topp.featurelets 0.3.0

topp.featurelets provides an infrastructure for “featurelets”. Featurelets are feature plug-ins, little bundles of functionality that can be installed into a particular location within a Plone or CMF site. It’s a very simple concept, but is a bit hard to explain in the abstract, so a concrete example would probably be helpful.

In an OpenCore site, eg. http://www.coactivate.org, anyone can create a project. In these projects, we offer feature modules that can be turned on and off. The optional features that someone might want to add to her project include, for instance, blogging capabilities, or mailing lists. Each of these is a featurelet. The project, into which the featurelets are installed, is a “featurelet supporter”.

Featurelets are deliberately vague so that they can be flexible. Each featurelet contains a “package”, and when a featurelet is installed into a featurelet supporter this package is delivered to the supporter. Common operations associated w/ the delivery of a package include the creation of content objects and the registration of menu items; support for both of these operations are built into the featurelets core. It’s possible to make a featurelet do anything, however, provided the featurelet supporter can support the operations. To ensure this, featurelets support the idea of required interfaces; if a featurelet is installed into a supporter that does not implement or adapt to all of the featurelet’s required interfaces, an adaptation exception will be raised.

Requires Zope 2, version 2.10 or later, and CMF.