Thanks for the clarifications. I understand wanting to make the
distinction from an implementer point of view, I'm just not sure that
developers make the distinction between [[Put]] and
[[DefineOwnProperty]] even using regular object literals. Is there a
reason that this:
var obj = {};
obj.{
name: "JS"
};
Can't act the same as this:
var obj = {};
obj.name = "JS";
Wherein, if the property is already defined that acts as [[Put]] and
otherwise acts as [[DefineOwnProperty]]?
Thanks,
Nicholas
On 5/28/2012 2:27 PM, Allen Wirfs-Brock wrote:
On May 28, 2012, at 1:23 PM, Erik Arvidsson wrote:
On Mon, May 28, 2012 at 12:19 PM, Nicholas C. Zakas
<[email protected]> wrote:
Is it intentional that the first example uses colons between the property
and value while all others use the equals sign?
Yes this is intentional. We discussed this a bit at the F2F meeting
and we came up with the proposal to use = for [[Put]] and : for
[[DefineOwnProperty]]. Having a way to do [[Put]] is important because
it is common to want to trigger setters.
At added a clarification of this to the strawman....
For example:
class Monster {
set health(value) {
this.barColor = value< 10 ? 'red' : 'green';
this._health = value;
}
}
class GiantSpider extends Monster {
constructor() {
this.{
health = 100
}
}
}
If you use .{health: 100} then the setter would not be invoked and the
object would not be in a correct state. This example might be a bit
contrived but using [[DefineOwnProperty]] is not the right answer in a
lot of cases.
This is especially important for setting values of DOM node properties which
are generally implemented as accessor properties (ie, getters/setters). That
is why I used (thanks to dherman) a DOM element in most of the example that use
+.
Allen
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Nicholas C. Zakas
http://www.nczonline.net
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