Allen Wirfs-Brock (2014-06-13T19:40:48.000Z)
domenic at domenicdenicola.com (2014-06-20T19:43:24.372Z)
On Jun 13, 2014, at 12:07 PM, Jussi Kalliokoski wrote: > ```js > function Foo () {} > > Foo.prototype[Symbol.create] = null; > ``` @@create methods are normally defined as methods of the constructor function rather than as an instance method on the prototype. So the above should be: ```js Foo[Symbol.create] = null; ``` > ```js > // ??? > // Maybe error out, like currently host objects without [[Construct]]: > // TypeError: Foo is not a constructor. > new Foo(); > ``` as currently specified [1] (and after I fix a bug I just noticed) it will fall back to doing the equivalent of Object.create(). I did that to maximize backwards compatibility for this specific situation: ```js function Foo() {}; Foo.__proto__ = null; //in ES6 default @@create inherited from Function.prototype becomes unavailable new Foo; //but in ES1-5 this still does the equivalent of Object.create(); ``` If we go down the route of eliminating [[Construct]] and are willing to break backwards compat. for this case, then we could make 'new' throw if a constructor doesn't have a callable @@create. That would provide a good way to indicate that a function is not a constructor (which is current determine based upon it having a [[Construct]] internal method.