Question

Ok, I have a winforms app and my code works fine.
But I want to know if my code is bullet proof or if it only works without load.

Let me explain it:

I have a windows form where I have overridden the OnKeyDown method:

    Protected Overrides Sub OnKeyDown(ByVal e As System.Windows.Forms.KeyEventArgs)

        dim args as new ActionEventArgs(ActionType.Bark)
        RaiseEvent Action(me, args)

        e.Handled = args.Handled
        MyBase.OnKeyDown(e)

    End Sub

As you can see I raise an custom event and query the Handled Variable of it afterwards.
My Event / ActionEventArgs looks like this:

    Public Event Action(sender as Object, e as ActionEventArgs)

    Public Class ActionEventArgs
        Inherits EventArgs

        Public Handled as Boolean
        Public Action as Action
        Public Sub New(ByVal action as ActionType)
            Me.Action = action
        End Sub
    End Class

where ActionType is this Enum

    Public Enum ActionType
        Bark,
        Jump,
        FireNukeWithoutFurtherWarning
    End Enum

Now I have a class that is registered to this event and, if it knows how to handle the ActionType it sets Handled to true.

    Public Sub actionHandler(ByVal sender as Object, e as ActionEventArgs) Handles me.Action

        If e.Handled then return

        If e.Action = ActionType.Bark
            Bark()
            e.Handled = true
        End If
    End If

I tried this code at my developer machine and it seems to work. In the OnKeyDown Method, everytime I query the Handled variable, my actionHandler method did run first.
But I asking me if this is only the case because my developer machine is in idle state and the event queue is processed so fast or can I expect the

    RaiseEvent(...)

method to wait until every registered EventHandler has finished it’s taks?

Answer 1

Raising an event is exactly the same as calling a method (specifically, it’s calling a MulticastDelegate, which is a list of pointers to other methods, each of which will be executed); the code will process all of the event handlers before it continues to your next statement.