How to determine if an event is already subscribed

Question

In my .NET application I am subscribing to events from another class. The subscription is conditional. I am subscribing to events when the control is visible and de-subscrib

Answer 1

Can't you just remember whether you already subscribed? That approach worked fine for me so far. Even if you have a lot of events or objects, you may still want to just remember that (in a dictionary, for example).

On the other hand, visibility change was, at least for me, not a good point to subscribe/unsubscribe. I typically rather go with construction / Disposed, which are more clear than each time visibility changes.