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Re: [css3-values] Computed Values definition wrong

From: L. David Baron <dbaron@dbaron.org>
Date: Fri, 26 Mar 2010 09:20:40 -0400
To: Håkon Wium Lie <howcome@opera.com>
Cc: fantasai <fantasai.lists@inkedblade.net>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <20100326132040.GA27406@pickering.dbaron.org>
On Friday 2010-03-26 06:21 +0100, Håkon Wium Lie wrote:
> In many cases, percentages can be resolved without formatting the
> document. For example:
> 
>    p { font-size: 120% }
> 
>    div { width: 10cm }
>    div div { width: 50% }
> 
> These types of expansions should take place in the computed values
> stage where the values are processed as far as possible without
> formatting the document.
> 
> The draft still needs to be updates. It currently states:
> 
>   "percentages must be multiplied by a reference value"
> 
> I sugggest changing it to something along the lines of:
> 
>   "percentages must, whenever possible, be converted to an absolute value"

But then you're left to defining what "whenever possible" means, and
without a clear definition it's likely to vary by the details of the
implementation.  That means, in turn, that the behavior of 'inherit'
would vary between implementations, which is bad.

We already dealt with this problem, and we solved it by adding
"Computed value" lines to the definition of every property to say
exactly what computation should be performed at this stage.

The spec should refer to the "Computed value" lines of properties
instead of defining things as "whenever possible".

-David

-- 
L. David Baron                                 http://dbaron.org/
Mozilla Corporation                       http://www.mozilla.com/
Received on Friday, 26 March 2010 13:21:28 GMT

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