Can concrete class delegate the method implementation to child class?-CodePudding

I have a concrete top-class FooBase and an interface IFoo:

public class FooBase
{
    //some code
}

public interface IFoo
{
    void DoBar();
}

every child-classes FooChild implements and extends both:

public class FooChild : FooBase, IFoo
{
    public void DoBar()
    {
        //some implementation
    }
}

Can concrete FooBase define the signature of an empty method in order to delegate the implementation to child-classes as IFoo interface does?

CodePudding user response：

There are three ways in which a base class can allow or force it's inheritors to implement the desired signature:

1. Virtual method (allows to implement)

public interface IFoo { void DoBar(); }
public class Foo : IFoo { public virtual void DoBar() { /*Default impl. */ }
public class FooChild : Foo { public override void DoBar() { /* Child impl. */ }

2. Abstract method (forces to implement)

public interface IFoo { void DoBar(); }
public abstract class FooBase : IFoo { public abstract void DoBar(); }
public class FooChild : FooBase { public override void DoBar() { /* Child impl. */ }

3. Abstract separated method (forces to implement, no direct logical attachment to the interface)

public interface IFoo
{
    void DoBar();
}
public abstract class FooBase : IFoo
{
    public void DoBar() { DoBarRelatedWork(); }
    protected abstract void DoBarRelatedWork();
}
public class FooChild : FooBase
{
    public override void DoBarRelatedWork() { /* Child impl. */ }
}