''Object invalidation'' refers to the marking of an object as ''invalid'', preferably in a controlled way so that further access to the object results in controlled failure (rather than UndefinedBehavior).  In some ways, a form of TypeMigration.

Can be implemented in several ways:

By the class designer:

* Have a "valid" flag in the object, and an IsValidMethod.  The DestroyMethod (or whatever means are used to invalidate the object) clear this flag; all other methods check the flag via the IsValidMethod and fail if it returns false.

By the language implementer:

* Change the VeeTable pointer (or whatever magic field contains runtime type information) to null or some other distinguished value indicating a DestroyedObject (which might be a type recognized by the type system).

* If TombStone''''''s are used; change the TombStone to point to a DestroyedObject.