C＃：提高继承的事件 [英] C#: Raising an inherited event

问题描述

我有一个包含下列事件的基类：

I have a base class that contains the following events:

public event EventHandler Loading;
public event EventHandler Finished;

在从这个基类继承我尽量抬高事件类：

In a class that inherits from this base class I try to raise the event:

this.Loading(this, new EventHandler()); // All we care about is which object is loading.

我收到以下错误：

I receive the following error:

的事件BaseClass.Loading只能出现在左手侧+ =或 - =（BaseClass的'）的

我假设我无法访问这些事件同其他继承的成员？

I am assuming I cannot access these events the same as other inherited members?

推荐答案

您所要做的，是这样的：

What you have to do , is this:

在你的基类（如您已声明的事件），创建保护方法，可用于提高事件：

In your base class (where you have declared the events), create protected methods which can be used to raise the events:

public class MyClass
{
   public event EventHandler Loading;
   public event EventHandler Finished;

   protected virtual void OnLoading(EventArgs e)
   {
       EventHandler handler = Loading;
       if( handler != null )
       {
           handler(this, e);
       }
   }

   protected virtual void OnFinished(EventArgs e)
   {
       EventHandler handler = Finished;
       if( handler != null )
       {
           handler(this, e);
       }
   }
}

（请注意，你应该改变那些方法，以检查是否有调用事件处理程序或没有）。

(Note that you should probably change those methods, in order to check whether you have to Invoke the eventhandler or not).

然后，从这个基类继承的类，你可以调用OnFinished或OnLoading方式，筹集的事件：

Then, in classes that inherit from this base class, you can just call the OnFinished or OnLoading methods to raise the events:

public AnotherClass : MyClass
{
    public void DoSomeStuff()
    {
        ...
        OnLoading(EventArgs.Empty);
        ...
        OnFinished(EventArgs.Empty);
    }
}

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