[Zope] URLs, objects, and <dtml-

[Dennis Allison]

I am pretty sure there are some clever techniques I have missed.

When I first started using Zope accessing objects at different places in
the object hiearchy was a problem.  I found some workarounds and learned
to cope, but I am now revisiting the issue.

For specificity, consider the following folder hiearchy:

R
   A1
       B1
	  D1
       C1
   A2
       B2
       C2
          D2

URLs would reference the somepage object in  D2 using the 
URL R/A2/C2/D2/somepage.    


Now, DTML, for example, <dtml-var >, specifies an object which is located
the current namespace by one of a variety of rules including acqusition.

Control over the namespace is provided using <dtml-with> but using it can
be cumbersome.  To reference an object in the folder D2 from D1 would
require wrapping the referencing <dtml-var> in a next of <dtml-with>
statements which make the namespace of A2, C2, and D2 available.  For a
site with a deep and complicated hiearchy, this is a mess. Hard to write,
hard to maintain, and very error prone.  The tendancy is to make all
scripts look like central mechanism wrapped in multiple with's to setup
the right namespace.

A better approach might be to access all nonlocal objects through a Python
Script that traverses a URL parameter and returns the specified object.
In this case, referencing the object foo in D2 above would be accomplished
by

  <dtml-var name="traverse_to_object('R/A2/C2/D2/foo')">

and so forth.  

This should work, but it kneecaps Zopes namespace management features because 
it returns an object, not a name to be resolved to an object in context through
bobo_traverse, acqusition, and so forth.

So, finally, the question:  How does one manage in an efficient and
compact fashion accesses to objects stored outside of the acquisition
path?


There are a couple of other notational issues that are a bit confusing.
If I have a folder (call it scripts) at my site root, I can reference 
the individual scripts by the names 'scripts.script1()'.  When does 
this notation extend to objects stored in nested folders?

One the defining notions of Zope is the equivalence of a page as specified
by a URL and an object.  What's the reason that something like 

   <dtml-var name="R/A2/C2/D2/foo">

does not resolve to the name foo in the container reachable by traversing
"R/A2/C2/D2" when accessed from within Zope.  It does work from the Web.

-dra