> On Jul 20, 2015, at 10:29 PM, Domenic Denicola <d...@domenic.me> wrote:
> Thanks very much for your feedback Maciej! I know we'll be talking a lot more 
> tomorrow, but one point in particular confused me:
> From: Maciej Stachowiak [mailto:m...@apple.com] 
>> 4. Specifically, we don't really like the "Optional Upgrades, Optional 
>> Constructors" proposal (seems like it's the worst of both worlds in terms of 
>> complexity and weirdness) or the "Parser-Created Classes" proposal (not 
>> clear how this even solves the problem).
> Specifically with regard to the latter, what is unclear about how it solves 
> the problem? It completely gets rid of upgrades, which I thought you would be 
> in favor of.
> The former is, as you noted, a compromise solution, that brings in the best 
> of both worlds (from some perspectives) and the worst of them (from others).

Sorry that this was unclear.

From our (many Apple folks') perspective, the biggest problem with the 
"prototype swizzling" solution is that it doesn't allow natural use of ES6 
classes, in particular with initialization happening through the constructor. 
It seems like parser-created classes do not solve that problem, since 
initialization happens before the class is even defined. It also does not solve 
the secondary problem of FOUC, or the related flash of non-interactive content. 
It *does* seem to solve the secondary problem of modifying prototype chains 
after the fact and in some sense changing the "class identity" of elements. 

By my best understanding of the anti "synchronous constructors" position, I 
think there are two key concerns - the need to run arbitrary user code at 
possibly inconvenient moments of parsing or cloning; and the fact that elements 
can't be upgraded to a fancier version after the fact if they are parsed before 
a relevant library loads. It does seem to solve both those problems.

Does that sound right to you?

If so, it is not much more appealing than "prototype swizzling" to us, since 
our biggest concern is allowing natural use of ES6 classes.


(The "we" in this case includes at least myself, Ryosuke Niwa, Sam Weinig, and 
Gavin Barraclough who composed this position statement today; but others at 
Apple have also expressed similar vies in the past.)

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