sub make_rollover {
    my( $completion_list ) = @_;
    my $ix = -1;
    my $xx = @$completion_list  - 1;
    sub {
        $ix++;
        return $completion_list->[  $ix % $xx ];
    };
}

my $rollover = make_rollover( \@tlud );
while ( my $next = $rollover->() ){
    ...
}