Dependencies

Currently we depend on collective.indexing as a means to hook into the normal catalog machinery of Plone to detect content changes. c.indexing before version two had some persistent data structures that frequently caused problems when removing the add-on. These problems have been fixed in version two. Unfortunately c.indexing still has to hook the catalog machinery in various evil ways, as the machinery lacks the required hooks for its use-case. Going forward it is expected for c.indexing to be merged into the underlying ZCatalog implementation, at which point collective.solr can use those hooks directly.