Question

How would you suggest the best way of avoiding duplicate event subscriptions? if this line of code executes in two places, the event will get ran twice. I’m trying to avoid 3rd party events from subscribing twice.

theOBject.TheEvent += RunMyCode;

In my delegate setter, I can effectively run this …

theOBject.TheEvent -= RunMyCode;
theOBject.TheEvent += RunMyCode;

but is that the best way?

Answer 1

I think, the most efficient way, is to make your event a property and add concurrency locks to it as in this Example:

private EventHandler _theEvent;
private object _eventLock = new object();
public event EventHandler TheEvent
{
    add
    {
        lock (_eventLock) 
        { 
            _theEvent -= value; 
            _theEvent += value; 
        }
    }
    remove
    {
        lock (_eventLock) 
        { 
           _theEvent -= value; 
        }
    }
}