Input_0_Text Output_1_Text Input_0_Text Output_1_Text ##
##

use strict;
use warnings;
use XML::Twig;

my $XML='

  
    
    
    
    
    
    
    
  
  
    
    
    
    
    
    
';

# build a new file in the output format.
my $Output_file_name='testOutput.xml';
my $outRoot=XML::Twig::Elt->new('Motors');

#process input XML data
my $twig_roots={'Sheet'=>1};
my $twig_handlers={'Sheet' => \&Motors};
my $twig=new XML::Twig(TwigRoots=>$twig_roots, TwigHandlers=>$twig_handlers);
$twig->parse($XML);

#output results
$outRoot->set_pretty_print('indented');
$outRoot->print_to_file($Output_file_name);

sub Motors{
  my ($twig, $Motor)=@_;
  my $motor_name="";
  my $motorID=-1;

#  I want to find the ID of the Motor Instruction
  
#  This seems like what I want to do  
#  $motorID = $Motor->first_child('Instruction')=>{Type=>'Motor'}->att('Name');
#  Error: "Can't call method "att" on unblessed reference..."

#  This works but seems to be non-twigish
  foreach my $instr ($Motor->children('Instruction')){ #iterate through all the instructions on this sheet
    if($instr->att('Type') eq 'Motor'){  #this instruction is a motor type; set attributes
      $motorID=$instr->att('ID');
      $motor_name=$instr->att('Name');
      $outRoot->insert_new_elt('Motor'=>{Name=>$motor_name, ID=>$motorID});
    }
  }

#  I want to find all wires that have a ToID or FromID that matches the motorID  
  foreach my $wire ($Motor->children('Wire')){ #iterate through all wires on this sheet

#    do once for ToID
    if($wire->att('ToID') == $motorID){  #this is a wire that goes to the motor
      my $ToParam = $wire->att('ToText');
      my $FromID = $wire->att('FromID');
      my $FromText;
            
#nested foreach -> lots of iteration :(
      foreach my $motor_item ($Motor->children()){ #iterate though all items on the sheet
        if (defined ($motor_item->att('ID'))){ #if the item has an ID attribute
          if($motor_item->att('ID')==$FromID){ #that matches the wire to the motor
            $FromText=$motor_item->att('Text'); #set output attribute
          }
        }
      }
      my $newRoot = $outRoot->first_child('Motor'=>{Name=>$motor_name}); #set current motor as root
      $newRoot->insert_new_elt('last_child', $ToParam, $FromText); #add this wire to output.
    }    
    
#    do again for FromID  pretty much the same as above.  
    if($wire->att('FromID') == $motorID){
      my $FromParam = $wire->att('FromText');
      my $ToID = $wire->att('ToID');
      my $ToText;

      foreach my $motor_item ($Motor->children()){
        if (defined ($motor_item->att('ID'))){
          if($motor_item->att('ID')==$ToID){
            $ToText=$motor_item->att('Text');
          }
        }
      }
      my $newRoot = $outRoot->first_child('Motor'=>{Name=>$motor_name});
      $newRoot->insert_new_elt('last_child', $FromParam, $ToText);
    }    
  }
  
}