Ruby:是否可以在不对类名进行硬编码的情况下确定我的 Ruby 方法在其中执行的类？

Question

我是 Ruby 的 Nuby。我正在寻找一种方法来获取当前执行行的方法的包含类对象。如果不对类名进行硬编码，这可能吗？

# hardcoded example
class A
  def to_s
    "I am a " + A.to_s   # Class "A" is hardcoded here. Is there another way to reference the class A?
  end
end

我想也许 self.class 会起作用，但是当类被子类化时，它并没有给我我想要的东西。

# Following Outputs=> I am a Camel I am a Camel I am a Camel
# but I want       => I am a Camel I am a Mammal I am a Animal

class Animal
  def to_s
    "I am a " + self.class.to_s
  end
end

class Mammal < Animal
  def to_s
    "I am a " + self.class.to_s + " " + super
  end
end

class Camel < Mammal
  def to_s
    "I am a " + self.class.to_s + " " + super
  end
end

puts Camel.new()

那么，是否存在允许访问包含类的关键字、方法或其他内容？

Answer 1

你需要 Class#ancestors :

Camel.ancestors
#=> [Camel, Mammal, Animal, Object, Kernel, BasicObject]

您将获得比您定义的更多的类，因此您需要在 Object 处停止:

class Animal
  def to_s
    "I am a " + self.class.ancestors.take_while{|klass| klass != Object}.join(' and a ')
  end
end

class Mammal < Animal
end

class Camel < Mammal
end

puts Animal.new
# => I am a Animal
puts Mammal.new
# => I am a Mammal and a Animal
puts Camel.new
# => I am a Camel and a Mammal and a Animal

ancestors 可以是模块或类，所以如果你只想要类，你可以使用:

def to_s
  "I am a " + self.class.ancestors.take_while{|klass| klass < Object}.join(' and a ')
end

---

So, is there a keyword, method or something that allows accessing the containing class?

我找不到一个。添加

puts method(__method__).owner

到 Animal#to_s 或 Mammal#to_s 仍然返回 Camel。