[% classes = ['odd','even'] %]
[% BLOCK row %]
   [% class = classes.shift %]
   <tr>
      <td class="[% class %]">[% person.name %]</td>
      <td class="[% class %]">[% person.age %]</td>
      <td class="[% class %]">[% person.weight %]</td>
   </tr>
   [% classes.push(class) %]
[% END %]