# specify twig_handlers (see the XML::Twig documentation)
twig_handlers => 
   { # create a new hash-ref
       map { # transform a list into a new list 
             # create a name / subroutine pair
             $_ => sub {
                # when the subroutine is called
                # get the element name from $_->name()
                # and increase it's count entry in %found
                #
                # note: $_ is set by XML::Twig when the sub is called
                $found{$_->name()}++ 
             }; 
       } @nodes # for each element in @nodes
   }
[download]

See also map.

So I am assuming that the first $_ gets populated buy 'map' with the values from 'node'?

What about the $_ in the hash found? Where does it get its value from?

I searched for name() on the CPAN page for XML Parser and XML Twig and I could not find it? Where is the subroutine name() coming from.

This code works but I am still abit confused on the mechanics of it.

Sorry for the late reply.

Anyway: map works by calling a codeblock for each element of the supplied list and passes the element as $_. (click the link to see the official docs for map)

name() is mentioned on the XML::Twig documentation, in the (very long and not very well structured) section called METHODS. It just returns the "tag-name" for an XML::Elt, i.e. for <tagname attr="value" att2="value2"/> it returns the string "tagname".

The code I supplied basically creates an anonymous subroutine, or code block, for each tag-name you're interested in and XML::Twig will call that subroutine whenever it finds a tag with that tag-name, passing an object (update: as $_ - which is generally considered poor style, but makes for short and possibly more readable code) that represents that tag (and you can call ->name() on that object to retrieve the tag name)

"What should it profit a man, if he should win a flame war, yet lose his cool?"