hernyákféle storage class

class storage
    {
        protected List<tablet> list = new List<tablet>();
        public void Add(tablet a)
        {
            if (a == null) throw new Exception("null nem lehet");
            list.Add(a);
        }
        public void Delete(tablet a)
        {
            int i = list.IndexOf(a);
            if (i == -1) throw new Exception("nincs a listan");
            list.RemoveAt(i);
        }
        public void Delete(int i)
        {
            if (i<0) throw new Exception("nincs ilyen index");
            if (i >= list.Count ) throw new Exception("nincs ilyen index");
            list.RemoveAt(i);
        }
        public int dbszam
        {
            get { return list.Count; }
        }
        public int total_cost
        {
            get
            {
                int sum = 0;
                foreach (tablet t in list)
                    sum = sum + t.cost;
                return sum;
            }

        }
    }