Hello, beloved Perl monks. My learning journey has taken me to a far and exciting land called Object-Oriented Programming (OOP). I find OOP interesting as it entails a different way of thinking and approach in programming. I am currently studying a book, Perl Objects, References & Modules (1993) by Randal L. Schwartz, and was introduced to the concepts of getters and setters. Personally, I do not feel comfortable with the idea of using setter and getter functions. I understood clearly the disadvantages of accessing class objects directly. If down the road I would need to design a class object, I would try to stay away, as possible, from using accessors. However, I am a bit frustrated because the book only illustrated how setters/getters could break the encapsulation of a class object. I made up my own example to illustrate how encapsulation could be broken into despite the success of changing the color attribute from 'red' to ‘green’.

use strict;
use warnings;

{
    package Fruit;

    sub new {

        my $class = shift;
        my $fruit = shift;
        my $self = { name => $fruit, color => 'red' };
        
        bless $self, $class;
    };    

    sub set_color {
    
        my $self = shift;
        $self->{'color'} = shift;
    };

    sub get_color {
        my $self = shift;
        $self->{'color'};
    };    

}

    my $obj = Fruit->new('apple');
    $obj->set_color('green');
    $obj->get_color;
    
    use Data::Dumper;    
    print Dumper($obj);
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I used Data::Dumper and the result is shown below:

$VAR1 = bless( {                                                      
+                                                                     
+                                      
                 'color' => 'green',                                  
+                                                                     
+                                      
                 'name' => 'apple'                                    
+                                                                     
+                                      
               }, 'Fruit' );
[download]

The chapter I read, chapter 9, did not offer definitive and non-invasive solutions on updating an object’s attribute. On the other hand, It’s also possible that I have failed to understand some key points in the chapter. My question is, are setters and getters still used these days in Perl programming? Is there a non-invasive way to update an object’s attribute? Is OOP considered a universal subject that it could be discussed without any reference to a particular programming language? Are there books that you could recommend on the subject? Thank you. :)