Question

Is RaiseEvent thread safe?

In C# you write

if (event != null)
{
    event.invoke();
}

and the C# code is not thread safe….

Answer 1

If I need to do thread safe events, I write this:

Class Test

    Public Event Click(ByVal sender As Object, ByVal e As EventArgs)
    Public Event MouseIn(ByVal sender As Object, ByVal e As EventArgs)

    Private Delegate Sub EventArgsDelegate(ByVal e As EventArgs)
    Private ReadOnly _parent As Control

    Public Sub New(ByVal parent As Control)
        _parent = parent
    End Sub

    Private Sub OnClick(ByVal e As EventArgs)

        If _parent.InvokeRequired Then
            _parent.Invoke(New EventArgsDelegate(AddressOf OnClick), e)
        Else
            RaiseEvent Click(Me, e)
        End If

    End Sub

    Private Sub OnMouseIn(ByVal e As EventArgs)

        If _parent.InvokeRequired Then
            _parent.Invoke(New EventArgsDelegate(AddressOf OnMouseIn), e)
        Else
            RaiseEvent MouseIn(Me, e)
        End If

    End Sub

End Class

Then whenever I need to raise the event I just use the OnClick(new eventargs(...)), etc. If you use Reflector you can observe that most thread safe controls use a similar system.