有没有办法将命名范围组合成新的命名范围？

I have

class Foo < ActiveRecord::Base
  named_scope :a, lambda { |a| :conditions => { :a => a } }
  named_scope :b, lambda { |b| :conditions => { :b => b } }
end

I'd like

class Foo < ActiveRecord::Base
  named_scope :ab, lambda { |a,b| :conditions => { :a => a, :b => b } }
end

但我更喜欢以干的方式来做。我可以通过使用获得相同的效果

 Foo.a(something).b(something_else)

但它并不是特别可爱。

至少从 3.2 开始有一个聪明的解决方案：

scope :optional, ->() {where(option: true)}
scope :accepted, ->() {where(accepted: true)}
scope :optional_and_accepted, ->() { self.optional.merge(self.accepted) }