def add_single_rule(field, key_or_klass, params = nil)
      klass = if key_or_klass.respond_to?(:new)
        key_or_klass
      else
        get_rule_class_by_name(key_or_klass)
      end

      args = [params].compact
      rule = klass.new(*args)
      rule.obj = @obj if rule.respond_to?(:obj=)
      rules[field] << rule
    end
def add_single_rule(field, key_or_klass, params = nil)
      klass = if key_or_klass.respond_to?(:new)
        key_or_klass
      else
        get_rule_class_by_name(key_or_klass)
      end

      args = [params].compact
      rule = klass.new(*args)
      rule.obj = @obj if rule.respond_to?(:obj=)
      rules[field] << rule
    end
Adds a single rule to this object