Inheritance mechanism

Perl
Object Oriented
Inheritance mechanism

I will explain the mechanism of inheritance in Perl.

1. Inheritance mechanism

The inheritance mechanism is that the method is searched for the upper class. Let's take a look at the previous code again.

use strict;
use warnings;

# Component class
package Component;
sub x {return 5}


# Button class
package Button;
# Inheritance description
our @ISA = ('Component');

sub new {bless {}, 'Button'}

package main;
# Use button class
my $button = Button->new;
print $button->x;

The Button class didn't have a method called x, but it was calling a method called x. I explained that this is because it inherits with the description @ISA = ('Component').

But in reality, it's just a method search.

2. Method search algorithm

The following is the method search algorithm.

If your package (Button in this example) has an x method, call it. If not, call the x method of the package (Component in this example) contained in @ISA.

Repeat this until the top superclass. Here is the implementation of inheritance in Perl.

Perl ABC