Classes as Singletons : Singletons « Design Patterns « Ruby

1. Ruby
2. Design Patterns
3. 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')

 

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