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RE: Make its:param optional?

From: Yves Savourel <ysavourel@enlaso.com>
Date: Fri, 12 Oct 2012 05:31:06 -0600
To: <public-multilingualweb-lt@w3.org>
Message-ID: <assp.063211a22c.assp.0632aeba70.006501cda86d$11e16c20$35a44460$@com>
Hi Felix, Jirka, Shaun, all,

> OK, so we keep its:param I guess. 
> Would it be OK to add the following note to the its:param section:
>
> its:param adds flexibility in real-life situations. However in general 
> it is recommended not to use its:param. It is disallowed in CSS, 
> see section 5.3.5, since the current version of CSS does not allow 
> variable bindings.

Hum, I have nothing about a note touching on the difficulty of implementation. But the CSS part, I think, is a different story. It sounds like the fact its:param is not part of ITS-with-CSS is a valid reason to not use it with XPath either. That's a bit strong for a best practice.

-- a) Likely, its:param is going to be used only in the cases where there is no other way to write the rule. So it'll be for use cases where you can't use CSS anyway. So re-suing those rules doesn't really applies.

-- b) You can make a rule that uses its:param not use it by just replacing the variable by a given value, then you convert that to CSS. It's not much more work than actually converting the XPath selector to a CSS selector. Sure it's not a 1-to-1 port of the rules, but the point is that first: its:param is not a show-stopper, and second: if someone wants to convert XPath-based rules to CSS-based rules, the hard part is to convert XPath to CSS, not its:param.

-- c) Why its:param cannot be used in CSS in the first place? CSS may not have a binding mechanism but what's preventing CSS implementers to use the mechanism Jirka described in http://lists.w3.org/Archives/Public/public-multilingualweb-lt/2012Oct/0148.html? In most programming languages it's simple to substitute the variables by their values before applying the selectors. If I were an implementor of a CSS-based ITS engine I would be puzzled by the section 5.3.5.

-- d) Do we have anyone implementing ITS with CSS selectors? If we don't at this stage, I wonder if any CSS-based argument is applicable.


Cheers,
-yves
Received on Friday, 12 October 2012 11:31:39 UTC

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