[Zope-CMF] Proposal: CMF Topic with sub-topic.

[Tres Seaver]

On Thu, 14 Mar 2002, Yuan-Chen Cheng wrote:

> 
> Change Proposal:
> 
> Add a flag in CMFTopic, which is show match even with subtopic.
> which is used when subtop exist.
> 
> If this flag is false, the View of CMFTopic won't show
> item matched with subtop exists.
> 
> Comment is welcome !

The old ZTopic product had this feature.  In order to implement
the feature efficiently, the topic objects actually held on to
the result sets for the indexes they were based on, and performed
set operations on them.  This strategy relied on an intimate
knowledge of the internal implementation details of the catalog,
which is why ZTopics don't work with newer versions of Zope.
Because they cached the result sets from individual indices, the
topic objects were also prone to "staleness":  they had no good
way to be notified that the underlying index had been changed.

A re-implementation should depend only on public interfaces of
the catalog, and should be immune to the "staleness" problem.
I can't think of a good way to do this in Zope 2 without creating
a specialized index type.  The TopicIndex type, which will be
available in Zope 2.6, might be useful here:

  http://dev.zope.org/Wikis/DevSite/Proposals/TopicIndexes

Tres.
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Tres Seaver                                tseaver@zope.com
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