最简洁的, 支持同时打印到 STDOUT 与 FILE 的日志系统.

logger.rb

require 'logger'
require 'forwardable'

module Ping
  class MultiIO
    def initialize(*targets)
      @targets = targets
    end
    
    def write(*args)
      @targets.each { |t| t.write(*args) }
    end
    
    def close
      @targets.each { |t| t.close }
    end
  end
  
  class Logger
    log_file = File.open( File.join( File.dirname(__FILE__), '..', 'log', 'dev.log'), 'a' )
    @logger = ::Logger.new( MultiIO.new( STDOUT, log_file ) )
    class <<self
      extend Forwardable
      def_delegators :@logger, :debug, :info, :warn, :error
    end
  end
  
end