my $person={Alter=>25, Name=>'Peter', Größe=>172};
print $person->{Alter}."\n"

package Person;
sub new
{
  my $class=shift;
  my %opts=@_;
  my $self={};
  $self->{$_}=$opts{$_} for( qw(Alter Name Größe) )
}

sub _attr
{
  my $self=shift;
  my $attr=shift;
  $self->{$attr}=shift if(@_);
  return $self->{$attr};
}

sub Alter{ shift->_attr('Alter',@_) }
sub Name{ shift->_attr('Name',@_) }
sub Groesse{ shift->_attr('Groesse',@_) }

my $person=Person->new(Alter=>25, Name=>'Peter', Groesse=>172);
print $person->Alter();

package Person;

  use Moose;

  has 'Name' => (
      is  => 'rw',
      isa => 'Str',
  );

  has 'Groesse' => (
      is  => 'rw',
      isa => 'Num',
  );

  has 'Alter' => (
      is  => 'rw',
      isa => 'Num',
  );

  no Moose;
  __PACKAGE__->meta->make_immutable;