package Some::Package;

use strict;
use warnings;

our $VERSION = '0.1';
our $AUTOLOAD;

my %fields = (
  name          => undef,
);

sub new {
  my $proto     = shift;
  my $class     = ref($proto) || $proto;
  my %args      = @_;
  my $self      = {
    _permitted  => \%fields,
    %fields,
  };
  bless($self, $class);
  foreach my $arg (keys(%args)) {
    $self->$arg($args{$arg});
  }

sub AUTOLOAD {
  my $self = shift;
  my $type = ref($self) or croak "$self is not an object";
  my $name = $AUTOLOAD;
  $name =~ s/.*://;
  unless(exists $self->{_permitted}->{$name} ) {
    croak "Can't access `$name' field in class $type";
  }
  if (@_) {
    return $self->{$name} = shift;
  } else {
    return $self->{$name};
  }
}

1;

##</code><code>##

package Some::Package::Sub;

use strict;
use warnings;

our $VERSION = '0.1';
our $AUTOLOAD;

my %fields = (
  name          => undef,
  needthis      => undef,
);

1;

##</code><code>##

use strict;
use warnings;
use Some::Package;
use Some::Package::Sub;

my $object = Some::Package::Sub->new(
  name     => 'Test',
  needthis => 'Value',
}