my %cache;
sub _iso8601_rx {
   my($self,$rx) = @_;
   my $dmt       = $$self{'tz'};
   my $dmb       = $$dmt{'base'};

   return $cache{ $rx } if exists $cache{ $rx };
}

$cache{cdate} = '(?<y>\d\d\d\d)-(?<m>\d\d)-(?<d>\d\d)';
$cache{ctime} = '(?<h>\d\d):(?<mn>\d\d):(?<s>\d\d)';
$cache{fulldate} = "$cache{cdate}\\s+$cache{ctime}";

1;