convenience function, <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.threads.deferToThread.html" title="twisted.internet.threads.deferToThread">deferToThread</a></code>, to help you with the

143

threaded approach -- but be sure to read <a href="threading.html">Using

144

Threads in Twisted</a>.</p><h3>I get <q>exceptions.ValueError: signal only works in main thread</q> when I

145

try to run my Twisted program! What's wrong?<a name="auto22"></a></h3><p>The default reactor, by default, will install signal handlers to catch

146

events like Ctrl-C, SIGTERM, and so on. However, you can't install signal

147

handlers from non-main threads in Python, which means that

148

<code>reactor.run()</code> will cause an

149

error. Pass the <code>installSignalHandlers=0</code> keyword argument to

150

<code>reactor.run</code> (or <code>Application.run</code>) to work around

151

this.</p><h3>I'm trying to stop my program with <code>sys.exit()</code>, but Twisted

152

seems to catch it! How do I exit my program?<a name="auto23"></a></h3><p>Use <code>reactor.stop()</code> instead. This will cleanly shutdown the

153

reactor.</p><h3>How do I find out the IP address of the other end of my connection?<a name="auto24"></a></h3><p>The <code>.transport</code> object (which implements the <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.interfaces.ITransport.html" title="twisted.internet.interfaces.ITransport">ITransport</a></code> interface) offers a pair

154

of methods named <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.interfaces.ITransport.getPeer.html" title="twisted.internet.interfaces.ITransport.getPeer">getPeer</a></code> and <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.internet.interfaces.ITransport.getHost.html" title="twisted.internet.interfaces.ITransport.getHost">getHost</a></code>.

155

<code>getPeer</code> will give you a tuple that describes the address of the

156

system at the other end of the connection. For example:</p><pre class="python">

157

<span class="py-src-keyword">class</span> <span class="py-src-identifier">MyProtocol</span><span class="py-src-op">(</span><span class="py-src-parameter">protocol</span><span class="py-src-op">.</span><span class="py-src-parameter">Protocol</span><span class="py-src-op">)</span><span class="py-src-op">:</span><span class="py-src-newline">

158

</span><span class="py-src-indent"> </span><span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionMade</span><span class="py-src-op">(</span><span class="py-src-parameter">self</span><span class="py-src-op">)</span><span class="py-src-op">:</span><span class="py-src-newline">

159

</span><span class="py-src-indent"> </span><span class="py-src-keyword">print</span> <span class="py-src-string">"connection from"</span><span class="py-src-op">,</span> <span class="py-src-variable">self</span><span class="py-src-op">.</span><span class="py-src-variable">transport</span><span class="py-src-op">.</span><span class="py-src-variable">getPeer</span><span class="py-src-op">(</span><span class="py-src-op">)</span><span class="py-src-newline">

160

</span><span class="py-src-dedent"></span><span class="py-src-dedent"></span><span class="py-src-endmarker"></span></pre><h2>Web<a name="auto25"></a></h2><h3>Is the Twisted web server a toy?<a name="auto26"></a></h3><p>No. It is a production grade server. It is running continously on several

161

sites and has been proven quite stable. The server can take loads of up to 3000

162

users at a time and still keep churning several million requests a day, even on

163

low end hardware. It can serve static files or dynamically rendered pages.</p><h3>But can Twisted Web do PHP?<a name="auto27"></a></h3><p>Yes. It works out-of-the-box, so long as you've got the standalone php

164

interpreter installed.

165

</p><h3>And can Twisted Web do virtual hosting?<a name="auto28"></a></h3><p>Can it ever!</p><p>You can decide to go with one big process for all of them, a front server

166

and a seperate server for each virtual host (for example, for permission

167

reasons), and you can even mix-and-match between Apache and Twisted (for

168

example, put Apache in the front and have Twisted handle some subset of the

169

virtual host).</p><h3>How do I use twisted.web to do complex things?<a name="auto29"></a></h3><p>See <a href="using-twistedweb.html">the Twisted.Web Howto</a>.</p><h3>I've been using Woven since before it was called Woven. I just upgraded

170

and now I'm getting a confusing traceback talking about INodeMutator. What

171

gives?<a name="auto30"></a></h3><p>You probably have code that's survived the upgrade from PyXML's

