On 04/25/2015 01:58 PM, Ryosuke Niwa wrote:
On Apr 25, 2015, at 1:17 PM, Olli Pettay <o...@pettay.fi> wrote:
On 04/25/2015 09:28 AM, Anne van Kesteren wrote:
On Sat, Apr 25, 2015 at 12:17 AM, Ryosuke Niwa <rn...@apple.com> wrote:
In today's F2F, I've got an action item to come up with a concrete workable
proposal for imperative API. I had a great chat about this
afterwards with various people who attended F2F and here's a summary. I'll
continue to work with Dimitri & Erik to work out details in the
coming months (our deadline is July 13th).
https://gist.github.com/rniwa/2f14588926e1a11c65d3
I thought we came up with something somewhat simpler that didn't require adding
an event or adding remove() for that matter:
https://gist.github.com/annevk/e9e61801fcfb251389ef
That is pretty much exactly how I was thinking the imperative API to work.
(well, assuming errors in the example fixed)
An example explaining how this all works in case of nested shadow trees would
be good. I assume the more nested shadow tree just may get some
nodes, which were already distributed, in the distributionList.
Right, that was the design we discussed.
How does the distribute() behave? Does it end up invoking distribution in all
the nested shadow roots or only in the callee?
Yes, that's the only reason we need distribute() in the first place. If we
didn't have to care about redistribution, simply exposing methods to
insert/remove distributed nodes on content element is sufficient.
Should distribute callback be called automatically at the end of the microtask
if there has been relevant[1] DOM mutations since the last manual
call to distribute()? That would make the API a bit simpler to use, if one
wouldn't have to use MutationObservers.
That's a possibility. It could be an option to specify as well. But there
might be components that are not interested in updating distributed
nodes for the sake of performance for example. I'm not certain forcing
everyone to always update distributed nodes is necessarily desirable given
the lack of experience with an imperative API for distributing nodes.
[1] Assuming we want to distribute only direct children, then any child list
change or any attribute change in the children might cause
distribution() automatically.
I think that's a big if now that we've gotten rid of "select" attribute and
multiple generations of shadow DOM.
It is not clear to me at all how you would handle the case when a node has
several ancestors with shadow trees, and each of those want to distribute
the node to some insertion point.
Also, what is the use case to distribute non-direct descendants?
As far as I could recall, one of
the reasons we only supported distributing direct children was so that we could implement
"select" attribute and multiple generations of shadow
DOM. If we wanted, we could always impose such a restriction in a declarative
syntax and inheritance mechanism we add in v2 since those v2 APIs
are supposed to build on top of this imperative API.
Another big if is whether we even need to let each shadow DOM select nodes to
redistribute. If we don't need to support filtering distributed
nodes in insertion points for re-distribution (i.e. we either distribute
everything under a given content element or nothing), then we don't need
all of this redistribution mechanism baked into the browser and the model where
we just have insert/remove on content element will work.
- R. Niwa
