public function set($name)
    {
        $filters = array_unique ($this->session->get('filters', array()));

        if (in_array ($name, $filters)) {
            return array_search ($name, $filters);
        }
        
        $filterKey = 'filter_'.sha1(microtime(true).mt_rand().$name);
        $filters[$filterKey] = $name;
        $this->session->set('filters', $filters);

        return $filterKey;
    }