protected function _addWeighableBehavior() {
        $model = $this->getModel();
        $weighableRels = $model->relations->getRelations('weighable', true);

        if (!$weighableRels) {
            return;
        }

        $weighableConfig = array();

        foreach ($weighableRels as $relName => $rel) {
            $weightColumn = Garp_Spawn_Util::camelcased2underscored($relName) . '_weight';
            $weighableConfig[$relName] = array(
                'foreignKeyColumn' => $rel->column,
                'weightColumn'     => $weightColumn
            );
        }

        $this->_add('relation', 'Weighable', $weighableConfig);
    }