Simple RSS feed reader in python

Writing a simple RSS feed reader is pretty simple in python.Here i have presented a simple snippet that prints the "title" element of the RSS feed

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.


from urllib2 import urlopen
from xml.sax import make_parser, ContentHandler
import sys

__author__ = "Suvash Sedhain"
__date__ = "Fri Sep 12 16:46:44 NPT 2008"

class RSSHandler (ContentHandler):

  def __init__(self):
      ContentHandler.__init__(self)
      self.__inItem = False
      self.__inTitle = False

  def characters(self,data):
      if self.__inTitle:
          sys.stdout.write(data)
       
  def startElement(self, tag, attrs):
      if tag == "item":
          self.__inItem = True
      if tag == "title" and self.__inItem:
          self.__inTitle = True

  def endElement(self, tag):
      if tag == "title" and self.__inTitle:
          sys.stdout.write("\n")
          self.__inTitle = False
      if tag == "item":
          self.__inItem = False

def listFeedTitle(url):
  infile = urlopen(url)
  parser = make_parser()
  parser.setContentHandler(RSSHandler())
  parser.parse(infile)

#extract all the python related links from dzone
listFeedTitle("http://www.dzone.com/links/feed/search/python/rss.xml")

Code Explanation:

The class RSSHandler is derived from the class ContentHandler, which is a interface that provides functionality of Parsing XML. we override methods characters, startElement and endElement to customize the parser as per our need.

The method invocation can be summarized as:

• "characters" method is called when stream of text is encountered

• "startElement" method is called when any starting tag is encountered

• "endElement" method is called when any ending tag is encountered

The function make_parser is a factory function that returns the generic XML parser.