Factory Design Pattern in Perl

#source:http://www.perl.com/pub/a/2003/08/15/design3.html
START ===== D:\etl\Perl\DesignPatterns\RunFactoryDesignPattern.cmd
perl -w "D:\etl\Perl\DesignPatterns\RunFactoryDesignPattern.pl"

pause
END ================== D:\etl\Perl\DesignPatterns\RunFactoryDesignPattern.cmd

.
START ===== D:\etl\Perl\DesignPatterns\RunFactoryDesignPattern.pl
use strict; use warnings;

use GreetFactory;

my $greeter_n = GreetFactory->instantiate("Repeat", "I am repeating Hello x amount of times \n", 3);
$greeter_n->greet();

my $greeter_stamp = GreetFactory->instantiate("Stamp", "The Stamp says Good-bye\n");
$greeter_stamp->greet();
END ================== D:\etl\Perl\DesignPatterns\RunFactoryDesignPattern.pl

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START ===== D:\etl\Perl\DesignPatterns\GreetFactory.pm
package GreetFactory;
use strict; use warnings;

# ARHH NO TIME HARDCODING ...
BEGIN{ push @INC, 'D:/etl/Perl/DesignPatterns'; }

sub instantiate {
my $class = shift;
my $requested_type = shift;
my $location = "Greet/$requested_type.pm";
my $class = "Greet::$requested_type";

require $location;

return $class->new(@_);
}

1;
END ================== D:\etl\Perl\DesignPatterns\GreetFactory.pm

.
START ===== D:\etl\Perl\DesignPatterns\Greet\Repeat.pm
package Greet::Repeat;

sub new {
my $class = shift;
my $self = {
greeting => shift,
repeat => shift,
};
return bless $self, $class;
}

sub greet {
my $self = shift;
print ($self->{greeting} x $self->{repeat});
}

1;
END ================== D:\etl\Perl\DesignPatterns\Greet\Repeat.pm

.
START ===== D:\etl\Perl\DesignPatterns\Greet\Stamp.pm
package Greet::Stamp;
use strict; use warnings;

sub new {
my $class = shift;
my $greeting = shift;
return bless \$greeting, $class;
}

sub greet {
my $greeting = shift;
my $stamp = timestamp();
print "$stamp $$greeting";
}


sub timestamp {
#
# Purpose: returns the time in yyyymmdd-format
#
my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst) = localtime(time);
#---- change 'month'- and 'year'-values to correct format ----
$min = "0$min" if ($min < 10);
$hour = "0$hour" if ($hour < 10);
$mon = $mon + 1;
$mon = "0$mon" if ($mon < 10);
$year = $year + 1900;
$mday = "0$mday" if ($mday < 10);
return "$year$mon$mday" . "_" . "$hour$min" . "_" . $sec;
}

1;
END ================== D:\etl\Perl\DesignPatterns\Greet\Stamp.pm