use strict;
use warnings;
use Hash::Util::FieldHash;
fieldhash my %attr1;  # You need one for each attribute.

sub new {bless \do {my $var}, shift}
sub set_attr1 {
    my $self = shift;
    $attr1{$self} = shift;
}
sub get_attr1 {
    my $self = shift;
    $attr1{$self}
}
etc.