nesquena/rabl — pull request #453 by leoc (2013-05-16 09:48:25+00:00)
Title: Add symbol conditions

Now you can give symbols as conditions for :if and :unless, which are
used as method names for the object in question.

Example:

collection @posts
attribute :coolness, if: :cool?

Here Post#cool? would be invoked when resolving the condition, to
determine whether to include the :coolness attribute or not.