Question

I have a class:

public abstract class BaseComponent { ... }

Within the constructor of that class we subscribe to an event handler e.g.

protected ObjectWithEventHandler eventObject { get; private set; }

public BaseComponent (ObjectWithEventHandler obj)
{
    eventObject = obj;
    eventObject.ChangedEvent += new EventHandler(eventObject_OnChangedEvent );
}

protected void eventObject_OnChangedEvent (object sender, EventArgs e) { ... }

Are there any hard and fast rules when it comes to EventHandler subscription & unsubscription?

Is it considered good practice to provide some clean-up code that unsubscribes the function from the EventHandler? I.e. implement IDisposable and unsubscribe from the EventHandler then?

Or am I worrying unduly?

Answer 1

If you have full control of the usage of BaseComponent and you know that EventObject’s lifecycle is shorter or equal* with regard to BaseComponent’s lifecycle, you can skip unsubscription code.

In all other cases I would include it. In this case implementing IDisposable is good style.

_{*) effectively, you are coupling eventObject’s lifetime to BaseComponent, so it cannot live shorter, but it could still be equal when the two go out of scope together.}