On 9/27/2011 11:39 PM, Roland Steiner wrote:
Expanding on the general web component discussion, one area that
hasn't been touched on AFAIK is how components fit within the content
model of HTML elements.
Take for example a list
(http://www.whatwg.org/specs/web-apps/current-work/multipage/grouping-content.html#the-ul-element):
<ol> and <ul> have "Zero or more <li> elements" as content model,
while <li> is specified to only be usable within <ol>, <ul> and <menu>.
Now it is not inconceivable that someone would like to create a
component <x-li> that acts as a list item, but expands on it. In order
to allow this, the content model for <ol>, <ul>, <menu> would need to
be changed to accomodate this. I can see this happening in a few ways:
A.) allow elements derived from a certain element to always take their
place within element content models.
In this case, only components whose host element is derived from <li>
would be allowed within <ol>, <ul>, <menu>, whether or not it is
rendered (q.v. the "Should the shadow host element be rendered?"
thread on this ML).
B.) allow all components within all elements.
While quite broad, this may be necessary in case the host element
isn't rendered and perhaps derivation isn't used. Presumably the
shadow DOM in this case contains one - or even several - <li> elements
as topmost elements in the tree.
C.) Just don't allow components to be used in places that have a
special content model.
Thoughts?
Consider the CSS content model: we can easily override the model of
various tags.
Then consider ARIA role types, where we can easily override the
semantics of various tags.
I'm a big fan of using appropriate tag names, but I'm not convinced that
HTML should restrict CSS or ARIA.
The HTML5 editor has repeatedly tried to enforce option C, restricting
components in the DOM tree in relation to ARIA and HTML Canvas.
Why bother over-specifying? Why remove that flexibility?
HTML tag names are fantastic, I'm not saying lets just toss HTML, but I
don't think HTML is the top of the hierarchy.
We have ARIA for semantics, CSS for display and DOM for serialization.
-Charles
