From another approach, is it possible to output sections of a tree structure to an array or something that I could use to compare against same section in older xml file. Following is code I am using to output class, file, and namespace information. Example, I am trying to output each class and all its related information into one array (or something) and second class into another array, etc. Is there an equivalent to $class->print such as $class->array. 
#!/bin/perl
use strict;
use warnings;
use XML::Twig;

my $twig_handlers = {
                     'panoply/classes' => \&class_info,
                     'panoply/files' => \&file_info,
                     'panoply/namespaces' => \&namespace_info,
                    };

        
my $twig1;
my @xfiles = @ARGV;
foreach my $xfile (@xfiles) {
  $twig1 = new XML::Twig(ignore_elts => { brief => 'discard', detailed
+ => 'discard', includes => 'discard', included_by => 'discard', reimp
+lemented_by => 'discard' }, TwigRoots => {panoply => 1}, TwigHandlers
+ => $twig_handlers);
  eval { $twig1->parsefile( $xfile ) };
  die "can't parse file: $@" if $@;
}

sub class_info {
  my ($twig, $class) = @_;
  $class->set_pretty_print( 'indented' );
  $class->print;
}

sub file_info {
  my ($twig, $file) = @_;
  $file->set_pretty_print( 'indented' );
  $file->print;
}

sub namespace_info {
  my ($twig, $nsp) = @_;
  $nsp->set_pretty_print( 'indented' );
  $nsp->print;
}

[download]
Sample xml file 
<panoply>
  <classes name="Panoply::AccessLogic">
    <all_members name="accessLogic" protection="public"/>
    <all_members name="DDR_VIA_JTAG" protection="public"/>
    <brief></brief>
    <detailed>
      <doc type="text">Models the access logic</doc>
    </detailed>
    <includes name="AccessLogic.hpp" local="no" />
    <public_methods>
      <members name="handledErrors" const="yes" kind="function" protec
+tion="public" static="no">
      </members>
      <members name="AccessLogic" const="no" kind="function" protectio
+n="public" static="no">
        <parameters declaration_name="accessLogic" type="AccessLogicTy
+pes" />
        <parameters declaration_name="handledErrors" type="const Handl
+edErrors &amp;" />
      </members>
    </public_methods>
    <public_typedefs>
      <members name="AccessLogicTypes" kind="enum" protection="public"
+>
        <values name="IO_CF8_CFC">
        </values>
      </members>
      <members name="MJTAG" kind="enumvalue">
      </members>
    </public_typedefs>
  </classes>
  <classes name="Panoply::Details::ActionBatch">
    <detailed></detailed>
    <includes name="PlatformActionBatch.hpp" local="no" />
  </classes>
  <classes name="Panoply::Details::ActionResult">
    <derived name="Panoply::Details::CPUIDActionResult"/>
    <includes name="PlatformAction.hpp" local="no" />
  </classes>
  <classes name="Panoply::Details::AddressIndex">
    <includes name="Panoply.hpp" local="no" />
  </classes>
  <files name="panoplydoc.hpp">
  </files>
  <files name="PanoplyExports.hpp">
     <defines>
      <members name="NOMINMAX" kind="define" protection="public">
      </members>
      <members name="_SCL_SECURE_NO_WARNINGS" kind="define">
      </members>
    </defines>
  </files>
  <namespaces name="AMD">
    <namespaces name="AMD::RegisterDef" />
  </namespaces>
  <namespaces name="AMD::RegisterDef">
    <classes name="AMD::RegisterDef::BaseDevice" />
    <enums>
      <members name="PermissionLevel" kind="enum" protection="public">
        <values name="PERMISSION_PUBLIC" initializer=" 10">
        </values>
        <values name="PERMISSION_NDA" initializer=" 20">
        </values>
      </members>
      <members name="RegisterType" kind="enum" protection="public">
        <values name="REGISTER_PCI" initializer=" 0">
        </values>
        <values name="REGISTER_MSR" initializer=" 1">
        </values>
      </members>
    </enums>
    <functions>
      <members name="Compare" const="no" kind="function" protection="p
+ublic">
        <parameters declaration_name="first" type="T" />
        <parameters declaration_name="second" type="T" />
      </members>
    </functions>
  <namespaces name="AMD::RegisterDef::Buffalo" />
    <variables>
      <members name="LIBRARY_VERSION">
      </members>
    </variables>
  </namespaces>
  <namespaces name="AMD::RegisterDef::Buffalo">
    <classes name="AMD::RegisterDef::Buffalo::BaseEntity" />
  </namespaces>
</panoply>

[download]

In reply to Re^2: XML::Twig traversing tree and storing in an array by jccunning
in thread XML::Twig traversing tree and storing in an array by jccunning

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