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Re: [css-syntax] Ready for wide review, FPWD request coming soon

From: Zack Weinberg <zackw@panix.com>
Date: Fri, 17 May 2013 14:12:29 -0400
Message-ID: <5196730D.5090809@panix.com>
To: www-style@w3.org
On 2013-05-09 6:37 PM, Tab Atkins Jr. wrote:
> Hey all!  I believe that Syntax is now at a state where it is both
> stable and correct, and ready to review.

I plan to go through this draft line-by-line on Sunday, when I have a 
long plane flight.  Here are some high-level points for now.

I see that I never responded to your response to my critique of the
February draft -- sorry about that.  I'll start with things that are
dangling threads from then:

* Regarding the comments-in-SVG-presentation-attrs thing, I'm happy to
   leave this out of the spec unless and until the SVG WG decides they're
   *not* going to allow comments.

* Regarding recursive-descent-style tokenization and removal of
   pushback, you were skeptical that this would be easier to read.
   Would you be interested in me attempting to rewrite section 4 with
   those changes, to see how it goes?  It would be pretty major so I
   don't want to do it if you're not at least curious whether it would
   be better.

* 3.2.1 "Preprocessing the input stream": I still think that *either*
   FORM FEED should be converted to LINE FEED here, *or* all four
   possible newline sequences (LF, CR, CR LF, and FF) should be listed
   as such in 4.3 (tokenizer definitions) and the only preprocessing
   step should be to convert U+0000 to U+FFFD.

   Last time around I was advocating for the latter option, but I've
   thought about it some more and I think it will be clearer to do the
   former.

* 4.2 "transform function whitespace flag": I reiterate that this wart
   does not belong in this spec *at all*; it belongs in the value grammar
   for the SVG transform attribute.  You said back in February that
   this would be "annoying to express at that end", but this I
   disbelieve.  It should be as simple as

     transform-atom: transform-function transform-args ')'  ;
     transform-function: FUNCTION | IDENT '(' ;

   in yacc-ese.  (Which spec exactly would have to change if this wart
   were removed?  It would help me understand your position if I had
   read that.)

Other, mostly minor issues:

* throughout: I support decapitalizing all the token names, but I
   think we need *some* sort of typographical convention to distinguish
   them from running text, particularly as some of the names are
   punctuation and others aren't.  I would suggest sans-serif, but the
   bulk of the document is already sans-serif so that won't work.
   Italics and boldface are already in use for other purposes.  Maybe
   quoting with [LEFT, RIGHT]-POINTING ANGLE BRACKET?  (e.g. 〈ident〉)

* throughout: Unlike other Unicode character names, U+FFFD REPLACEMENT
   CHARACTER should *not* be followed by the literal character in
   parens (�).

* 3. "Conformance checkers are not required to recover from parse
   errors": ... but if they do, they should be required to obey the
   same recovery rules as user agents.

* 4. Didn't we resolve to remove the "id"/"unrestricted" distinction
   for HASH tokens from Selectors, and thus also from here?  (I could
   be misremembering.)

* 4. Unicode-range tokens may need a "valid" flag.  I need to
   cross-check the code in Gecko against the algorithm in this spec
   carefully, but the definition of UNICODE-RANGE in CSS2.1 included
   several forms that were semantically invalid.

* 4.6 "changes from CSS 2.1":  Should mention the column token.  I
   still think we need to hear from dbaron about the change to bad-uri.

* 5 "declaration": Is now maybe the right time to generalize
   !important?  (presumably to ! <list of component values>)

* 5 "recognized at-rule names": Didn't we agree to get rid of this?

* 6 "an+b microsyntax": Yay for specifying this in terms of normal
   tokens, but I'm going to have to try to implement it in Gecko before
   I can tell you if it's workable.
Received on Friday, 17 May 2013 18:12:59 UTC

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