ComputerCraft Tutorial: msg_receiver_0_6

-- ##############################
-- msg_receiver
-- version 0.6
-- (a paired program: msg_sender 0.6, http://pastebin.com/yUgqzL98)
-- http://hevohevo.hatenablog.com/

rednet.open("right")

function myRefuelAll()
  for i=1,16 do
    turtle.select(i)
    turtle.refuel()
  end
  turtle.select(1)
end

function printResults(sender_id, message, tbl_results)
  local exist_status, run_status, err_msg = unpack(tbl_results)
  if exist_status then -- found a function
    if run_status then -- success for running
     print("#",sender_id,": ",message)
    else -- failed or doesn't reply
      print("#",sender_id,": ",message)
      if err_msg then
        print(" (Error) ",err_msg)
      else
        print(" (No reply) ")
      end
    end
  else -- failed with running by wrong string
    print("#",sender_id,": ",message)
    print(" (NotFound) ")
  end
end

-- main
while true do
  local sender_id, message, distance = rednet.receive()

  -- when a message includes the plural functions, doesn't return values.
  if not string.find(message,";") then
    message = "return "..message
  end

  -- make a function and run
  local func = loadstring(message)
  setfenv(func, getfenv()) -- change func's environment(_G) to current one.
  local results = {pcall(func)} -- table: 1) exist_status, 2) run_status, 3) err_msg

  -- respond results to the sender
  rednet.send(sender_id, textutils.serialize(results))

  -- print results to the terminal display.
  printResults(sender_id, message, results)
end