调用基类一集派生方法 [英] calling derived methods on a baseclass collection

问题描述

我有一个抽象类命名为A，和其他类（B，C，D，E，...）实现A.
我的派生类持有不同类型的值。
我也有一个对象的列表

I have one abstract class named A, and other classes (B, C, D, E, ...) that implements A. My derived classes are holding values of different types. I also have a list of A objects.

    abstract class A { }
    class B : class A
    {
      public int val {get;private set;}
    }
    class C : class A
    {
      public double val {get;private set;}
    }
    class D : class A
    {
      public string val {get;private set;}
    }

    class Program
    {
        static void Main(string[] args)
        {
          List list = new List { new B(), new C(), new D(), new E() };
          // ... 

          foreach (A item in list)
          {
            Console.WriteLine(String.Format("Value is: {0}", item.val);
          }
        }
    }

。 ..where的.VAL不是由基类OFC闻名。

...where the .val is not known by the base-class ofc.

我怎样才能得到这个动态的行为吗？我不想在长时间使用的getType 。开关/ if语句

How can i get this dynamic behaviour? I don't want to use getType in a long switch/if-statements.

推荐答案

试试这个：

using System;
using System.Collections.Generic;

abstract class A
{
    public abstract dynamic Val { get;   set; }

}
class B : A
{
    public override dynamic Val { get;  set; }
}
class C : A
{
    public override dynamic Val { get;  set; }
}
class D : A
{
    public override dynamic Val { get;  set; }
}

class Program
{
    static void Main(string[] args)
    {
        var list = new List<A> { new B(), new C(), new D() };
        // ... 

        foreach (A item in list)
        {
            Console.WriteLine(String.Format("Value is: {0}", item.Val));
        }
    }
}

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