* Checks if a user can assign users to a particular role in this context

 *

 * @param object $context

 * @param int $targetroleid - the id of the role you want to assign users to

 * @return boolean

 */

function user_can_assign($context, $targetroleid) {

    global $DB;

    // first check if user has override capability

    // if not return false;

    if (!has_capability('moodle/role:assign', $context)) {

        return false;

    }

    // pull out all active roles of this user from this context(or above)

    if ($userroles = get_user_roles($context)) {

        foreach ($userroles as $userrole) {

            // if any in the role_allow_override table, then it's ok

            if ($DB->get_record('role_allow_assign', array('roleid'=>$userrole->roleid, 'allowassign'=>$targetroleid))) {

                return true;

            }

        }

    }

    return false;

}