[Zope] Data aggregation within a tree

Hello all-- My application has two custom objects types (one of them is folderish). I'm trying to add a view to the folderish object that'll aggregate statistics information on the lower-levels of the tree. Specifically, I'd like a flavor for how to do the following: traverse a tree w/o rendering it test an object's type if an object is a specific type: update counters appropriately based on the internal state of the object render the results Since I only want to traverse the tree (not render it), am I correct in presuming dtml-tree isn't my friend in this case and I'll need to work in straight Python instead? Thanks in advance. --Brad