歧路

   1: // 适用 foreach 遍历 Dictionary 集合中的元素时,

   2: // 元素的正确类型应该是 KeyValuePair<TKey, TValue>.

   3: Console.WriteLine();

   4: foreach( KeyValuePair<string, string> kvp in openWith )

   5: {

   6:     Console.WriteLine("Key = {0}, Value = {1}", 

   7:         kvp.Key, kvp.Value);

   8: }

   1: // 声明, 想想看，我需要多少个 if, typeof 判断?

   2: public class Factory {

   3:     public static IMath Init<T>() {

   4:         if( typeof( T ) is int ) {

   5:             return new IntImplIMath();

   6:         }

   7:     }

   8: }

   9:  

  10: // 调用

  11: ops.Math = Factory.Init<int>();