Automatically unsubscribe an event

Question

Is it possible to do something like this in C#? Probably with Expressions. The EventHandlers are not members of a Control or any class that I own.

E.g.:

Microsoft.Win32.SystemEvents.SessionSwitch += new Microsoft.Win32.SessionSwitchEventHandler(SystemEvents_SessionSwitch);

The EventHandler is a static reference that I don't own. How can I pass that type of statement to the following function?

private void RegisterEvent(EventHandler handler, Action<EventArgs> action)
{
   handler += action;
   m_toUnsubscribe.Add(handler, action);
}

... in Dispose()
{
  foreach(var pair in m_toUnsubscribe)
  {
    pair.handler -= pair.action;
  }
}

I may not be able to use the += and -= operators on a base EventHandler, so I might have to write the entire += and -= expressions as anonymous functions: RegistertEvent( ()=>SomeEvent+=SomeReaction, ()=>SomeEvent-=SomeReaction ) — Cat Zimmermann, May 04 '10 at 19:47

score 3 · Answer 1 · answered May 03 '10 at 17:12

3

Like described in the forum thread you can set the event to null in the dispose method of your object. Of course that requires your class to implement IDisposable.

Here the link: http://channel9.msdn.com/forums/TechOff/148255-Event-disposal/

answered May 03 '10 at 17:12

Sebastian P.R. Gingter

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I don't own the event, so I can't set it to null. – Cat Zimmermann May 05 '10 at 22:26
Wayback machine link: https://web.archive.org/web/20121108042110/http://channel9.msdn.com/forums/TechOff/148255-Event-disposal/ – Issung Jun 08 '21 at 23:50

score 0 · Answer 2 · edited May 01 '18 at 15:12

0

You can take a look at this post and use the answer I posted. The Suppress function will remove the handlers from a control. You could modify this more to suit your needs.

edited May 01 '18 at 15:12

sonnyb

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answered May 03 '10 at 17:13

SwDevMan81

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1

Actual URL: http://stackoverflow.com/questions/91778/how-to-remove-all-event-handlers-from-a-control/1597332#1597332 – Cat Zimmermann May 03 '10 at 20:21
This is not a Control, and I don't own the events passed to RegisterEvent. – Cat Zimmermann May 05 '10 at 22:27

Automatically unsubscribe an event

2 Answers2