On Jun 8, 2013, at 9:31 PM, Yehuda Katz wrote:
>
>
> Yehuda Katz
> (ph) 718.877.1325
>
>
> On Sat, Jun 8, 2013 at 9:23 PM, Dmitry Soshnikov <dmitry.soshni...@gmail.com>
> wrote:
> I might be missing something, but how for-of help solving parametrized
> enumeration (that is, specifying an action applied on a value/key in a
> functional style)?
>
> I see clear use-case of Object.values(...) in addition to Object.keys(...),
> and it has nothing to do with for/of enumeration.
>
> Why refuse a convenient library method and force users to 1) let values = [];
> 2) for (v of values(o)) { values.push(v); }, if it can be just let values =
> Object.values(o);?
>
> I'm confused. Your example shows (correctly) that a `values` method exists
> that does what you want. What more are you asking for?
>
I'm confused either (please correct me if I'm mistaken), since values(...)
generator method doesn't do what I want, it returns a _gen_, but not an array
of values corresponding to own enumerable properties (returned by
Object.keys(...) with the same enumeration order).
> Why refuse a _parametrized_ functional iteration such as Object.forEach(o,
> parametrizedAction) and force users to write different static for-of loops
> with own loop body per each condition, if this condition can be passed as a
> function?
>
> I am personally in favor of a collections module that works across any
> iterable. I don't think we have anything on tap for ES6, but it would be
> trivial to write in pure JS in the ES6 timeframe and I don't see any reason
> it couldn't be folded in to ES7 once it gets some real-world usage.
>
Yeah, a generic parametrized enumeration in the function style would be nice to
have. As for a clear practical use-case, I don't see the reason to wait until
ES7 if this may happen now:
process(o, action) {
if (action == 'init') {
for (let v of values(o)) {
this.initValue(v);
}
} else if (action == 'dump') {
for (let v of values(o)) {
this.dumpData(v);
}
} else if (/* whaever */) {
// how many else parametrized actions
// should I apply before we have a parametrized
// enumerator?
}
}
Which reduces basically to:
Object.forEach(o, this.init);
Object.forEach(o, this.dump);
// etc.
And of course everything can be implemented on a user-level, but why not to
provide it out of the box?
Dmitry
>
> P.S.: for consistency with [].forEach, it probably would make sense having
> {}.forEach, but it's O.prototype pollution.
>
> Dmitry
>
> On Jun 7, 2013, at 10:18 AM, Dean Landolt wrote:
>
>> The for/of iterators solve this nicely. This is definitely something that
>> comes up a lot though, and this seems like a very handy cowpath to pave. If
>> it were spec'd I'd suggest the naming and argument values should align with
>> the for/of variants.
>>
>>
>> On Fri, Jun 7, 2013 at 12:57 PM, Andrea Giammarchi
>> <andrea.giammar...@gmail.com> wrote:
>> it comes out from time to time devs would like to have `Object.values()` as
>> equivalent of `Object.keys()` except the returned array would contain values.
>>
>> Better than repeated
>> `Object.keys(obj).map(function(p){return this[k];}, obj);`
>> all over
>>
>> but probably less useful than a more generic `Object.forEach(obj, callback,
>> thisValue)` where `callback` would receive `(value, key, originalObject)`
>> and `thisValue` as context.
>>
>> This is consistent with `Array#forEach` and could simplify `for/in` loops
>> passing over own enumerable properties only, as keys would do.
>>
>> Thoughts ?
>>
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