writing @output to a file with a custom output class

dump_output.rb

class DoubleOutputter
  def initialize(filename)
    @file = File.new(filename, 'w+')
  end
  
  def puts(string)
    @file.puts string
    $stdout.puts string
  end
  
  def close
    @file.close
  end
end

@output = DoubleOutputter.new('dump.txt')

@output.puts "line 1"
@output.puts "line 2"
@output.puts "line 3"

@output.close