#! perl
use strict;
use warnings;
use XML::Twig;

#---------------------------------------------------------------------
+---------
package Shape;

use Moo;
use namespace::clean;

has type   => ( is => 'ro' );
has class  => ( is => 'ro' );
has coords => ( is => 'ro' );

sub print
{
    my $self = shift;
    printf qq[<%s class = "%s" coordinates = "%s">\n],
           $self->type, $self->class, $self->coords;
}

#---------------------------------------------------------------------
+---------
package main;

my $twig = XML::Twig->new;
   $twig->parse( do { local $/; <DATA> } );
my @shapes;

for my $class ($twig->root->children('class'))
{
    my $class_name = $class->att('id');

    push @shapes,
         Shape->new(type   => $_->gi,
                    class  => $class_name,
                    coords => $_->att('coordinates')) for $class->chil
+dren;
}

$_->print() for @shapes;

__DATA__
<data>
<class id="abc">
  <polygon coordinates="AA"/>
  <polygon coordinates="BB"/>
  <rectangle coordinates="CC"/>
</class>

<class id="def">
  <polygon coordinates="DD"/>
  <rectangle coordinates="EE"/>
  <rectangle coordinates="FF"/>
</class>
</data>
[download]

Output:

23:58 >perl 967_SoPW.pl
<polygon class = "abc" coordinates = "AA">
<polygon class = "abc" coordinates = "BB">
<rectangle class = "abc" coordinates = "CC">
<polygon class = "def" coordinates = "DD">
<rectangle class = "def" coordinates = "EE">
<rectangle class = "def" coordinates = "FF">

23:58 >
[download]