Vector3

Vector3 = {}

function Vector3.IsVector(otherVec)
    local is = pcall(function ()
        -- If this is legitimate, it should concatenate without a problem.
        return otherVec.X .. otherVec.Y .. otherVec.Z .. otherVec.magnitude .. otherVec.unit
    end)
    return is
end

function Vector3.new(x,y,z)
    local x,y,z = tonumber(x) or 0, tonumber(y) or 0, tonumber(z) or 0
    local m = math.sqrt(x^2+y^2+z^2)
    local meta = {}
    local function insert(k,v)
        meta["__"..k] = v
    end
    local vec = {}
    vec.X = x;
    vec.Y = y;
    vec.Z = z;
    vec.magnitude = m;
    vec.unit = (vec.magnitude == 1 and vec or Vector3.new(x/m,y/m,z/m))
    --
    local vecStr = function ()
        return vec.X .. ", " .. vec.Y .. ", " .. vec.Z
    end
    insert("newindex",error)
    insert("tostring",vecStr)
    local operators = {add = "+"; sub = "-"; mul = "*"; div = "/"};
    for key,op in pairs(operators) do
        insert(key,function (_,v)
            local x,y,z do
                if type(v) == "number" then
                    x,y,z = v,v,v
                else
                    assert(Vector3.IsVector(v),"attempt to perform arithmetic on a Vector3 using a " .. type(v))
                    x,y,z = v.X,v.Y,v.Z
                end
            end
            local xOp = vec.X .. op .. x
            local yOp = vec.Y .. op .. y
            local zOp = vec.Z .. op .. z
            return loadstring("return Vector3.new(" .. xOp .. "," .. yOp .. "," .. zOp .. ")")()
        end)
    end
    setmetatable(vec,meta)
    return vec
end