[Ruby]How to create singleton class ?

最新推荐文章于 2025-11-15 09:02:52 发布

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#singleton #design pattern #instance #ruby

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本文介绍了Ruby中实现单例模式的方法，通过两个例子展示了如何创建单例类，并使用私有类方法和引入Singleton模块来确保类只有一个实例。

Singleton is one design pattern in the software engineering. Ruby has its own special feature to declare singleton class. I will demonstrate two examples as below:

class Logger
  def initialize
    @log = File.open("log.txt", "a")
  end
   
  @@instance = Logger.new
 
  def self.instance
    return @@instance
  end
 
  def log(msg)
    @log.puts(msg)
  end
 
  private_class_method :new
end
 
Logger.instance.log('message 1')

require "singleton"

class Test
  
  include Singleton
  
  def idea
    puts "this is test"
  end
  
  def self.good
    puts "good idea"
  end
  
end

puts Test.good()

puts Test.instance.idea()