JavaScript: providing a backward compatibility layer for changed function names/signatures

bc.function.js

/*
    Figuring out how to provide a Backward Compatibility Layer

    GOALS:
      [aliasing]    provide a function (nextGeneration) in another name (previousGeneration)
      [parameters]  the functions might differ in argument order (or length, …)
      [warnings]    log each access/mutation to the alias (previousGeneration) so old code bases can be cleaned up
*/

var myObject = { 
  nextGeneration: function(first, second) {
    console.log('nextGeneration executed!', first, second);
  }
  // the same function in an older version:
  // previousGeneration: function(second, first) {
  //   console.log('previousGeneration executed!', first, second);
  // }
};


Object.defineProperty(myObject, 'previousGeneration', {
  enumerable: true,
  configurable: true,
  get: function() {
    console.warn('the property previousGeneration was replaced by nextGeneration');
    return function(second, first) {
      console.warn('previousGeneration(second, first) changed to nextGeneration(first, second)');
      return this.nextGeneration(first, second);
    };
  },
  set: function(value) {
    console.warn('the property previousGeneration was replaced by nextGeneration (both have been updated!)');
    Object.defineProperty(this, 'previousGeneration', {
      enumerable: true,
      writable: true,
      value: value
    });
    this.nextGeneration = function(first, second) {
      return this.previousGeneration(second, first);
    };
  }
});



// testing

console.log('--------------------------------');
console.log('checking existence', !!myObject.nextGeneration, !!myObject.previousGeneration);

console.log('--------------------------------');
console.log('calling nextGeneration()');
myObject.nextGeneration('alpha', 'bravo');
console.log('--------------------------------');
console.log('calling previousGeneration()');
myObject.previousGeneration('bravo', 'alpha');

console.log('--------------------------------');
console.log('overwriting nextGeneration()');
myObject.nextGeneration = function(first, second) {
  console.log('new next()', first, second);
};

console.log('--------------------------------');
console.log('calling nextGeneration()');
myObject.nextGeneration('alpha', 'bravo');
console.log('--------------------------------');
console.log('calling previousGeneration()');
myObject.previousGeneration('bravo', 'alpha');

console.log('--------------------------------');
console.log('overwriting previousGeneration()');
myObject.previousGeneration = function(second, first) {
  console.log('new previous()', first, second);
};

console.log('--------------------------------');
console.log('calling nextGeneration()');
myObject.nextGeneration('alpha', 'bravo');
console.log('--------------------------------');
console.log('calling previousGeneration()');
myObject.previousGeneration('bravo', 'alpha');

/*

OUTPUT:

--------------------------------
warning: the property previousGeneration was replaced by nextGeneration
checking existence true true
--------------------------------
calling nextGeneration()
nextGeneration executed! alpha bravo
--------------------------------
calling previousGeneration()
warning: the property previousGeneration was replaced by nextGeneration
warning: previousGeneration(second, first) changed to nextGeneration(first, second)
nextGeneration executed! alpha bravo
--------------------------------
overwriting nextGeneration()
--------------------------------
calling nextGeneration()
new next() alpha bravo
--------------------------------
calling previousGeneration()
warning: the property previousGeneration was replaced by nextGeneration
warning: previousGeneration(second, first) changed to nextGeneration(first, second)
new next() alpha bravo
--------------------------------
overwriting previousGeneration()
warning: the property previousGeneration was replaced by nextGeneration (both have been updated!)
--------------------------------
calling nextGeneration()
new previous() alpha bravo
--------------------------------
calling previousGeneration()
new previous() alpha bravo

*/