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RE: [css3-values] RE: CSSStyleDeclaration#length and shorthands.

From: Brian Manthos <brianman@microsoft.com>
Date: Fri, 3 Feb 2012 21:31:44 +0000
To: 'Alexis Menard' <alexis.menard@openbossa.org>
CC: "www-style@w3.org" <www-style@w3.org>
Message-ID: <9710FCC2E88860489239BE0308AC5D170EB478E1@TK5EX14MBXC266.redmond.corp.microsoft.com>
Alexis:
> I don't think having a shorthand part of item() brings any benefit :

Sure it does.  Keeping (constructible) shorthands accessible by item() index means that you're talking about 1 collection with predictable behavior.

Having access-by-index and access-by-name supporting different sets is a weird collection model, IMO.


Alexis:
> I think at any time you can query a shorthand by name and get a value
> (that UA can compute from longhands) with getPropertyValue.

Only constructible ones.  Shorthand-unfriendly disjoint state prevents that in some cases, as previously shown.


Alexis:
> See that way if the shorthand concept didn't exist could you achieve
> the same result as today? Yes, so in any case they are not critical
> and does not represent the way an element is described therefore they
> should not be part of its object representation.

I don't see how this speaks to the example you quoted.

When something becomes a shorthand in the future, it's a compatibility breaking change.


Example HTML:
	<div style="box-shadow: 1px 2px 3px 4px red;"/>

function TestForBoxShadow()
{
    var d = document.getElementsByTagName("div")[0];
    var s = d.style;
    for (var i = 0; i < style.length; i++)
    {
        if (style.item(i) == "box-shadow"))
        {
            return true;
        }
    }
    return false;
}

In CSS3, this returns true.
In CSS7 when box-shadow is a shorthand, it would return false with the only-longhands item() proposal.

As such, this would either be compatibility breaking in CSS7 *or* it couldn't be done to avoid that.

Both results are failure modes, IMO.
Received on Friday, 3 February 2012 21:32:24 GMT

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