我可以覆盖子类中的类变量，并将其类型更改为子类

Question

是否有方法来覆盖子类中的变量，但也可以将类型更改为该类型的子类。 即。

public class BaseClass 
{ 
    public BaseClass() { } 
    protected virtual MyBase WorkField { get { return new MyBase(); } } 
    public int WorkProperty 
    { 
     get { return WorkField.Value; } 
    } 
} 

public class DerivedClass : BaseClass 
{ 
    public DerivedClass():base() { } 

    /* I get an error here saying that WorkField needs to be MyBase type*/ 
    protected override MyExtend WorkField 
    { 
     get 
     { 
      return new MyExtend(); 
     } 
    } 

    //public new int WorkProperty 
    //{ 
    // get { return 0; } 
    //} 
} 

public class MyBase 
{ 
    public int Value = 1; 
} 

public class MyExtend : MyBase 
{ 
    public int value = 20; 
} 

有没有类似这样的方法，但有效？ 所以我可以有一个在MyBase上执行任务的superClass，然后有一个在MyEntend版本上执行任务的子类。 没有铸造它，每次我使用它。

Answer 1

在这种情况下没有理由更改签名。只需返回派生类型：

public class DerivedClass : BaseClass 
{ 
    public DerivedClass():base() { } 

    protected override MyBase WorkField 
    { 
     get 
     { 
      return new MyExtend(); 
     } 
    } 

    //public new int WorkProperty 
    //{ 
    // get { return 0; } 
    //} 
} 

您的子类的多态行为将允许您返回它。

Answer 2

public class BaseClass<T> where T: MyBase, new() 
    { 
     public BaseClass() { } 
     protected virtual T WorkField { get { return new T(); } } 
     public int WorkProperty { get { return WorkField.Value; } } 
    } 

    public class DerivedClass : BaseClass<MyExtend> 
    { 
     public DerivedClass() : base() { } 
     protected override MyExtend WorkField { get { return new MyExtend(); } } 

     //public new int WorkProperty 
     //{ 
     // get { return 0; } 
     //} 
    } 

    public class MyBase 
    { 
     public MyBase() 
     { 

     } 
     public int Value = 1; 
    } 
    public class MyExtend : MyBase 
    { 
     public int value = 20; 
    } 

Answer 3

重写签名应该是基本的基础方法。

public class BaseClass<T> where T : MyBase, new() 
{ 
    public BaseClass() { } 
    protected virtual T WorkField { get { return new T(); } } 
    public int WorkProperty { get { return WorkField.Value; } } 
} 

public class DerivedClass : BaseClass<MyBase> 
{ 
    public DerivedClass() : base() { } 

//相同的错误发生是由于基属性的类型是 “MyBase”

保护覆盖MyExtend WorkField {{返回新MyExtend（）; }}

//public new int WorkProperty 
    //{ 
    // get { return 0; } 
    //} 
}