# File lib/dm-core/resource.rb, line 510
    def <=>(other)
      model = self.model
      unless other.kind_of?(model.base_model)
        raise ArgumentError, "Cannot compare a #{other.class} instance with a #{model} instance"
      end
      model.default_order(repository_name).each do |direction|
        cmp = direction.get(self) <=> direction.get(other)
        return cmp if cmp.nonzero?
      end
      0
    end