Classes as Singletons : Singletons « Design Patterns

Classes as Singletons : Singletons « Design Patterns « Ruby

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Ruby » Design Patterns » Singletons

Classes as Singletons





class ClassBasedLogger

  ERROR = 1

  WARNING = 2

  INFO = 3



  @@log = File.open('log.txt', 'w')

  @@level = WARNING



  def self.error(msg)

    @@log.puts(msg)

    @@log.flush

  end



  def self.warning(msg)

    @@log.puts(msg) if @@level >= WARNING

    @@log.flush

  end



  def self.info(msg)

    @@log.puts(msg) if @@level >= INFO

    @@log.flush

  end



  def self.level=(new_level)

    @@level = new_level

  end



  def self.level

    @@level

  end

end



ClassBasedLogger.level = ClassBasedLogger::INFO



ClassBasedLogger.info('A')

ClassBasedLogger.warning('B')

ClassBasedLogger.error('C')

Related examples in the same category

1.	define class methods by using a class within a class's singleton class like the code
2.	Define a singleton method, one that is tied to a single object
3.	Singleton a class
4.	Modules as Singletons
5.	include Singleton

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