委派的多点传输

可以使用一个委派调用多个方法，委派和方法都有一个限制：委派和方法都必须返回void。

下面的例子定义了一个叫DelegateCalculation的返回值为void的派生类：

    public delegate void DelegateCalculation(
        double acceleration, double time
    );

 1 /*
 2   Example12_2.cs illustrates the use of a multicast delegate
 3  */
 4 
 5 using System;
 6 
 7 
 8 // declare the DelegateCalculation delegate class
 9 public delegate void DelegateCalculation(
10   double acceleration, double time
11 );
12 
13 
14 // declare the MotionCalculations class
15 public class MotionCalculations
16 {
17 
18   // FinalSpeed() calculates the final speed
19   public static void FinalSpeed(
20     double acceleration, double time
21   )
22   {
23     double finalSpeed = acceleration * time;
24     Console.WriteLine("finalSpeed = " + finalSpeed +
25       " meters per second");
26   }
27 
28   // Distance() calculates the distance traveled
29   public static void Distance(
30     double acceleration, double time
31   )
32   {
33     double distance = acceleration * Math.Pow(time, 2) / 2;
34     Console.WriteLine("distance = " + distance + " meters");
35   }
36 
37 }
38 
39 
40 class Example12_2
41 {
42 
43   public static void Main()
44   {
45 
46     // declare and initialize the acceleration and time
47     double acceleration = 10;  // meters per second per second
48     double time = 5;  // seconds
49     Console.WriteLine("acceleration = " + acceleration +
50       " meters per second per second");
51     Console.WriteLine("time = " + time + " seconds");
52 
53     // create delegate object that call the
54     // MotionCalculations.FinalSpeed() and
55     // MotionCalculations.Distance() methods
56     DelegateCalculation myDelegateCalculation1 =
57       new DelegateCalculation(MotionCalculations.FinalSpeed);
58     DelegateCalculation myDelegateCalculation2 =
59       new DelegateCalculation(MotionCalculations.Distance);
60 
61     // create a multicast delegate object from
62     // myDelegateCalculation1 and
63     // myDelegateCalculation2
64     DelegateCalculation myDelegateCalculations =
65       myDelegateCalculation1 + myDelegateCalculation2;
66 
67     // calculate and display the final speed and distance
68     // using myDelegateCalculations
69     myDelegateCalculations(acceleration, time);
70 
71   }
72 
73 }

接着，在MotionCalculations类中定义两个返回void的叫FinalSpeed和Distancede方法。

public class MotionCalculations
{

  // FinalSpeed() calculates the final speed
  public static void FinalSpeed(
    double acceleration, double time
  )
  {
    double finalSpeed = acceleration * time;
    Console.WriteLine("finalSpeed = " + finalSpeed +
      " meters per second");
  }

  // Distance() calculates the distance traveled
  public static void Distance(
    double acceleration, double time
  )
  {
    double distance = acceleration * Math.Pow(time, 2) / 2;
    Console.WriteLine("distance = " + distance + " meters");
  }

}

接着，创建两个委派对象，并把MotionCalculations.FinalSpeed和MotionCalculations.Distance传递给它的构建函数

DelegateCalculation myDelegateCalculation1 =
    new DelegateCalculation(MotionCalculations.FinalSpeed);
DelegateCalculation myDelegateCalculation2 =
    new DelegateCalculation(MotionCalculations.Distance);

这两个委派可以使用重载的加运算符(+)来合在一起

myDelegateCalculations(acceleration, time);

全部代码为：