如何确定Ruby模块是否已扩展实例？

Given an object and a module, how do I check that the object has been extended by the module?

给定一个对象和一个模块，如何检查该对象是否已被模块扩展？

There doesn't seem to be any corresponding extend? method

似乎没有任何相应的延伸？方法

moirb(main):001:0> module Foobar
irb(main):002:1> end
=> nil
irb(main):003:0> o=Object.new
=> #<Object:0x000001010d1400>
irb(main):004:0> o.class.include? Foobar
=> false
irb(main):005:0> o.extend Foobar
=> #<Object:0x000001010d1400>
irb(main):006:0> o.class.include? Foobar
=> false
irb(main):007:0> o.class.included_modules
=> [PP::ObjectMixin, Kernel]
irb(main):016:0* o.methods.grep /extend/
=> [:extend]
irb(main):019:0> o.class.methods.grep /extend/
=> [:extend]

2 个解决方案

#1

Is there any reason why you are not just using is_a?:

你有没有理由不使用is_a ?:

o.is_a? Foobar
# => true

#2

You can use

您可以使用

o.singleton_class.included_modules

Or if you want to be really pithy:

或者如果你想要真正精辟：

o.singleton_class < Foobar

An object's singleton class is where all of its singleton methods live - extending is (as far as I understand) equivalent to including into the singleton class. This is why

对象的单例类是其所有单例方法所在的位置 - 扩展（据我所知）相当于包含在单例类中。这就是为什么

class Foo
  extend Bar
end

and

和

class Foo
  class << self
    include Bar
  end
end

Both add the methods from Bar as class methods (ie singleton methods) on Foo

两者都在Bar上添加方法作为Foo上的类方法（即单例方法）

#1