Re: Proposal for changes to manage Shadow DOM content distribution

FWIW, we're working to implement what we call named blocks in Ember.js and
believe this proposal aligns very closely to what our users have been
asking us to build for them.

- Erik

On Wednesday, April 22, 2015, Tab Atkins Jr. <jackalmage@gmail.com> wrote:

> This is literally reinventing Selectors at this point.  The solution
> to "we don't think it's worth implementing *all* of Selectors" is to
> define a subset of supported Selectors, not to define a brand new
> mechanism that's equivalent to selectors but with a new syntax.
>
> On Wed, Apr 22, 2015 at 10:21 AM, Justin Fagnani
> <justinfagnani@google.com <javascript:;>> wrote:
> > Another technique I've seen used is compound selectors, which could be
> used
> > to migrate from one selector to another while preserving backwards
> > compatibility, or to provide some nice default distributions that are
> also
> > accessible via a class or attribute (ie, select="header, .header").
> >
> > Could slots have multiple names to support something like this?
> >
> > On Wed, Apr 22, 2015 at 10:16 AM, Justin Fagnani <
> justinfagnani@google.com <javascript:;>>
> > wrote:
> >>
> >>
> >>
> >> On Tue, Apr 21, 2015 at 10:40 PM, Ryosuke Niwa <rniwa@apple.com
> <javascript:;>> wrote:
> >>>
> >>>
> >>> > On Apr 21, 2015, at 10:23 PM, Justin Fagnani <
> justinfagnani@google.com <javascript:;>>
> >>> > wrote:
> >>> >
> >>> > I do want the ability to redirect distributed nodes into a holes in
> the
> >>> > base template, so that part is welcome to me. However, my first
> reaction to
> >>> > the slot idea is that forcing users to add the content-slot
> attribute on
> >>> > children significantly impairs the DOM API surface area of custom
> elements.
> >>> >
> >>> > For the single-level distribution case, how is this different from
> >>> > <content select="[content-slot=name]"> except that content select can
> >>> > distribute based on features of the children that might already
> exist, like
> >>> > tag names or an attribute?
> >>>
> >>> At the conceptual level, they're equivalent.  However, we didn't find
> the
> >>> extra flexibility of using CSS selectors compelling as we mentioned in
> our
> >>> proposal [1].
> >>
> >>
> >> I personally would like to see more power, especially positional
> >> selectors. Some components would be better off selecting their first
> child,
> >> rather than requiring a class.
> >>>
> >>>
> >>> [1] See points 3 and 4 in
> >>>
> https://github.com/w3c/webcomponents/wiki/Proposal-for-changes-to-manage-Shadow-DOM-content-distribution#some-issues-with-the-current-shadow-dom-spec
> >>
> >>
> >> Point 4 is interesting, because unless I'm missing something (which
> could
> >> be!) it's incorrect. You can create selectors with :not() that exclude
> the
> >> content selectors that come after in document order. I would rewrite the
> >> example as:
> >>
> >> <template>
> >>   <content select=".header"></content>
> >>   <content select=":not(.footer)"></content>
> >>   <content select=".footer"></content>
> >> </template>
> >>
> >> Cheers,
> >>   Justin
> >>
> >>>
> >>>
> >>>
> >>> - R. Niwa
> >>>
> >>
> >
>
>