sfContext::has PHP Method

    public function has($name)
    {
        return isset($this->factories[$name]);
    }

 /**
  * @param sfContext $context
  */
 public static function addEngineToContext(sfContext $context)
 {
     if (!$context->has(self::SF_CONTEXT_ATTR_NAME)) {
         $context->set(self::SF_CONTEXT_ATTR_NAME, new sfTwigRenderEngine($context));
     }
 }