<?xml version="1.0"?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"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 Evolution of Finger: cleaning up the finger code</title><link href="../../howto/stylesheet.css" type="text/css" rel="stylesheet" /></head><body bgcolor="white"><h1 class="title">The Evolution of Finger: cleaning up the finger code</h1><div class="toc"><ol><li><a href="#auto0">Introduction</a></li><li><a href="#auto1">Write Readable Code</a></li></ol></div><div class="content"><span></span><h2>Introduction<a name="auto0"></a></h2><p> This is the third part of the Twisted tutorial <a href="index.html">Twisted from Scratch, or The Evolution of Finger</a>.</p><p>In this section of the tutorial, we'll clean up our code so that it is
closer to a readable and extendable style.</p><h2>Write Readable Code<a name="auto1"></a></h2><p>The last version of the application had a lot of hacks. We avoided
sub-classing, didn't support things like user listings over the web,
and removed all blank lines -- all in the interest of code
which is shorter. Here we take a step back, subclass what is more
naturally a subclass, make things which should take multiple lines
take them, etc. This shows a much better style of developing Twisted
applications, though the hacks in the previous stages are sometimes
used in throw-away prototypes.</p><div class="py-listing"><pre>
<span class="py-src-comment"># Do everything properly
</span><span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">application</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">internet</span>, <span class="py-src-variable">service</span>
<span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</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-variable">reactor</span>, <span class="py-src-variable">defer</span>
<span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">words</span>.<span class="py-src-variable">protocols</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">irc</span>
<span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">protocols</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">basic</span>
<span class="py-src-keyword">from</span> <span class="py-src-variable">twisted</span>.<span class="py-src-variable">web</span> <span class="py-src-keyword">import</span> <span class="py-src-variable">resource</span>, <span class="py-src-variable">server</span>, <span class="py-src-variable">static</span>, <span class="py-src-variable">xmlrpc</span>
<span class="py-src-keyword">import</span> <span class="py-src-variable">cgi</span>
<span class="py-src-keyword">def</span> <span class="py-src-identifier">catchError</span>(<span class="py-src-parameter">err</span>):
<span class="py-src-keyword">return</span> <span class="py-src-string">"Internal error in server"</span>
<span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerProtocol</span>(<span class="py-src-parameter">basic</span>.<span class="py-src-parameter">LineReceiver</span>):
<span class="py-src-keyword">def</span> <span class="py-src-identifier">lineReceived</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
<span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addErrback</span>(<span class="py-src-variable">catchError</span>)
<span class="py-src-keyword">def</span> <span class="py-src-identifier">writeValue</span>(<span class="py-src-parameter">value</span>):
<span class="py-src-variable">self</span>.<span class="py-src-variable">transport</span>.<span class="py-src-variable">write</span>(<span class="py-src-variable">value</span>+<span class="py-src-string">'\r\n'</span>)
<span class="py-src-variable">self</span>.<span class="py-src-variable">transport</span>.<span class="py-src-variable">loseConnection</span>()
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">writeValue</span>)
<span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerSetterProtocol</span>(<span class="py-src-parameter">basic</span>.<span class="py-src-parameter">LineReceiver</span>):
<span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionMade</span>(<span class="py-src-parameter">self</span>):
<span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span> = []
<span class="py-src-keyword">def</span> <span class="py-src-identifier">lineReceived</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">line</span>):
<span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>.<span class="py-src-variable">append</span>(<span class="py-src-variable">line</span>)
<span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionLost</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">reason</span>):
