class Thing
  def greeting
    'yo,man'
  end
end

Thing.instance_methods(false)
  #=> [:greeting]

object = Thing.new
  #=> #<Thing:0x007fc4ba276c90> 

object.greeting
  #=> "yo,man"

在对象上定义两个方法(这将是对象的单例类中的实例方法.

def object.greeting
  'hey,dude'
end

def object.farewell
  'see ya'
end

object.methods(false)
  #=> [:greeting,:farewell] 
object.singleton_class.instance_methods(false) #=> [:greeting,:farewell]

object.greeting
  #=> "hey,dude" 
object.farewell
  #=> "see ya"

new_obj = Thing.new
new_obj.greeting
  #=> "yo,man"
new_obj.farewell
  #NoMethodError: undefined method `farewell' for #<Thing:0x007fe5a406f590>

删除对象的单例方法问候语.

object.singleton_class.send(:remove_method,:greeting)

object.methods(false)
  #=> [:farewell] 
object.greeting
  #=> "yo,man"

另一种删除方法：来自对象的单例类的问候语如下.

class << object
  remove_method(:greeting)
end