[Zope] Containment or context

[Stephen Harrison]

Hi,

I've been trying to piece together a site which exploites acquisition,
but I have come up against a problem.

This basically boils down to the chosen method for acquisiton.

I can have a site with the following structure:

/
+- foo
|  +- stuff
|  +- etc...
+- bar
|  +- more stuff
|  +- etc...
+- baz
   +- and so on

where foo, bar and baz are folder objects, which contain various
methods, etc.

Now, I can construct urls such as:

/foo
/bar
/baz
/foo/baz
/bar/baz
...

and in each of these the child will operate within the context of the
parent.  At least that is how I would like it to work.

But, having read the AcquisitionAlgebra,

http://www.zope.org/Members/jim/Info/IPC8/AcquisitionAlgebra/siframes.htm

and a post to the list a while back,

http://zope.nipltd.com/public/lists/zope-archive.nsf/ByKey/4C6995D8A903E711

I have learnt that acquisition works on the principle of containment
before context.  Unfortunately this is exactly what I don't want.  I
want context before containment, because that is the whole reason that I
am construction urls in this way.  The only reason that foo, bar and baz
are all contained in / is so that they will all be available within the
context of each other (the wonders of acquisition), but once they have
been acquired, the context is all-important.

Imaging that baz produces a set of data.  Imagine also that within the
context of foo or bar only certain subsets of baz's data are relevant. 
So I could go to /baz and see all the data, or /foo/baz and see only the
data relevant to foo.

But because of "containment before context", if I have a property as an
atribute of foo to let baz know which data is important, baz will ignore
it, because there is a property as an attribute of / to define the
global case, which baz will use.

Why is this?  In

http://www.zope.org/Members/Hoekstra/ChangingContexts1

it states that PARENTS is defined as the acquisition parents of an
object.  But this is not true.  The acquisition parents of baz are /
alone, but if I evaluate PARENTS from the url /foo/bar/baz/foo I will
get parents of foo, baz, bar, foo, /.  This is inconsistent with the
idea of containment before context, and yet this is, in my opinion, the
more useful case.

Asuming that acquisition works the way that it does and that it is right
that it should work that way (although I could be missing some reason as
to why that is best), is there some other way by which I can acquire
properties by, effectively, the context route?

Either way, any feedback would be most welcome.

Cheers,
Stephen

-- 
Stephen Harrison            stephen@nipltd.com
New Information Paradigms   www.nipltd.com