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Re: :host pseudo-class

From: Anne van Kesteren <annevk@annevk.nl>
Date: Fri, 1 May 2015 07:25:45 +0200
Message-ID: <CADnb78gGSqtb3wNVDmbPC=YxDLkrezuHr10Jrci=iWYZUgQuhQ@mail.gmail.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: "www-style@w3.org" <www-style@w3.org>, "L. David Baron" <dbaron@dbaron.org>, WebApps WG <public-webapps@w3.org>
On Fri, May 1, 2015 at 2:07 AM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
> On Thu, Apr 30, 2015 at 2:27 AM, Anne van Kesteren <annevk@annevk.nl> wrote:
>> On Mon, Apr 27, 2015 at 11:14 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
>>> Pseudo-elements are things that aren't DOM elements, but are created
>>> by Selectors for the purpose of CSS to act like elements.
>> That's not true for e.g. ::-webkit-slider-thumb as I already indicated.
> Sure it is.  <input type=range> has no children, and the shadow tree
> is sealed, so the fact that a shadow tree even exists is hidden from
> DOM.  As far as CSS is capable of discerning, there is no thumb
> element, so the pseudo-element makes sense.

That seems rather arbitrary. To the browser it is a DOM element and to
CSS it is too. E.g. at the global level CSS will have to reason about
what it means to override the element's existing styles.

>> My problem is not with the ability to address the host element, but by
>> addressing it through a pseudo-class, which has so far only been used
>> for matching elements in the tree that have a particular internal
>> slot.
> I don't understand what distinction you're trying to draw here.  Can
> you elaborate?

A pseudo-class selector is like a class selector. You match an element
based on a particular trait it has. Your suggestion for :host()
however is to make it match an element that cannot otherwise be
matched. That's vastly different semantics

Received on Friday, 1 May 2015 05:26:10 UTC

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