root/trunk/lib/helper/BlogHelper.php

<?php
sfLoader::loadHelpers('Url');

/**
 * Generates url for a blog post
 *
 * @param  BlogPost $post
 * @param  boolean  $absolute
 * @return string
 */
function blog_post_url($post, $absolute = false)
{
  $route = _gen_blog_post_route($post);
  return url_for($route, $absolute);
}

/**
 * Generates a link to a blog post
 *
 * @param  BlogPost $post
 * @param  mixed    $options
 * @return string
 */
function link_to_post($post, $options = null)
{
  $post_route = _gen_blog_post_route($post);
  return link_to($post->getTitle(), $post_route, $options);
}

/**
 * Generates the url to a blog post
 *
 * @param  BlogPost $post
 * @param  mixed    $options
 * @return string
 */
function _gen_blog_post_route($post)
{
  if (is_null($post))
  {
    return null;
  }
  if (!$post instanceof BlogPost)
  {
    $post = $post->getRawValue();
  }
  return $post->getRoute();
}