!Re: proposal: Object Members

[Ranando King]

> It certainly doesn't look or feel like JS - it feels more like Java or C#.

`private`, `protected`, `class`, and a few other such keywords have all
been part of ES since long be for the TC39 board got their hands on it.
They hadn't been implemented, but they were all a very real part of ES. Now
that `class` has been implemented, it makes little sense to leave behind
the `private` and `protected` keywords when we are trying to implement
their functionality.

> `private` looks like an identifier, and IMHO getters, setters, and async
functions suffer the same issue of the keyword seeming to blend in a little
with surrounding code.

Have you ever thought that `var` or `let` look like identifiers? The
`private` and `protected` keywords serve the same role as `var` and `let`:
declaring a variable within a given scope or context. If you think there is
a good logical or rational reason to avoid using the keywords that have
been embedded in the language and left languishing, waiting for their
meaning to be implemented, then I'm willing to entertain that. If the
reason is based on mere feeling or emotion, well. I will only entertain
such arguments if my reason for doing things a certain way is equally
emotion based. Nothing I'm aware of in this proposal falls into that
category. I have logical reasons for every choice I've made.

>> 2. `protected` on an object literal is next to useless. I've used that kind
of feature almost never.

> And how would that be accessible?

As you said, the vast majority of the time, this feature will go unused.
However, when it's needed, it would look something like this:

```js
var a = {
   protected sharedData: 1,
   increment() { ++this#.sharedData; },
   print() { console.log(`sharedData = ${this#.sharedData}`); }
};

var b = {
   __proto__: a,
   decrement() { --this#.sharedData; }
};
```

Setting `b.__proto__ = a` causes `b.[[PrivateValues]].__proto__ =
a.[[PrivateValues]]`, `b.[[DeclarationInfo]].__proto__ =
a.[[InheritanceInfo]]`, and `b.[[InheritanceInfo]].proto =
a.[[InheritanceInfo]]`. So it all just works.

> I saw `obj#['key']`, which *strongly* suggests dynamic keys are supported.

Dynamic **_keys_** are supported. Dynamic **_properties_** are not! Please
don't conflate the two. Dynamic keys are calculated property names. I am
definitely supporting that. Dynamic properties refers to the ability to add
and remove properties from an object at any time. I am not supporting that
for private/protected members (unless someone can logically convince me
it's a good idea).

On Fri, Aug 3, 2018 at 1:02 PM Isiah Meadows <isiahmeadows at gmail.com> wrote:

> Inline
>
> On Fri, Aug 3, 2018, 11:12 Ranando King <kingmph at gmail.com> wrote:
>
>> > 1. It's *super incredibly boilerplatey* and verbose syntactically.
>>
>> I'm not sure what you mean by "boilerplatey". As for being verbose, I'm
>> just using the keywords everyone understands for this purpose. IMO, there's
>> no advantage in trying to find some shorthand to do the same thing just
>> because it saves a keystroke or two when it makes the code significantly
>> more difficult to understand.
>>
>
> But on the same token, it's verbose enough that I feel readability starts
> to suffer substantiallly. `private` looks like an identifier, and IMHO
> getters, setters, and async functions suffer the same issue of the keyword
> seeming to blend in a little with surrounding code. But those are more like
> decorating the function than the name.
>
> Based on reading the several meeting notes, I don't believe the keyword
> has been especially popular there, either. It certainly doesn't look or
> feel like JS - it feels more like Java or C#.
>
>
>> > 2. `protected` on an object literal is next to useless. I've used that kind
>> of feature almost never.
>>
>> I get where you're coming from with that. I don't see it being used very
>> often (kinda like `with`), but it has to be there. If someone wants to use
>> the facilities of `class` without the limitations of the keyword, and the
>> intent is to build vertical hierarchies, they'll need the "protected"
>> keyword on their prototype definition to share private data with descendant
>> factories.
>>
>
> And how would that be accessible? Because you can't expose it via the same
> way you do in classes without basically making them public (and several
> workarounds suffer similar issues).
>
> > I also find it odd you're supporting private dynamic properties.
>>
>> How'd you get to the idea that I'm supporting dynamic private properties?
>>
>
> I saw `obj#['key']`, which *strongly* suggests dynamic keys are supported.
>
> > I actually think it's odd there is no attempt to implement dynamic
>> properties in the other "private properties" proposals.
>>
>
>> It's not that odd. There are issues around inheritance when a subclass
>> can remove the `protected` properties of its base. Further, exactly how do
>> you add a new `protected` property at runtime? Under both
>> proposal-class-fields and proposal-object-members, there is never any
>> direct access to the private container record, so use of
>> `Object.defineProperty` will never work. IMO, any attempt to implement
>> dynamic private properties in any sensible and consistent fashion would
>> require somehow exposing the private data record to the code. That's a
>> recipe for a private data leak. Not worth it.
>>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.mozilla.org/pipermail/es-discuss/attachments/20180803/4eb6469e/attachment-0001.html>