Well, this is pretty doggone interesting. I do worry that the last sentence is pretty optimistic.
I wonder, in light of our #repoze discussions about theming, what you think this would mean if the stuff below landed? --Paul On Apr 28, 2009, at 11:41 AM, Malthe Borch wrote: > Adressing the Repoze-list here, since Chameleon is currently kept in > this repository. > > For those not in the know (certainly before I read the > documentation[1], I was one of them), Genshi has a feature called > "match templates" which lets you first render a template, then apply a > second template to elements matched by an XPath-expression. > > If this sounds a bit strange, it's because it is––but it's useful > because it can be used to sculpt HTML in a way similar to Deliverance > and/or XSLT. At any rate, it's a Genshi feature and we do support it > in ``chameleon.genshi``. Problem is, ``lxml`` is required for this to > function––what's more, this solution is suboptimal in terms of > performance (which is the raison d'etre for Chameleon in the first > place). > > There are two scenarios: > > 1) Match templates are defined and used on elements appearing in the > same template; > 2) Match templates are brought in through an XInclude, dynamically, at > render-time. > > Assuming we know how to match elements using XPath, the first scenario > is reasonably easy; the difficult being only that the XPath ``select`` > method (corresponding to the matched elements) must be made available. > > The second scenario is more difficult, because these includes aren't > predictable at compile-time; as such, we have to match elements as we > render and apply the templates. As mentioned, this is currently solved > by post-processing the output using ``lxml`` and applying match > templates using callback-methods. It's not horrific, but it's also > convoluted and slow–––and slightly buggy. > > However, I think there's a way out of the deadlock. If we compile the > template specifically for each XPath-expression (on-demand, of > course), we can match the elements at compile-time and have a > situation similar to (1). > > This leaves us with the task of porting/writing an XPath selection > routine; it needn't be complete I think (Genshi's surely isn't). > > \malthe > > [1] http://genshi.edgewall.org/wiki/Documentation/xml-templates.html#id5 > _______________________________________________ > Repoze-dev mailing list > Repoze-dev@lists.repoze.org > http://lists.repoze.org/listinfo/repoze-dev _______________________________________________ Repoze-dev mailing list Repoze-dev@lists.repoze.org http://lists.repoze.org/listinfo/repoze-dev
