#!/usr/bin/perl -w
use strict;
use Data::Dumper;
package Foo;

sub new {
    my $class = shift;
    bless {}, $class;
}

sub foobared {
    my $self = shift;
    $self->{foo} = _test( 3 );
}

sub _test { shift }

package Bar;
@Bar::ISA = 'Foo';
sub foobared {
    my $self = shift;
    $self->{foo} = $self->_test( 3 );
}

package Main;
my $o = Foo->new;
$o->foobared;
print $o->{foo},$/;
my $o2 = Bar->new;
$o2->foobared;
print $o2->{foo};