New Features in C# 2.0 Sergey Baidachni MCT, MCSD, MCDBA

C# ver. 2.0  Generics  Iterators  Partial types  Anonymous method

Generics  Array of object?  What is it?  How to create Generics

Array of object?  Boxing and Unboxing ArrayList list=new ArrayList(); list.Add(4); list[0]=(int)list[0]+1;  Explicit conversion int j; j=(int)list[0]; //unboxing  Problem with performance and exceptions

Generics (What is it?)  Templates in C++  No problem with performance List list=new List[int](); list.add(2); list.add(“table”); //compilation error  No problem with conversion int j; j=list[0];

How create Generics (base syntaxes)  Please use any name for your type class MyClass { private ItemType item; }  Limitation: You can use only methods inherited from object

Generics (extensions)  Use Where in order to extend your possibilities Class MyClass where T1: IMyInterface where T2: IComparable {…..}  Interfaces public interface IMyInterface { void WhatIsIt(T i); }

Iterators  Enumerators vs. Iterators  yield keyword public IEnumerator GetEnumerator() { for(int i = 1;i< 5;i++) { yield return i; if(i > 2) yield break; }  Benifits

Partial Types  One class – many files?  partial keyword //first file (MyClass_1.cs) public partial class MyClass { private int nCount;..... } //second file (MyClass_2.cs) public partial class MyClass { private bool isPresent..... }

Anonymous method  Too lazy to write a separate method? There’s no need to. Button b=new Button(); b.Click+= new Button.ClickEventHandler(object s,EventArgs e) { Console.WriteLine(“Hello”); };  You can use local variable  new? Who needs it?

Books .NET Framework: Secret tips on Windows Applications Creation by Sergey Baidachni .NET Framework: Secret tips on Web- application creation by Sergey Baidachni (coming up soon)