as a note this works in JS too.

  var mariner= {};

  mariner.new = function(){
      var self = {};
      var maxhp = 200;
      var hp = maxhp;
      
      self.heal = function(deltahp) {
          if (hp + deltahp < maxhp){
              hp = hp + deltahp;
          } else {
              hp = maxhp;
          }
      }
      self.sethp = function(newhp) {
          if (newhp < maxhp){
              hp = newhp;
          } else {
              hp = maxhp;
          }
      }
      self.gethp = function(){
          return hp;
      }
      
      return self; 
  }

  var m1 = mariner.new();
  m1.sethp(100);
  m1.heal(13);
  alert(m1.gethp());

(shamelessly stolen from http://lua-users.org/wiki/ObjectOrientationClosureApproach)