Loss of identity, extra allocations, and forwarding overhead remain
problems.
It seems to me that you are focusing too much on "share ... to untrusted
parties." It's true you want either a membrane or an already-frozen
object in such a setting. But the latter case, already-frozen object,
does not want a membrane, both to avoid identity change and to avoid the
allocation and forwarding overheads. And outside of untrusted parties,
frozen objects have their uses -- arguably more over time with safe
parallelism in JS.
/be
David Bruant wrote:
Hi,
The main use case (correct me if I'm wrong) for freezing/sealing an
object is sharing an object to untrusted parties while preserving the
object integrity. There is also the tamper-proofing of objects
everyone has access to (Object.prototype in the browser)
In a world with proxies, it's easy to build new objects with high
integrity without Object.freeze: build your object, share only a
wrapped version to untrusted parties, the handler takes care of the
integrity.
function thrower(){
throw new Error('nope');
}
var frozenHandler = {
set: thrower,
defineProperty: thrower,
delete: thrower
};
function makeFrozen(o){
return new Proxy(o, frozenHandler);
}
This is true to a point that I wonder why anyone would call
Object.freeze on script-created objects any longer... By design and
for good reasons, proxies are a subset of "script-created objects", so
my previous sentence contained: "I wonder why anyone would call
Object.freeze on proxies..."
There were concerned about Object.freeze/seal being costly on proxies
if defined as preventExtension + enumerate + nbProps*defineProperty.
Assuming Object.freeze becomes de-facto deprecated in favor of
proxy-wrapping for high-integrity use cases, maybe that cost is not
that big of a deal.
David
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