[vtkusers] Interfacing Parallel VTK with other parallel API

[Moreland, Kenneth]

Hi all,

I'm having trouble interfacing the parallel VTK objects with another
parallel API which exclusively uses MPI.  Specifically, I'm making a VTK
object (as a wrapper over the auxiliary API) which accepts a
vtkMPIController and must extract the MPI_Comm object from the associated
vtkMPICommunicator.

The tricky bit is that the reference to the MPI_Comm object in the
vtkMPICommunicator is protected.  I previously got around this problem by
making a dummy class that inherited from vtkMPICommunicator and provided a
public method to return the MPI_Comm object.  This has been working for
quite a while, but yesterday I checked out the latest nightly build and
found that the constructor and destructor for vtkMPICommunicator have been
made private, making inheritance impossible.

Is there another way to get at the MPI_Comm object?  If not, could the
vtkMPICommunicator constructor and destructor be made protected again?  Or
could a public method for returning the vtkMPICommunicatorOpaqueComm be
added?

-Ken

   ****      Kenneth Moreland
    ***      Sandia National Laboratories
***********  
*** *** ***  email: kmorel at sandia.gov
**  ***  **  phone: (505) 844-8919
    ***      fax:   (505) 844-9297