<?php
/**
 * Get a unique ID key for current $wp_the_query object. 
 *
 * @return string|int unique key on success, 0 on failure
 */
function zdt_get_object_key() {
	$queried_object = get_queried_object();
	$queried_object_id = get_queried_object_id();

	if ( ! is_null( $queried_object ) && $queried_object_id > 0 )
		return md5( serialize( $queried_object ) . $queried_object_id );
	else
		return 0;
}