CODEWITHSUNDEEP
c#asp.net
iJade
iJade

Reputation: 23801

Pass extra parameter to C# callback

How to add extra parameters to the following callback :

objXmpp.OnLogin += new ObjectHandler(objXmppArun_OnLogin);

private void objXmppArun_OnLogin(object sender)
{

}

Is it possible to send one extra parameter to the objXmppArun_OnLogin event handler?

Upvotes: 2

Views: 2473

Answers (2)

Rhumborl
Rhumborl

Reputation: 16609

No, it's not possible. Events (and delegates in general) in C# define a specific method signature with fixed parameters, so you cannot add extra ones.

The best thing to do is create a separate method which your event handler can call and pass the extra parameter to:

objXmpp.OnLogin += new ObjectHandler(objXmppArun_OnLogin);

private void objXmppArun_OnLogin(object sender)
{
    LoginCheck(sender, "Some Info");
}

private void LoginCheck(object sender, string extraParameter)
{
    // do your thing here
}

Or if the value you need is only known when you attach the handler, you can wrap it up in an anonymous method:

private void AttachHandlers()
{
    string parameter = "Some Info";
    objXmpp.OnLogin += new ObjectHandler(sender => {
        objXmppArun_OnLogin(sender, parameter);
    });
}

private void objXmppArun_OnLogin(object sender, string extraParameter)
{
}

Upvotes: 6

Jamiec
Jamiec

Reputation: 136104

You cant change the delegate expected by whatever component you're using (objXmpp.OnLogin) so you therefore cant change the parameters that you handler method expects.

However, that handler has access to properties & methods of the class it is within, just like any normal method would.

(You might like to update youre question to what you're trying to achieve rather than how you're trying to achieve it - you might be able to get a better answer)

Upvotes: 0

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