an XPath engine that can be re-used by other classes that implement trees

Michel Rodriguez, the XML genius, has done it again. First it was with XML::Twig. Now, he has implemented Tree::XPathEngine to allow to XPath usage on any tree module that implements the required methods!

Filed under: Perl Software Design Blog » perl » cpan » xpath-engine

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HTML::Seamstress::new_from_file() now reblesses the whole tree

To date, Seamstress has supported tree-based rewriting of HTML trees by blessing the $tree into a class which has these superclasses - HTML::Seamstress, HTML::Element::Library, HTML::Element, and any local Element library. That way, you can rewrite the $tree by going:

$tree->this;
$tree->that;

Well, that was all good and fine until today when I tried to call this and that on a subtree of $tree:

my $div = $tree->look_down('_tag' => 'div');
$div->this;
$div->that;

and it did not work because $div was blessed into HTML::Element instead of a class which inherited from the above-mentioned superclasses.

So, the solution was to simply bless all nodes of $tree into the same class. A test case 02.treebless.t shows the new functionality:

package tree::bless;

use Test::More qw(no_plan);
use TestUtils;

use base qw(HTML::Seamstress) ;

my $root = 't/html/treebless';

my $tree = __PACKAGE__->new_from_file("$root.html");

my $li = $tree->look_down(class => 'greg');

is (ref $li, 'tree::bless', 'blessed into proper class');

Filed under: Perl Software Design Blog » perl » html-seamstress » reblessing-whole-tree

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Literal text in attributes of HTML::Element nodes

I had to create an attribute for an HTML::Element like this:

Filed under: Perl Software Design Blog » perl » html-seamstress » literal-text-in-attr

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Good articles from Perl.com

Massive Data Aggregation with Perl by Fred Moyer

Shows how to do a mod-perl based upload and give the user constant feedback via Javascript

More Advancements in Perl Programming

has a great piece on Yahoo’s public API for getting keywords from a document.

Filed under: Perl Software Design Blog » perl » perldotcom » good-articles

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IBM Developerworks Perl Articles

• Create mosaic images with Perl and ImageMagick

Filed under: Perl Software Design Blog » perl » ibm » articles

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Catalyst SVN

How to check out the Catalyst CPAN distro via SVN

How to import sources

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 &#8216;KEY&#8217;) { <& 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

Filed under: Perl Software Design Blog » perl » html-seamstress » componentize-your-seamstress-usage

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