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Re: [css3-2d-transforms][css3-images] <position> grammar is duplicated or points to the wrong spec

From: L. David Baron <dbaron@dbaron.org>
Date: Tue, 24 Jan 2012 11:17:37 -0800
To: Brian Manthos <brianman@microsoft.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, Sylvain Galineau <sylvaing@microsoft.com>, fantasai <fantasai@inkedblade.net>, www-style list <www-style@w3.org>
Message-ID: <20120124191737.GB24172@pickering.dbaron.org>
On Tuesday 2012-01-24 19:03 +0000, Brian Manthos wrote:
> Tab:
> >Brian:
> >> The fact that "background-position: 10%;" and "background-position: calc(10%);"
> >> can result in differ renderings is perhaps unfortunate, but required by the specs as I read them.
> > Yes, it's currently required by the specs.  I've stated this several times.  
> 
> You might be saying that.  My interpretation of David's comments
> is that he was saying otherwise.

I don't understand the current calc() spec well enough to comment on
what it says.

However, I firmly believe that if Tab's assertion about what it
currently says is correct (which I believe is at the very least what
it's trying to say), then the spec is wrong and needs to be fixed.
I think calc() should not have any discontinuities, i.e., putting
"calc()" around a valid value shouldn't change its behavior, and
putting a "+1px" inside a calc() should move change the result by
1px.

> Tab:
> > This is why I'm proposing to *change* the specs here, to match
> > what Gecko currently does.
> 
> Ok, well I think you're both wrong.  It's the wrong direction for
> CSS to fundamentally change (in this case add functionality to)
> the behavior of one property by doing parlor tricks with calc in a
> different module.

It's not at all changing the behavior of a property -- it's keeping
that property's behavior as it always has been, since CSS1 in 1996.

-David

-- 
𝄞   L. David Baron                         http://dbaron.org/   𝄂
𝄢   Mozilla                           http://www.mozilla.org/   𝄂
Received on Tuesday, 24 January 2012 19:18:16 GMT

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