On Nov 15, 2011, at 9:56 AM, Brendan Eich wrote:
> On Nov 15, 2011, at 8:16 AM, Russell Leggett wrote:
>
>> I think this example is contrived, but illustrates the point that JavaScript
>> is very dynamic, and sometimes in the building process an object can be out
>> of sync from its constructor. My expectations when I see this would be that
>> my results would be a constructor function that can be used to produce a new
>> version of the UnaryExpression, calling its constructor code. The best way I
>> can think of to do this would be:
>>
>> function classify(obj){
>> let sub = obj <| {
>> constructor(...args){
>> super.constructor(...args);
>> }
>> }
>> sub.constructor.prototype = sub;
>> return sub.constructor;
>> }
>>
>> The key is that the UnaryExpression is not modified, and it should still
>> work even if a constructor is missing. If the UnaryExpression is
>> unobservable and had an own constructor property I would expect that the <|
>> portion can be skipped, and the constructor would just be modified directly
>> to point back at the enclosing object literal.
>
> Optimizations must be unobservable except by benchmarking or other kinds of
> profiling. But if I'm following you correctly, even if the UnaryExpression
> operand is a fresh object literal with an own 'constructor' property, the
> result of skipping <| differs observably from the case where the operand is
> not fresh:
>
> class {p: "I'm own"}
Oops, that should have been:
class {p: "I'm own", constructor(){}}
of course.
/be
>
> vs.
>
> class compute_object_with_own_p();
>
> where compute_object_with_own_p returns an object {p: "I'm own too"}.
>
> In the latter case, returning a new object whose [[Prototype]] references the
> non-fresh {p: "I'm own too"} object makes an observable difference in where
> 'p' lives.
>
> /be
> _______________________________________________
> es-discuss mailing list
> [email protected]
> https://mail.mozilla.org/listinfo/es-discuss
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
