Inheritance in Perl

Inheritance with an Example using Perl

Inheritance:
Inheritance is nothing but inheriting methods/properties from Parent class to child class.
Inheritance is one of main pillars of Object Oriented Concepts.

Inheritance in Perl :
In Perl, inheritance is accomplished by placing the names of parent classes into a special array called @ISA
The elements of @ISA are searched left to right for any missing methods.

E.g.,
our @ISA = qw(AAA BBB);
#This represents we are inheriting from Packages AAA and BBB respectively.

 Lets define with an example as mentioned below :

Inventory.pm (Parent of Pen)
Pen.pm           (Pen inherits methods from Inventory)
main.pl            (Create instance of Pen and accessing the methods of Inventory class as well)


Inventory.pm

#!/usr/bin/perl

package Inventory;

use strict;
use warnings;
use Data::Dumper;

sub new {
    my($class)  = shift;
    my(%params) = @_;
    bless {
       "NUMBER"    => $params{"NUMBER"},
       "QUANTITY" => $params{"QUANTITY"}
    }, $class;
}

1;  

Pen.pm

#!/usr/bin/perl

package Pen;

use strict;
use warnings;
use Data::Dumper;

use Inventory;

our @ISA = qw(Inventory);    #### Inheritance

sub new {
    my($class) = shift;
    my(%params) = @_;

    #my($self) = Inventory->new(@_);
    my($self) = new Inventory(@_);

    $self->{"COLOR"} = $params{"COLOR"};
    return(bless($self, $class));
}

1;
  

main.pl

#!/usr/bin/perl

use strict;
use warnings;
use Data::Dumper;
use Pen;

my $pen = new Pen(
        "NUMBER"   => "12A-34",
        "QUANTITY" => 34,
        "COLOR"    => "blue"
        );

print("The part number is " . $pen->{'NUMBER'}   . "\n");
print("The quantity is "    . $pen->{'QUANTITY'} . "\n");
print("The ink color is "   . $pen->{'COLOR'}    . "\n");
  

Output:

The part number is 12A-34
The quantity is 34
The ink color is blue