使用委派调用对象的方法

    委派即可以调用静态类方法，也可以调用对象方法。如下面的类Person定义了两个私有域来存储一个人的名字和年龄

 

public class Person
{

  // declare two private fields
   private string name;
  private int age;

  // define a constructor
  public Person(string name, int age)
  {
    this.name = name;
    this.age = age;
  }

  // define a method that returns a string containing
  // the person's name and age
  public string NameAndAge()
  {
    return(name + " is " + age + " years old");
  }

}

接着在Main方法中创建Person对象

 

Person myPerson = new Person("Jason Price", 32);

然后创建委托类并调用

 

DelegateDescription myDelegateDescription =
      new DelegateDescription(myPerson.NameAndAge);

// call myPerson.NameAndAge() through myDelegateDescription
string personDescription = myDelegateDescription();
Console.WriteLine("personDescription = " + personDescription);

完整代码：

/*
  Example12_3.cs illustrates the use of a delegate
  that calls object methods
*/

using System;


// declare the DelegateCalculation delegate class
public delegate string DelegateDescription();


// declare the Person class
public class Person
{

  // declare two private fields
  private string name;
  private int age;

  // define a constructor
  public Person(string name, int age)
  {
    this.name = name;
    this.age = age;
  }

  // define a method that returns a string containing
  // the person's name and age
  public string NameAndAge()
  {
    return(name + " is " + age + " years old");
  }

}


// declare the Car class
public class Car
{

  // declare two private fields
  private string model;
  private int topSpeed;

  // define a constructor
  public Car(string model, int topSpeed)
  {
    this.model = model;
    this.topSpeed = topSpeed;
  }

  // define a method that returns a string containing
  // the car's model and top speed
  public string MakeAndTopSpeed()
  {
    return("The top speed of the " + model + " is " +
      topSpeed + " mph");
  }

}


class Example12_3
{

  public static void Main()
  {

    // create a Person object named myPerson
    Person myPerson = new Person("Jason Price", 32);

    // create a delegate object that calls myPerson.NameAndAge()
    DelegateDescription myDelegateDescription =
      new DelegateDescription(myPerson.NameAndAge);

    // call myPerson.NameAndAge() through myDelegateDescription
    string personDescription = myDelegateDescription();
    Console.WriteLine("personDescription = " + personDescription);

    // create a Car object named myCar
    Car myCar = new Car("MR2", 140);

    // set myDelegateDescription to call myCar.MakeAndTopSpeed()
    myDelegateDescription =
      new DelegateDescription(myCar.MakeAndTopSpeed);

    // call myCar.MakeAndTopSpeed() through myDelegateDescription
    string carDescription = myDelegateDescription();
    Console.WriteLine("carDescription = " + carDescription);

  }

}