function.next meta-property proposal

[Andrea Giammarchi]

actually, that won't work ... so yeah, that pattern is somehow compromise,
arguments is used to indeed initialize the generator, no way to put first
value in ... oh well

On Thu, May 14, 2015 at 11:44 PM, Andrea Giammarchi <
andrea.giammarchi at gmail.com> wrote:

> Alexander ES6 "is out" as it is, here the proposal is to make reachable
> that argument because indeed, since about ever, in JS you can ignore
> arguments, but you can also always reach them through the argument object.
>
> When it comes to generators, arguments object would be a misleading place
> to give you any sent value 'cause that's rather how you initialize the
> generator, hence the function.nect proposal, and I must say I like it in
> all its weird glory.
>
> Like you said, Python throws, meaning devs coming from Python won't ever
> make such mistake of sending values a tthe very first `.next` invoke, so JS
> early adopters know thanks to all bounce of early articles regarding the
> early specs :D
>
> My only concern, is that the "famous" Promise based generator wrap
> https://www.promisejs.org/generators/#both needs an update:
>
> ```js
> function async(makeGenerator){
>   return function (value) { // <= here
>     var generator = makeGenerator.apply(this, arguments);
>
>     function handle(result){
>       // result => { done: [Boolean], value: [Object] }
>       if (result.done) return Promise.resolve(result.value);
>
>       return Promise.resolve(result.value).then(function (res){
>         return handle(generator.next(res));
>       }, function (err){
>         return handle(generator.throw(err));
>       });
>     }
>
>     try {
>       return handle(generator.next(value)); // <= here
>     } catch (ex) {
>       return Promise.reject(ex);
>     }
>   }
> }
> ```
>
> Best Regards
>
>
> On Thu, May 14, 2015 at 11:25 PM, Alexander Jones <alex at weej.com> wrote:
>
>> I don't think that's a good enough reason by itself to make this
>> observable. You can pass arbitrary numbers of arguments to any function in
>> JS, and they are generally ignored.
>>
>> On Thursday, 14 May 2015, Kevin Smith <zenparsing at gmail.com> wrote:
>>
>>> Alexander, ES6 generators accept any arbitrary values for the first
>>> invocation of "next".  That's not going to change.
>>>
>>> On Thu, May 14, 2015 at 3:49 PM Alexander Jones <alex at weej.com> wrote:
>>>
>>>> In Python, sending a value other than `None` into the first invocation
>>>> of `send` raises an error. That seems like a reasonable behaviour to me,
>>>> without introducing too much weirdness.
>>>>
>>>>     TypeError: can't send non-None value to a just-started generator
>>>>
>>>> On Thursday, May 14, 2015, Allen Wirfs-Brock <allen at wirfs-brock.com>
>>>> wrote:
>>>>
>>>>> At the March TC39 meeting we agreed that the `function.next`
>>>>> metapropty should be made into a standalone stage 1 proposal.
>>>>>
>>>>> That proposal is now available at:
>>>>> https://github.com/allenwb/ESideas/blob/master/Generator%20metaproperty.md
>>>>>
>>>>>
>>>>> Allen
>>>>>
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>>>>
>>>
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>>
>
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