Question

Is there a way to catch these Exceptions? (I am not looking for “just put try/catch or on error goto around them”). I am trying to find out if these errors can be caught by something outside of them.

Public Class ABC
   Shared Sub New()
     throw new Exception("Ha!")
   End Sub
End Class

or this:

Public Class ABC
  Dim obj as Object = CreateObject()

  Public Function CreateObject()
    throw new Exception("Ha!")
  End Function
End Class

BTW, Putting these in my startup class’s (it’s a Windows form) as the first lines in “Shared Sub New()” isn’t working:

AddHandler Application.ThreadException, AddressOf Application_ThreadException
AddHandler AppDomain.CurrentDomain.UnhandledException, AddressOf CurrentDomain_UnhandledException

Answer 1

See this:
http://temujin.blogsome.com/2006/03/15/static-constructors-and-exceptions/ (now dead – archive)

Key points:

if an exception occurrs the runtime will allways wrap it in a TypeInitializationException

So try looking for a TypeInitializationException at the application/AppDomain level. Also:

the static constructor only is executed one time by the runtime, when the type is initialized; the second time the static field is accessed the initial exception will be thrown again

In a nutshell – don’t do anything that might throw exceptions in static (Shared) constructors. Move the code to static properties or methods or an instance constructor.