using System; public interface I1 { void i1(); } public interface I2 { void i2(); } class C : I1, I2 { public void i1() { Console.WriteLine("I1.i1()"); } public void i2() { Console.WriteLine("I2.i2()"); } } public class Test { public static void Main() { f(new C()); } public static void f(T t) where T : I1, I2 { t.i1(); t.i2(); } }