[Ruby]How to create singleton class ?
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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