On Wed Jan 21 2015 at 4:11:04 PM Mark Miller <[email protected]> wrote:
> On Wed, Jan 21, 2015 at 1:05 PM, Jordan Harband <[email protected]> wrote: > >> > Just checking: Are we talking about adding it to each instance as a >> non-configurable non-writable data property? >> >> Mark: No, not to each instance, but to Array.prototype, >> Function.prototype, etc. If someone wants to override it on a specific >> instance that's fine, and I don't think it's important to protect against >> that. >> > > In that case, I find this unacceptable, as it breaks the branding > invariant that some legacy ES5 code depends on. > I just want to clarify, this is what you're referring to, correct? > Object.getOwnPropertyDescriptor(Object.prototype, Symbol.toStringTag) undefined > Object.defineProperty(Object.prototype, Symbol.toStringTag, { value: "Whatever I want it to be" }); > Object.prototype.toString.call(function() {}) "[object Whatever I want it to be]" > Object.prototype.toString.call("A string") "[object Whatever I want it to be]" > Object.prototype.toString.call({}) "[object Whatever I want it to be]" > Object.prototype.toString.call(1) "[object Whatever I want it to be]" This wouldn't be possible if all built-in prototypes had an explicitly defined @@toStringTag that was { [[Enumerable]]: false, [[Writable]]: false, [[Configurable]]: false } (which is what I believe Jordan is presenting) Rick > > > >> >> > I would not be happy with making the built-ins nonconfigurable. Just >> like Function.prototype.length, it should be unlocked. >> >> Domenic: Changing Function#length makes sense to me - the Function#bind >> shim does nasty things to ensure "length" is set properly, for example, and >> it would be much easier if the length was editable. Do you have a use case >> in mind where you'd want to change a language builtins' @@toStringTag value? >> >> We can always unlock it later, but it seems like we can't lock it down >> once it's unlocked, so without any valid use cases, it seems like a risky >> move to unlock it now. >> >> On Wed, Jan 21, 2015 at 1:00 PM, Mark S. Miller <[email protected]> >> wrote: >> >>> On Wed, Jan 21, 2015 at 12:57 PM, Mark Miller <[email protected]> wrote: >>> [...] >>> >>>> Is there anyone who wouldn't be happy with "all >>>>> builtins' @@toStringTag is not configurable" and "drop the ~ prefixing >>>>> completely"? >>>>> >>>> >>>> Just checking: Are we talking about adding it to each instance as >>>> unconfigurable? >>>> >>> >>> Sorry, incomplete question. Meant: >>> >>> Just checking: Are we talking about adding it to each instance as a >>> non-configurable non-writable data property? >>> >>> >>> -- >>> Cheers, >>> --MarkM >>> >> >> > > > -- > Cheers, > --MarkM > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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