調用父構造函數，但保留孩子的參考C＃

Question

我打電話給基礎構造函數，但不知何故，我需要指向孩子回來。看看波紋管的例子：

//兒童

public CompanyEventsView(IAggregator aggregator, IRepository<CompanyEvents> repository, int i) 
     : base(aggregator, repository, i) 
    { 

    } 

//基地

public BaseViewModelFor(IAggregator aggregator, IRepository<TSource> repository, int i) 
    { 
     Aggregator = aggregator; 
     var source = repository.GetKey(i); 
     this.MapFromSourceObject(source); // So "This" here should be pointing to the child class 
    } 

是否有這樣做的方法嗎？

Answer 1

this和base不引用不同的實例，它們是相同的。

如果您在子類中定義了MapFromSourceObject方法，則可以將this轉換爲子類型，例如：(this as CompanyEventsView).MapFromSourceObject(source)。

但是這會打敗整個繼承點。

也許定義爲MapFromSourceObject抽象或虛擬的基類？

如果你的基類依賴於子類的實現，那麼使得類本身抽象將是一個更好的主意。

Answer 2

也許這個例子可以幫助你一點點好繼承：

namespace CSharpConsoleApplication.Tests 
{ 
    using System; 
    using System.Collections.Generic; 
    using System.Linq; 

    class TemporaryTest 
    { 
     public static void Run() 
     { 
      Mother<FirstCompanyEvent> firstChild = new FirstChild(new FirstCompanyEvent("this is wrong")); 
      firstChild.Print(); 


      Mother<SecondCompanyEvent> intChild = new SecondChild(new SecondCompanyEvent("you are too young to do this")); 
      intChild.Print(); 
     } 
    } 


    public abstract class BaseCompanyEvent 
    { 
     protected string Value { get; private set; } 

     public BaseCompanyEvent(string value) 
     { 
      Value = value; 
     } 

     public abstract string GetMessage(); 
    } 

    public class FirstCompanyEvent : BaseCompanyEvent 
    { 
     public FirstCompanyEvent(string value) 
      : base(value) 
     { } 

     public override string GetMessage() 
     { 
      return "First born: " + Value; 
     } 
    } 

    public class SecondCompanyEvent : BaseCompanyEvent 
    { 
     public SecondCompanyEvent(string value) 
      : base(value) 
     { } 

     public override string GetMessage() 
     { 
      return "Younger brother: " + Value; 
     } 
    } 



    public abstract class Mother<T> where T : BaseCompanyEvent 
    { 
     protected T CustomEvent { get; private set; } 

     public Mother(T customEvent) 
     { 
      CustomEvent = customEvent; 
     } 

     public abstract void Print(); 
    } 

    public class FirstChild : Mother<FirstCompanyEvent> 
    { 
     public FirstChild(FirstCompanyEvent e) 
      : base(e) 
     { } 

     public override void Print() 
     { 
      Console.WriteLine(CustomEvent.GetMessage()); 
     } 
    } 

    public class SecondChild : Mother<SecondCompanyEvent> 
    { 
     public SecondChild(SecondCompanyEvent e) 
      : base(e) 
     { } 

     public override void Print() 
     { 
      Console.WriteLine(CustomEvent.GetMessage()); 
     } 
    } 
}