Concise Method Binding

[JD Isaacks]

I like this very much. I would prefer this to my recommendation. So how to
we go about proposing it as a change to an existing proposal?

On Wed, Nov 11, 2015 at 11:45 AM, Andrea Giammarchi <
andrea.giammarchi at gmail.com> wrote:

> The way it could work is similar to the following one:
>
> ```js
>
> (function (wm){'use strict';
>
>   // just to show the possible internal slot mechanism
>   Object.prototype.boundTo = function (method) {
>     // since I've used this for ages now in eddy.js, just replicating
>     var fn = typeof method === 'function' ? method : this[method];
>     var bound = wm.get(this);
>     if (!bound) wm.set(this, bound = {fn:[], bound:[]});
>     var i = bound.fn.indexOf(fn);
>     if (i < 0) bound.bound[i = bound.fn.push(fn) - 1] = fn.bind(this);
>     return bound.bound[i];
>   };
>
> }(new WeakMap));
>
>
> // example
> var obj = {method: function () { return this; }};
>
> // now, whenever needed
> obj.boundTo(obj.method);
>
> // will create the slot and set it up with obj.method
> // so that the following is true
> obj.boundTo(obj.method) === obj.boundTo('method') &&
> obj.boundTo('method')() === obj;
>
> // if it's about another method
> // the equivalent of this
> ::obj.anotherMethod
>
> // whould be
> obj.boundTo(anotherMethod);
>
> ```
>
> The string fallback is not needed or relevant, it's just a semantic
> shortcut in my example to reach the method through the object without
> repeating the object name
>
> Regards
>
>
>
>
> On Wed, Nov 11, 2015 at 4:23 PM, JD Isaacks <jd at jisaacks.com> wrote:
>
>> Yes your point of view is more clear now, I like this is a lot.
>>
>> But I do not know how that would be transpiled or what the desugared
>> version would look like. However, that would be awesome as you described.
>>
>> A thing to note. You keep using `obj::method` which is different from
>> `::object.method` the former is when method is not already attached to the
>> object, the later is for then it is.
>>
>> An example:
>>
>> ```
>> let foo = function(){};
>> let bar = {};
>>
>> bar::foo // foo.bind(bar);
>> ```
>>
>> verses
>>
>> ```
>> let bar = { foo(){} };
>>
>> ::foo.bar // foo.bar.bind(foo);
>> ```
>>
>> I think both cases theoretically would be awesome to work as you
>> described. Just fuzzy on how it would look underneath.
>>
>> On Wed, Nov 11, 2015 at 11:14 AM, Andrea Giammarchi <
>> andrea.giammarchi at gmail.com> wrote:
>>
>>> Yeah, I've got that, my point is that whenever you need it you just
>>> `obj::method`
>>>
>>> Your example indeed says that currently the proposal is that
>>> `obj::method` is similar to `obj.method.bind(obj)` which is indeed always
>>> different and indeed you want something that makes method always the
>>> same/unique bound one, which I believe is universally the preferred way.
>>>
>>> What are two different bound of the same method useful for? Pretty much
>>> nothing, IMHO, while having a shortcut to lazily obtain a single bound
>>> version of that method for that object can be useful in many ways, as
>>> example `obj.on('event', anotherObj::method)` where it's always possible at
>>> that point to `obj.removeListener('event', anotherObj::method)` in case its
>>> needed.
>>>
>>> Having a shortcut that all it does is replace something already short to
>>> write like a `.bind` feels to me like a missed opportunity.
>>>
>>> Moreover, with this improvement you won't need/care to have self-bound
>>> methods at all
>>>
>>> ```js
>>> let obj = { method(){} };
>>>
>>> // and whenever needed you use
>>> obj::method;
>>> ```
>>>
>>> Hope my POV is more clear now.
>>>
>>> Regards
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Wed, Nov 11, 2015 at 4:01 PM, JD Isaacks <jd at jisaacks.com> wrote:
>>>
>>>> I think what you are suggesting already exists with `::obj.method`
>>>> which evaluates to `obj.method.bind(obj)`
>>>>
>>>> However, this creates a new function each time so `::obj.method
>>>> !== ::obj.method`, not sure how `::obj.method === ::obj.method` would work.
>>>>
>>>> I sort of agree with you that using it that way would be preferred.
>>>> However if the community wants bound methods attached to objects, there is
>>>> currently no way to do that with an object literal.
>>>>
>>>> You would have to do something like:
>>>>
>>>> ```
>>>> let obj = {};
>>>> obj.method = function(){}.bind(obj);
>>>> ```
>>>>
>>>> With my proposal you can.
>>>>
>>>> ```
>>>> let obj = { ::method(){} };
>>>> ```
>>>>
>>>>
>>>>
>>>>
>>>> On Wed, Nov 11, 2015 at 10:20 AM, Andrea Giammarchi <
>>>> andrea.giammarchi at gmail.com> wrote:
>>>>
>>>>> Just my thoughts, I wouldn't put any self-bound thing in the class and
>>>>> rather improve that `::` proposal so that whenever you `obj::method` it
>>>>> creates a uniquely bound callback so that `obj::method === obj::method` and
>>>>> at that point whenever you need to export, pass, or use such method you
>>>>> just `obj::method` or `obj::method()` or `let method = obj::method` and
>>>>> bring the pattern whenever it's needed instead of being slightly different
>>>>> per each "place" (class rather than objects)
>>>>>
>>>>> That would make it lazy, usable for events (in order to be able to
>>>>> also remove them) and easily transpilable for smoother migration.
>>>>>
>>>>> Having `class A { ::method() {} }` feels like somebody is playing too
>>>>> much with the protoype or "accidentally" polluting the constructor
>>>>>
>>>>> Regards
>>>>>
>>>>>
>>>>> On Wed, Nov 11, 2015 at 2:50 PM, JD Isaacks <jd at jisaacks.com> wrote:
>>>>>
>>>>>> Andrea, Sort of. I am talking about adding an additional place where
>>>>>> that operator `::` can be used -- with concise methods.
>>>>>>
>>>>>> Currently they cannot be used in the way I described above but I
>>>>>> think there are several reasons why it makes sense.
>>>>>>
>>>>>> _______________________________________________
>>>>>> es-discuss mailing list
>>>>>> es-discuss at mozilla.org
>>>>>> https://mail.mozilla.org/listinfo/es-discuss
>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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