Question

I’m trying to create a custom control and need to raise an event from it. The idea is to raise an event at the end of the click event (OnAfterClick). I found one or two tutorials on doing this, but am clearly missing a step somewhere; I have the following.

In the control:

public class AfterClickEventArgs : EventArgs
{
  ...
}

public partial class MyButton : CommandButton
{
    public delegate void AfterClickEvnt(object sender, AfterClickEventArgs e);

    public event AfterClickUpdatedEvnt AfterClick;

}

protected override void OnClick(EventArgs e)
{
    ...
    Processing here
    ...

    AfterClickEventArgs myArgs = new AfterClickEventArgs();                
    AfterClick(this, myArgs);
}

In the program using the control:

In InitializeComponent():

this.MyButton.AfterClick += new System.EventHandler(this.cmdMyButton_Click);

This line is giving me a compile error (cmdMyButton_Click does exist). It tells me:
Cannot implicitly convert type ‘System.EventHandler’ to ‘Namespace.MyButton.AfterClick’

Can anyone tell me what I’m missing, or misunderstanding about this, please?

Answer 1

Your event is declared to be of type AfterClickEvnt, but you’re trying to subscribe to it using an EventHandler. You can’t convert between the two.

Options:

• Explicitly state the right type:

  this.MyButton.AfterClick += new AfterClickEvnt(this.cmdMyButton_Click);
  

• Use an implicit method group conversion:

  this.MyButton.AfterClick += cmdMyButton_Click;
  

By the way, I suggest you remove your custom delegate type and instead use the generic EventHandler<T> delegate:

public event EventHandler<AfterClickEventArgs> AfterClick;