C＃处理事件 [英] C# Handle Event

问题描述

我试图做一个排序库中，我试图抓住我怎么能实现它，他们的方式，我想。
我创建了一个极简的例子来告诉你什么，我试图做的。

I am trying to make sort of a library and i am trying to grasp how can i implement it they way i want. I created a minimalist example to show you what i am trying to do.

using System;
namespace example
{
    public class Car
    {
        public int Price;
        public string ModelName;
        public Boolean Sold;
        public delegate void SellEventHandler(string str);
        public static event SellEventHandler _OnSell;

        public void OnSell(string str)
        {
            Console.WriteLine("event was fired");
        }

        public Car(int price, string modelname)
        {
            Price = price;
            ModelName = modelname;
            Sold = false;
            _OnSell = OnSell;
        }
    }

    public class Program
    {
        static void Main()
        {
            Car _car = new Car(6000, "audi");
            _car._OnSell += Car_OnSell;
        }

        public void Car_OnSell(string message)
        {
            Console.WriteLine(message);
        }
    }
}

虽然我还没有实施在事件将被调用（它应该被调用时，销售的属性 _car 的变化），我想执行车类的 OnSell（字符串str）办法（打印事件被解雇），并在此之后，我想执行 Car_OnSell 功能（见代码 _car.OnSell + = Car_OnSell ）

Even though i haven't implemented when the event will be invoked ( it should be invoked when the Sold property of the _car changes ), i want to execute the OnSell(string str) method of the Car class ( prints "event was fired" ) and after that, i want to execute the Car_OnSell function ( see code _car.OnSell += Car_OnSell )

希望你得到什么，我想在这里做的想法。现在，我得到的错误是会员'example.Car._OnSell不能用一个实例引用来访问;与类型名称，而不是就行了限定它 _car.OnSell + = Car_OnSell; 。但是我不知道如果我在正确的方向与此去的。

Hopefully you get the idea of what i am trying to do here. Right now the error i get is Member 'example.Car._OnSell' cannot be accessed with an instance reference; qualify it with a type name instead on the line _car.OnSell += Car_OnSell;. However i am not sure if i am going in the right direction with this at all.

推荐答案

我想我明白你的重新做的，这里是我会怎么做。

I think I understand what you're doing, and here's how I would do it.

1. 请不要在你的类挂钩的事件。相反，创建一个卖出的方法，做什么类通常会做（如集销售==真），但首先检查客户端是否迷上了你的 _OnSell 事件，火灾，第一。您可能要提供一些方式为客户取消了 _OnSell 事件中的销售以及


2. 您还需要你的 Car_OnSell 静态的，因为你是从一个静态方法挂钩起来（主）。这是因为非静态方法需要一个类的实例来访问它

1. Don't hook up an event in your class. Instead, create a 'Sell' method that does whatever the class would normally do (like set Sold == true), but first check if the client hooked up your _OnSell event, and fire that first. You may want to provide some way for the client to cancel the sale in the _OnSell event as well.
2. You also need to make your Car_OnSell static, since you're hooking it up from a static method (Main). This is because a non-static method requires a class instance to access it.

下面是一个例子：

static void Main()
{
    var car = new Car(6000, "audi");
    car._OnSell += Car_OnSell;
    car.Sell(string.Format("Selling the car: {0}", car.ModelName));
}

public static void Car_OnSell(string message)
{
    Console.WriteLine(message);
}

public class Car
{
    public int Price { get; set; }
    public string ModelName { get; set; }
    public Boolean Sold { get; set; }
    public delegate void SellEventHandler(string str);
    public event SellEventHandler _OnSell;

    public void Sell(string str)
    {
        if (_OnSell != null)
        {
            _OnSell(str);
        }

        this.Sold = true;
    }

    public Car(int price, string modelname)
    {
        Price = price;
        ModelName = modelname;
        Sold = false;
    }
}

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