Practical advantage of generics vs interfaces

Question

What would be a practical advantage of using generics vs interfaces in this case:

void MyMethod(IFoo f) 
{
}

void MyMethod(T f) : where T : IFoo
{
         


        

Answer 1

referring to the benchmark reported above

@Branko, calling a method through an interface is actually slower than >a "normal" virtual method call... Here's a simple benchmark: >pastebin.com/jx3W5zWb – Thomas Levesque Aug 29 '11 at 0:33

running the code in Visual Studio 2015 the result are roughly equivalent between Direct call and Through interface:

• Direct call: 90,51 millisec; 112,49 millisec; 81,22 millisec
• Through interface: 92,85 millisec;90,14 millisec; 88,56 millisec

the code used to benchmark (from http://pastebin.com/jx3W5zWb ) is:

using System;
using System.Diagnostics;

namespace test

{
    class MainApp
    {
        static void Main()
        {
            Foo f = new Foo();
            IFoo f2 = f;

            // JIT warm-up
            f.Bar();
            f2.Bar();

            int N = 10000000;
            Stopwatch sw = new Stopwatch();

            sw.Start();
            for (int i = 0; i < N; i++)
            {
                f2.Bar();
            }
            sw.Stop();
            Console.WriteLine("Through interface: {0:F2}", sw.Elapsed.TotalMilliseconds);

            sw.Reset();

            sw.Start();
            for (int i = 0; i < N; i++)
            {
                f.Bar();
            }
            sw.Stop();
            Console.WriteLine("Direct call: {0:F2}", sw.Elapsed.TotalMilliseconds);

            Console.Read();

        }

        interface IFoo
        {
            void Bar();
        }

        class Foo : IFoo
        {
            public virtual void Bar()
            {
            }
        }
    }
}