#!/usr/bin/perl
use strict;
use warnings;

{
    package Parent;
    sub f {
        my $self = shift;
        $self->classvar += 5;

    }
}

{
    package Child;
    our @ISA = qw(Parent);
    our $classvar = 3;
    sub classvar :lvalue {
        $classvar;
    }
}

my $obj = bless {}, 'Child';
$obj->f();
print $Child::classvar, $/;
# output: 8