如何捕获事件订阅？

Question

I have interface with the event. My class implements the interface.

The logic of the class requires to fix all the facts subscription and unsubscribe from the event.

How to implement interception subscriptions and unsubscribe from the event?

Answer 1

Try this:

    private event EventHandler<EventArgs> shibby;

    public event EventHandler<EventArgs> Shibby
    {
        add
        {
            // your logic here
            this.shibby += value;
            // or here
        }
        remove
        {
            // your logic here
            this.shibby -= value;
            // or here
        }
    }

Answer 2

Well, if you definitely need to intercept subscriptions:

private EventHandler fooEventHandler;

public event EventHandler Foo
{
    add
    {
        // Put any extra logic in here
        fooEventHandler += value;
    }
    remove
    {
        fooEventHandler -= value;
    }
}

(Note that if you need thread-safety, you'll need to amend the code above.)

But if you're using a field-like event, like this:

public event EventHandler Foo;

then you can "unsubscribe" everything just by writing (in the class):

Foo = null;