[vtk] Error handling

[Roland Schwarz]

Dear VTK Users,
    I wonder if anyone can tell me how to do proper error
handling in VTK. I am relatively new to VTK and have
only limited understanding of the inner workings of the
visualization pipeline. Yes I have read the book 'The Visualization
Toolkit' and also bought the printed users manual.

I have come over this question as I tried to set different 
input files for the reader. Now if the file is in error i.e. has
corrupt data, this first results in a call to an error macro and
then in a pop up message. The only coice at this point is
to terminate the application or to leave the piplene in an
inconsistent state. The latter is bad since this will trigger
some VERY bad things as invalid pointer derefs and that
like.

What I would like to do is giving the user an option to choose
a different file or otherwise be able to correct this error. (I expect
similar problems when manipulating the pipeline in other
ways that can result in errors.)

The first idea that came to me was to use the C++ throw and catch
mechanism triggered from the vtkObject::BreakOnError member.
But that will end up at the point where an Update was requested
what is likely a bad place to actually correct the error.

This kind of things must have been solved by some other users
and I am sure that I am missing something so please give me
any pointers where to learn about this (I did'nt find anything in the
FAQ too).

Thank you, 
Roland.

Dipl.-Ing. Roland Schwarz
Business Email: RSchwarz at riegl.co.at
Private Email: roland.schwarz at telecom.at



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