Ruby 中的匿名类
我有两个问题：
- 方法
f_1是否属于元类匿名类？ - 方法
f_2属于匿名类吗？
与以下代码相关：
car = "car"
class << car
def self.f_1
puts "f_1"
end
def f_2
puts "f_2"
end
end
I have two questions:
- Does method
f_1belong to the metaclass anonymous class? - Does method
f_2belong to the anonymous class?
related to the following code:
car = "car"
class << car
def self.f_1
puts "f_1"
end
def f_2
puts "f_2"
end
end
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评论（4）
由于 ruby 自己的 API 使用术语“单例类”，我可以说以下内容是正确的：
f_1是汽车单例类的类方法，可以像这样调用：<前><代码>car.singleton_class.f_1
f_2是 car 单例类的实例方法可以这样调用：<前><代码>car.f_2
Since ruby's own API uses the term "singleton class," I'd say the following are true:
f_1is a class method on car's singleton class and can be called like this:f_2is an instance method on car's singleton class and can be called like this:好吧，术语很脆弱，但FWIW我想说你的班级并不是真正的匿名班级。至于归属感，这两个方法都只存在于 car 对象中。
我会诚实地承认，当类是针对像这样的单个对象定义的时，我对类方法和实例方法之间的区别有点模糊——我猜如果有任何区别，它会是一个晦涩的代码，会让你的代码更难阅读；）
更新：你可能会发现这个 有帮助，如果你有以前没见过。 （就我个人而言，这让我很头疼，但每个人都不一样......）
Well, terminology is frangible, but FWIW I would say your class wasn't really an anonymous class. As for belonging, both of these methods only exist in the car object.
I'll be honest and admit that I'm a little vague about the difference between a class method and an instance method when the class is defined against an individual object like this -- I would guess that if there is any difference, it will be an obscure one that will make your code much harder to read ;)
Update: You might find this helpful, if you've not seen it before. (Personally, it makes my head hurt, but everyone's different...)
我的印象是匿名类是没有名称的类：
但是，Pickaxe 将其称为未命名类而不是匿名类。
I was under the impression that an anonymous class is a class that has no name:
However, the Pickaxe refers to it as a unnamed class rather than as an anonymous class.
Rob Davis 答案的重新表述：
:f_1的方法所有者是car.singleton_class.singleton_class。:f_2的方法所有者是car.singleton_class。链
car→car.singleton_class→car.singleton_class.singleton_class对应于图中 http://www.atalon.cz/rb-om/ruby-object-model/#sc-inheritance-sample。注意：
A reformulation of Rob Davis' answer:
:f_1iscar.singleton_class.singleton_class.:f_2iscar.singleton_class.The chain
car→car.singleton_class→car.singleton_class.singleton_classcorresponds to the bottom row in the diagram at http://www.atalon.cz/rb-om/ruby-object-model/#sc-inheritance-sample.Notes: