Symfony Hook form

class ProjectConfiguration
function setup
    $this->dispatcher->connect('form.post_configure', array($this, 'formPostConfigure'));
    # more
    # $this->dispatcher->connect('form.validation_error', array($this, 'formPostConfigure'));

# Call-back function is defined here
function formPostConfigure (sfEvent $event) {
  $form = $event->getSubject();
  # attack form
}