<span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">setUser</span>(*<span class="py-src-variable">self</span>.<span class="py-src-variable">lines</span>[:<span class="py-src-number">2</span>])
<span class="py-src-keyword">class</span> <span class="py-src-identifier">IRCReplyBot</span>(<span class="py-src-parameter">irc</span>.<span class="py-src-parameter">IRCClient</span>):
<span class="py-src-keyword">def</span> <span class="py-src-identifier">connectionMade</span>(<span class="py-src-parameter">self</span>):
<span class="py-src-variable">self</span>.<span class="py-src-variable">nickname</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">nickname</span>
<span class="py-src-variable">irc</span>.<span class="py-src-variable">IRCClient</span>.<span class="py-src-variable">connectionMade</span>(<span class="py-src-variable">self</span>)
<span class="py-src-keyword">def</span> <span class="py-src-identifier">privmsg</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">channel</span>, <span class="py-src-parameter">msg</span>):
<span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">split</span>(<span class="py-src-string">'!'</span>)[<span class="py-src-number">0</span>]
<span class="py-src-keyword">if</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">nickname</span>.<span class="py-src-variable">lower</span>() == <span class="py-src-variable">channel</span>.<span class="py-src-variable">lower</span>():
<span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">factory</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">msg</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addErrback</span>(<span class="py-src-variable">catchError</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>: <span class="py-src-string">"Status of %s: %s"</span> % (<span class="py-src-variable">msg</span>, <span class="py-src-variable">m</span>))
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>: <span class="py-src-variable">self</span>.<span class="py-src-variable">msg</span>(<span class="py-src-variable">user</span>, <span class="py-src-variable">m</span>))
<span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatusTree</span>(<span class="py-src-parameter">resource</span>.<span class="py-src-parameter">Resource</span>):
<span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
<span class="py-src-variable">resource</span>.<span class="py-src-variable">Resource</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
<span class="py-src-keyword">def</span> <span class="py-src-identifier">render_GET</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">request</span>):
<span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUsers</span>()
<span class="py-src-keyword">def</span> <span class="py-src-identifier">formatUsers</span>(<span class="py-src-parameter">users</span>):
<span class="py-src-variable">l</span> = [<span class="py-src-string">'<li><a href="%s">%s</a></li>'</span> % (<span class="py-src-variable">user</span>, <span class="py-src-variable">user</span>)
<span class="py-src-keyword">for</span> <span class="py-src-variable">user</span> <span class="py-src-keyword">in</span> <span class="py-src-variable">users</span>]
<span class="py-src-keyword">return</span> <span class="py-src-string">'<ul>'</span>+<span class="py-src-string">''</span>.<span class="py-src-variable">join</span>(<span class="py-src-variable">l</span>)+<span class="py-src-string">'</ul>'</span>
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">formatUsers</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">request</span>.<span class="py-src-variable">write</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">_</span>: <span class="py-src-variable">request</span>.<span class="py-src-variable">finish</span>())
<span class="py-src-keyword">return</span> <span class="py-src-variable">server</span>.<span class="py-src-variable">NOT_DONE_YET</span>
<span class="py-src-keyword">def</span> <span class="py-src-identifier">getChild</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">path</span>, <span class="py-src-parameter">request</span>):
<span class="py-src-keyword">if</span> <span class="py-src-variable">path</span>==<span class="py-src-string">""</span>:
<span class="py-src-keyword">return</span> <span class="py-src-variable">UserStatusTree</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>)
<span class="py-src-keyword">else</span>:
<span class="py-src-keyword">return</span> <span class="py-src-variable">UserStatus</span>(<span class="py-src-variable">path</span>, <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>)
<span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatus</span>(<span class="py-src-parameter">resource</span>.<span class="py-src-parameter">Resource</span>):
