[Zope] Acquisition problem - please help

[Jeff K. Hoffman]

On Fri, 17 Dec 1999, Dave Parker wrote:

> Ok, most of what you said rings true, but here's the solution I've
> found, and given your explanation it's confusing to me that my solution
> works (which it does):
> 
> /one
> -methodX
> 	/two
> 	-propertyA(1)
> 	/three
> 		/four
> 	/five
> 	-propertyA(2)
> 
> http://host/one/two/three/four - methodX sees propertyA(1)
> http://host/one/five/three/four - methodX sees propertyA(2)

Ok, let's look at the first case. It evaluates to:

  one.two.three.four.methodX

The publisher traverses to one, and then from one to two. It cannot find
three.four.methodX in two, so, *in the context of two*, it acquires
three.four.methodX. This is basically the same as acquiring methodX
directly into two, since methodX is a DTML Method. The fact that you put
three/four/methodX in the URL line does not change the context of the
acquisition.

(Someone correct me if I'm wrong, please.)

> So the thing that doesn't jibe is that it can't *just* be the physical
> path - were that the case what I'm doing here would not work at all,
> right?

It's the physical path combined with the context in which the acquisition
is occurring. I think. :)

> > Coming from an OO background (C++, Java, and Eiffel), I can tell you that
> > thinking of acquisition as inheritance will kill you. Acquisition *IS NOT*
> > inheritance. If you want inheritance, use ZClasses.
> 
> I have been meaning to look into that.  Aren't ZClasses a function of a
> product (so that to use them you have to install your product that you
> created using ZClasses)?

ZClasses are contained in a product. So, yes, to use a ZClass, the product
that contains it must be installed. ZClasses are "above" the OFS, so to
speak.

> My trouble has been in imagining what the development cycle for a
> specific application (not a generic product) would look like in that
> context.

I am using ZClasses for a specific application. I just make sure they're
installed on whatever server is going to serve my app. :)

--Jeff