seancribbs/ripple — pull request #288 by seancribbs (2012-04-17 15:58:45+00:00)
Title: Allow index blocks/methods to return nil, excluding index entry

This allows for patterns where the index should not be available on some documents that fail to meet certain criteria. I'd appreciate arguments for/against this change. Some caveats to start the discussion:

* `nil` is treated specially to mean "don't index this". This doesn't allow patterns where you want to find documents that are *NOT* indexed (a general problem).
* `nil` is checked specifically when adding the index entry to the persistence hash. Should falsey values be allowed instead? What is the implication of lumping `false` with `nil` in this case?

/cc @stevenbristol