package Foo;

use strict;

sub erf {
  my ($self) = shift;
  print $self->name();
}

sub new {
  my ($proto, $args) = @_;
  my $class = ref($proto) || $proto;
  my $self = {};
  if (ref($args) eq 'HASH') {
    if (exists $args->{'name'}) {
      $self->{'_name'} = $args->{'name'};
    } else {
      return undef;
    }
  } else {
    $self->{'_name'} = $args->name();
  }
  bless $self, $class;
  return $self;
}

sub name {
  my ($self) = shift;
  return $self->{'_name'};
}

package Foo::Bar;

use strict;

@Foo::Bar::ISA = qw/Foo/;

sub doit {
  my ($self) = shift;
  $self->erf();
}

package main;

use strict;

my %hash = (name => 'Homer');
my $foo = Foo->new(\%hash);
my $bar = Foo::Bar->new($foo);
$bar->doit();