GibboK - Pattern OLOO and pseudo-polymorphism

gibbok-pattern-oloo-pseudo-polymorphism.js

/* 
  Behavior delegation examples
  OLOO (Objects Linking to Other Objects) pattern idea from Kyle Sypson
  Example at: Delegating Widget Objects
  https://github.com/getify/You-Dont-Know-JS/blob/master/this%20%26%20object%20prototypes/ch6.md
*/
// good example
var base = {
    a : 3,
    init: function(b, c) {
        this.b = b || 1;
        this.c = c || 2;
    }
};
var obj = Object.create(base);
obj.init();
obj.d = '4';
obj.e = function(){};

alert(obj.hasOwnProperty('a')); //false (lookup protoype chain)
alert(obj.hasOwnProperty('b')); //true
alert(obj.hasOwnProperty('c')); //true
alert(obj.hasOwnProperty('d')); //true
alert(obj.hasOwnProperty('e')); //true

// bad example which use pseudo-polymorphism
var base2 = {
    a: undefined,
    b: undefined,
    c: undefined,
    init: function() {
    }
};
var obj2 = Object.create(base2);
obj2.init();
alert(obj2.hasOwnProperty('b')); //false
obj2.b = '2';
alert(obj2.hasOwnProperty('b')); //true !!! ugly pseudo-polymorphism
obj2.d = function(){};

alert(obj2.hasOwnProperty('a')); //false
alert(obj2.hasOwnProperty('c')); //false
alert(obj2.hasOwnProperty('d')); //true