ruby - create singleton with parameters?

Question

I\'ve seen how to define a class as being a singleton (how to create a singleton in ruby):

require \'singleton\'

class Example
  include Singleton
end
         


        

Answer 1

Simple singleton that doesn't depend on Singleton module

class MyLogger
  def self.instance(filepath = File.join('some', 'default', 'path'))
    @@instance ||= new(filepath).send(:configure)
  end

  def initialize(filepath)
    @filepath = filepath
  end
  private_class_method :new

  def info(msg)
    puts msg
  end

  private

  def configure
    # do stuff
    self
  end
end

Example usage

logger_a = MyLogger.instance
# => #

logger_b = MyLogger.instance
# => #

logger_a.info logger_a.object_id
# 70125579507760
# => nil

logger_b.info logger_b.object_id
# 70125579507760
# => nil

logger_c = MyLogger.new('file/path')
# NoMethodError: private method `new' called for MyLogger:Class