package Base;

sub new {
    my $type = shift;
    my $self = {};
    $self->{buz} = 42;
    return bless $self, $type;
}

package Derived;
@ISA = qw( Base );

sub new {
    my $type = shift;
    my $self = Base->new;
    $self->{biz} = 11;
    return bless $self, $type;
}

package main;

$a = Derived->new;
print "buz = ", $a->{buz}, "\n";
print "biz = ", $a->{biz}, "\n";