Wednesday·25·January·2006

When writing Seamstress pages, componentize your tree transforms

Working with our Mason codebase today showed me something that would have been a lot harder in Seamstress. Basically, I was told to add a vonage advertisement in another table cell everywhere that we displayed a vbase_banner.

Up to this point, all pages using the vbase_banner looked something like this:

<& 'comp/related_topics_lander_2', aconf => $aconf, query => $query &>

<& 'comp/vbase_banner', aconf => $aconf, query => $query, align => 'left' &>

% if ($query->{'brand'} eq 'tbar') {
  <& 'comp/tbar_foot', aconf => $aconf, query => $query &>
% } else {
  <& 'comp/quickfoot', aconf => $aconf, query => $query, align => 'center' &>
% }

<& 'comp/footer', aconf => $aconf, query => $query &>

So all I had to do was toss a bit of logic in vbase_banner for the vonage_ad and I was done:

<tr> <td align='<% $align %>'><iframe width=468 height=60 noresize scrolling=no \frameborder=0 marginheight=0 marginwidth=0 src='http://t.trafficmp.com/b.t/<% $\id %>/<% $rn %>/'></iframe> </td> <td> % if ($query->{pagetype} ne ‘KEY’) { <& vonage_ad &> % } </td> </tr>

With Seamstress, one could componentize a page by creating subroutines for processing each part, but one does not have to. This is a downfall in Seamstress in a sense. But nevertheless, with Params::Validate and HTML::Tree, one can still do the trick, but one must be disciplined about placing each tree transformation into a separate subroutine instead of having a subroutine with a series of

The end result of disciplined Seamstress usage is that you can refine subroutines and make wholesale changes across several webpages if they all point to the same place