Combining functional constructors/modules with the prototypal inheritance chain.

test.js

var sys = require('sys');

// Namespace
var o2 = function O2() {
  var o = {};

  // Core extensions
  if (typeof Object.create !== 'function') {
    Object.create = function(o) {
      var F = function() {};
      F.prototype = o;
      return new F();
    };
  }

  // Types
  function ConfigurationProfile(settings) {
    var o = Object.create({});

    o.settings = settings;
    var toString = function toString() {
      throw(new Error('Override toString() in the subclass.'));
    }

    o.toString = toString;
    return o;
  };

  function AndroidProfile(settings) {
    var o = Object.create(new ConfigurationProfile(settings));

    var toString = function toString() { return 'Android'; }

    // Public interface
    o.toString = toString;

    return o; 
  };

  function IPhoneProfile(settings) {
    var o = Object.create(new ConfigurationProfile(settings));

    var toString = function toString() { return 'iPhone'; }

    // Public interface
    o.toString = toString;

    return o; 
  };

  // Export Types
  o.AndroidProfile = AndroidProfile;
  o.IPhoneProfile = IPhoneProfile;

  return o;
}();

var profile = o2.AndroidProfile({msisdn: 12345678});
sys.puts(sys.inspect(profile));
sys.puts(sys.inspect(profile.settings));
sys.puts(sys.inspect(profile.toString())); //=> Android

var profile = o2.IPhoneProfile({msisdn: 87654321});
sys.puts(sys.inspect(profile));
sys.puts(sys.inspect(profile.settings));
sys.puts(sys.inspect(profile.toString())); //=> iPhone