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
