Re: objection re: RESOLVED: setProperty's handling of importance logically behaves same as appending a declaraiton (like IE/WebKit)

On Thursday 2013-09-12 12:36 -0400, Zack Weinberg wrote:
> On 2013-09-12 3:59 AM, Simon Pieters wrote:
> >On Wed, 11 Sep 2013 16:38:26 +0200, Zack Weinberg <zackw@panix.com> wrote:
> >>For avoidance of doubt, I do not object to setProperty(prop, value)
> >>=== setProperty(prop, value, "") nor to the addition of
> >>setPropertyPriority and setPropertyValue with always-update-in-place
> >>semantics.
> >
> >Understood. David Baron objects to setProperty(prop, value, "")
> >overriding an !important declaration, as I understand it.

It's not the strongest objection I had in the discussion, but I do
indeed object.  (My strongest objection was about introducing a ""
vs undefined distinction, and especially because it was to a
function that used to require the argument to be "".)

I object to this for two reasons:

 (1) I think we should stick to the behavior we had interop on and
 could easily get interop on again if Gecko changes back.

 (2) I think the behavior is most consistent with how the CSS
 cascade works.

> This is the crux of the issue.
> 
> 1) I specifically object to setProperty(prop, value, "")
>    _not_ overriding an !important declaration.  All else is negotiable.
> 
> 2) I don't think David's position is actually incompatible with mine.
>    I don't wish to put words in his mouth, but as I said above, I am
>    under the impression that what he actually cares about is the
>    always-move-the-new-declaration-to-the-end side effect.  Hence my
>    alternative proposal of behaving as if removeProperty() were always
>    called first.

No, I think the ordering side effects (or not) are going to be
horrible and probably non-interoperable anyway.  (I think Gecko has
optimizations that change the ordering side effect as a result of
whether we can take the optimized codepath.)

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                          https://www.mozilla.org/   𝄂
             Before I built a wall I'd ask to know
             What I was walling in or walling out,
             And to whom I was like to give offense.
               - Robert Frost, Mending Wall (1914)