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Re: document.register and ES6

From: Scott Miles <sjmiles@google.com>
Date: Wed, 6 Feb 2013 12:47:37 -0800
Message-ID: <CAHbmOLaem-DUi8DWpHHAiU5Aek6U5JDEjN4T90bfsTUp4_70PQ@mail.gmail.com>
To: Daniel Buchner <daniel@mozilla.com>
Cc: Erik Arvidsson <arv@chromium.org>, Dimitri Glazkov <dglazkov@google.com>, public-webapps <public-webapps@w3.org>, Boris Zbarsky <bzbarsky@mit.edu>
Sorry for the flood, but here is another version that shows inheriting from
custom elements (Webkit/FF only).

http://jsfiddle.net/cEmZq/


On Wed, Feb 6, 2013 at 12:43 PM, Scott Miles <sjmiles@google.com> wrote:

> Yes, it's not intended to work in IE ... I used __proto__.
>
>
> On Wed, Feb 6, 2013 at 12:41 PM, Daniel Buchner <daniel@mozilla.com>wrote:
>
>> Scott: is this example not intended to work in IE9? It throws, the output
>> object is missing the 'oranginate' method.
>>
>> Daniel J. Buchner
>> Product Manager, Developer Ecosystem
>> Mozilla Corporation
>>
>>
>> On Wed, Feb 6, 2013 at 12:32 PM, Scott Miles <sjmiles@google.com> wrote:
>>
>>> There were several errors in my pseudo-code, here is a working version:
>>>
>>> http://jsfiddle.net/yNbnL/1/
>>>
>>> S
>>>
>>>
>>> On Wed, Feb 6, 2013 at 12:01 PM, Scott Miles <sjmiles@google.com> wrote:
>>>
>>>> Errata:
>>>>  makePrototypeTwiddlingConstructorForDomNodes needs to know the extendee
>>>>
>>>>  var ctor = makePrototypeTwiddlingConstructorForDomNodes(inExtends,
>>>> inClass);
>>>>
>>>>
>>>> On Wed, Feb 6, 2013 at 11:59 AM, Scott Miles <sjmiles@google.com>wrote:
>>>>
>>>>> On Wed, Feb 6, 2013 at 11:18 AM, Erik Arvidsson <arv@chromium.org>wrote:
>>>>>
>>>>>> On Wed, Feb 6, 2013 at 1:38 PM, Scott Miles <sjmiles@google.com>
>>>>>> wrote:
>>>>>> > Sorry, replace MyButton.super() with MyButton.super.call(this);
>>>>>> >
>>>>>> >
>>>>>> > On Wed, Feb 6, 2013 at 10:37 AM, Scott Miles <sjmiles@google.com>
>>>>>> wrote:
>>>>>> >>
>>>>>> >> So, neglecting issues around the syntax of document.register and
>>>>>> the
>>>>>> >> privatization of callbacks, is it fair to say the following is the
>>>>>> intended
>>>>>> >> future:
>>>>>> >>
>>>>>> >> class MyButton extends HTMLButtonElement {
>>>>>> >>   constructor() {
>>>>>> >>     super();
>>>>>> >>     // make root, etc.
>>>>>> >>   }
>>>>>> >> }
>>>>>> >> document.register('x-button', MyButton);
>>>>>> >>
>>>>>> >> If so then can we do this in the present:
>>>>>> >>
>>>>>> >> MyButtonImpl = function() {
>>>>>>
>>>>>> What do you mean here?
>>>>>>
>>>>>> >>   MyButton.super();
>>>>>>
>>>>>> Did you get that backwards? I don't see how MyButtonImpl can be
>>>>>> derived from MyButton.
>>>>>>
>>>>>
>>>>> Its not. The 'super' means 'the super-class constructor for MyButton
>>>>> that does not include magic DOM object generation' (in this case,
>>>>> HTMLButtonElement). For MyDerivedButton, MyDerivedButton.super would point
>>>>> to MyButtonImpl.
>>>>>
>>>>> The existence of MyButtonImpl is an unfortunate side-effect of needing
>>>>> a generated constructor.
>>>>>
>>>>> The idea is to correspond as closely as possible with the ES6
>>>>> version. MyButtonImpl goes away in ES6, it's purpose in the meantime is
>>>>> just to provide something that looks like a proper class.
>>>>>
>>>>> I could write it this way:
>>>>>
>>>>> *MyButton = function() {
>>>>>
>>>>>   MyButton.super();
>>>>>   // make root, etc.
>>>>> };
>>>>> MyButton.prototype = Object.create(HTMLButtonElement, { ... });*
>>>>> *
>>>>> MyButton = document.register(‘x-button’, MyButton);
>>>>> *
>>>>>
>>>>> Written this way, MyButton no longer refers to the constructor you
>>>>> specified, but instead refers to the generated constructor. This is
>>>>> conceptually cleaner, but it's a bit tricky. For maximum clarity, I named
>>>>> the internal version MyButtonImpl in my example code, but there is no
>>>>> reason to have that symbol.
>>>>>
>>>>>
>>>>>>
>>>>>> >>   // make root, etc.
>>>>>> >> };
>>>>>> >> MyButtonImpl.prototype = Object.create(HTMLButtonElement, { ... });
>>>>>> >>
>>>>>> >> // the ‘real’ constructor comes from document.register
>>>>>> >> // register injects ‘super’ into MyButton
>>>>>> >> MyButton = document.register(‘x-button’, MyButtonImpl);
>>>>>>
>>>>>> What is the relationship between MyButton and MyButtonImpl?
>>>>>>
>>>>>> If MyButton.__proto__ === MyButtonImpl and
>>>>>> MyButton.prototype.__proto__ === MyButtonImpl.prototype then this
>>>>>> might work (but this cannot be polyfilled either).
>>>>>>
>>>>>>
>>>>> MyButton.prototype == MyButtonImpl.prototype or
>>>>> MyButton.prototype.__proto__ == MyButtonImpl.prototype, depending on needs.
>>>>>
>>>>> MyButton itself does magic DOM construction work that we cannot do
>>>>> with normal inheritance, then invokes MyButtonImpl. MyButtonImpl is never
>>>>> used as a constructor itself (not as an argument to 'new' anyway).
>>>>>
>>>>> From the user's perspective, he has made a single class which
>>>>> implements his element (the goal!). The unfortunate name shenanigan (I
>>>>> called my class MyButtonImpl, but after 'register' I refer to it as
>>>>> MyButton) is the simplest way I could conceive to overcome the 'generated
>>>>> constructor' problem.
>>>>>
>>>>> To be clear, everything I come up with is intended to polyfill (modulo
>>>>> my error), because I generally am writing those myself (at first anyway).
>>>>> One version might look like this:
>>>>>
>>>>> document.register = function(inExtends, inClass) {
>>>>>   var ctor = makePrototypeTwiddlingConstructorForDomNodes(inClass);
>>>>>   ctor.prototype = inClass.prototype;
>>>>>   addToTagRegistry(inExtends, ctor, inClass);
>>>>>   ctor.super = getClassForExtendee(inExtends);
>>>>>   return ctor;
>>>>> };
>>>>>
>>>>>
>>>>> --
>>>>>> erik
>>>>>>
>>>>>
>>>>>
>>>>
>>>
>>
>
Received on Wednesday, 6 February 2013 20:48:06 GMT

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