Return values of mutating MOP operations (Was: response chapter 8 except 8.5 (was Re: ES6 Rev13 Review: MOP-refactoring, symbols, proxies, Reflect module))

Tom Van Cutsem at
Wed Jan 2 23:23:45 PST 2013

2013/1/2 Allen Wirfs-Brock <allen at>

> Symbols don't need to fail on [[PreventExtensions]].  It always succeeds
> for them since they are born non-extensible.

Sounds reasonable.

> The major user facing change here is the possibility that
> Object.preventExtensions will through if the object can not be made
> non-extensible.  This wasn't specified  in ES5, but I'm ok making that
> change.

Ok. Recall that in the old Proxy API, we already had the fix() trap
returning a boolean, and Object.{preventExtensions,seal,freeze} throwing on

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