package Password;
use Carp;
use strict;

my $security = 'reallysecure';

sub TIESCALAR {
  my $class = shift;
  my $arg;
  return bless \$arg, $class;
}

sub FETCH {
  my $self = shift;
  confess "wrong type" unless ref $self;
  croak "usage error" if @_;
  return substr($$self ^ $security, 0, length($$self));
}

sub STORE {
  my $self = shift;
  confess "wrong type" unless ref $self;
  my $newval = shift;
  croak "usage error" if @_;
  if    (length($newval) < 5)  { carp "Not long enough" }
  elsif (length($newval) > 12) { carp "Too long" }
  else {
    $$self = substr($newval ^ $security, 0, length($newval));
   # print "Stored ", join('.', unpack('H2'x length($$self), $$self)), "\n";
   # print "Plain is ", join('.', unpack('H2'x length($$self), $newval)), "\n";
  }
}

sub encoded_form {
  my $self = shift;
  $$self;
}

package Main;
my $foo; # This would be my object
my $pwref = tie $foo->{'bar'}, 'Password';
$foo->{'bar'} = 'squamous';
print $foo->{'bar'}, "\n";
$foo->{'bar'} =~ s/am/a1m/;
print $foo->{'bar'}, "\n";
print "Encoded form is ", $pwref->encoded_form, "\n";