function block_instance($blockname, $instance = NULL)
{
    if (!block_load_class($blockname)) {
        return false;
    }
    $classname = 'block_' . $blockname;
    $retval = new $classname();
    if ($instance !== NULL) {
        $retval->_load_instance($instance);
    }
    return $retval;
}

/**
 * Creates a new instance of the specified block class.
 *
 * @param string $blockname the name of the block.
 * @param $instance block_instances DB table row (optional).
 * @param moodle_page $page the page this block is appearing on.
 * @return block_base the requested block instance.
 */
function block_instance($blockname, $instance = NULL, $page = NULL)
{
    if (!block_load_class($blockname)) {
        return false;
    }
    $classname = 'block_' . $blockname;
    $retval = new $classname();
    if ($instance !== NULL) {
        if (is_null($page)) {
            global $PAGE;
            $page = $PAGE;
        }
        $retval->_load_instance($instance, $page);
    }
    return $retval;
}