web page retrieve problems

[golu]

the following function retrieves pages from the web and saves them in
a specified dir. i want to extract the respective filenames from the
urls e.g the page code.google.com shud be saved as code-google.htm  or
something similar. can u suggest me a way to do it
def retrieve_url(self,url):
        """ The main method of the robot class and is called
        run method to retrieve the given urls from the web."""

        if url is not None:

         try:
            if visited.has_key(url): return
            pieces=urlparse.urlparse(url)
            filepath=pieces[2]
            if filepath != '':
             filepath=filepath[1:]
             filename=filepath.split("/")[-1]
            else:
              filename='home.htm'


            path=os.path.join(PAGE_DIR,filename)
            url=urlparse.urlunparse(pieces)
            p=url.rfind('#')                   #temporary
            if p!=-1:
                url=url[:p]

            visited[url]=1
            m=urllib2.urlopen(url)

            fopen=open(path,'wb')

            fopen.seek(0)
            fopen.write(url+'|')

            fopen.write(m.read())
            fopen.close()
            print url ,'retrieved'

         except IOError:
            print url
            print "ERROR:OOPS! THE URL CAN'T BE RETRIEVED"

        return