casting generic list to generic list of interfaces

I have a class looking somwhat like this:

public class TestClass : IMyInterface

{

}

and a generic list:

List<TestClass> list = new List<TestClass>();

list.Add(new TestClass());

Now I want to cast my list to a list of interfaces:

List<IMyInterFace> list1 = (List<IMyInterFace>)list;

That doesn't work

List<IMyInterFace> list1 = list;

Doesn't work either. It is easy to cast the individual elements in the list but not the entire list. Howcome

Best regards

Alex

.NET Development1

Because there's no inheritance relation between List<X> and List<Y> even if there is one between X and Y.

Also keep in mind that if such a cast was possible, you would then be able to do list1.Add(new SomeOtherIMyInterfaceImplementation()) which would violate the type of your list object.

As a workaround, perhaps you can create a new list with List<T>.ConvertAll