[uf-discuss] Human and machine readable data format
Toby A Inkster
mail at tobyinkster.co.uk
Fri Jul 11 01:17:54 PDT 2008
Martin McEvoy wrote:
> <div class="item updated">
> <p>Date <span class="value 2008-07-11T00:01+0100">Friday, July the
> 11th 2008</span></p>
There are a couple of problems with this:
Firstly, the class element may contain more than two classes - e.g.
it may contain some others that have been added for styling or
will need to have some kind of heuristic to figure out which one to
parse as the value. This may be pretty easy for dates, but if someone
wanted to use the pattern for one of the other problematic properties
that have been identified (e.g "type" in hCard tel, or in hReview),
this would become harder.
Secondly, and more importantly, it breaks the existing interpretation
of class="value", which on <span> elements is currently used to mean
that the textual content of the element should be used as the value.
Faced with a "value" class, how should parsers know whether to parse
by the old method (take a value from the class attribute) or the new
method (from the element contents)? And yes, they will need to
continue to support the old method because of the existing corpus of
published data out there.
Frances' proposal with the "data-" prefix can suffer from the first
problem (if there are two classes with a "data-" prefix), but that is
easily spec'ed around by saying that in those situations, the longest
such value is to be used. And it doesn't suffer from the second
problem at all - the existence of a class with a data-prefix is a
clear heuristic for parsers to determine whether to use the old
method or new method.
Toby A Inkster
<mailto:mail at tobyinkster.co.uk>
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