# File lib/dm-core/resource.rb, line 435
    def <=>(other)
      unless other.kind_of?(model.base_model)
        raise ArgumentError, "Cannot compare a #{other.model} instance with a #{model} instance"
      end
      cmp = 0
      model.default_order(repository_name).each do |direction|
        cmp = direction.get(self) <=> direction.get(other)
        break if cmp != 0
      end
      cmp
    end