委派/委托

using System;

public delegate double MathFunction();

public class Addition
{
    double x, y;
    public Addition(double x, double y)
    {
        this.x = x;
        this.y = y;
    }

    public double Add()
    {
        return x + y;
    }
}

public class Multiplication
{
    double x, y;
    public Multiplication(double x, double y)
    {
        this.x = x;
        this.y = y;
    }

    public double Multiply()
    {
        return x * y;
    }
}

public class Division 
{
    double x, y;
    public Division(double x, double y)
    {
        this.x = x;
        this.y = y;
    }

    public double Divide()
    {
        return x / y;
    }
}

public partial class Default9 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        double x = 3.0;
        double y = 4.0;
        double z, z1, z2;
        Addition a = new Addition(x, y);
        Multiplication m = new Multiplication(x, y);
        Division d = new Division(x, y);
        z = Apply(x, y, a.Add);
        z1 = Apply(x, y, m.Multiply);
        z2 = Apply(x, y, d.Divide);
        Response.Write(z.ToString() + "<br/>" + z1.ToString() + "<br/>" + z2.ToString());
    }

    protected double Apply(double x, double y, MathFunction mf)
    {
        double z = mf();
        return z;
    }
}