Method with same name and signature but different return type in C#

Question

I had an interview where I was asked the following:

Question: A method with same name and signature but different return type. Is it possible and what is this type c

Answer 1

Though return type covariance is not supported in C#, it is possible to emulate it by using explicit implementation and method hiding. That is a pattern which is used thoroughly in the ADO.NET APIs.

E.g.:

public interface ISomeValue { }
public abstract class SomeValueBase : ISomeValue { }
public class SomeValueImpl : SomeValueBase { }

public interface ISomeObject { ISomeValue GetValue(); }

public abstract class SomeObjectBase : ISomeObject
{
    ISomeValue ISomeObject.GetValue() { return GetValue(); }
    public SomeValueBase GetValue() { return GetValueImpl(); }

    protected abstract SomeValueBase GetValueImpl();
}

public class SomeObjectImpl : SomeObjectBase
{
    protected override SomeValueBase GetValueImpl() { return GetValue(); }
    public new SomeValueImpl GetValue() { return null; }
}

By doing that, the net result of calling GetValue() is that it will always match the most specific available type.