第三部分 类和结构2---------------

经典的代码:

using System;

class CommaDelimitedFile
...{
            public CommaDelimitedFile(string fileName)
                  ...{
                                 Console.WriteLine("[CommaDelimitedFile."+"CommaDelimitedFile]file name={0}",filename);
                                 }
 }

enum TableId
...{
   Customers,
   Suppliers,
        Vendors
};
class DbTable:CommaDelimitedFile
         static string GetFileName(TableId tableId)
               ...{
                    string fileName;
                   switch(tableId)
                                   ...{
                                             case TableId.Customers:
                                                                fileName="customers.txt";
                                                                break;
                                             case  TableId.Supplied;
                                                                fileName="suppliers.txt";
                                                                break;
                                             case   TableId.Vendors:
                                                                fileName="venders.txt";
                                                                break;
                                             default:
                                                        throw new ArgumentException("[DbTable."+
                                                        "GetFileName] Could not resolve table name"];
                                     }
                         return fileName;
               }
                 public DbTable(TableId tableId):base(GetFileName(tableId))
...{
                         Console.WriteLine("[DbTable.DbTable]tableId={0}","+tableId.ToString());
                             }
}
class BaseInitializer4
   ...{
            public static void Main()
              ...{
                     Cosole.WriteLine("[Main] Instantiating a " + "Customer Table object...");
                     DbTable derived=new Dbtable(TableId.Customers);
               }
    }