我已经实现了这个WeakEvent委托,但是由于某种原因,它只能工作几秒钟,之后便停止工作:
public class WeakEventHandler<TE> where TE : EventArgs
{
private readonly Action<WeakEventHandler<TE>> _unsubscriber;
private readonly WeakReference<EventHandler<TE>> _targetRef;
private readonly EventHandler<TE> _handler;
public WeakEventHandler(EventHandler<TE> eventReceiver, Action<WeakEventHandler<TE>> unsubscriber)
{
_unsubscriber = unsubscriber;
_targetRef = new WeakReference<EventHandler<TE>>(eventReceiver);
_handler = Invoke;
}
public void Invoke(object sender, TE e)
{
EventHandler<TE> method;
if (_targetRef.TryGetTarget(out method))
{
method(sender, e);
}
else
{
_unsubscriber(this);
}
}
public static implicit operator EventHandler<TE>(WeakEventHandler<TE> weh)
{
return weh._handler;
}
}
public static class EventHandlerUtils
{
public static EventHandler<TE> MakeWeak<TE>(this EventHandler<TE> eventReceiver, Action<WeakEventHandler<TE>> unsubscriber) where TE : EventArgs
{
return new WeakEventHandler<TE>(eventReceiver, unsubscriber);
}
}
用法:
private EventHandler<MouseInteractionArgs> _mouseInteractionDelegate;
public event EventHandler<MouseInteractionArgs> MouseAction
{
add
{
_mouseInteractionDelegate += value.MakeWeak(handler => _mouseInteractionDelegate -= handler );
}
remove
{
throw new InvalidOperationException("This is a weak Event, dont worry about unsubscribing");
}
}
我从未停止引用该方法的所有者,所以我不知道为什么它不起作用,委托的行为是否有所不同?
最佳答案
但“ eventreceiver”由该方法的实例拥有
抱歉,但是您已经倒退了。 “ eventReceiver”是您要添加到MouseAction事件的委托实例。该委托实例保留对目标对象和MethodInfo的引用,而不是相反。除了您的WeakReference以外,没有代码保留对委托实例的引用,当然,根据设计,这不足以使对象保持活动状态。