use strict;
package Demo;
my @handles;

sub new {

  my $thingy=shift;
  my $args=shift;
  my $id=$args->{'id'};
  # Note that $args->{'id'} is autovivified here, but
  # this is no problem as we're testing for definedness
  # further on
  my $class=ref($thingy)||$thingy;
  unless (defined $id) {$id=scalar @handles};
  my $self=bless $id, $class;
  $handle[$self]={string => $args->{'string'}};
  return $self;
}