[Zope3-dev] Catalog only depeding on ZODB Was: Complexness of Zope3

[Steve Alexander]

> The major dependency of the existing index classes is on persistent
> BTrees, which are packaged with ZODB.

Right. And the base classes of the Zope 3 indexes can be used in ZODB 
applications with no further dependencies on the rest of Zope. They 
could be made available as a separate package (in the download an 
install sense of "package") that would work as well with the ZODB as 
with Zope.

You can use the BTrees API to combine and filter the results of queries 
on these index.

Zope 3 will have a higher-level means for composing queries among 
different indexes, and managing indexes. This software may not work well 
outside of Zope 3.

Basically, we have two different subsystems of Zope 3:

* Indexes

* The other machinery to make indexes useful within Zope 3

You could write indexes that store their data in the ZODB, in flat 
files, or in a relational database management system.

For a particular index to be managed and used within Zope 3 in the same 
way as other indexes, it will need to be adaptable to a couple of 
interfaces to allow querying and management of the index.

--
Steve Alexander