[Zope] "Acquisition Algebra"; interaction of containment and acquisition is confusing

Fred Yankowski fred@ontosys.com
Fri, 26 Jan 2001 12:52:51 -0600


Thank you for describing the transformation rules in detail.  With those
I can mechanically create the same acquisition expression that you get. 
Working some further examples with this knowledge [and how can I use
this knowledge to make mo' money?], I find that given a containment tree
like this:

  a --> b --> c
   \--> x --> y

the access path a.b.c.x.y results in a search order of (y, x, a, b, c)

Evan Simpson wrote:
> Trying to control or predict the exact search order for any but
> the simplest acquisition trees is a dangerous game.  You can read it off
> directly from the algebra form, as in (((x o a) o (b o a)) o (c o (b o a)))
> => x, a, b, c (ignoring duplicates), but it's unlikely to be useful, as you
> saw.

Now, does that bother anyone besides me?  Since acquisition is intrinsic
and ubiquitous in Zope, shouldn't we be concerned that it is hard to
control or predict?

-- 
Fred Yankowski           fred@OntoSys.com      tel: +1.630.879.1312
Principal Consultant     www.OntoSys.com       fax: +1.630.879.1370
OntoSys, Inc             38W242 Deerpath Rd, Batavia, IL 60510, USA