use base qw(Some::Package);

##</code><code>##

sub new {
  my $proto     = shift;
  my $class     = ref($proto) || $proto;
  my %args      = @_;
  bless($self, $class);
  $self->init();

    foreach my $arg (keys(%args)) {
      $self->$arg($args{$arg});
    }
  }

##</code><code>##

sub init {
   my $self=shift;
   $self->{_permitted} = \%fields;
   #... and add the other fields also
  };