# Foo.pl
package Foo;

sub new {
    my ($class, @args) = @_;
    my $self = bless({}, $class); # bless is a magic function that takes an object (int, string, hash, ...) and makes it of class $class
    $self->{name} = "Alice";
    return $self;
}

sub name { # this is like descriptor, called on #obj->name
    my $self = shift;
    if (@_) {
        my $new_name = shift;
        $self->{name} = $new_name;
    }
    return $self->{name};
}

sub say {
    my $self = shift;
    print "Hi, I'm $self->{name}";
}

# main.pl
use Foo;

my $foo = Foo->new;
$foo->name("Bob");
$foo->say; # prints "Hi, I'm Bob