W3C home > Mailing lists > Public > www-style@w3.org > December 2009

Re: Request for ::di pseudoelement

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Mon, 21 Dec 2009 20:30:02 -0600
Message-ID: <dd0fbad0912211830o3be3bb19xefc447536782f721@mail.gmail.com>
To: Alexis Deveria <adeveria@gmail.com>
Cc: www-style list <www-style@w3.org>
On Mon, Dec 21, 2009 at 12:12 PM, Alexis Deveria <adeveria@gmail.com> wrote:
> On Fri, Dec 18, 2009 at 6:18 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
>> Well, I find myself once again ripping out a <dl> and replacing it
>> with a <ul> with headers in the <li>s, because there's no grouping
>> element around <dt>s and <dd>s.  There's a perennial request for a
>> <di> element, but that's not really the correct place to solve the
>> problem - HTML has no need for any additional help in grouping the
>> dt/dd elements, as the grouping is well-defined in the spec.  This is
>> purely a styling issue, and a common one for me.
> Have you considered using a table instead? I know at first glance it
> may seem a bit weird, but if you style the elements to be blocks
> instead of rows/cells, you may be able to get the effect you want
> while maintaining proper semantics.

<table> certainly provides all the structure one needs, but it doesn't
feel like the semantically right element to use - I'm presenting
key/value pairs, not 2-dimensional data.

> I mentioned it before for my problem here [1]. Also worth noting is
> the comment under mine which mentions a problem with zcorpan's
> ::key-value-group.
> [1] http://forums.whatwg.org/viewtopic.php?p=496#496

Ah, yes, that is a problem.  There are a number of structural
pseudoclasses that one could want to apply to <dt>/<dd>s based on
treating them like children of a grouping <di>, and you can't do that
with ::di as I described it.

There are some ways around that - we could promote pseudoelements to
first-class selectors (this is desirable for other reasons as well),
allowing you to write selectors like "dl ::di dd:last-child".  That's
definitely non-trivial, though, and to work properly would require the
dd to be aware that the ::di was in the selector, so it should treat
itself as a child of the pseudoelement rather than of the <dl>.  I
don't know if this is the right way to go.

A probably better way is to use XBL2 to rewrite the <dl> into having a
<di> element for styling purposes.  This approach doesn't require
possibly-tricky changes to the way pseudoelements and structural
pseudoclasses work, because as far as CSS is concerned there now is a
real element wrapping the <dt>/<dd> groups, and they are no longer
children of the <dl> but rather grandchildren.  I'm not sure how easy
this would be, however - the algorithm grouping <dt>/<dd>s into groups
is trivial but looks like it may be beyond what XBL2 can do natively.
However, this could possibly be exposed as a browser-builtin binding
defined by HTML5 itself.

Received on Tuesday, 22 December 2009 02:30:34 UTC

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