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.)