> On Apr 27, 2015, at 1:45 PM, Ryosuke Niwa <rn...@apple.com> wrote: > > >> On Apr 27, 2015, at 11:47 AM, Steve Orvell <sorv...@google.com >> <mailto:sorv...@google.com>> wrote: >> >> Here's a minimal and hopefully simple proposal that we can flesh out if this >> seems like an interesting api direction: >> >> https://gist.github.com/sorvell/e201c25ec39480be66aa >> <https://gist.github.com/sorvell/e201c25ec39480be66aa> > > It seems like with this API, we’d have to make O(n^k)
I meant to say O(nk). Sorry, I'm still waking up :( > calls where n is the number of distribution candidates and k is the number of > insertion points, and that’s bad. Or am I misunderstanding your design? > >> >> We keep the currently spec'd distribution algorithm/timing but remove >> `select` in favor of an explicit selection callback. > > What do you mean by keeping the currently spec’ed timing? We certainly can’t > do it at “style resolution time” because style resolution is an > implementation detail that we shouldn’t expose to the Web just like GC and > its timing is an implementation detail in JS. Besides that, avoiding style > resolution is a very important optimizations and spec’ing when it happens > will prevent us from optimizing it away in the future/ > > Do you mean instead that we synchronously invoke this algorithm when a child > node is inserted or removed from the host? If so, that’ll impose > unacceptable runtime cost for DOM mutations. > > I think the only timing UA can support by default will be at the end of micro > task or at UA-code / user-code boundary as done for custom element lifestyle > callbacks at the moment. > >> The user simply returns true if the node should be distributed to the given >> insertion point. >> >> Advantages: >> * the callback can be synchronous-ish because it acts only on a specific >> node when possible. Distribution then won't break existing expectations >> since `offsetHeight` is always correct. > > “always correct” is somewhat stronger statement than I would state here since > during UA calls these shouldDistributeToInsertionPoint callbacks, we'll > certainly see transient offsetHeight values. > > - R. Niwa >
