C# 進階（八）：委派、匿名方法與多點廣播委派

委派基本範例

public class NumberOption {
    public static double NumOne(double x) { return x * 2; }
    public static double NumTwo(double x) { return x * x; }
}

delegate double DoubleOperation(double x);

static void PrintNumber(DoubleOperation op, double x) {
    double result = op(x);
    Console.WriteLine("Value is {0}, result of DoubleOperation is {1}", x, result);
}

static void Main() {
    DoubleOperation d1 = new DoubleOperation(NumberOption.NumOne);
    DoubleOperation d2 = new DoubleOperation(NumberOption.NumTwo);
    PrintNumber(d1, 1.5);  // Value is 1.5, result ... 3
    PrintNumber(d2, 3.2);  // Value is 3.2, result ... 10.24
}

匿名方法簡化委派建立

delegate double DoubleOperation(double x);
static void PrintNumber(DoubleOperation op, double x) { ... }
static void Main() {
    DoubleOperation d1 = delegate(double x) { return x * 2; };
    DoubleOperation d2 = delegate(double x) { return x * x; };
    PrintNumber(d1, 1.5);
    PrintNumber(d2, 3.2);
}

多點廣播委派

委派可串聯多個方法，依序呼叫。後續應用再詳細說明。