tracking table acceses in lua

trackingTableAccess2.lua

local index = {}
-- create private index

local mt = {
  __index = function ( t, k )
		print("*access to element " .. tostring(k))
		return t[index][k]		--access the original table
	end,

	__newindex = function ( t, k, v)
		print("*update of element " .. tostring(k) ..
							 " to " .. tostring(v))
		t[index][k] = v
	end
}


function track( t )
	local proxy = {}
	proxy[index] = t
	setmetatable(proxy, mt)
	return proxy
end

tab = track(tab)

tab[2] = "hello"
print(tab[2])