add_placeholder_escape example

        } else {
            $class = get_class( $this );

            wp_load_translations_early();
            /* translators: %s: Database access abstraction class, usually wpdb or a class extending wpdb. */
            _doing_it_wrong( $class, sprintf( __( '%s must set a database connection for use with escaping.' ), $class ), '3.6.0' );

            $escaped = addslashes( $data );
        }

        return $this->add_placeholder_escape( $escaped );
    }

    /** * Escapes data. Works on arrays. * * @since 2.8.0 * * @uses wpdb::_real_escape() * * @param string|array $data Data to escape. * @return string|array Escaped data, in the same type as supplied. */