Zope/DTML Infuriating...

[Jens]

Hello Everyone.

I am relatively new to Zope(using it for a work project) and I was
wondering if someone here could help me out or at least refer me to a
decent documentationg for Zope/DTML/Python (at the detail level of
php.net or Java API reference).  http://www.zope.org/Documentation/Books/ZopeBook/2_6Edition/
isn't really detailed enough for my taste. if it doesn't contain a
exhautive description of all available base classes it's simply no
good as a reference resource.

Anyway I have the following problem. I'm using zope 2.9 and I would
expect the following dtml code to yield a list containing main1, main2
etc.

<dtml-let prefix="'main'">
<ul>
<dtml-in expr="_.range(1,10)">
  <li><dtml-var expr="_['prefix'] + _['sequence-item']"></li>
</dtml-in>
</ul>
</dtml-let>

But it doesn't work(and yes i know that i could simply do "... <dtml-
var prefix><dtml-var sequence-item>...", but that's not what i need).
I've the checked that i'm referring to the variables correctly, so the
only explanation i can come up with, is that '+' doesn't result in a
string concatenation (with implicit typecast to string of the integer
variable(this is a interpreted language after all)). It apparently
works in other cases but for some reason not here. I get the following
cryptical error message which makes me none the wiser.

An error was encountered while publishing this resource.

Error Type: AttributeError
Error Value: 'NoneType' object has no attribute 'group'

I would appreciate any feedback you might have regarding this. Thanks
in Advance.