use Tie::Cycle;

tie my $cycle, 'Tie::Cycle', [ qw( even odd  ) ];

foreach my $row ( 0 .. 6 )
	{
	print qq|<tr class="$cycle">...</tr>\n|;
	}

##</code><code>##

<tr class="even">...</tr>
<tr class="odd">...</tr>
<tr class="even">...</tr>
<tr class="odd">...</tr>
<tr class="even">...</tr>
<tr class="odd">...</tr>
<tr class="even">...</tr>

##</code><code>##

use Tie::Cycle;

tie my $cycle, 'Tie::Cycle', [ qw( red white blue ) ];

foreach my $row ( 0 .. 6 )
	{
	print qq|<tr class="$cycle">...</tr>\n|;
	}