172

<code>minidom</code> to Twisted's <code>microdom</code>. Try deleting any

173

<code>.pxp</code> files that you have lying around and the error will probably

174

go away.</p><h3>My Woven pages are sent to the browser with a trailing slash appended to the

175

URL, which breaks all of the relative links. How do I get rid of the trailing

176

slash?<a name="auto31"></a></h3><p>If you are subclassing <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.page.Page.html" title="twisted.web.woven.page.Page">Page</a></code>, you can add a class attribute <code class="python">addSlash = 0</code>, like this:</p><pre class="python">

177

<span class="py-src-keyword">class</span> <span class="py-src-identifier">Foo</span><span class="py-src-op">(</span><span class="py-src-parameter">page</span><span class="py-src-op">.</span><span class="py-src-parameter">Page</span><span class="py-src-op">)</span><span class="py-src-op">:</span><span class="py-src-newline">

178

</span><span class="py-src-indent"> </span><span class="py-src-variable">addSlash</span> <span class="py-src-op">=</span> <span class="py-src-number">0</span><span class="py-src-newline">

179

</span><span class="py-src-dedent"></span><span class="py-src-endmarker"></span></pre><p>If you are still subclassing <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.controller.Controller.html" title="twisted.web.woven.controller.Controller">Controller</a></code>, you can put the <code class="python">addSlash = 0</code> there. Consider subclassing <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.page.Page.html" title="twisted.web.woven.page.Page">Page</a></code> instead, as having a <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.model.Model.html" title="twisted.web.woven.model.Model">Model</a></code>, <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.view.View.html" title="twisted.web.woven.view.View">View</a></code>, <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.controller.Controller.html" title="twisted.web.woven.controller.Controller">Controller</a></code> triad as the base of a

180

<code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.page.Page.html" title="twisted.web.woven.page.Page">Page</a></code> will be deprecated

181

in the near future.</p><p>If you're just using the generic <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.page.Page.html" title="twisted.web.woven.page.Page">Page</a></code> instance, you can set it after

182

creation like this:</p><pre class="python">

183

<span class="py-src-variable">resource</span> <span class="py-src-op">=</span> <span class="py-src-variable">page</span><span class="py-src-op">.</span><span class="py-src-variable">Page</span><span class="py-src-op">(</span><span class="py-src-string">"foo"</span><span class="py-src-op">)</span><span class="py-src-newline">

184

</span><span class="py-src-variable">resource</span><span class="py-src-op">.</span><span class="py-src-variable">addSlash</span> <span class="py-src-op">=</span> <span class="py-src-number">0</span><span class="py-src-newline">

185

</span><span class="py-src-endmarker"></span></pre><p>The default behavior of Woven is now to automatically add a slash

186

because it makes creating relative links far easier, ironically ;-)</p><h3>Argh! When using Woven, my newlines get mangled inside a <pre><a name="auto32"></a></h3><p>Use the <code>RawText</code> view.</p><h3>When trying to use Guard, I get infinite redirects to URLs with long

187

hexadecimal numbers. What's the deal?<a name="auto33"></a></h3><p>Are you using an RPY? Add a single line containing <code>cache()</code> as

188

the first line of your RPY.</p><p>An RPY file is executed every time it is accessed, so the call to <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.web.woven.guard.SessionWrapper.html" title="twisted.web.woven.guard.SessionWrapper">guard.SessionWrapper</a></code> is executed

189

once per request, making a new SessionWrapper for each request. There should be

190

only one SessionWrapper object for your application. Caching the RPY file

191

enforces this.</p><h2>Perspective Broker<a name="auto34"></a></h2><h3>How can I get the reference to a client from a Perspective?<a name="auto35"></a></h3><p>Firstly, the client must send a reference when it connects to the

192

perspective broker. This can be done by passing the reference as a parameter to

193

<code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.spread.pb.connect.html" title="twisted.spread.pb.connect">pb.connect</a></code>.</p><p>At the server end, you must override the <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.spread.pb.Perspective.attach.html" title="twisted.spread.pb.Perspective.attach">Perspective.attach</a></code>, which is called when a client attaches

