Excellent. On Jun 10, 2013, at 19:26 , Allen Wirfs-Brock <al...@wirfs-brock.com> wrote:
> The corresponding text describing [[Configurable]] in the ES6 draft has > already been updated to clarify that [[Writable]] can always be set to false. > > Allen > > On Jun 10, 2013, at 4:57 AM, Axel Rauschmayer wrote: > >> The ECMAScript 5.1 spec says (8.6.1): >> [[Configurable]]: If false, attempts to delete the property, change the >> property to be an accessor property, or change its attributes (other than >> [[Value]]) will fail. >> >> On the other hand [[DefineOwnProperty]] (8.12.9) allows one to change >> writability from true to false, even if a property is not configurable: >> >> 10 Else, if IsDataDescriptor(current) and IsDataDescriptor(Desc) are both >> true, then >> a. If the [[Configurable]] field of current is false, then >> i. Reject, if the [[Writable]] field of current is false and >> the [[Writable]] field of Desc is true. >> ii. If the [[Writable]] field of current is false, then >> 1. Reject, if the [[Value]] field of Desc is present >> and SameValue(Desc.[[Value]], current.[[Value]]) is false. >> b. else, the [[Configurable]] field of current is true, so any change >> is acceptable. >> >> (10.a) seems to ignore the case of [[Writable]] of `current` being true. Is >> this deliberate? >> >> Should the description of [[Configurable]] be changed to better reflect the >> status quo? -- Dr. Axel Rauschmayer a...@rauschma.de home: rauschma.de twitter: twitter.com/rauschma blog: 2ality.com
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