rails--rails/lib/arel/attributes/attribute.rb

module Arel
  module Attributes
    class Attribute < Struct.new :relation, :name, :column
    end

    class String < Attribute; end
    class Time < Attribute; end
    class Boolean < Attribute; end
    class Decimal < Attribute; end
    class Float < Attribute; end
    class Integer < Attribute; end
  end
end