Exception Handling in Exception Handlers

[David Williams]

Sorry to do this to you folks

I am using the Try.... Catch.... Finally structure with great success,
however...

How can I turn OFF the exception handling in a situation where I know that
errors are likely to happen, and should be ignored? I.E. in a Unhanded
Exception Handler? I code heavily to avoid ever going into this handler
(don't we all?), but to write a completely stable service, I need to handle
the cases where the system is already going South on me, and something so
exceptional has happened that it is outside of my trappings. Such as the
network going down or the database server crashing. In these cases, I want
to turn off the exception handler so that I can get what information I can,
and log it somewhere. (Hopefully to the event log, but I could be so dead,
that it may be just to a file or heaven forbid, to a console screen [no
saving that report!])

In the past I would just do an On Error Resume Next. However, I know that
this is something the C/C++ programmers have been handling (I hope!?!?!?!)
for years in a structured exception handling world. So, I come to you and
ask -- how?

Thanks for any ideas,

David

[Russell Jones]

One answer is to nest Try blocks--something like this. This is not tested
code--it's only meant to give you an idea. The example below would try to
log the error to the event log, and if that failed, would try to log the
error to a file. If that fails, it gives up.

You could obviously simplify this code a great deal by moving the
file-logging code into an error trap in the event-logging code if you
*always* wanted to log errors to a file if the event log doesn't work.

Also, be aware that the Exceptions themselves may contain InnerExceptions
that have more information than the exception you actually catch, so be sure
to unwind the exceptions when you log error.

Try
' do something
Catch (ex as Exception)
' Try to log the error info
Try
logError(ex)
Catch (LogEx as Exception)
' can't log, try to write a file
Try
writeFileError(ex)
Catch (FileEx as Exception)
' can't write a file either, give up
End Try
End Try
Finally
Try
' cleanup here
Catch
' whatever you want
End Try
End Try


"David Williams" <d.w.i.l.l.i.a.m.s.@strohlsystems.com> wrote in message
news:3cf3b0cb$1@10.1.10.29...
> Sorry to do this to you folks
>
> I am using the Try.... Catch.... Finally structure with great success,
> however...
>
> How can I turn OFF the exception handling in a situation where I know that
> errors are likely to happen, and should be ignored? I.E. in a Unhanded
> Exception Handler? I code heavily to avoid ever going into this handler
> (don't we all?), but to write a completely stable service, I need to
handle
> the cases where the system is already going South on me, and something so
> exceptional has happened that it is outside of my trappings. Such as the
> network going down or the database server crashing. In these cases, I
want
> to turn off the exception handler so that I can get what information I
can,
> and log it somewhere. (Hopefully to the event log, but I could be so
dead,
> that it may be just to a file or heaven forbid, to a console screen [no
> saving that report!])
>
> In the past I would just do an On Error Resume Next. However, I know that
> this is something the C/C++ programmers have been handling (I hope!?!?!?!)
> for years in a structured exception handling world. So, I come to you and
> ask -- how?
>
> Thanks for any ideas,
>
> David
>
>
>