Axel Rauschmayer (2015-02-14T21:45:59.000Z)
d at domenic.me (2015-02-21T00:45:36.364Z)
On 14 Feb 2015, at 22:26, Mark S. Miller <erights at google.com> wrote: > I didn't mean to imply an early error. The "extends X" can only produce a dynamic error, so I'm arguing that "extends null" should do the same. When I say “early”, I don’t mean “static”, I mean: dynamically, when the class definition is evaluated, not later when the class is instantiated via `new`. I’m not seeing a dynamic error in the spec when the `extends` clause is null (step 6e): https://people.mozilla.org/~jorendorff/es6-draft.html#sec-runtime-semantics-classdefinitionevaluation <https://people.mozilla.org/~jorendorff/es6-draft.html#sec-runtime-semantics-classdefinitionevaluation> > > Or dynamically switching from "derived" to "base" (but you seem to be saying that doing this dynamically is not a good idea). > > Dynamically switching from derived to base does not work, because our super semantics depends statically on the difference. Ah, checked statically, I wasn’t aware! Hadn’t found the check beforehand. Searched some more and it is indeed there, in 14.5.1.