C#用更具体的类型覆盖抽象属性

Question

I have a rather simple problem, but I can't find a proper solution anywhere. I would like to specify an abstract object CustomValues as property in my abstract parent class. However, the class inheriting from it should be able to use a more specific type as an object for this property CustomValues. At first I thought I would solve the problem by an interface, but unfortunately that didn't work out either. How do you do something like that, that it works?

public abstract class MyAbstract {
    public abstract object CustomValues { get; set; }
}

public class MyImplementation : MyAbstract {
    public override MySpecificClass CustomValues { get; set; }
}

This will throw me three errors:

• Missing implementation for getter
• Missing implementation for setter
• Type missmatch between type object and MySpecificClass

Answer 1

The solution suggested in the comments would look something like this. (I'm assuming CustomValues should be a collection of something.)

public class MyClass<T>
{
    public ICollection<T> CustomValues { get; set; }
}

Or to ensure CustomValues itself cannot be reassigned, but can be accessed and added to:

public class MyClass<T>
{
    public ICollection<T> CustomValues { get; } = new List<T>();
}

Answer 2

I think your original thought that use an interface (+ generic) was at the correct direction. In general you might want to add type constraints as well.

public interface ICustomValues {
  ....
}

public class MySpecificClass : ICustomValues {
  ....
}

public abstract class MyAbstract<T> where T : ICustomValues {
   public abstract T CustomValues {
     get;
     set;
   }
}


public class MyImplementation: MyAbstract<MySpecificClass>  {
  public override   MySpecificClass CustomValues { get; set; }
}

Answer 3

Thanks to you all guys. I found the solution by using a generic properly :

public abstract class MyAbstract<T> {
    public abstract T CustomValues { get; set; }
}

public class MyImplementation : MyAbstract<MySpecificClass> {
    public override MySpecificClass CustomValues { get; set; }
}