C#中的委托样例代码(二)

using System;

namespace Wrox.ProCSharp.AdvancedCSharp
...{
    delegate void DoubleOp(double value);

    class MainEntryPoint
    ...{
        static void Main()
        ...{
            DoubleOp operations = new DoubleOp(MathsOperations.MultiplyByTwo);
            operations += new DoubleOp(MathsOperations.Square);

            ProcessAndDisplayNumber(operations, 2.0);
            ProcessAndDisplayNumber(operations, 7.94);
            ProcessAndDisplayNumber(operations, 1.414);
            Console.WriteLine();
        }

        static void ProcessAndDisplayNumber(DoubleOp action, double value)
        ...{
            Console.WriteLine(" ProcessAndDisplayNumber called with value = " + value);
            action(value);
        }
    }

    class MathsOperations
    ...{
        public static void MultiplyByTwo(double value)
        ...{
            double result = value*2;
            Console.WriteLine("Multiplying 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);
        }
    }
}