is it possible to mark overridden method as final

Question

In C#, is it possible to mark an overridden virtual method as final so implementers cannot override it? How would I do it?

An example may make it easier to understand:

class A {    abstract void DoAction(); } class B : A {    override void DoAction()    {        // Implements action in a way that it doesn't make        // sense for children to override, e.g. by setting private state        // later operations depend on      } } class C: B {    // This would be a bug    override void DoAction() { } } 

Is there a way to modify B in order to prevent other children C from overriding DoAction, either at compile-time or runtime?

Answer 1

Yes, with "sealed":

class A {    abstract void DoAction(); } class B : A {    sealed override void DoAction()    {        // Implements action in a way that it doesn't make        // sense for children to override, e.g. by setting private state        // later operations depend on      } } class C: B {    override void DoAction() { } // will not compile } 

Answer 2

You can mark the method as sealed.

http://msdn.microsoft.com/en-us/library/aa645769(VS.71).aspx

class A {    public virtual void F() { } } class B : A {    public sealed override void F() { } } class C : B {    public override void F() { } // Compilation error - 'C.F()': cannot override                                  // inherited member 'B.F()' because it is sealed }