Ruby string template

my_logger.rb

require "socket"

class MyLogger
  attr_accessor :format

  def initialize
    @format = '%<severity>s %<time>s %<host>s %<pid>s %<message>s'
  end

  def error(message)
    data = {
      message: message,
      time: Time.now,
      host: Socket.gethostname,
      pid: $$,
      severity: "ERROR"
    }

    printf @format, data
  end
end

logger = MyLogger.new
logger.format = "%<severity>.1s %{message} %{time} %{host}"
logger.error "Klingons off the starboard bow!"