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)

Dan Tao · Accepted Answer · 2010-08-30 13:21:58Z

8

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 (e.g., where S : T where T : U).

answered Aug 30, 2010 at 13:21

Dan Tao

129k57 gold badges309 silver badges451 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Jorge Córdoba Over a year ago

Oh, I was going for this: public static List<T> interfacelist = new List<T>; public static void Add(S input); And yeah, it will work too if T is just a base class but the client should be getting interfaces, not base classes.

MianenCZ Over a year ago

Here is one (probably edge case) scenario where I would use where T : interface. In unity, there is a method TryGetComponent<T>(), where T is just an object, but when calling it, you get an error that > TryGetComponent should be called only with Types that extend UnityEngine.Component, or Types that are an Interface So I need to specify one option for where T:UnityEngine.Component and second for any interface. Which is not possible at the moment

Tokk · Accepted Answer · 2010-08-30 13:21:43Z

3

where T: IMyOtherInterfaceForT

Example:

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

answered Aug 30, 2010 at 13:21

Tokk

4,5223 gold badges35 silver badges48 bronze badges

Comments

ScottS · Accepted Answer · 2013-10-04 20:37:21Z

2

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" );
  }
}

answered Oct 4, 2013 at 20:37

ScottS

211 bronze badge

Collectives™ on Stack Overflow

Force generic interface implementation in C#

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related