Question

鉴于

class Bird
  def self.bird_ancestors
    ancestors.first(ancestors.find_index(Bird)+1)
  end
end

class Duck < Bird
end

class FeatheredDuck < Duck
end

FeatheredDuck.bird_ancestors => [FeatheredDuck,Duck,Bird]
Duck.bird_ancestors => [Duck,Bird]
Bird.bird_ancestors => [Bird]

如何在Bird内引用Bird而不明确？我知道self和__class__ doesnt有效。

Answer 1

在类方法中，self引用当前的类对象：

class Bird
  def self.foo
    self
  end
end

p Bird.foo # => "Bird"

Answer 2

这样做：

class Bird
  def self.bird_ancestors
    ancestors.take_while { |c| c.respond_to? __method__ }
  end  
end

class Duck < Bird
end

class FeatheredDuck < Duck
end

FeatheredDuck.bird_ancestors #=> [FeatheredDuck, Duck, Bird]
Duck.bird_ancestors          #=> [Duck, Bird]
Bird.bird_ancestors          #=> [Bird]

select也有效，但take_while（由@Aditya建议）更好，因为一旦从块中返回ancestors，它就会停止搜索false。

Answer 3

你可以这样做：

class Bird
  def self.bird_ancestors
      class_name =  method(__method__).owner.to_s.gsub(/#<Class:|>/,'')
      ancestors.first(ancestors.map{|x| x.to_s}.find_index(class_name)+1)
  end
end

(__method__ is the current method)

将祖先提取到“我”

3 个答案: