继承（六）：new virtual的作用

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;


namespace InheritanceApp
{
    class Employee
    {
        public string name;
        public Employee(string name)
        {
            this.name = name;
        }       
        public  virtual void  CalculatePay()
        {
            Console.WriteLine("Employee.CalculatePay called for {0}",name);
        }
    }  
   
    class SalariedEmployee : Employee
    {
        public SalariedEmployee(string name)
            : base(name)
        { }
        //public override  void CalculatePay()
        //{
        //    Console.WriteLine("SalariedEmployee.CalculatePay called for {0} ",name);
        //}
        //这里将override改为new virtrual<===>virtual(new 是默认的)
        public new virtual  void CalculatePay()
        {
            Console.WriteLine("SalariedEmployee.CalculatePay called for {0} ", name);
        }
    }
    //ContractEmployee 继承自 SalariedEmployee
    class ContractEmployee : SalariedEmployee
    {
        public ContractEmployee(string name)
            : base(name)
        { }
        public override void CalculatePay()
        {
            Console.WriteLine("ContractEmployee.CalculatePay called for {0}", name);
        }
    }
    class Program
    {
        protected Employee[] employees;
        public void LoadEmployees()
        {
            employees = new Employee[2];
            employees[0] = new ContractEmployee("Adam Barr");
            employees[1] = new SalariedEmployee("Max Benson");
        }
        public void DoPayroll()
        {
            for (int i = 0; i < employees.GetLength(0); i++)
            {
                employees[i].CalculatePay();
            }
        }
        public void ProcessSalariedEmployees()
        {
            SalariedEmployee[] se = new SalariedEmployee[2];
            se[0] = new ContractEmployee("Adam Barr");
            se[1] = new SalariedEmployee("Max Benson");
            foreach(SalariedEmployee s in se )
            {
                s.CalculatePay();
            }

        }
        static void Main(string[] args)
        {
            Program p = new Program();
            //Employee的调用：会出现那样的结果分析：
            //1.SalariedEmployee.CalculatePay的声明中添加new关键字以为着，在DoPayroll方法中遍历Employee对象引用时就不在考虑这个方法
            //2.因为他是虚拟的，所以下一级别的派生类ContractEmployee中的重定义方法现在是对SalariedEmployee中的虚拟方法进行重新定义，而不是对Employee中的虚拟方法进行重新定义。
            //因此ContractEmployee.CalculatePay方法也不被考虑
            p.LoadEmployees();
            p.DoPayroll();
            //new virtual的意义：假设我们希望在一个含有所有SalariedEmployee的子集上对雇员进行分类           
            p.ProcessSalariedEmployees();
            Console.ReadKey();     

        }
    }

   
}