Allen Wirfs-Brock wrote:
On Apr 21, 2013, at 12:31 PM, Brendan Eich wrote:
> You don't want that to affect object literals evaluated in the same realm
after such a deletion. Why not?
Why should it?
... because it did in ES5-conforming implementations that support
__proto__ as a de-facto standard *and* allow delete
Object.prototype.__proto__.
We already used the existence of {__proto__: whatever} got rid of<| as
declarative syntax for defining an object literal with a [[Prototype]] other than
object prototype. Making {__proto__: whatever} only work some of the times means
it isn't a reliable declarative syntax.
What?
Mark insists on delete Object.prototype.__proto__ making the magic go
away. (Summoning Mark.)
Triangle died for several reasons, and I'm surprised to hear it here.
Grinding an axe?
Why would we want to do that? There is arguably a good motivation wanting
disable the ability to dynamically __proto__ modify arbitrary pare-existing
objects. But what is the motifacation for doing that on newly created objects?
I will tag Mark in here, but first make my own move:
Answer: because the clear way to implement this in ES5-conforming
implementations that support __proto__ is to call [[Put]] not
[[DefineOwnProperty]] if the name of the property being initialized in
the object literal is '__proto__', and that's what engines implement.
That makes a new de-facto standard, which you should not be wasting
energy trying to break!
SpiderMonkey at least goes out of its way to do [[Set]] (let's call it) not
[[DefineOwnProperty]] for 'o = {__proto__: 42}', so why wouldn't [[Set]] create
a fresh property, seeing nothing on Object.prototype named '__proto__' with a
setter to run?
Because the semantics that says you can't use [[DefineOwnProperty]] may say to
go out of the way to do something else.
Too late, ES5+reality happened. You are now proposing to break the web,
at the limit. JS implementors will not go for that, so you are wasting
your time.
It my strawman spec. it says use [[SetInhertiance]] rather than [[Put]].
Either is a special case semantics and [[SetInheritance]] is a much more direct
expression of the likely user intent.
Direct, schmirect.
This is about compatibility and consistency, not what you can edit into
a draft. Please reconsider. Must we put this on the next meeting's agenda?
/be
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