Concise Method Binding

[JD Isaacks]

Ahh, good point Bergi. Thanks for brining that up.

On Wed, Nov 11, 2015 at 11:55 AM, JD Isaacks <jd at jisaacks.com> wrote:

> 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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