如何从HtmlElement对象分离事件处理程序？ C＃

Question

first of all, I'm new to this forum and relatively new to programming. My problem is that I can't detach event handlers attached previously. At least, DetachEventHandler in the following code doesn't do it:

private void addHandlersToElement(HtmlElement thiselement)
{
        thiselement.DetachEventHandler("onclick", delegate { myClickHandler(thiselement, EventArgs.Empty); });
        thiselement.AttachEventHandler("onclick", delegate { myClickHandler(thiselement, EventArgs.Empty); });
}

It obviously doesn't work because the code in the event handler executes as many times as I called addHandlersToElements , that is, attach works but detach doesn't.

The truth is that I don't know very much about delegates, just that they are wrappers for methods to make it possible to pass them as parameters. This delegate{} block I stole from some post, because this seemed the only solution to work for passing thiselement as the sender object (which I'm referring to in my actual handler method). Using

new EventHandler(myMouseoverEventHandler)

for parameter actually works, but then, AFAIK, I cannot pass the sender.

Any help would be appreciated.

Answer 1

I think it will solve the problem if you assign the delegate to a reference, like this:

var del = delegate { myClickHandler(thiselement, EventArgs.Empty); };

and then attach and detach the same delegate object instead of attaching one delegate and detaching another:

thiselement.AttachEventHandler("onclick", del);
thiselement.DetachEventHandler("onclick", del);