日期:2010-09-13 浏览次数:20390 次
集合类型初始化器(Collection Initializers)
想看一段“奇怪”的代码:
1class Program
2 {
3 static void Main(string[] args)
4 {
5 var a = new Point { x = 10, y = 13 };
6 var b = new Point { x = 33, y = 66 };
7
8 var r1 = new Rectangle { p1 = a, p2 = b };
9 Console.WriteLine("r1: p1 = {0},{1}, p2 = {2},{3}",
10 r1.p1.x, r1.p1.y, r1.p2.x, r1.p2.y);
11
12 var c = new Point { x = 13, y = 17 };
13 var r2 = new Rectangle { p2 = c };
14
15 Console.WriteLine("r2: p1 == {0}, p2 = {1}, {2}",
16 r2.p1, r2.p2.x, r2.p2.y);
17 }
18 }
19
20 public class Point
21 {
22 public int x, y;
23 }
24 public class Rectangle
25 {
26 public Point p1, p2;
27 }
注意到集合类型的初始化语法了吗?直截了当!
这也是C# 3.0语法规范中的一个新特性。
也许下面的例子更能说明问题:
这是我们以前的写法:
1class Program
2 {
3 private static List<string> keywords = new List<string>();
4
5 public static void InitKeywords()
6 {
7 keywords.Add("while");
8 keywords.Add("for");
9 keywords.Add("break");
10 keywords.Add("switch");
11 keywords.Add("new");
12 keywords.Add("if");
13 keywords.Add("else");
14 }
15
16 public static bool IsKeyword(string s)
17 {
18 return keywords.Contains(s);
19 }
20 static void Main(string[] args)
21 {
22 InitKeywords();
23 string[] toTest = { "some", "identifiers", "for", "testing" };
24
25 foreach (string s in toTest)
26 if (IsKeyword(s)) Console.WriteLine("'{0}' is a