Is this scenario possible in c# method inheritance

Question

I want to know if this scenario is possible in C# inheritance.

Let's assume we have 3 classes.

public class Base
{   
    public abstract void SomeMethod(Base param);
}

public class ChildA : Base
{   
    public override void SomeMethod(ChildA param);
}

public class ChildB : Base
{   
    public override void SomeMethod(ChildB param);
}

I do not want to typecast the base param everytime in the child class method. So, is this possible?

Answer 1

That feature is called formal parameter type covariance. It is not supported by c#. Also it is not typesafe.

Two variations on it are typesafe. Formal parameter contravariance and return type covariance. C# does support those for generic delegate conversions and for method group to delegate conversions but does not support them for virtual method overriding.

You're out of luck here I'm afraid.