以匿名方法捕获委托

考虑

    Action _captureAction;
    private void TestSimpleCapturedAction()
    {
        Action action = new Action(delegate { });
        Action printAction = () => Console.WriteLine("Printing...");

        action += printAction;
        CaptureActionFromParam(action);
        action -= printAction;

        _captureAction(); //printAction will be called!
    }

    private void CaptureActionFromParam(Action action)
    {
        _captureAction = () => action();
    }

“CaptureAction调用printAction的原因是

action -= printAction;

实际上转化为

action = (Action) Delegate.Remove(action, printAction);

因此captureActionFromParam()中的captureAction捕获的操作没有更改-只影响testsSimpleCaptureDaction()中的本地“action”变量。

在这种情况下,我希望的行为是不调用printaction。我能想到的唯一解决方案是将一个新的“委托容器”类定义为:

    class ActionContainer
    {
        public Action Action = new Action(delegate { });
    }

    private void TestCapturedActionContainer()
    {
        var actionContainer = new ActionContainer();
        Action printAction = () => Console.WriteLine("Printing...");

        actionContainer.Action += printAction;
        CaptureInvoker(actionContainer);
        actionContainer.Action -= printAction;

        _captureAction();
    }

    private void CaptureInvoker(ActionContainer actionContainer)
    {
        _captureAction = () => actionContainer.Action();
    }

这是可行的,但我想知道,如果不引入这一新的抽象层,是否可以实现我所期望的行为。实现策略模式很容易导致这种情况,因此人们会认为语言和/或BCL会以某种方式支持它。

谢谢!