Standard event handler (with operator +=) is one of the memory leakage cause (if it is not unregistered/disposed (with -= operator)).

微软通过 WeakEventManager 及其继承方式解决了这个问题，例如:PropertyChangedEventManager、CollectionChangedEventManager、CurrentChangedEventManager、ErrorsChangedEventManager 等等.

And Microsoft solved it with WeakEventManager and its inheritance like: PropertyChangedEventManager, CollectionChangedEventManager, CurrentChangedEventManager, ErrorsChangedEventManager and so on.

内存泄漏的简单示例代码为:

public class EventCaller
{
    public static event EventHandler MyEvent;
    
    public static void Call()
    {
        var handler = MyEvent;
        if (handler != null)
        {
            handler(null, EventArgs.Empty);
            Debug.WriteLine("=============");
        }
    }
}

public class A
{
    string myText;

    public A(string text)
    {
        myText = text;
        EventCaller.MyEvent += OnCall;

        // Use code below and comment out code above to avoid memory leakage.
        // System.Windows.WeakEventManager<EventCaller, EventArgs>.AddHandler(null, "MyEvent", OnCall);  
    }
    
    void OnCall(object sender, EventArgs e)
    {
        Debug.WriteLine(myText);
    }
    
    ~A()
    {
        Debug.WriteLine(myText + " destructor");
    }
}

void Main()
{
    var a = new A("A");
    var b = new A("B");
    EventCaller.Call();
    a = null;
    GC.Collect();
    EventCaller.Call();
}

输出为:

A
B
+++++++
A
B
+++++++

我们可以看到析构函数不会被调用.但是如果我们改变(通过注释未使用的代码):

We can see that the destructor will not be called. But if we change (by commenting the unused code) from:

    EventCaller.MyEvent += OnCall;

到

    System.Windows.WeakEventManager<EventCaller, EventArgs>.AddHandler(null, "MyEvent", OnCall);  

输出为:

A
B
+++++++
B
+++++++
A destructor
B destructor

在 A 为空后，它的事件处理程序将不再被调用.没有 -= 操作符的 A 和 B 将在不再使用后被丢弃.

After A is nulled then its event handler will not be called anymore. A and B will be disposed after not be used anymore without -= operator.

1. 我是否可以安全地将所有 += 运算符替换为 System.Windows.WeakEventManager 以避免由于可能丢失事件注销和保存代码而导致的内存泄漏不应实现 IDisposable?