This is a set of custom virtus attributes that use ruby-units to convert between different units of measure.
The project is currently only a code spike, a proof of concept. We'll see how it goes.
It can look more or less like this:
class WaterPool include Virtus attribute :capacity, Volume, :input_unit => :gallon, :output_unit => :liter end water_pool = WaterPool.new(:capacity => 10000) water_pool.capacity # 37854.118