[读书笔记]多播委托
委托也可以包含多个方法，这种委托称为多播委托。如果调用多播委托，就可以按顺序连续调用多个方法。为此，委托的签名就必须返回void.否则，就只能得到委托调用的最后一个方法的结果。
/*
* Created by SharpDevelop.
* User: Herbert
* Date: 2010-3-20
* Time: 23:11
*
* To change this template use Tools | Options | Coding | Edit Standard Headers.
*/
using System;
namespace MulticastDelegate
{
delegate void DoubleOp(double value);
class MathOperations
{
public static void MultiplyByTwo(double value)
{
double result = value*2;
Console.WriteLine("Multiply by 2: {0} gives {1}", value, result);
}
public static void Square(double value)
{
double result = value*value;
Console.WriteLine("Squaring: {0} gives {1}", value, result);
}
}
class Program
{
public static void Main(string[] args)
{
DoubleOp operations = MathOperations.MultiplyByTwo;
operations += MathOperations.Square;
ProcessAndDisplayNmber(operations, 2.0);
ProcessAndDisplayNmber(operations, 7.94);
ProcessAndDisplayNmber(operations, 1.414);
Console.Write("Press any key to continue . . . ");
Console.ReadKey(true);
}
static void ProcessAndDisplayNmber(DoubleOp action, double valueToProcess)
{
Console.WriteLine();
Console.WriteLine("ProcessAndDisplayNumber called with value = {0}", valueToProcess);
action(valueToProcess);
}
}
}
下面的code
DoubleOp operations = MathOperations.MultiplyByTwo; operations += MathOperations.Square;
等价于：
DoubleOp operation1 = MathOperations.MultipleByTow; DoubleOp operation2 = MathOperation.Square; DoubleOp operations = operation1 + operation2;