Sealing abstract class or interface in .NET class

Question

In Scala, it is possible to have define a base class or trait(interface) sealed, so that the only classes which are allowed to extend that class must be placed in the same class.

This is a useful pattern when coding libraries, is there any equivalent in .NET?

Answer 1

The only way to simulate that is to have a private constructor in the abstract class and provide implementation as nested classes.

Example

public abstract class Foo
{
  private Foo(int k) {}

  public class Bar : Foo
  {
     public Bar() : base(10) {}
  }
}