Question

我看过几篇关于如何做到这一点的帖子。答案都依赖于将Action放在字典中。然而，我遇到的问题是我需要将带有未知签名的Actions传递给方法，而不是字典中。

我有使用以下方法的现有代码。我想添加一个重载，这样我就可以保持与现有代码的兼容性。

    // Collection of notification observers.
    private static Dictionary<string, List<NotificationObserver>> _Observers = new Dictionary<string, List<NotificationObserver>>();
    public static SynchronizationContext Context { get; set; }

    public static void RegisterObserver(object observer, string notification, Action<object, Dictionary<string, object>> action)
    {
        // We only register valid objects.
        if (string.IsNullOrWhiteSpace(notification) || action == null || observer == null) return;

        // Create a new NotificationObserver object.
        // Currently you provide it a reference to the observer. This is not used anywhere; there are plans to use this.
        var registeredObserver = new NotificationObserver(observer, action);

        // Make sure the notification has already been registered.
        // If not, we add the notification to the dictionary, then add the observer.
        if (_Observers.ContainsKey(notification))
            _Observers[notification].Add(registeredObserver);
        else
        {
            var observerList = new List<NotificationObserver>();
            observerList.Add(registeredObserver);
            _Observers.Add(notification, observerList);
        }
    }

    public static void PostNotification(object sender, string notification, Dictionary<string, object> userData = null)
    {
        // Make sure the notification exists.
        if (_Observers.ContainsKey(notification))
        {
            // Loop through each objects in the collection and invoke their methods.
            foreach (NotificationObserver observer in _Observers[notification].Where(obs => obs != null))
            {
                if (Context == null)
                    observer.Action(sender, userData);
                else
                {
                    Context.Send((state) => observer.Action(sender, userData), null);
                }
            }

            // Clean ourself up.
            Task.Run(new Action(() =>
            {
                PurgeNullObservers();
            }));
        }
    }

通知观察员

internal sealed class NotificationObserver
{
    internal NotificationObserver(object observer, Action<object, Dictionary<string, object>> action)
    {
        this.Observer = observer;
        this.Action = action;
    }

    internal object Observer { get; private set; }
    internal Action<object, Dictionary<string, object>> Action { get; private set; }

}

我想在我的代码库中执行以下操作：

NotificationManager.RegisterObserver(this.SomeProperty, "SomeString", this.SomeProperty.DoStuff);
NotificationManager.RegisterObserver(this.Logger, "LogInfo", this.Logger.LogInfo);

基本上，我想为第三方库对象提供支持，我无权访问源代码，并且无法添加与我预先确定的Action签名匹配的方法。对于大量不同的签名变化，我也不想要30次重载。

任何人都知道有一个很好的方式来完成这个？如果我必须修改我的RegisterObserver和NotificationObserver，我希望这样做，而不必修改现有的方法签名，只需添加一个重载。

提前致谢！

Answer 1

为什么不在构造RegisterObserver调用时使用lambda expresssion？

NotificationManager.RegisterObserver(this.ThirdParty, 
    "ThirdPartyData", 
    (i,j) => 
        {
             // call the third party method
             this.ThirdParty.ThirdPartyMethod(null, false, i);
             // other custom logic here using j (the action dictionary)
        });

只要您拥有“适应”第三方通话所需的信息以与您现有的签名兼容，您就没有问题。您将自动捕获由lambda表达式创建的闭包中的所有此类信息。

在C＃中存储对具有未知签名的方法的引用

1 个答案: