getter

function split(str, pat)
   local t = {}  -- NOTE: use {n = 0} in Lua-5.0
   local fpat = "(.-)" .. pat
   local last_end = 1
   local s, e, cap = str:find(fpat, 1)
   while s do
      if s ~= 1 or cap ~= "" then
	 table.insert(t,cap)
      end
      last_end = e+1
      s, e, cap = str:find(fpat, last_end)
   end
   if last_end <= #str then
      cap = str:sub(last_end)
      table.insert(t, cap)
   end
   return t
end

rednet.open("back")
sorterr = peripheral.wrap("right")
sorterl = peripheral.wrap("left")
while true do
	a, id, t = os.pullEvent("rednet_message")
	sp = split(t, ":")
        if #sp > 2 then
		id = tonumber(sp[1]) * (tonumber(sp[3]) + 32768)
	else
		id = tonumber(sp[1])
        end
	am = tonumber(sp[2])
	sorterr.extract(1, id, 0, am)
	sorterl.extract(1, id, 0, am)
end