spinFarm.lua

local farmItem, farmBlock, maxMeta = ...
maxMeta = tonumber(maxMeta) or 7

if farmItem == "help" then
  print("Usage: <filename> <seedName> <blockName> [maxGrowth(default:7)]")
end

farmItem = type(farmItem) == "string" and farmItem
  or error("Bad argument #1: Expected a string")
farmBlock = type(farmBlock) == "string" and farmBlock
  or error("Bad argument #2: Expected a string")

local function find()
  for i = 1, 16 do
    if turtle.getItemCount(i) > 0
        and (turtle.getItemDetail(i)).name == farmItem then
      turtle.select(i)
      return
    end
  end
  error("Cannot place anything")
end

local oldplc = turtle.place
function turtle.place()
  find()
  return oldplc()
end

local olddig = turtle.dig
function turtle.dig()
  local isBlock, block = turtle.inspect()
  if isBlock then
    if block.name == farmBlock and block.metadata >= maxMeta then
      return olddig()
    end
    return false
  end
  return true
end

while true do
  print("START LOOP")
  for i = 1, 4 do
    print("CHECKING " .. tostring(i))
    if turtle.dig() then
      print("IT IS SO, WE PLACE.")
      turtle.place()
    end
    print("RIGHT WE GO")
    turtle.turnRight()
  end
  print("WE HAVE DONE THIS LOOP, LET US WAIT SOME TIME.")
  os.sleep(10)
end