我们如何在不同的Ruby类之间复制单例方法？

class Foo
  def singleton_method
    puts "This is a singleton method"
  end
end

foo = Foo.new

def foo.another_singleton_method
  puts "This is another singleton method"
end

foo.singleton_method  # 输出："This is a singleton method"
foo.another_singleton_method  # 输出："This is another singleton method"

# 复制单例方法到另一个类
class Bar
end

bar = Bar.new

# 使用singleton_class方法获取foo对象的单例类
singleton_class = foo.singleton_class

# 使用define_method将单例方法复制到Bar类的单例类中
singleton_class.define_method(:copied_singleton_method, singleton_class.instance_method(:singleton_method))

bar.copied_singleton_method  # 输出："This is a singleton method"