package Parent;

use strict;
use warnings;
use Child;

sub new
{  my $class = shift;
   my $this = {};
   bless $this, $class;
   $this->setChild( Child->new( @_ ) );
   return $this;
}

sub setChild
{  my ( $this, $child ) = @_;
   if ( defined $child )
   {  $this->{_child} = $child;
      return 1;
   }
   return undef;
}

sub getChild
{  my $this = shift;
   return $this->{_child};
}

sub setChildValue1
{  my ( $this, $value ) = @_;
   if ( defined $value )
   {  return $this->getChild()->setValue1( $value );
   }
   return undef;
}

sub getChildValue1
{  my $this = shift;
   return $this->getChild()->getValue1();
}

sub setChildValue2
{  my ( $this, $value ) = @_;
   if ( defined $value )
   {  return $this->getChild()->setValue2( $value );
   }
   return undef;
}

sub getChildValue2
{  my $this = shift;
   return $this->getChild()->getValue2();
}

1;

##</code><code>##

package Child;

use strict;
use warnings;

sub new
{  my ( $class, $value1, $value2 ) = @_;
   my $this = {};
   bless $this, $class;
   $this->setValue1( $value1 );
   $this->setValue2( $value2 );
   return $this;
}

sub setValue1
{  my ( $this, $value ) = @_;
   if ( defined $value )
   {  $this->{_value1} = $value;
      return 1;
   }
   return undef;
}

sub getValue1
{  my $this = shift;
   return $this->{_value1};
}

sub setValue2
{  my ( $this, $value ) = @_;
   if ( defined $value )
   {  $this->{_value2} = $value;
      return 1;
   }
   return undef;
}

sub getValue2
{  my $this = shift;
   return $this->{_value2};
}

1;

##</code><code>##

use Parent;

use strict;
use warnings;

my $parent = new Parent( 'value1', 'value2' );
my $child = $parent->getChild();
print "Values 1 and two from the child are:\n1....",
      $child->getValue1(),"\n2....",
      $child->getValue2(),"\n";
print "Values 1 and two from the child via the parent are:\n1....",
      $parent->getChildValue1(),"\n2....",
      $parent->getChildValue2(),"\n";