Why is this cast not possible?

Question

interface IFolderOrItem where TFolderOrItem : FolderOrItem {}

abstract class FolderOrItem {}

class Folder : FolderOrItem {}

abstract class It         


        

Answer 1

The problem is that a cast does not work on the generic arguments, but on the class as a whole. Document inherits from Item, true, but IFolderOrItem< Document> does not inherit from IFolderOrItem< Item>, nor is related with it in any way.