[笔记]接口VS代理

声明代理

 public delegate void Transfrom(int i);

定义工具类

  public class Util
    {
        
        public static void Square(int i)              //此方法用于在控制台打印I*I
        {
            i = i * i;
            Console.WriteLine(i);
        }
        public static void Print(int i)                //此方法写入文件
        {
            i = i * i;
            
            System.IO.File.WriteAllText("C:\\Test.txt", i.ToString());
           
        }
        public static void TransformALL(int value,Transfrom t)
        {
            
                t += Util.Print;                            //多播委托
                t(value);
        }
    }

测试类

 public class Test
    {
        public static void Main()
        {
          
            Util.TransformALL(2, Util.Square);
            Console.Read();
        }
    }

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以下是接口实现

public interface ITransformer
{
  int Transform (int x);
}

public class Util
{
 public static void TransformAll (int[] values, ITransformer t)
 {
   for (int i = 0; i < values.Length; i++)
     values[i] = t.Transform(values[i]);
 }
}

class Test : ITransformer
{
 static void Main(  )
 {
   int[] values = new int[] {1, 2, 3};
   Util.TransformAll(values, new Test(  ));
   foreach (int i in values)
     Console.WriteLine (i);
 }

 public int Transform (int x) { return x * x; }
}

接口的弊端

In the ITransformer example, we don't need to multicast. However, the interface defines only a single method. Furthermore, our listener may need to implement ITransformer multiple times, to support different transforms, such as square or cube. With interfaces, we're forced into writing a separate type per transform, since Test can only implement ITransformer once. This is quite cumbersome: