CODEWITHSUNDEEP
c#event-handling
ebattulga
ebattulga

Reputation: 10981

How to check event handler assigned or not

my previos question is how to clear event handles in c#

Now i need to know that how to check any event handler already assigned?

Upvotes: 3

Views: 4246

Answers (4)

user153923
user153923

Reputation:

An old solution presented by Jon Skeet where you explicitly implemented event handling would be the best way to address this.

Here is how:

private EventHandler m_myEvent;

public event EventHandler OnEvent
{
    add
    {
        // First try to remove the handler, then re-add it
        m_myEvent -= value;
        m_myEvent += value;
    }
    remove
    {
        m_myEvent -= value;
    }
}

In the unlikely scenario that you have multicast delegates, you could experience odd behaviors.

Upvotes: 0

deep
deep

Reputation: 47

In quick watch window I found the btnSubmit click handler with the following expression: 

(((System.Web.UI.Control)(btnSubmit)).Events.head.handler).Method

Upvotes: 0

Petar Minchev
Petar Minchev

Reputation: 47373

If the event is in the same class where you will do the check, you can compare to null. But if this is not the case, you should ask yourself why do you care about the inside workings of a class. I mean it is the job of the class which contains the event to care about its subscribers not the opposite. But if you really want this information, the event containing class can expose a property for the outside world - like HasEventHandlers.

Upvotes: 1

Cylon Cat
Cylon Cat

Reputation: 7201

Unless I misunderstand the question, a simple check for null should be sufficient. You always need to check for a null in the event handler anyway before calling any event handlers.

Upvotes: 0

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