- From: Amelia Bellamy-Royds via GitHub <sysbot+gh@w3.org>
- Date: Wed, 24 Aug 2016 16:53:17 +0000
- To: public-css-archive@w3.org
**SVG 2 has already gotten rid of `<number-optional-number>`, and
Filter Effects should follow suit.**
No need to add to the confusion to CSS.
`<number-optional-number>` in SVG 1.1 was for values that could take
one or two numbers; if two, they could be comma or space separated.
E.g., for standard deviation of a blur, you can either give one value
that applies in both directions, or you can give two different values,
one for x-direction and one for y.
As you've all noted, there are lots of ways to express this syntax in
standard CSS notation. I'm pretty sure `<number>,?<number>?` covers
it given that CSS already makes whitespace optional so long as the
tokenization is the same. Or `<number>{1,2} | <number>#{1,2}` as
@nikosandronikos suggested.
For arbitrary-length lists of items separated by comma or whitespace,
that's another matter. SVG has them all over the place, and the
syntax we're currently using for SVG 2 is `[<item>#]+`, though we're
quite happy to simplify that to `<item>#+` if it gets added to CSS
Values & Units.
If you then allow numerical qualifications on the `#+` combinator,
that would allow us to nicely encapsulate the syntax for other
properties. For example, SVG `viewBox` would be `<number>#+{4}`:
exactly 4 numbers, separated by any combination of whitespace or
commas. E.g [`viewBox="0,0 50,50"` is perfectly
valid](http://jsbin.com/dohusakeqo/1/edit?html,output). (Aside: just
added an SVG issue that the current syntax we have for `viewBox` is a
mess.)
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Received on Wednesday, 24 August 2016 16:53:24 UTC