Greeting message wsgi application with various wsgi components

wsgihello.py

import os

import formencode
from formencode import validators
from formencode import htmlfill

from routes import Mapper
from mako.lookup import TemplateLookup

from webob import Response
from webob.exc import HTTPNotFound, HTTPFound
from webob.dec import wsgify

here = os.path.dirname(__file__)
templates = TemplateLookup(directories=[os.path.join(here, 'templates')])

class Dispatcher(object):
    def __init__(self):
        self.mapper = Mapper()
        self.controllers = {}

    def add_route(self, route_name, pattern, controller):
        self.mapper.connect(route_name, pattern)
        self.controllers[route_name] = controller

    @wsgify
    def __call__(self, request):
        matched = self.mapper.routematch(request.path_info, request.method)
        if not matched:
            raise HTTPNotFound
        matchdict, route = matched
        if route.name not in self.controllers:
            raise HTTPNotFound
        request.routes = self.mapper._routenames
        return self.controllers[route.name](request)

class HelloSchema(formencode.Schema):
    name = validators.UnicodeString(not_empty=True)

def index(request):
    tmpl = templates.get_template('index.mak')
    return Response(tmpl.render(request=request))

def hello(request):
    try:
        params = HelloSchema.to_python(request.params)
    except formencode.Invalid, e:
        res = index(request)
        res.text = htmlfill.render(res.body, request.params, errors=e.error_dict)
        return res
    tmpl = templates.get_template('hello.mak')
    return Response(tmpl.render(name=params['name']))

application = Dispatcher()
application.add_route('index', '/', index)
application.add_route('hello', '/hello', hello)

from wsgiref.simple_server import make_server

httpd = make_server('', 8000, application)
print "Serving HTTP on port 8000..."

httpd.serve_forever()