Le 17/04/2012 22:44, Brendan Eich a écrit :
Brendan Eich wrote:
Irakli Gozalishvili wrote:
It would be amazing to have clojure like protocols in JS even
without `IFn`. I think it's very good feet and very useful in JS
where each library has it's own flavored API. I wrote more about it
here:
http://jeditoolkit.com/2012/03/21/protocol-based-polymorphism.html#post
Still hoping Mark will weigh in.
Ok, I talked to Mark and Tom Van Cutsem, and they see no problem
provided we prevent overriding built-in [[Call]] and [[Construct]] on
function objects.
Let there be private names @call and @construct (I'll spell them this
way to avoid tedious imports of const bindings from "@std" or another
built-in module).
(...)
This also simplifies direct proxies by allowing any proxy to have call
and construct traps.
Speaking of proxies and private names, how would the 2 private name
interact with the proxies? It seems that it would be poorly because of
the "private-names-can-be-revealed-as-property-names-in-traps" rule.
Is it time to consider unique names? Since @call and @construct would be
available to anyone, they are not much that private anyway.
Change 11.4.3 "The typeof Operator", the table row with "Object
(native or host and does implement [[Call]])" in column 1, to test not
for [[Call]] and *not* for @call, rather to test [[NativeBrand]] ===
"Function" (see ES6 draft 15.2.4.2 "Object.prototype.toString ( )").
This last point is important: we do not want an object's typeof-type
to change by giving it a @call property.
This was a strong concern and the solution is satisfying as far as I'm
concerned.
David
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