[Zope-dev] TALES idea: tuple unpacking

[Fred L. Drake, Jr.]

Paul Winkler writes:
 > In this case, consider a trivial change to (or wrapper around) 
 > listFilesByUser to make it return a sequence of dictionaries
 > like {'user': some_user, 'files': (file1, file2...)}

This is exactly what the proposal I posted a couple of weeks ago was
trying to avoid.  While adding another layer of indirection around the
actual call to listFilesByUser() isn't all that costly, these things
add up, especially since so many temporary objects are getting created
and thrown away.

I know for Zope 3, we'd like to get away from having to write a view
class simply to hook up helpers like this when something simpler would
do.

So far, two distinct approaches have been presented, with minor
variations for each.  I won't go into the variations, but the two
approaches are:

- Use a Python-like sequence unpacking syntax.  This is probably most
  comfortable to template authors who are Python programmers first,
  and web guys (or gals!) second.

- Use the namespace qualifiers to get an adapter to handle converting
  container lookup to a sequence indexing operation.  This plays off
  the machinery being built anyway, so is quite attractive, and
  doesn't affect the basic syntax or implementation of TAL, but only
  of the TALES expression engine.  This is very attractive because it
  pushes the support for this feature somewhere the application
  controls in as much detail as it wants.


  -Fred

-- 
Fred L. Drake, Jr.  <fred at zope.com>
PythonLabs at Zope Corporation