Mootools and object.__proto__ - mootools

Question

Object.each, Object.keys, ... doesn't work fine when I try to use with an object that is a class attribute, check this example:
var map = {a: 1, b: []}; // simple object
var SomeClass = new Class({'map': map}); // class attribute
var sc = new SomeClass();
With a simple object, everything works ok
console.log(map.hasOwnProperty('a')); // true
console.log(map.hasOwnProperty('b')); // true
console.log(Object.keys(map)); // ['a', 'b']
But with sc.map, does not work with scalar values (int, boolean, string)
console.log(sc.map.hasOwnProperty('a')); // expected: true, returns: false
console.log(sc.map.hasOwnProperty('b')); // expected: true, returns: true
console.log(Object.keys(sc.map)); // expected: ['a', 'b'], returns: [b]
I realize it is beacuse sc.map has a __proto__ property
console.log(map.__proto__); // expected: empty Object
console.log(sc.map.__proto__); // expected: the "map" Object
I think it is a recent issue, because I have a huge bunch of code and some things stopped working because of this. I don't want to change all my code to fix this problem, i guess some patch for mootools is needed.

Answer 1

wow. so source code, https://github.com/mootools/mootools-core/blob/master/Source/Class/Class.js#L85, much merge: https://github.com/mootools/mootools-core/blob/master/Source/Core/Core.js#L348-L369
want derefrence. excellent.
var map = {a: 1, b: []}; // simple object
var SomeClass = new Class({'map': map}); // class attribute
var sc = new SomeClass();
console.log(sc.map.b.length);
map.b.push('doge');
console.log(sc.map.b.length); // 0
console.log(map.b.length); // 1
map.a = 'doge';
console.log(sc.map.a); // 1
in seriousness, not a recent change at all, any non-primitives are being copied in, don't panic. it is a good thing. You probably don't want a prototype for your object that can change because of something it references outside.
now. that being said, it's weird where a ends up from. http://jsfiddle.net/mMURe/2/ - I agree this is not ideal and is somewhat unexpected. filing an issue on GH, though don't hold your breath. if it's a recent change, it will be related to browser changes. Same code breaks in 1.3.2 and mootools 1.4.5 is quite old now and unchanged. The issue I filed on your behalf is here: https://github.com/mootools/mootools-core/issues/2544 - feel free to elaborate and add more usecases of where this is actually useful (I still don't like passing objects into prototypes)
But if you need to have your object have the map object by reference and avoid the merge, you can just put the reference in your constructor method instead:
var map = {a:1},
foo = new Class({
initialize: function(){
this.map = map;
}
});
var bar = new foo();
map.a++;
console.log(bar.map.a); // 2
but if you absolutely must break the norm and know the side effects, then you can.
var map = {a: 1, b: []}; // simple object
var SomeClass = new Class(); // class attribute
// avoid the derefrence rush, go prototypal manually
SomeClass.prototype.map = map;
var instance = new SomeClass,
other = new SomeClass;
console.log(instance.map.a); // 1
map.a++;
console.log(instance.map.a); // 2
// but also:
console.log(other.map.a); // 2
remember, MooTools Class is just constructor creation sugar that takes the pain away from having to do repetitive and non-terse actions. it still is javascript under the hood and you can use classic prototypal patterns on top.

Answer 2

I just encountered this issue as well. To avoid it I used Object.clone(). Object.clone() returns a normal object rather than a class object, so it does not have the __proto__ property, and everything should run fine. In the example you gave above, I would do this:
var scMap = Object.clone(sc.map);
console.log(scMap.hasOwnProperty('a'));
console.log(scMap.hasOwnProperty('b'));
console.log(Object.keys(scMap));
Hope this helps.