use strict;
use warnings;

package Base;

sub method {
    my ($self) = @_;
    my $class = ref $self;
    
    print "In Base::method(). I'm a $class instance.\n";
}

package Derived;

push @Derived::ISA, 'Base';

sub new {
    my ($class) = @_;
    
    return bless {}, $class;
}

sub method {
    my ($self) = @_;
    
    print "In Derived::method()\n";
    $self->SUPER::method();
}

package main;

my $obj = Derived->new();

$obj->method();