如何为Ruby类的Singleton实例定义类变量？

require 'singleton'

class MySingleton
  include Singleton
  
  def initialize
    @my_class_variable = "Hello, World!"
  end
  
  def self.get_instance
    instance
  end
  
  def self.my_class_variable
    singleton_class.class_variable_get(:@@my_class_variable)
  end
  
  def self.my_class_variable=(value)
    singleton_class.class_variable_set(:@@my_class_variable, value)
  end
end

# 获取Singleton实例
instance = MySingleton.get_instance

# 获取和设置类变量
puts MySingleton.my_class_variable # 输出："Hello, World!"
MySingleton.my_class_variable = "New value"
puts MySingleton.my_class_variable # 输出："New value"