Force generic interface implementation in C#

Question

Is there anyway to force a constraints for a generic definition to implement a "generic interface" ... that is, I want the class to support passing an interface and a generic class constraining it so that the class implements the interface. For example if I say:

MyGenericClass<IMyInterface, MyImplementation>.DoSomething();

That should be constrained so that MyImplementation implements IMyInterface

As far as I know that can be achieved by

public class Dynamic_Loader<T, S> where S: T

Now, is there anyway to also force T to be an interface?

Edit: The purpose of this was to have something like:

private static List<T> interfaceList = new List<T>();

public static List<T> InterfaceList {get { return interfaceList;}}

public static void Add(S input) { interfaceList.Add(input);}

and have the list restricted to only interfaces (since it is supposed to return implementations of certain interfaces)

Answer 1

Do you mean, can a constraint also be put on T like where T : interface ?

If so, then no : this list pretty much covers your options.

What you have is as close as it gets, I believe.

Out of curiosity, what would be your reason for wanting to constrain T to be an interface?

Or do you mean can a constraint also be put on T for T to implement some specific interface?

If so, then yes : simply have two where clauses (eg, where S : T where T : U ).

Answer 2

where T: IMyOtherInterfaceForT

Example:

    public class Test<T, V>
    where T : V
    where V : IEnumerable<int>
    {
    }

Answer 3

You could do something like this to enforce it at runtime instead of compile time.

public class Test<T> where T : class
{
  public Test()
  {
    Type t = typeof( T );
    if( !t.IsInterface )
      throw new ArgumentException( "T must be an interface type" );
  }
}