sub PROTECTED {
  my $self = shift;
  
  my @caller = caller(1);
  $caller[3] =~ m{(.*)::(.*)$};
  my ($pack, $sub) = ($1,$2);
  
  local $Carp::CarpLevel += 1;
  confess "method '$sub' is protected by '$pack'" 
   unless ($caller[0]->can($sub));
  
  return $self;
}