给定Ruby对象的实例，如何获取其元类?

问题描述

通常，我可能会获得像这样的Ruby对象的特定实例的元类:

Normally, I might get the metaclass for a particular instance of a Ruby object with something like this:

class C
  def metaclass
    class << self; self; end
  end
end

# This is this instance's metaclass.
C.new.metaclass => #<Class:#<C:0x01234567>>

# Successive invocations will have different metaclasses,
# since they're different instances.
C.new.metaclass => #<Class:#<C:0x01233...>>
C.new.metaclass => #<Class:#<C:0x01232...>>
C.new.metaclass => #<Class:#<C:0x01231...>>

比方说，我只想知道任意类的任意对象实例obj的元类，并且我不想在obj的类上定义metaclass(或类似的)方法.

Let's say I just want to know the metaclass of an arbitrary object instance obj of an arbitrary class, and I don't want to define a metaclass (or similar) method on the class of obj.

有办法吗?

推荐答案

是的.

metaclass = class << obj; self; end

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