# use Class::XSAccessor { getters => ['foo'] };
# is equivalent to:

sub foo {
  my $self = shift;
  if (@_) {
    $self->{foo} = $_[0];
  }
  $self->{foo};
}

# use YourModule { getters => { bar => { isa => "HASH" } } }
# is equivalent to:

sub bar {
  my $self = shift;
  if (@_) {
    die "not a HASH" unless ref $_[0] eq "HASH";
    $self->{bar} = $_[0];
  }
  $self->{bar};
}