W3C home > Mailing lists > Public > www-style@w3.org > April 1996

Problem with RGB value syntax

From: Chris Lilley <Chris.Lilley@sophia.inria.fr>
Date: Mon, 22 Apr 1996 15:36:37 +0200
Message-Id: <199604221336.PAA29768@www47.inria.fr>
To: rieger@bse.de (Wolfgang Rieger)
Cc: www-style@www10.w3.org
Wolfgang Rieger writes:
 > There is a problem with the proposed syntax for RGB and RRGGBB values.
 > Because both id-selector and RGB values are prefixed with '#', it is
 > not possible to use Lex in a straightforward way to implement the
 > lexical analyzer.

This is clearly a problem with lex, not with CSS. The selector appears
on the lhs and the rgb vales appear on the rhs; there is no ambiguity
in the syntax.

 > Reason: '#f00' would be '#' followed by a legal identifier, but '#0f0'
 > would be '#' and a number ('0') followed by an identifier ('f0').

Altering CSS to work around deficiencies of a particular code
generation tool does not seem desirable or necessary.

 > Because of this conflict it would be necessary to make the lexical
 > analyzer context-sensitive, i.e. '#' in the selector part of a rule
 > and '#' in the declaration list would be handled different.

Yes. That seems a workable solution. Put it this way - how would you
react to further change requests to ease programming for (say) visual
basic, perl, awk, snobol ... the CSS syntax introduces no ambiguity
for the use of # to mean ID on the lhs and as an rgb color prefix (as
widely used by browsers) on the rhs.

If it ain't broke, don't fix it ;-)

Chris Lilley, W3C                          [ http://www.w3.org/ ]
http://www.w3.org/people/chris/                       INRIA/W3C
chris@w3.org                       2004 Rt des Lucioles / BP 93
+33 93 65 79 87            06902 Sophia Antipolis Cedex, France
Received on Monday, 22 April 1996 09:40:05 UTC

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