Another inconsistency just spotted in this (IMHO) funny way
Object.defineProperty consider inherited properties for the descriptor, is
that Object.defineProperties **does not**, so doesn't create.
I believe if there's a use case for recycled, inherited, descriptors,
that's much more defineProperties/create rather than defineProperty.
Here a simple use case showing that this stuff is not consistent:
function Inherited() {
return Inherited._singleton || (
Inherited._singleton = new Inherited
);
}
Inherited.prototype.test = {value: "test"};
Object.defineProperties({}, Inherited()).test; // udnefined
this will obviously work
function Forced(){
this.test = this.test;
}
Forced.prototype.test = {value: "test"};
Object.defineProperties({}, new Forced).test; //"test"
If we would like to reuse inheritance to create hierarchies ... as showed
already, things are also broken.
function P(){}
P.prototype.test = {value: "test"};
Object.create(null, new P).test; // undefined
Why Does This Matter
Specially create, but defineProperties only, are mechanism used to define
object properties in a more powerful way.
These are also promoted as better way than simulated classical OOP in ES5
function enrich(base, current) {
var self = Object.create(base), k;
for (k in current) {
self[k] = current[k];
}
return self;
}
var
// Animal Descriptor
Animal = enrich(null, {
alive: {
value: true
}
}),
// Cat Descriptor
Cat = enrich(Animal, {
tail: {
value: true
}
})
;
// each Animal
var generic = Object.create(null, Animal);
var cat = Object.create(null, Cat);
generic.alive; // true
cat.tail; // true
cat.alive; // undefined
So, accordingly you find defineProperty consider inheritance a correct
behavior in specs, what do you think about all other cases that are not
behaving consistently or as expected?
Thanks for your attention.
br
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
