tracks/lua/exercises/luhn/example.lua in trackler-2.0.6.10 vs tracks/lua/exercises/luhn/example.lua in trackler-2.0.6.11

@@ -1,43 +1,27 @@
-local Luhn = {}
-Luhn.__index = Luhn
-
-function Luhn:check_digit()
-  return tonumber(self.s:sub(-1))
-end
-
-function Luhn:addends()
+local function addends(s)
   local result = {}
-  for i = #self.s, 1, -1 do
-    local digit = tonumber(self.s:sub(i, i))
+  for i = #s, 1, -1 do
+    local digit = tonumber(s:sub(i, i))
     if #result % 2 > 0 then digit = digit * 2 end
     if digit > 9 then digit = digit - 9 end
     table.insert(result, 1, digit)
   end
   return result
 end
 
-function Luhn:checksum()
+local function checksum(s)
   local checksum = 0
-  for _, addend in ipairs(self:addends()) do
+  for _, addend in ipairs(addends(s)) do
     checksum = checksum + addend
   end
   return checksum
 end
 
-function Luhn:valid()
-  return self:checksum() % 10 == 0
-end
-
-local function new(s)
-  return setmetatable({ s = s }, Luhn)
-end
-
-local function create(s)
-  local checksum = new(s .. '0'):checksum()
-  return s .. tostring((10 - (checksum % 10)) % 10)
-end
-
 return {
-  new = new,
-  create = create
+  valid = function(s)
+    s = s:gsub(' ', '')
+    if #s < 2 then return false end
+    if s:find('%D') then return false end
+    return checksum(s) % 10 == 0
+  end
 }