addLink() to header

this is about the same as discussed in #1126 I am willing to see more potential in this ticket because it brings better examples than the one we had in 1126. I am closing #1126 and hoping someone comes up with a good patch for this :-)

I'm strongly against added this to the sfWebResponse class. Why not create a helper for this?

I created a simple add_link helper that fills a slot named "links". See http://jnotes.jonasfischer.net/2009/10/symfony-link-tags-e-g-canonical/ for example usage. Perhaps this helps?

/**
* Add link tag to slot 'links'
*
* @param String $href [Absolute or internat URI]
* @param String $rel [value for 'rel' attribtue, e.g. 'canonical']
*
* @return void
*/
function add_link($href, $rel)
{
  $slot = $slot  = get_slot('links');
  try {
    $href = url_for($href, true);
    $slot  .= "\n<link rel=\"$rel\" href=\"$href\" />";
  } catch (InvalidArgumentException $e) {
    $slot  .= "\n<!-- Could not add Link '$href': Only absolute or internal URIs allowed -->";
  }
  slot('links', $slot);
}