From: Allen Wirfs-Brock <[email protected]> > No, even if you removed the checks in Map and Promise and WeakMap that > prevent them from trying to initialize an object that lacks the appropriate > internal slots it still wouldn't work because obj does not have the internal > slots necessary to support the built-in operations upon those objects and > implementations commonly implement such objects in a manner that prevents the > dynamic addition of such slots.
> The whole purpose of @@create is to allow implementations to allocate prior > to invoking a constructor the correctly shaped object for built-ins. Well, but you could just move the internal slot initialization into the constructor itself (as Scott has done in his es6-shim promises). Unlike e.g. `Array`, the objects returned by `Promise[@@create]` are not exotic objects; they are simply normal objects with some internal slots initialized. So the movement of code between `@@create` and the constructor does not impact very much. _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
