IEnumerable扩展支持Add，Remove等操作

 1 public static class CollectionExtend
 2 {
 3 /// <summary>
 4 /// 向集合中添加元素
 5 /// </summary>
 6 /// <typeparam name="T"></typeparam>
 7 /// <param name="collection"></param>
 8 /// <param name="value"></param>
 9 public static void Add<T>(this IEnumerable<T> collection, T value)
10 {
11 var list = collection as List<T>;
12 if (list != null) list.Add(value);
13 }
14 
15 /// <summary>
16 /// 从集合中删除元素
17 /// </summary>
18 /// <typeparam name="T"></typeparam>
19 /// <param name="collection"></param>
20 /// <param name="value"></param>
21 public static void Remove<T>(this IEnumerable<T> collection, T value)
22 {
23 var list = collection as List<T>;
24 if (list != null) list.Remove(value);
25 }
26 /// <summary>
27 /// 检索集合中是否包含某个元素
28 /// </summary>
29 /// <typeparam name="T"></typeparam>
30 /// <param name="collection"></param>
31 /// <param name="value"></param>
32 /// <returns></returns>
33 public static bool Contains<T>(this IEnumerable<T> collection, T value)
34 {
35 var list = collection as List<T>;
36 return list != null && list.Contains(value);
37 }
38 }