package Thing;

# default constructor for all "Thing"s
sub new
{
    my ($class,%options) = @_;
    my $self = { %options };
    return bless $self, ref($class) || $class;
}

# abstract method stub
sub do
{
   my $self = shift;
   die ref($self) || $self . " did not implement do()\n";
}

package Thing::A

sub do
{
   my $self = shift;
   print "This is " . ref($self) || $self . "\n";
}

package Thing::B

sub do
{
   my $self = shift;
   print "I'm a really cool " . ref($self) || $self . "\n";
}

package ThingFactory;

my %dispatch = (
 'A' => 'Thing::A',
 'B' => 'Thing::B',
 '_default' => 'Thing::A',
);

sub createThing
{
   my ($class,%options) = @_;

   unless( exists($options{'thing'}) && $options{'thing'} )
   {
        return $dispatch{'_default'}->new(%options);
   }
   elsif( !exists($dispatch{$options{'thing'}}) )
   {
        return $dispatch{'_default'}->new(%options);
   }
   else
   {
        return $dispatch{$options{'thing'}}->new(%options);
   }
}

package main;

my $thing = ThingFactory->createThing('thing' => 'A');
$thing->do();