Something

class xen_config {
        case $virtual {
                xenu: {
                  case $suse_version {
                    "sles10": {
                        # Set to no for domU machines
                        $force_persistent_names = "no"
                        include
                           xenu_network
                    }
                  }
                }

                xen0: {
                  case $iscsi {
                    "true": { include xend_init }
                  }
                }
        }
}