On 13 April 2013 00:12, Brandon Benvie <[email protected]> wrote: > 3.) A new type of primitive along with a new type of wrapper. In this case > we use the String/Number/Boolean precedent where `Symbol()` and `new > Symbol()` produce different kinds of results. The problem here is the > confusion that comes with ToString/ToPropertyKey when called on a Symbol > wrapper. What does `obj[new Symbol] = 5` do, for example? It allows footguns > like `obj[key + '_ext']` to silently do the wrong thing.
That was the consensus at the last meeting, and it's already implemented in V8. The decision included that Symbol.prototype.toString is poisoned, i.e., any attempt to implicitly convert a symbol or a wrapped symbol to a string will throw, including both of your examples. So no footgun, which I agree is important. (Object.prototype.toString is not on that path, however, so can treat symbols separately.) I'm a bit confused about some bits of Allen's comment on your Gist, though, which don't line up with what I thought we decided on. In particular, ToObject(symbol) should be perfectly fine and creates a wrapper object. Similarly, Symbol()["foo"] auto-converts to a wrapper object and returns undefined as usual, and new Symbol() directly creates a wrapper object. /Andreas _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
