~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 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"><h2>Introduction<a name="auto0"></a></h2> This is the third part of the Twisted tutorial <a href="index.html">Twisted from Scratch, or The Evolution of Finger</a>.In this section of the tutorial, we'll clean up our code so that it is

closer to a readable and extendable style.<h2>Write Readable Code<a name="auto1"></a></h2>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.<div class="py-listing"><pre>

# Do everything properly

from twisted.application import internet, service

from twisted.internet import protocol, reactor, defer

from twisted.protocols import basic, irc

from twisted.web import resource, server, static, xmlrpc

import cgi

def catchError(err):

return "Internal error in server"

class FingerProtocol(basic.LineReceiver):

def lineReceived(self, user):

d = self.factory.getUser(user)

d.addErrback(catchError)

def writeValue(value):

self.transport.write(value+'\r\n')

self.transport.loseConnection()

d.addCallback(writeValue)

class FingerSetterProtocol(basic.LineReceiver):

def connectionMade(self):

self.lines = []

def lineReceived(self, line):

self.lines.append(line)

def connectionLost(self, reason):

self.factory.setUser(*self.lines[:2])

class IRCReplyBot(irc.IRCClient):

def connectionMade(self):

self.nickname = self.factory.nickname

irc.IRCClient.connectionMade(self)

def privmsg(self, user, channel, msg):

user = user.split('!')[0]

if self.nickname.lower() == channel.lower():

d.addErrback(catchError)

d.addCallback(lambda m: "Status of %s: %s" % (msg, m))

d.addCallback(lambda m: self.msg(user, m))

class UserStatusTree(resource.Resource):

def __init__(self, service):

resource.Resource.__init__(self)

self.service = service

def render_GET(self, request):

d = self.service.getUsers()

def formatUsers(users):

l = ['<li><a href="%s">%s</a></li>' % (user, user)

for user in users]

return '<ul>'+''.join(l)+'</ul>'

d.addCallback(formatUsers)

d.addCallback(request.write)

d.addCallback(lambda _: request.finish())

return server.NOT_DONE_YET

def getChild(self, path, request):

if path=="":

return UserStatusTree(self.service)

else:

return UserStatus(path, self.service)

class UserStatus(resource.Resource):

def __init__(self, user, service):

resource.Resource.__init__(self)

self.user = user

self.service = service

def render_GET(self, request):

d = self.service.getUser(self.user)

d.addCallback(cgi.escape)

d.addCallback(lambda m:

'<h1>%s</h1>'%self.user+'%s'%m)

d.addCallback(request.write)

d.addCallback(lambda _: request.finish())

return server.NOT_DONE_YET

class UserStatusXR(xmlrpc.XMLRPC):

100

def __init__(self, service):

101

xmlrpc.XMLRPC.__init__(self)

102

self.service = service

103

104

def xmlrpc_getUser(self, user):

105

return self.service.getUser(user)

106

107

108

class FingerService(service.Service):

109

110

def __init__(self, filename):

111

self.filename = filename

112

self._read()

113

114

def _read(self):

115

self.users = {}

116

for line in file(self.filename):

117

user, status = line.split(':', 1)

118

user = user.strip()

119

status = status.strip()

120

self.users[user] = status

121

self.call = reactor.callLater(30, self._read)

122

123

def getUser(self, user):

124

return defer.succeed(self.users.get(user, "No such user"))

125

126

def getUsers(self):

127

128

129

def getFingerFactory(self):

130

f = protocol.ServerFactory()

131

f.protocol = FingerProtocol

132

f.getUser = self.getUser

133

return f

134

135

def getResource(self):

136

r = UserStatusTree(self)

137

x = UserStatusXR(self)

138

r.putChild('RPC2', x)

139

return r

140

141

def getIRCBot(self, nickname):

142

f = protocol.ReconnectingClientFactory()

143

f.protocol = IRCReplyBot

144

f.nickname = nickname

145

f.getUser = self.getUser

146

return f

147

148

application = service.Application('finger', uid=1, gid=1)

149

f = FingerService('/etc/users')

150

serviceCollection = service.IServiceCollection(application)

151

internet.TCPServer(79, f.getFingerFactory()

152

).setServiceParent(serviceCollection)

153

internet.TCPServer(8000, server.Site(f.getResource())

154

).setServiceParent(serviceCollection)

155

internet.TCPClient('irc.freenode.org', 6667, f.getIRCBot('fingerbot')

156

).setServiceParent(serviceCollection)

157

</pre><div class="caption">Source listing - <a href="listings/finger/finger18.py">listings/finger/finger18.py</a></div></div></div><a href="../howto/index.html">Index</a>Version: 2.0.1</body></html>

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