集合

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 keyword", s);
27        }
28    }
这是我们在C# 3.0中的写法：
 1class Program
 2    {
 3        private static List<string> keywords = new List<string> {
 4                            "while", "for", "break", "switch", "new", "if", "else"
 5                            };
 6
 7        public static bool IsKeyword(string s)
 8        {
 9            return keywords.Contains(s);
10        }
11
12        static void Main(string[] args)
13        {
14            string[] toTest = { "some", "identifiers", "for", "testing" };
15
16            foreach (string s in toTest)
17                if (IsKeyword(s)) Console.WriteLine("'{0}' is a keyword", s);
18        }
19    }是不是变得像枚举类型的初始化了？
个人觉得这对提高代码的阅读质量是很有帮助的，
否则一堆Add（）看上去不简洁，感觉很啰嗦。