sealed

VS compiler does not allow to create sealed exposed types for WINMD type library. Why is this restriction placed ? (I know about sealed types advantages, my question is with respect to Win RT components). This is an architectural limitation, imposed by COM. Which sits at the core of any WinRT type, they are derived from IUnknown and IInspectable. The problem with COM is that it only supports interface inheritance but not implementation inheritance. Which was a strong COM design goal, implementation inheritance is too fraught with implementation details, including the infamous diamond problem.

I was looking through some C# code for extending language support in VS2010 (Ook example). I saw some classes called internal sealed class What do these do? Would one use them? It is a class that: internal : Can only be accessed from within the assembly it is defined (or friend assemblies). sealed : Cannot be inherited. Marking classes as internal is a way of preventing outside users of an assembly from using them. It's really a form of design encapsulation and IMHO it is good practice to mark types that are not part of the intended public API\object models as internal . In the long term this

What is the difference between sealed abstract and abstract Scala class? The difference is that all subclasses of a sealed class (whether it's abstract or not) must be in the same file as the sealed class. Daniel C. Sobral As answered , all directly inheriting subclasses of a sealed class (abstract or not) must be in the same file. A practical consequence of this is that the compiler can warn if the pattern match is incomplete. For instance: sealed abstract class Tree case class Node(left: Tree, right: Tree) extends Tree case class Leaf[T](value: T) extends Tree case object Empty extends Tree

I'm trying to create a class that uses its own state to operate on the state of an external object that it holds a reference to. The external object can be of class A or B, which are similar, but not controlled by the author. So a sealed class is created to access their common attributes, per this earlier answer from @SimY4 . // *** DOES NOT COMPILE *** class A { // foreign class whose structure is not modifiable val prop get()= "some string made the Class-A way" } class B { // foreign class whose structure is not modifiable val prop get()= "some string made the Class-B way" } data class

After reading the answer here , I decided to mark my class as sealed in order to simplify the IDisposable implementation. Why does sealed affect the implementation of IDisposable (e.g. GC.SuppressFinalize(this); does not need to be called)? Please explain what is happening. I need to be able to explain to a fellow developer why I made the class sealed. If a class which implements IDisposable is not sealed, it is likely that a derived class will need to do something in response to Dispose , but the base-class actions for Dispose should be performed as well. If the class exposes a public Dispose

Is it always necessary to follow the sealed keyword with override in the signature of a method like the below code: public sealed override string Method1(){.....} I mean, if I want to "seal" the method within the base class without overriding, is the override keyword still necessary? Sealing a method only makes sense if you override it. What happens here is the following: You are overriding a method from a base class ( override ) and tell the compiler that classes derived from your class are no longer allowed to override this method ( sealed ). If the method is a new one declared by you in

Would anybody please tell me as the reason the following use of sealed does not compile? Whereas, if I replace sealed with final and compile it as Java, it works. private sealed int compInt = 100; public bool check(int someInt) { if (someInt > compInt) { return true; } return false; } That's because final in Java means plenty of different things depending on where you use it whereas sealed in C# applies only to classes and potentially virtual members (methods, properties, events). In Java final can be applied to: classes , which means that the class cannot be inherited. This is the equivalent