[...]... C# Until now, C# generics have generics have been invariant been invariant C# 4.0 supports C# 4.0 supports safe co- and safe co- and contra-variance contra-variance public interface IEnumerable T> public interface IEnumerable IEnumerable public interface IEnumerator IEnumerator dynamic mapping We need to cast We need to cast ((Excel.Range)xl.Cells[1,1]).Value2 == “ID”; ((Excel.Range)xl.Cells[1,1]).Value2 “ID”; xl.Cells[1,1].Value2 = “ID”; Optional and named parameters xlChart.ChartWizard(cellRange.CurrentRegion,... y); int Compare(T x, y); }} IComparer objComp == GetComparer(); IComparer objComp GetComparer(); IComparer strComp == objComp; IComparer strComp objComp; Variance in C# 4.0 class Base {{ class Base public virtual void Foo(int xx == 4, int yy == 5) {{ public virtual void Foo(int 4, int 5) Console.WriteLine("x:{0}, y:{1}", x, y); Console.WriteLine("x:{0}, y:{1}", x, y); . class="bi x0 y0 w0 h0" alt=""