my $next_file = rotate( qw/FileA FileB FileC/ );
print $next_file->(), "\n" for 1 .. 10;

sub rotate {
    my @list = @_;
    my $index = -1;
    return sub {
        $index++;
        $index = 0 if $index > $#list;
        return $list[ $index ];
    };
}