[Zope] DTML reformulated as XML (was RE: [Zope] <% ... %> ?)

[Tony McDonald]

>> I do want to point one thing out, though: adding namespaces does break
>> the DTD.  Currently there is no way to validate a document that uses
>
> Hmm, didn't realize that.
>

There's a big difference between validation (against a DTD) and
well-formedness however. I suppose ideally you'll want validity, but for now
(IMHO)  stick with well-formedness (is that a word?).


>
> Here's one thing in DTML that would be awfully obscure in XML:
>
> <a href="<!--#var BASE1-->">
>
> That is, putting a tag inside an attribute.  Chris Petrilli and Jim
> talked about this today, perhaps as as entity references.
>

That'd be ok for the Zope variables that take no arguments (BASEn, URLn
etc.) ie map BASE1 to &BASE1; but what about Zope variables that take
attributes, eg ZopeTime fmt=whatever (for example, you'd use this awful
construct to create a URL that had subparts such as /990612/)

A very hairy problem.

>> > At any rate, I'd love for someone in the Zope community to march off and
>> > take a look at this, then make a proposal for how things should be
>> > changed.  As always, patches are accepted. :^)
>>
>> I've been meaning to do something like this.  I might just spend some
>> time thinking about it this weekend.  Any actual coding probably won't
>> happen, though. :)
>
> Understood.  If you produced a clear definition of the goals, some
> samples for the syntax, and a list of things that are good and bad about
> it, then that would be a major win.
>
>> The simple stuff is easy:
>>
>> <?xml version='1.0'?>
>> <xdtml:xdtml xmlns:xdtml="http://www.zope.org/xdtml"
>> xmlns="http://www.w3.org/TR/xhtml1">
>>
>> <xdtml:var name='standard_html_header'/>
>> <h1><xdtml:var name='title'/></h1>
>> <p>This is a paragraph.</p>
>>
>> <xdtml:if expr='age &gt; 18'>
>> <p>Text not everyone should read.</p>
>> </xdtml:if>
>>
>> <xdtml:var name='standard_html_footer'/>
>>
>> </xtml:xdtml>
>
> I'd love to do a straw vote from the "I hate SSI" crowd: is the above
> better?
>

No dis to Otto, but NIMHO. Too much typing. I'm from a PHP background where
blocks of code exist in tandem with HTML. At first I had a real problem with
DTML (still do, but that's another story :), but reading Paul and Chris'
posts about separating code and data I realise that the DTML way is probably
the best way to do it (as with so many other Zopey things). ps I don't hate
SSI, and I don't have an alternative to the syntax Otto is describing - I
should shut up now.

>> The if gets really strange when you start adding 'elif' and 'else'
>> clauses.  I'll have to think about that one.
>>
>> The containing xdtml element is just there as a place to hang the
>> namespace declarations off of.  Also, it's there to make the DTML object
>> a full-fledged self-contained XML document, needed to make any kind of
>> editor useful.
>
> Precisely.  It comes from the namespace declaration at the top.
>
> One more thing to muse over is whether other things from XML land should
> surface.
>
> For instance, I've long wondered if the ubiquitous var tag should be
> broken apart.  People ask: why can't you give me a list of the things
> that can go in the var tag?  Why doesn't Zope check to see if my
> documents reference subdocuments that no longer exist?  The answer of
> "it's too dynamic" feels like less than an answer.
>
> Instead, we could begin granularizing the tags, perhaps into things that
> describe better where they came from.
>
> For instance, instead of saying <!--#var standard_html_header-->, which
> means insert a subdocument, why not use the XLink syntax from XML?
>

Would that not imply Zope parsing all elements in a page/object looking for
attributes called xml:link? Isn't this a largeish overhead? It could also
mean people writing <a xml:link="simple" href="standard_html_header"
show="embed"/> instead of the above. Of course, if you get XLink stuff
working in Zope, then presumably you get other interesting possibilities out
too.

rambling-ly yours,
tone.