[Zope] RE: Two newbie questions

[Michael Bernstein]

Paul Everitt wrote:

> Michael wrote:
> > Wow. I had no idea anyone was reading my old posts. I feel so special!
>
> Hey, nobody reads my _new_ posts. :^)

_I_ do, and I ain't nobody! No wait, um, can I rephrase that? ;^)

> <stuff deleted>
> > In any case, ZTables does indeed have the 'hierarchy'
> > functionality that we
> > want, but it has yet to be released. A related proposal
> > called 'Topics' popped
> > up on the Zope site yesterday:
> > http://www.zope.org:18200/Members/Amos/TopicProposal , which
> > seems to apply
> > ZTables Hierarchies to ZCatalog albeit with a somewhat
> > different interface.
>
> As mentioned in a private note to Michael just now:
>
> """
> I don't think it's the same machinery.  In fact, the machinery has not
> been created yet.  It's just a statement of what we'll build this week
> and next.

Understood. But now I'm even more excited to learn that the timetable is that
short!

> Hierarchies are keyed very tightly to the machinery of ZTables, where
> the data itself are contained inside the ZTable object.  Hierarchies
> leverage this fact to provide folderish, pseudo-objects based on the
> tabular representation of data.

Hmm, I think I see. But, isn't a list of objects obtained from a ZCatalog a
table of sorts? The Topics proposal seems to say that it creates pseudo
heirarchies (by nesting Topics) and uses the ZCatalog machinery to populate the
Topics with objects from the ZODB.

I guess I should have been more clear: The 'Topics' proposal sounds like the
ZTables concept of pseudo-heirarchies applied to ZCatalog.

> There are probably many cases where people don't want to be constrained
> into a flat, rigid schema for all their data, as is the case with
> ZTables.
> """

It is a fact of life that most product catalogs are contained in some sort of
flat file, probably indexed on SKU. The ZCommerce list has already discussed
that it would be ideal if the rest of the store machinery could ignore the
actual storage of the product information (whether flat file, ZODB heirarchy,
RDBMS, or external inventory management system), and provide a transparent API.

But presentation is another matter. Topics would seem to be ideal for
transforming flat lists of products into more meaningful heirarchies. I won't go
into rehashing my original 'Military-Memorabilia' example, you can find it here
if you like:

http://www.zope.org/pipermail/zope/1999-January/001190.html

> <stuff deleted>
> > The one thing that is unclear is whether you can set
> > properties on a Topic, or
> > if you would have to place a Document with properties on it
> > into the Topic.
>
> Don't worry, Topics will be (I think) folderish objects that can have
> properties.  More importantly, they can contain things like DTML
> methods, allowing you to spew multiple representions of data in that
> topic, such as RDF, RSS, or CDF.

All good stuff.

>
> > BTW, as this is so useful in contexts other than
> > news/informational, I propose
> > changing the name from Topics to 'Category' or 'ZCategory'.
>
> I think the idea of Topic better represents the idea that it has its own
> identity away from the objects that might have some particulary piece of
> metadata.

<Shrug> No big deal, we all have our preferences for nomenclature. Just so long
as it doesn't conflict with an established usage of a term (like
versions/sessions), I won't complain.

Cheers,

Michael Bernstein.