Re: Exception-handling problems

From: Daniel Wilson (d.wilson_at_embtrak.com)
Date: 11/10/04 

Date: Wed, 10 Nov 2004 13:14:38 -0500

I trap the errors all the way up. The error messages with which the program
crashes are not those I wrote. They are about not being able to accept a
NULL value.

I'm now investigating whether my problem has to do with multiple revisions
residing on my computer, and an older one being in the GAC.

dwilson
"Nick Malik" <nickmalik@hotmail.nospam.com> wrote in message
news:u1pkd.321852$wV.123003@attbi_s54...
> Hi Daniel,
>
> Well, I'm not sure of the error you are getting. The blocks appear well
> coded (it's a bit unusual to see to blocks of code, one in C++ and the
other
> in VB).
> In both blocks, you appear to be catching all errors and re-issuing an
> exception upstream with the offending exception encapsulated. While
you've
> broken a couple of best practices (handle the error locally, trap errors
> using a specific error type, only raise ApplicationException or a derived
> exception class, etc), I don't see any code that fails to trap the error.
>
> You say that this code is running and, at a point when you don't expect to
> get an error message, a message appears showing details of the error.
Does
> that error message include the strings "Unable to launch Mail UI" or
"failed
> to fill user list"? because, if it does, then you ARE trapping the
error...
> and then turning around and throwing another one.
>
> Are you trapping again upstream from the first code snippet?
>
> --- Nick
>
> "Daniel Wilson" <d.wilson@embtrak.com> wrote in message
> news:uNAVdScxEHA.824@TK2MSFTNGP11.phx.gbl...
> > Here's a sample of the extern code. I'm wondering if
> > SuppressUnmanagedCodeSecurity is also suppressing some checking that
would
> > enhance stability.
> > [DllImport("opengl32.dll", EntryPoint="glEnable"),
> > SuppressUnmanagedCodeSecurity, CLSCompliantAttribute(true)]
> >
> > public static extern void glEnable (int cap);
> >
> > Here's a sample of the error-handling code that's not catching the
> > exceptions.
> >
> > try{
> >
> > UpdateDataSet();
> >
> > mailBoxWin->fillUserList(GetUsers());
> >
> > mailBoxWin->updateDataSet(set);
> >
> > mailBoxWin->refreshView();
> >
> > mailBoxWin->Show();
> >
> > }catch(Exception *E){
> >
> > String *sE = new String("Unable to launch Mail UI\n");
> >
> > sE = sE->Concat(sE,E->Source);
> >
> > sE = sE->Concat(sE,E->Message);
> >
> > throw new Exception(sE);
> >
> > }
> >
> > return true;
> >
> > }
> >
> >
> >
> > And here is fillUserList, called by the block above:
> >
> > Public Sub fillUserList(ByVal users As ArrayList)
> >
> > Try
> >
> > newMsgWin.fillUserList(users)
> >
> > Catch E As Exception
> >
> > Throw New Exception("Failed to fill user list." & vbCrLf & E.Message)
> >
> > End Try
> >
> > End Sub
> >
> >
> >
> > Thanks for ideas!
> >
> > dwilson
> >
> > "Nick Malik" <nickmalik@hotmail.nospam.com> wrote in message
> > news:bfMjd.585466$8_6.498363@attbi_s04...
> > > Please post an example of code that is not working in exception
> handling.
> > >
> > > Also, depending on how the library was written, there is nothing wrong
> > with
> > > calling external library functions. well-written libraries are likely
> to
> > > raise their own errors at the proper places.
> > >
> > > -- Nick
> > >
> > > "Daniel Wilson" <d.wilson@embtrak.com> wrote in message
> > > news:%23H21j3ZxEHA.2040@tk2msftngp13.phx.gbl...
> > > > I am having exception-handling and stability problems with .NET. I
> will
> > > > have a block of managed code inside try...catch and will still get a
> > > generic
> > > > .NET exception box that will tell me which assemblies are loaded
> before
> > > > shutting down. In one case, some of my DB-accessing code didn't
> handle
> > a
> > > > NULL value properly. But try...catch wouldn't catch the exception
and
> > keep
> > > > going. I'd just get the error message and then it would shut the
> > > > application down.
> > > >
> > > > Does .NET have problems like this? Or am I doing something wrong?
I
> > > can't
> > > > roll code like this out to our customers.
> > > >
> > > > Elsewhere in the application, I am using an open-source .NET library
> > that
> > > > extern's lots of functions. I am going back through that library
> trying
> > > to
> > > > add exception-handling, but if all it is is a lot of externs, I
don't
> > see
> > > > what I can do. Is a library like that inherently unstable?
> > > >
> > > > Thanks
> > > >
> > > >
> > > > --
> > > > Daniel Wilson
> > > > Senior Software Solutions Developer
> > > > Embtrak Development Team
> > > > http://www.Embtrak.com
> > > > DVBrown Company
> > > >
> > > >
> > >
> > >
> >
> >
>
>

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