<span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>, <span class="py-src-parameter">service</span>):
<span class="py-src-variable">resource</span>.<span class="py-src-variable">Resource</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
<span class="py-src-variable">self</span>.<span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>
<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
<span class="py-src-keyword">def</span> <span class="py-src-identifier">render_GET</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">request</span>):
<span class="py-src-variable">d</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">user</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">cgi</span>.<span class="py-src-variable">escape</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">m</span>:
<span class="py-src-string">'<h1>%s</h1>'</span>%<span class="py-src-variable">self</span>.<span class="py-src-variable">user</span>+<span class="py-src-string">'<p>%s</p>'</span>%<span class="py-src-variable">m</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-variable">request</span>.<span class="py-src-variable">write</span>)
<span class="py-src-variable">d</span>.<span class="py-src-variable">addCallback</span>(<span class="py-src-keyword">lambda</span> <span class="py-src-variable">_</span>: <span class="py-src-variable">request</span>.<span class="py-src-variable">finish</span>())
<span class="py-src-keyword">return</span> <span class="py-src-variable">server</span>.<span class="py-src-variable">NOT_DONE_YET</span>
<span class="py-src-keyword">class</span> <span class="py-src-identifier">UserStatusXR</span>(<span class="py-src-parameter">xmlrpc</span>.<span class="py-src-parameter">XMLRPC</span>):
<span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">service</span>):
<span class="py-src-variable">xmlrpc</span>.<span class="py-src-variable">XMLRPC</span>.<span class="py-src-variable">__init__</span>(<span class="py-src-variable">self</span>)
<span class="py-src-variable">self</span>.<span class="py-src-variable">service</span> = <span class="py-src-variable">service</span>
<span class="py-src-keyword">def</span> <span class="py-src-identifier">xmlrpc_getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
<span class="py-src-keyword">return</span> <span class="py-src-variable">self</span>.<span class="py-src-variable">service</span>.<span class="py-src-variable">getUser</span>(<span class="py-src-variable">user</span>)
<span class="py-src-keyword">class</span> <span class="py-src-identifier">FingerService</span>(<span class="py-src-parameter">service</span>.<span class="py-src-parameter">Service</span>):
<span class="py-src-keyword">def</span> <span class="py-src-identifier">__init__</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">filename</span>):
<span class="py-src-variable">self</span>.<span class="py-src-variable">filename</span> = <span class="py-src-variable">filename</span>
<span class="py-src-variable">self</span>.<span class="py-src-variable">_read</span>()
<span class="py-src-keyword">def</span> <span class="py-src-identifier">_read</span>(<span class="py-src-parameter">self</span>):
<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span> = {}
<span class="py-src-keyword">for</span> <span class="py-src-variable">line</span> <span class="py-src-keyword">in</span> <span class="py-src-variable">file</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">filename</span>):
<span class="py-src-variable">user</span>, <span class="py-src-variable">status</span> = <span class="py-src-variable">line</span>.<span class="py-src-variable">split</span>(<span class="py-src-string">':'</span>, <span class="py-src-number">1</span>)
<span class="py-src-variable">user</span> = <span class="py-src-variable">user</span>.<span class="py-src-variable">strip</span>()
<span class="py-src-variable">status</span> = <span class="py-src-variable">status</span>.<span class="py-src-variable">strip</span>()
<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>[<span class="py-src-variable">user</span>] = <span class="py-src-variable">status</span>
<span class="py-src-variable">self</span>.<span class="py-src-variable">call</span> = <span class="py-src-variable">reactor</span>.<span class="py-src-variable">callLater</span>(<span class="py-src-number">30</span>, <span class="py-src-variable">self</span>.<span class="py-src-variable">_read</span>)
<span class="py-src-keyword">def</span> <span class="py-src-identifier">getUser</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">user</span>):
<span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">get</span>(<span class="py-src-variable">user</span>, <span class="py-src-string">"No such user"</span>))
