How to Inherit method but with different return type?

Question

Given the following classes:

ClassA
{
     public ClassA DoSomethingAndReturnNewObject()
     {}    
}

ClassB : ClassA
{}

ClassC : ClassA
{}

Answer 1

What you're describing is a covariant return type and is not supported in C#.

However, you could create ClassA as an open generic and have the closed generic inheritors return their own type.

Example:

public abstract class ClassA where T: ClassA, new()
{
    public abstract T DoSomethingAndReturnNewObject();
}

public class ClassB: ClassA
{
    public override ClassB DoSomethingAndReturnNewObject()
    {
        //do whatever
    }
}