gistfile1.cs

interface IFoo { void Method(); }
class Foo : IFoo { public void Method() { Console.WriteLine(“hello”); }  }

// Interface
class FooUser1 {
   void MethodUser(IFoo foo) { foo.Method(); }
}

// Generic
class FooUser2<T> where T : IFoo {
   void MethodUser(T foo) { foo.Method(); }
}

// Delegate
internal delegate void MyDelegate();
class FooUser3 {
   void MethodUser(MyDelegate fooMethod) { fooMethod(); }
}
…