194

to a perspective. The first argument of this method is a remote reference to

195

the client object that was passed to <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.spread.pb.connect.html" title="twisted.spread.pb.connect">pb.connect</a></code>. </p><p>Note that a single perspective can have many attached clients. For further

196

information, see <a href="pclients.html">Managing Clients of Perspectives</a>

197

HOWTO and the <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.spread.pb.html" title="twisted.spread.pb">twisted.spread.pb</a></code> API docs.</p><h2>Requests and Contributing<a name="auto36"></a></h2><h3>Twisted is cool, but I need to add more functionality.<a name="auto37"></a></h3><p>Great! Read our the docs, and if you're feeling generous, contribute

198

patches.</p><h3>I have a patch. How do I maximize the chances the Twisted developers

199

will include it?<a name="auto38"></a></h3><p>Use unified diff. Either use <code class="shell">svn diff</code>

200

or, better yet, make a clean checkout and use <code class="shell">diff

201

-urN</code> between them. Make sure your patch applies cleanly. In

202

your post to the mailing list, make sure it is inlined and without any

203

word wrapping.</p><h3>And to whom do I send it?<a name="auto39"></a></h3><p>Add it to the <a href="http://twistedmatrix.com/bugs/">bug tracker</a>, and if it's an urgent or important issue you may want to tell the <a href="http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python">mailing list</a>. about the issue you added</p><h3>My company would love to use Twisted, but it's missing feature X, can you implement it?<a name="auto40"></a></h3><p>You have 3 options:</p><ul><li>Pay one of the Twisted developers to implement the feature.</li><li>Implement the feature yourself.</li><li>Add a feature request to our bug tracker. We will try to implement the

204

feature, but there are no guarantees when and if this will happen.</li></ul><h2>Documentation<a name="auto41"></a></h2><h3>Twisted really needs documentation for X, Y or Z - how come it's not documented?.<a name="auto42"></a></h3><p>We are doing the best we can, and there is documentation

205

in progress for many parts of Twisted. There is a limit to how much we

206

can do in our free time. See also the answer to the next question.</p><h3>Wow the Twisted documentation is nice! I want my docs to look like that

207

too!<a name="auto43"></a></h3><p>Now you can, with <code class="API"><a href="http://twistedmatrix.com/documents/TwistedDocs/TwistedDocs-1.3.0/api/twisted.lore.html" title="twisted.lore">twisted.lore</a></code>. See the manual

208

page for <code class="shell">lore</code>. For

209

source format documentation, see <a href="policy/doc-standard.html">the documentation

210

standard description</a>. For a more comprehensive explanation, see

211

<a href="lore.html">the Lore HOWTO</a>.</p><h2>Communicating with us<a name="auto44"></a></h2><h3>There's a bug in Twisted. Where do I report it?<a name="auto45"></a></h3><p>Unless it is a show-stopper bug, we usually won't fix it if it's already

212

fixed in <a href="http://twistedmatrix.com/developers/cvs">Subversion</a>, so

213

you would do well to look there. Then send any pertinent information about the

214

bug (hopefully as much information needed to reproduce it: OS, Subversion

215

versions of any important files, Python version, code you wrote or things you

216

did to trigger the bug, etc.) to the <a href="http://twistedmatrix.com/cgi-bin/mailman/listinfo/twisted-python">mailing

217

list</a>. If no one answers immediately, you should add it to the <a href="http://twistedmatrix.com/bugs/">bug tracker</a>.</p><h3>Where do I go for help?<a name="auto46"></a></h3><p>Ask for help <a href="http://twistedmatrix.com/services/online-help">where

218

the Twisted team hangs out</a></p><h3>How do I e-mail a Twisted developer?<a name="auto47"></a></h3><p>First, note that in many cases this is the wrong thing to do: if

219

you have a question about a part of Twisted, it's usually better to

220

e-mail the mailing list. However, the preferred e-mail addresses for

221

all Twisted developers are listed in the file <q>CREDITS</q> in the

222

Subversion repository.</p></div><p><a href="../howto/index.html">Index</a></p><span class="version">Version: 1.3.0</span></body></html>

b'\\ No newline at end of file'

Older »