FAO @Ben_Nuttall :)

writing_a_file.rb

messages = [ "one,two,three", "un,deux,trois", "eins,zwei,drei" ]

File.open("messages.csv", "w") do |file|
  messages.each do |message|
    file.puts message
  end
end

writing_a_file_without_a_block.rb

messages = [ "one,two,three", "un,deux,trois", "eins,zwei,drei" ]

file = File.open("messages.csv", "w")
begin
  # This bit is the only thing that changes between different uses of a file
  messages.each do |message|
    file.puts message
  end
ensure
  file.close
end