CODEWITHSUNDEEP
c#.neteventsgarbage-collection
taquion
taquion

Reputation: 2767

Should I unsubscribe from events when publisher and handler are the same object?

There are already a couple of questions similar to this one: this and this

In particular I quote Marc Gravell's answer (here):

If you have A publishing an event, and B subscribing to an event (the handler), then it is only a problem not to unsubscribe if A is going to live a lot longer than B.

But I could not find any mention to the special case when the event source and the handler are the same reference, for example:

class Foo
{
    public event Action SomeEvent;

    public Foo() => SomeEvent += OnSomeEventHappened; //should I unsubscribe somewhere?

    private void OnSomeEventHappened(){}
}

I just want to be sure there is no hidden issue with the above code. As far as I know I may never unsubscribe from that event since both the subscriber and the publisher are exactly the same instance.

Would not subscribing prevent my Foo instance from being garbage collected?

Upvotes: 1

Views: 117

Answers (1)

Broots Waymb
Broots Waymb

Reputation: 4826

This doesn't appear to be necessary.
Based off your comment it sounds like you're most worried about garbage collection (or possible lack of).

I just wrote up a super quick test app inspired by this answer in order to test whether the object was garbage collected. It appears to have been.

Here is the code I used to test (running in Release), using the same code you have for your Foo class (left out for simplicity): 

class Program
{
    [STAThread]
    static void Main()
    {
        Foo foo = new Foo();

        WeakReference fooRef = new WeakReference(foo);

        Console.WriteLine(fooRef.IsAlive); //Displays "True"

        foo = null;
        GC.Collect();

        Console.WriteLine(fooRef.IsAlive); //Displays "False"

        Console.ReadKey();
    }
}

Output:

True
False

Here's a fiddle that seems to do the job as well (assuming it doesn't have its own garbage collection quirks... I'm not a super experienced "fiddler").

Upvotes: 2

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