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[Ruby]How to create singleton class ?

时间:2015-08-19 08:15:07      阅读:113      评论:0      收藏:0      [点我收藏+]

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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()

 

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[Ruby]How to create singleton class ?

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原文地址:http://www.cnblogs.com/lcchuguo/p/4741182.html

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