C＃：触发事件时的对象被添加到队列 [英] C#: Triggering an Event when an object is added to a Queue

问题描述

我需要能够触发当一个对象被添加到事件问答LT;委托方式＆gt;

I need to be able to trigger a event whenever an object is added to a Queue<Delegate>.

我创建的延伸队列一个新类：

I created a new class that extends Queue:

public delegate void ChangedEventHandler(object sender, EventArgs e);

public class QueueWithChange<Delegate> : Queue<Delegate>
{
    public event ChangedEventHandler Changed;

    protected virtual void OnChanged(EventArgs e) {
        if (Changed != null)
        {
            Changed(this, e);
        }
    }
}

，然后从另一个类连接的情况下，这样的一样：

And then attached the event from another class, like such:

QueueWithChange<TimerDelegate> eventQueue = new QueueWithChange<TimerDelegate>();

//

eventQueue.Changed += new ChangedEventHandler(delegate(object s, EventArgs ex) {
    //This event is not being triggered, so this code is unreachable atm...and that is my problem

    if (eventQueue.Count > 0)
    {
        eventQueue.Dequeue().Invoke(new DispatcherTimer() { Interval = TimeSpan.FromMilliseconds(5) });
        actionTimer.Stop();
    }
});

但每当我排队一个对象（ eventQueue.Enqueue（东西）），不被解雇的附加事件。

But whenever I enqueue an object (eventQueue.Enqueue(something)), the attached event is not being fired.

我是什么在这里失踪？

推荐答案

如果你指的是不通用的队列类，那么你可以只覆盖>排队：

If you mean the non-generic Queue class, then you can just override Enqueue:

public override void Enqueue(object obj)
{
    base.Enqueue(obj);
    OnChanged(EventArgs.Empty);
}

不过，如果你指的是普通的队列＆LT; T＆GT; 类，然后注意，是覆盖没有合适的虚方法。你可能会做的更好为封装队列与你自己的类：

However, if you mean the generic Queue<T> class, then note that there is no suitable virtual method to override. You might do better to encapsulate the queue with your own class:

（**重要修改：删除基类!!! **）

(** important edit: removed base-class!!! **)

class Foo<T>
{
    private readonly Queue<T> queue = new Queue<T>();
    public event EventHandler Changed;
    protected virtual void OnChanged()
    {
        if (Changed != null) Changed(this, EventArgs.Empty);
    }
    public virtual void Enqueue(T item)
    {
        queue.Enqueue(item);
        OnChanged();
    }
    public int Count { get { return queue.Count; } }

    public virtual T Dequeue()
    {
        T item = queue.Dequeue();
        OnChanged();
        return item;        
    }
}

不过，看着你的code，似乎有可能是你在这里使用多线程。如果是这样的话，可以考虑线程队列的吧。

这篇关于C＃：触发事件时的对象被添加到队列的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！