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RE: [css3-animations] Times are listed as unitless

From: Sylvain Galineau <sylvaing@microsoft.com>
Date: Fri, 6 May 2011 17:31:00 +0000
To: David Singer <singer@apple.com>
CC: "www-style@w3.org" <www-style@w3.org>
Message-ID: <045A765940533D4CA4933A4A7E32597E2AC8FEC0@TK5EX14MBXC111.redmond.corp.microsoft.com>

[David Singer:]
> On May 5, 2011, at 16:50 , Dean Jackson wrote:
> 
> >
> > On 03/05/2011, at 8:42 AM, Sylvain Galineau wrote:
> >
> >>
> >> [Simon Fraser:]
> >>> On May 2, 2011, at 12:17 PM, Sylvain Galineau wrote:
> >>>
> >>>> I also brought this up [1] and it seems Gradients assume zero
> >>>> angles require a unit.
> >>>>
> >>>> Given the precedent, I agree it would be more author-friendly if
> >>>> zero was allowed to have no unit everywhere. But even as someone
> >>>> who doesn't write CSS parsers for a living, I am not sure the
> >>>> convenience is worth the bug-prone ambiguity or more complex value
> >>>> syntax that can result. On balance, making length the exception -
> >>>> on historical grounds and because it is the most-used value type -
> >>>> does not seem unreasonable. But it does feel icky.
> >>>
> >>> I'm strongly in favor of unitless zero everywhere. As an author, I
> >>> wouldn't be able to remember where I need units and where I do not
> >>> if the rules differ for different values.
> >>
> >> Same everywhere is ideal. Or a single exception such as "not required
> >> for lengths but needed everywhere else". I'd be OK with either. Any
> >> more complicated is a fail imo.
> >
> > Count me in with Simon and Eric. The majority of CSS developers are
> going to expect 0 means 0 everywhere, and that you don't need to worry
> about units.
> 
> 
> From a metrics point of view, I have a hard time thinking of a case where
> 0<unit> means something different from 0 (with the units implied). From an
> authoring point of view, I agree that most would expect 0 to be clear as
> meaning, well, none of whatever is expected here.
> 
> 
> However, are we sure that there are no cases in the grammar where you
> understand something was left out, or not, based on its data type?  That
> is, say you have
> 
> something optional-angle optional-length
> 
> and the default values are not zero.  then something 0 could be setting
> the angle to zero and leaving the length at default, or vice versa.
> 
> Are we sure that there are no parsing-depends-on-units-implying-type
> places in CSS?
> 
> 
> David Singer
> Multimedia and Software Standards, Apple Inc.

Not sure this is what you're looking for but gradients need angles to
have a unit for all values including 0. See http://lists.w3.org/Archives/Public/www-style/2009Nov/0043.html.
Received on Friday, 6 May 2011 17:31:30 GMT

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