<span class="py-src-keyword">def</span> <span class="py-src-identifier">getUsers</span>(<span class="py-src-parameter">self</span>):
<span class="py-src-keyword">return</span> <span class="py-src-variable">defer</span>.<span class="py-src-variable">succeed</span>(<span class="py-src-variable">self</span>.<span class="py-src-variable">users</span>.<span class="py-src-variable">keys</span>())
<span class="py-src-keyword">def</span> <span class="py-src-identifier">getFingerFactory</span>(<span class="py-src-parameter">self</span>):
<span class="py-src-variable">f</span> = <span class="py-src-variable">protocol</span>.<span class="py-src-variable">ServerFactory</span>()
<span class="py-src-variable">f</span>.<span class="py-src-variable">protocol</span> = <span class="py-src-variable">FingerProtocol</span>
<span class="py-src-variable">f</span>.<span class="py-src-variable">getUser</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">getUser</span>
<span class="py-src-keyword">return</span> <span class="py-src-variable">f</span>
<span class="py-src-keyword">def</span> <span class="py-src-identifier">getResource</span>(<span class="py-src-parameter">self</span>):
<span class="py-src-variable">r</span> = <span class="py-src-variable">UserStatusTree</span>(<span class="py-src-variable">self</span>)
<span class="py-src-variable">x</span> = <span class="py-src-variable">UserStatusXR</span>(<span class="py-src-variable">self</span>)
<span class="py-src-variable">r</span>.<span class="py-src-variable">putChild</span>(<span class="py-src-string">'RPC2'</span>, <span class="py-src-variable">x</span>)
<span class="py-src-keyword">return</span> <span class="py-src-variable">r</span>
<span class="py-src-keyword">def</span> <span class="py-src-identifier">getIRCBot</span>(<span class="py-src-parameter">self</span>, <span class="py-src-parameter">nickname</span>):
<span class="py-src-variable">f</span> = <span class="py-src-variable">protocol</span>.<span class="py-src-variable">ReconnectingClientFactory</span>()
<span class="py-src-variable">f</span>.<span class="py-src-variable">protocol</span> = <span class="py-src-variable">IRCReplyBot</span>
<span class="py-src-variable">f</span>.<span class="py-src-variable">nickname</span> = <span class="py-src-variable">nickname</span>
<span class="py-src-variable">f</span>.<span class="py-src-variable">getUser</span> = <span class="py-src-variable">self</span>.<span class="py-src-variable">getUser</span>
<span class="py-src-keyword">return</span> <span class="py-src-variable">f</span>
<span class="py-src-variable">application</span> = <span class="py-src-variable">service</span>.<span class="py-src-variable">Application</span>(<span class="py-src-string">'finger'</span>, <span class="py-src-variable">uid</span>=<span class="py-src-number">1</span>, <span class="py-src-variable">gid</span>=<span class="py-src-number">1</span>)
<span class="py-src-variable">f</span> = <span class="py-src-variable">FingerService</span>(<span class="py-src-string">'/etc/users'</span>)
<span class="py-src-variable">serviceCollection</span> = <span class="py-src-variable">service</span>.<span class="py-src-variable">IServiceCollection</span>(<span class="py-src-variable">application</span>)
<span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPServer</span>(<span class="py-src-number">79</span>, <span class="py-src-variable">f</span>.<span class="py-src-variable">getFingerFactory</span>()
).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
<span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPServer</span>(<span class="py-src-number">8000</span>, <span class="py-src-variable">server</span>.<span class="py-src-variable">Site</span>(<span class="py-src-variable">f</span>.<span class="py-src-variable">getResource</span>())
).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
<span class="py-src-variable">internet</span>.<span class="py-src-variable">TCPClient</span>(<span class="py-src-string">'irc.freenode.org'</span>, <span class="py-src-number">6667</span>, <span class="py-src-variable">f</span>.<span class="py-src-variable">getIRCBot</span>(<span class="py-src-string">'fingerbot'</span>)
).<span class="py-src-variable">setServiceParent</span>(<span class="py-src-variable">serviceCollection</span>)
</pre><div class="caption">Source listing - <a href="listings/finger/finger18.py"><span class="filename">listings/finger/finger18.py</span></a></div></div></div><p><a href="../../howto/index.html">Index</a></p><span class="version">Version: 2.5.0</span></body></html>
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