LUA OO Problem!

local objs={}
objs.insts={}

function addObject(x, y, color)
    if not color then color=colors.black end
    local nobj={}
    if(not x) then x=0 end
    if(not y) then y=0 end
    nobj.x=x
    nobj.y=y
    nobj.color=color
    function nobj:create() end
    function nobj:update() end
    function nobj:draw() end
    return nobj
end

local function objCopy(t)
    local t2 = {}
    for k,v in pairs(t) do t2[k] = v end
    return t2
end

function instanceCreate(obj, x, y, color)
    if(not x) then x=obj.x end
    if(not y) then y=obj.y end
    if(not color) then color = obj.color end
    local temp_n=table.getn(objs.insts)+1
    local cO=objCopy(obj)
    cO.x=x
    cO.y=y
    cO.inst=true
    cO.SELF=cO
    cO.color=color
    objs.insts[temp_n]=cO
    cO.id=temp_n
    cO:create()
    return cO
end

function updateInsts()
    for i=1, table.getn(objs.insts) do
        objs.insts[i]:update()
    end
end

function drawInsts()
    for i=1, table.getn(objs.insts) do
        objs.insts[i]:draw()
    end
end


You use it like this:
objPlayer=addObject(nil, nil, colors.blue)
objEnemy=addObject(nil, nil, colors.red)

local w, h = term.getSize()

function objEnemy:create()
    self.dmg=math.random(2)
    self.health=math.random(50, 200)
end

function objEnemy:update() end --Well you get the idea!
objEnemy objEnemy:draw() end

instanceCreate(objPlayer, 3, 3)

--I dunno how to use repeat in lua but but I know what it does!
repeat(5) instanceCreate(objEnemy, math.random(w), math.random(h))

--This thing works great, you suply the object with the code you need and then you just create copies ( instances ) of that object!