[csswg-drafts] [css-values-5] attr()'s "px"/etc keywords (#11034)

tabatkins has just created a new issue for https://github.com/w3c/csswg-drafts:

== [css-values-5] attr()'s "px"/etc keywords ==
In <https://github.com/w3c/csswg-drafts/issues/10437#issuecomment-2377634442> we resolved to change `attr()`'s type argument from [a bespoke list of keywords](https://drafts.csswg.org/css-values-5/#typedef-attr-type) to the newly-minted "CSS grammar in CSS" syntax.

Most of the existing attr() type keywords translate over just fine (usually just wrapping them in `<>` characters), but the unit names don't. That is, under the current spec you can write `width: attr(foo px)`, and given an element like `<div foo=500>`, it'll be parsed as a number and then be assumed to be a `px` value. There's no way to express this sort of behavior in CSS grammar, tho.

Note that this is basically just a convenience; one could instead write `calc(1px * attr(foo <number>))` and get the same result. So the *use-case* is covered no matter what.

Do we want to try and allow this, tho? The issue is that bare keywords already have meaning in the `<css-syntax>` production (they represent those keywords, same as in any other CSS grammar), so it would be somewhat awkward to mix them in.

I propose that we just drop that functionality, and let `calc()` cover the issue of "interpret a number as a particular unit".

Please view or discuss this issue at https://github.com/w3c/csswg-drafts/issues/11034 using your GitHub account


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Received on Monday, 14 October 2024 20:02:41 UTC