function log(result) {
  var li;
  if (typeof(resultsList) === "undefined") {
    console.log(result);
  } else {
    li = document.createElement("li");
    li.textContent = result;
    resultsList.appendChild(li);
  }
}

log("Different ways of using a mixin to create property getter functions for model objects ...");
log("The model object properties are encapsulated and only accessible via the getter functions.");
log("See mixin.js for implementation details.");

// ************************************************
//
// Standard getter method accessing variables in closure (no use of mixin).
//
function Model1(options) {
  var myOptions = options;
  this.get = function(prop) {
    return myOptions[prop];
  };
}

log("----");
log("Standard getter method accessing variables in closure (no use of mixin).");
log("m1 = new Model1({ a:1, b:3, c:3 });");
log("a = m1.get('a'));");

m1 = new Model1({ a:1, b:3, c:3 });
log("a = " + m1.get("a"));

// ************************************************
//
// Standard getter mixin accessing variables saved as properties in Model object
//
// See: section 4. Adding Caching
//      http://javascriptweblog.wordpress.com/2011/05/31/a-fresh-look-at-javascript-mixins/
//
//
var addMixin2 = (function() {
  function get(prop) {
    return this.options[prop];
  }
  return function() {
    this.get = get;
    return this;
  };
})();

function Model2(options) {
  addMixin2.call(Model2.prototype);
  this.options = options;
}

log("----");
log("Standard getter mixin addMixin2() accessing variables saved as properties in Model object.");
log("m2 = new Model2({ a:4, b:5, c:6 });");
log("a = m2.get('a'));");

m2 = new Model2({ a:4, b:5, c:6 });
log("=> " + m2.get("a"));


// ************************************************
//
// Getter mixin accessing closure variables with the help of function in Model object
//
var addMixin3 = (function() {
  function get(prop) {
    return this.getPrivate()[prop];
  }
  return function() {
    this.get = get;
    return this;
  };
})();

function Model3(options) {
  addMixin3.call(Model3.prototype);
  var myOptions = options;
  this.getPrivate = function() {
    return myOptions;
  };
}

log("----");
log("Getter mixin addMixin3() accessing closure variables with the help of function in Model object.");
log("m3 = new Model3({ a:7, b:8, c:9 });");
log("a = m3.get('a'));");

m3 = new Model3({ a:7, b:8, c:9 });
log("=> " + m3.get("a"));

var Model3a = function(options) {
  addMixin3.call(Model3a.prototype);
  var myOptions = options;
  this.getPrivate = function() {
    return myOptions;
  };
};

log("Make a second model object with different initial variables.");
log("m3a = new Model3({ a:1, b:3, c:3 });");
log("a = m3a.get('a'));");

m3a = new Model3({ a:1, b:3, c:3 });
log("=> " + m3a.get("a"));

// ************************************************
//
// Mixin accessing it's own closure variables
//
// 'count' is scoped to the function mixed in to the model object
// 'total' is scoped to the mixin itself
//
var addMixin4 = (function() {
  var total = 0;
  function counter(num) {
    var count = num;
    return function() {
      total++;
      return count++;
    };
  }
  function totalCount() {
    return function() {
      return total;
    };
  }
  return function(num) {
    this.counter = counter(num);
    this.totalCount = totalCount();
    return this;
  };
})();

function Model4(num) {
  addMixin4.call(Model4.prototype, num);
}

var Model4a = function(num) {
  addMixin4.call(Model4a.prototype, num);
};

log("----");
log("Mixin accessing it's own closure variables that keeps track of both how many ");
log("times the mixin is called from each created function and also the total number");
log("times the mixin has been called from all functions that use it.");
log("In this case two different Model creation functions are created, Model4()");
log("and Model4A() and each of them are extended with the same mixin: addMixin4().");

log("m4 = new Model4(23);");
log("m4a = new Model4a(17);");

m4 = new Model4(23);
m4a = new Model4a(17);

log("function call counter tests ...");
log("m4 function counter starting at 23 ...");
log("m4.counter(); => " + m4.counter());
log("m4.counter(); => " + m4.counter());
log("m4.counter(); => " + m4.counter());
log("m4.counter(); => " + m4.counter());
log("total count by all uses of mixin: " + m4.totalCount());

log("m4a counter starting at 17 ...");
log("m4a.counter(); => " + m4a.counter());
log("m4a.counter(); => " + m4a.counter());
log("m4a.counter(); => " + m4a.counter());
log("total count by all uses of mixin addMixin4(): " + m4.totalCount());