[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