For comment 3424557

class FileEx
    {
        string path;
        Func<string> current;
        Func<bool> hasNext;

        public FileEx(string path, Func<string> current, Func<bool> hasNext)
        {
            this.path = path;
            this.current = current;
            this.hasNext = hasNext;
        }

        public void WriteAll()
        {
            System.IO.StreamWriter sw = new System.IO.StreamWriter(path);

            try
            {
                var line = current ();

                while (hasNext ())
                {
                    sw.WriteLine (line);
                    line = current ();
                }
            }
            catch (Exception ex)
            {
                throw;
            }
            finally
            {
                sw.Close ();
            }
        }
    }