[Zope] how to get rendered conten of a dtml method from python ??

[Robert Rottermann]

Hi there this fine Sunday evening,
I try to create a DTML Method on the fly, pass it some data and would like
to get back that data rendered
like so:
  context.manage_addProduct['OFSP'].manage_addDTMLMethod(id='tmp2',
title='')
  obj = context['tmp2']
  obj.manage_edit(data, '')
  data = obj(_, context.REQUEST)

now my question:
what do I have to pass in the call
obj(....)

I would like to have it rendered (for instance) <dtml-var absolute_url>

thanks for your insights

Robert