On Fri, Oct 08, 2010 at 11:04:51AM -0700, Walker, David wrote: [quoting Mark Diggory, I believe] > > So, to be clear, the ability to construct nested divisions, > > lists, options, meta sections is quite powerful for getting > > the structure of the content pushed into the presentation layer. > > I appreciate your opinion here, Mark. And, yet, I think this illustrates > precisely why DRI is problematic. > > How the content is structured on the page *is* presentation. Conceptually, > you cannot "push" that to the "presentation layer." Any code (regardless of > where it lives) that defines the structure of the page *is* the presentation > layer (or at least part of it).
Data structure != page structure. We need to keep the namespaces in
mind. A dri:div is not the same kind of thing as an xhtml:div. One
*can* use them in such a way that you eventually transform one into
the other, but then again one might have some completely different use
for a container of unordered data, just as one might use a dri:list to
express something which would never be noticed as an ordered
collection in the XHTML -- it might disappear completely. For that
matter, it might be consumed by a subsequent Aspect and never reach
the Theme engine. Data are structured to make them readily
comprehensible by later stages. A Theme isn't required to treat that
structure as prescriptive of the structure of its output.
Come to think of it, an Aspect *can't* reliably coerce the final page
structure, at least not in some ways you might want to try. An Aspect
has no way of knowing its position in the chain, or what other Aspects
are included before it, so it can't slot its work into the "right
place on the page"; if it has something to add, it may as well stick
it on the end and assume that some Theme will put it where that Theme
wants it. The DRI document *has to* be an abstract representation of
the content, because only the last stage in the pipeline has the
certainty required to produce a concrete one.
It took me a while to work out what the parts were doing,
conceptually, but what finally made sense to me was that the Aspect
chain accumulates a big pot of potentially useful data related to the
user's request, and the Theme selects and arranges them as required to
make them presentable. At least, that's the way I've tried to use the
pipeline, and it seems to work.
Regardless of how the physical structuring of the final page is done,
we need some way to represent logical structure of the data before
they are selected and laid out. That's what I thought DRI was
designed to be. If it isn't being used that way, I think we should
fix *that*.
--
Mark H. Wood, Lead System Programmer mw...@iupui.edu
Balance your desire for bells and whistles with the reality that only a
little more than 2 percent of world population has broadband.
-- Ledford and Tyler, _Google Analytics 2.0_
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