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Re: [css-style-attr] SVG WG comments on CSS Styling Attributes Level 1

From: Håkon Wium Lie <howcome@opera.com>
Date: Sun, 29 Aug 2010 15:13:30 +0200
Message-ID: <19578.23802.821960.454859@gargle.gargle.HOWL>
To: Doug Schepers <schepers@w3.org>
Cc: www-style@w3.org, www-svg@w3.org
Doug Schepers wrote:

 > ... for the sake of moving on, I am going to propose that we take a
 > serious look at dropping it, not only from CSS, but from SVG 2. For
 > SVG, obviously, this would mean deprecating it rather than simply
 > not including it.

I think this is the right approach. The feature is, as you say, little
used and only provides convenience -- not necessity. I don't know why
e-notation was allowed in numeric values on SVG attributes in the
first place, but it seems better to deprecate them there than to
mandate e-notation across the board.

Introducing e-notation in CSS would have a considerable cost. We would
need to change the CSS core grammar, which is -- sort of -- our
constitution. Constitutions can be changed, but only for truly
important things, when there is long-standing consensus. The
convenience that e-notation provides to some counts on the plus side,
but on the minus side we find incompatibility with existing browsers
and reduction of human readability. This has always been an important
design principle in CSS:

  CSS is a simple style language which is human readable and writable.


Further, the design principle states:

  The CSS properties are kept independent of each other to the largest
  extent possible and there is generally only one way to achieve a
  certain effect.

Introducing e-notation is against this principle, as it offers no new
functionality, only a different syntax for achieving the same thing.

Tab writes:

 > > You call it an artifact.  I call it a ubiquitous, living notation
 > > embraced by all the programming languages people are using today.

You're right, it's common in programming languages. But CSS was
explicitly designed to *not* be a programming language. The last words
in the CSS1 Recommendations are:

  We do not expect CSS to evolve into a programming language


The main competitor to CSS in the early days was DSSSL, which *was* a
programming language. I believe that one reason for the success of CSS
is its lack of features from programming languages:

  Compared to DSSSL-Lite, CSS was easier to support since it wasn't
  Turing-complete and didn't require a transformation step. So, in a
  way, it was the simplicity -- the lack of features -- that won people


Other features from programming languages can also be said to be
ubiquitous, e.g. regular expressions. In 1998 there was a big debate
about introducing regular expressions in CSS selectors. The debate is
worth recounting, both for its entertainment value and for its
arguments. Some key messages:



              Håkon Wium Lie                          CTO °þe®ª
howcome@opera.com                  http://people.opera.com/howcome
Received on Sunday, 29 August 2010 13:14:09 UTC

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