c# - How does an EventHandler know to allow = operator only in defining class? -

I started with a question, and in answering the question, got the answer, but instead of deleting, I thought it May be helpful from A), and b) Help others.

If I have an event, and add listeners to many places in the application, then what is the best way to remove all the listeners at once? For example, I ...

  myPage.OnPageOpened + = OpenPage;  

and later in my code ...

  myPage.OnPageOpened - = OpenPage;  

But what if I have an unknown third party member and I can press a magic reset button that clears everything and starts with scratch?

You can use + = - - Operator anywhere against = EventHandler, because operator overload is public = overloaded operator is private, it can only be said in defined category.

So in the defined category, I can use it to clean my EventHandler.

  OnPageOpened = null;  

And to expose that functionality, I could ...

  Public Zero ClearPageOpenedEvents () {OnPageOpened = null; }  

Is that correct?

Yes, you are right. The reason for this is that the compiler creates a personal representative object under the cover, like this:

  Private EventHeader page opens; Public event handler page request {{pageOpened + value = add; } Remove {pageOpened - = value; }}  

Inside your class, you have a reference of a private representative example, so you can do the assignment. You definitely want to expose a method to clear the goal, if you need it; You do not want to expose your representative .