proxy

function Node()
    local node = {}

    local proxy = {}
    setmetatable(proxy,{__newindex = function(t,k,v)
            rawset(node,k,v)
            if (type(v) == "table") then
                node[k].__parent = node
            end
        end,
        __index = function(t,k,v)
            return rawget(node,k) or rawget(_G,k)
        end,
        __pairs = function(t)
            local function stateless_iter(t, k)
                local v
                k, v = next(node, k)
                if v then return k,v end
            end
            return stateless_iter, node, nil
        end,
        __ipairs = function(t)
            local function stateless_iter(t, i)
                i = i + 1
                local v = node[i]
                if v then return i, v end
            end
            return stateless_iter, node, 0
        end
    })

    return proxy
end

local top = Node()
top.child = Node()
top.child.child2 = Node()
top.child.child2.child3 = Node()
top.child.child2.child3 = Node()