[Zope] Processing instructions (was Re: [Zope] <% ... %> ?)

[Eric Kidd]

On Fri, Jun 11, 1999 at 01:54:34PM -0400, Paul Everitt wrote:
> XHTML reworks HTML as an XML-compliant language.  Most imporantly, you
> can extend it with new namespaces (like Zope instructions) without
> breaking the DTD, as is the case with ColdFusion et al.

The big problem: DTML commands aren't really tags. They're something you
use to generate tags, and there's a lot of lossage lurking in between the
two concepts. You'd never be able to translate the following fragment:

  <!--#if sequence-index-even-->
  <tr bgcolor="lightblue">
  <!--#else-->
  <tr>
  <!--#/if-->

Another possibility: XML processing instructions. These are used to hold
"out-of-band" commands for processing tools. They look something like:

  <?dtml var ... ?>

These aren't quite a perfect solution, either, but they're closer. Like
tags, you shouldn't use them in attributes. They're invisible to the
validator, which causes trouble. But at least they're a standard, mandatory
part of the XML specification.

Cheers,
Eric