Object.getOwnPropertyDescriptors(O) ? // plural

[Tom Van Cutsem]

Object.getOwnPropertyDescriptors(obj) makes sense to me. As noted somewhere
upstream, it's symmetrical to Object.defineProperties.

When I designed traits.js, which was heavily based on property descriptors,
I even added it to the library's public API, under the slightly shorter
name Object.getOwnProperties(obj), cf. <http://traitsjs.org/api.html>

Brendan asked me whether Object.getOwnPropertyDescriptors would necessitate
a derived trap for proxies. I think the answer is no, just like
Object.defineProperties(proxy) triggers just the proxy's
getOwnPropertyNames trap, and then the defineProperty trap for each
property, Object.getOwnPropertyDescriptors(proxy) would trigger the
getOwnPropertyNames trap, followed by calls to the getOwnPropertyDescriptor
trap for each individual property.

Cheers,
Tom




2014-03-05 1:38 GMT+01:00 Andrea Giammarchi <andrea.giammarchi at gmail.com>:

> You are right, I've realized it after posting ... `Object.assign(target,
> source)` via `Get` and `Put` is basically the equivalent of a classic
> `for/in` with `hasOwnProperty` check ... well, once again, in ES6
> `Object.getOwnPropertyDescriptors(O)` seems to be a solution for other
> cases too (shallow copy of properties, shallow clone, not just for/in) plus
> yes, `Object.mixin(target, source)` might be simplified as well via this
> proposal, that's a good point ... so 3 problems solved at once! :-)
>
>
> On Tue, Mar 4, 2014 at 4:02 PM, Claude Pache <claude.pache at gmail.com>wrote:
>
>>
>>
>> Le 5 mars 2014 à 00:18, Andrea Giammarchi <andrea.giammarchi at gmail.com>
>> a écrit :
>>
>>
>> Also please note that this proposal simplifies [Object.assign(target,
>> source)](
>> https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.assign)
>> too since latter one is basically:
>>
>> ```javascript
>> Object.defineProperties(
>>   target,
>>   Object.getOwnPropertyDescriptors(source)
>> );
>> ```
>>
>>
>> No. `Object.assign` (1) uses the semantics of the assignment operator `=`
>> (for example, it makes a difference in case of setters), and (2) copies
>> only enumerable properties. Did you think about `Object.mixin`?
>>
>> --Claude
>>
>
>
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