VB.NET RemoveHandler & Anonymous Methods

vb.net anonymous-methods addhandler
acermate433s picture acermate433s · Sep 16, 2011 · Viewed 7.3k times · Source

How do I use RemoveHandler with anonymous methods?

This is how I add a handler for MyEvent event of the class MyClass:

AddHandler MyClass.MyEvent, Sub()
                                '...
                            End Sub

How do I then use RemoveHandler to remove the handler for the MyEvent event?

Answer

Reed Copsey picture Reed Copsey · Sep 16, 2011

In general, if you need to unsubscribe from the event, I would recommend not using a lambda like this, and instead use a standard method.

That being said, you can still use the anonymous method, but you need to store a reference to it for the unsubscription. If you must unsubscribe an anonymous method, at a minimum, you should store the delegate in a variable to remove it later:

Dim subscription = Sub()
                            ' ...
                   End Sub

AddHandler MyClass.MyEvent, subscription

' Later   
RemoveHandler MyClass.MyEvent, subscription

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