test2.lua

local Adder = {}
Adder.__index = Adder

function Adder.new()
   local adder = {}
   setmetatable(adder, Adder)
   adder.total = 0
   return adder
end

function Adder:add(i)
   self.total = self.total + i
end

local adder = Adder.new()

for i=1,1000000 do
   adder:add(i)
end