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RE: Selector Readabiliitiy [WAS: Backwards compatibility of

From: Neil St.Laurent <neil@bigpic.com>
Date: Thu, 4 Dec 1997 14:29:57 -0600
Message-Id: <199712042120.OAA01621@underworld.bigpic.com>
To: Andrew n marshall <amarshal@usc.edu>
CC: "'www-style@w3.org'" <www-style@w3.org>
> a computer, which probably treats the context as a state, but people
> don't make good state machines. It is even unlikely there reading it
> completely linearly..

There is no problem with a parser extracting meaning from future/past 
context, it shouldn't be a problem on the parsing side.  I'm guessing 
that resolving in the parsing state is a lot quicker than trying to 
resolve the pseudo-classes at a later time.
> to the parser. But maybe I'm just clueless (as I haven't taken a
> compiler class yet). At minimum there can be trouble with people
> parsing it, hence readability..

The grammar for the parser is quite simple and the translation to the 
implementation once the grammar is in place is quite trivial.
> Clean it what way?

H1 ~P

The operator appearst o work on P, rather than a relational 
operator.  Of course, this display would resolve my problem with 
determining which element the style applies to, it would more clearly 
be P than H1.
> It isn't even apparent this is possible from the specification since
> it does not use any examples with multiple selectors in the 'first'
> notation or explicitly say this is allowed.  My assume from that was
> it was not. Admittedly, this is not possible in my idea..

The specification appears to imply that complete selectors are pretty 
much allowed anywhere in the selector syntax, which could yield:

/ //H1/ ~ P / ~ EM //I/

Clearly that isn't human readable, but simply refers to the first I 
inside an EM that is the direct descendant of a P which is directly 
following the first H1.

Please, with your syntax show me how the above would be done (I'm not 
entirely clear on what you are proposing yet).

> > H1 ~(DIV P)
> > /H1 ~ /DIV P//
> > or whatever..
> How is your expression any different than:
> H1 ~DIV P /* P descendants of a DIV child of H1. Awkward, but

It is different, because I admit that in my example I have no idea 
what element the style applies to, it could be the DIV or the P?
In any case, my concern over what style the element applies to needs 
to be addressed.

Also, H1 ~DIV is entirely different from /H1 ~ DIV/.  Under your 
syntax I'mnot sure how to do sequential selectors, only acestral ones 
seem to exist?

> The only change I recommended with regards to the tilde was with
> respect to spacing. So:
> H1 ~P ~B ~EM

I was assuming the spacing before and after the ~ was optional so 
that you're syntax would be perfectly fine.
| Mortar: Advanced Web Development <http://mortar.bigpic.com/>
| Neil St.Laurent                  <mailto:stlaurent@bigpic.com>
| Big Picture Multimedia
Received on Thursday, 4 December 1997 16:24:43 UTC

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