package Student;
sub new { # Constructor
	my $class = shift;
	my $data={};
	our $students;

	my $ref = sub { # Closure
		my ($access_type, $key, $value) = @_;

		if ($access_type eq "set") {
        		$data->{$key} = $value;  
                        # $data still available here
		}
		elsif ($access_type eq "get") {
			return $data->{$key};
		}
		elsif ($access_type eq "keys") {
			return (keys %{$data});
		}
		elsif ($access_type eq "destroy") {
			$students--;
			return $students;
		}
		else {
		 die "Access type should be set or get";
		}
                print "New student created, we have ", 
                  ++$students, " students.\n";
		bless ($ref, $class);  
                  # bless anonymous subroutine
	}
} # End constructor

sub set {
	my ($self, $key, $value) = @_;  
            # $self reference anonymous sub
	$self->("set", $key, $value);
}

sub get {
	my ($self, $key) = @_;
	return $self->("get", $key);
}

sub display {
	my $self = shift;
	my @keys = $self->("keys");
	@keys=reverse(@keys);
	foreach my $key (@keys) {
	  my $value = $self->("get", $key);
	  printf "%-25s%-5s:%-20s\n", $self, $key, $value;
	}
	print "\n";
}

sub DESTROY {
  my $self = shift;
  print "Object going out of scope:\n";
  print "Students remain: ", $self->("destroy"), "\n";
}

1;

##</code><code>##

#!/usr/bin/perl -w
use lib("lib");
use Student;

$ptr1 = Student->new();  # Create new students
$ptr2 = Student->new();
$ptr3 = Student->new();

$ptr1->set("Name", "Jody Rogers"); # Set data for object
$ptr1->set("Major", "Law");

$ptr2->set("Name", "Christian Dobbins");
$ptr2->set("Major", "Drama");

$ptr3->set("Name", "Tina Savage");
$ptr3->set("Major", "Art");

$ptr1->display();  # Get all data for object
$ptr2->display();
$ptr3->display();

print "\nThe major for ", $ptr1->get("Name"), 
         " is ", $ptr1->get("Major"), ".\n\n";