Le 20/02/2013 21:08, Kevin Reid a écrit :
On Wed, Feb 20, 2013 at 11:52 AM, Nathan Wall <nathan.w...@live.com
<mailto:nathan.w...@live.com>> wrote:
`Object.isFrozen` and `Object.isSealed` don't really seem that
helpful to me for the very reasons you've discussed: They don't
represent any real object state, so they don't accurately tell me
what can be done with an object. If I could I would argue in
favor of their removal, though I know it's too late for that.
I would be curious to see legitimate uses of `isFrozen` and
`isSealed` in existing code if anyone has anything to offer.
I just took a look at uses of Object.isFrozen in Caja and I find that
all but one are either in tests (test that something is frozen) or in
sanity checks (if this isn't frozen, do not proceed further, or freeze
it and warn).
The remaining one is in a WeakMap abstraction used for trademarking:
an object cannot be given a trademark after it is frozen. (The
rationale here, while not written down, I assume is that a defensive
object's "interface" should not change, and it is an implementation
detail that this particular information is not stored in the object.)
There is a comment there suggesting we might strengthen this check to
only permitting _extensible_ objects to be marked.
And in an ES6 world, you'll probably use an actual WeakMap anyway?
Thanks for sharing this experience from Caja,
David
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