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使用.NET的WeakEventManager实现弱事件的示例

weakeventmanager weak-events .net

25

sourcenouveau · 技术社区 · 14 年前

WeakEventManager ?

我试图通过遵循文档中的“继承者注释”来实现它,但它是模糊的。例如,我不知道怎么打电话 ProtectedAddListener 从我的静态 AddListener

2 回复 | 直到 14 年前

1

28

tordal 12 年前

我是按照《继承人须知》一节中的指导原则自己想出来的 WeakEventManager 文档。下面是 WeakEventManager PropertyValue 事件名为 Changed .

public class PropertyValueChangedEventManager : WeakEventManager
{
    public static PropertyValueChangedEventManager CurrentManager
    {
        get
        {
            var manager_type = typeof(PropertyValueChangedEventManager);
            var manager = WeakEventManager.GetCurrentManager(manager_type) as PropertyValueChangedEventManager;

            if (manager == null)
            {
                manager = new PropertyValueChangedEventManager();
                WeakEventManager.SetCurrentManager(manager_type, manager);
            }

            return manager;
        }
    }

    public static void AddListener(PropertyValue source, IWeakEventListener listener)
    {
        CurrentManager.ProtectedAddListener(source, listener);
    }

    public static void RemoveListener(PropertyValue source, IWeakEventListener listener)
    {
        CurrentManager.ProtectedRemoveListener(source, listener);
    }

    protected override void StartListening(object source)
    {
        ((PropertyValue)source).Changed += DeliverEvent;
    }

    protected override void StopListening(object source)
    {
        ((PropertyValue)source).Changed -= DeliverEvent;
    }
}

2

7

angularsen Bcelik 13 年前

Sharp Observation

Usage

MakeWeak()方法返回一个新的委托,该委托调用相同的 target作为原始委托,但对

var handler= new PropertyChangingEventHandler(listener.HandleChange);
observable.PropertyChanging += handler.MakeWeak<PropertyChangingEventHandler>();

Limitations

当前的实现对委托有以下限制: