[petsc-dev] DMPlexCreateExodus directly from file

[Michael Lange]

Hi,

I keep hitting problems in my application code when I try to read in 
ExodusII meshes via DMPlex due to the exodus libs installed on my 
system. I can get around those simply by adding adding the ex_open() 
call required to get the exoid directly to DMPlexCreateExodus(). This 
solution works great with the ExodusII version PETSc downloads during 
configure and also makes the DMPlex-ExodusII interface self-contained, 
which means that I do not have to link my application code against 
exodus libs at all. The same argument applies to the DMPlex-CGNS interface.

So, I would like to prepare a pull request to make the ExodusII (CGNS) 
interface self-contained, and I can see two ways to do this:
a) Add the ex_open() call to DMPlexCreateExodus() and change the 
interface to use the file name directly
b) Add a utility function DMPlexCreateExodusFromFile() which calls 
ex_open and then invokes DMPlexCreateExodus() as before

Please tell me what you think and which way you prefer, and I will 
provide a pull request to implement this.

Kind regards,

Michael Lange