complex.rb

positionable do
  def insync?(is)
    # define sync
  end
end

current.rb

  ensurable do
    desc "Ensure the presence, absence or position of the entry"
    defaultvalues

    newvalue(:positioned) do
      current = self.retrieve
      if current == :absent
        provider.create
      elsif !provider.in_position?
        provider.destroy
        provider.create
      end
    end

    def insync?(is)
      return true if should == :positioned and is == :present and provider.in_position?
      super
    end
  end

simple.rb

# Implies the code above (including ensurable)
positionable