[vtkusers] file readers: determine file type before Update()?

[Nico Schlömer]

Hi,

for reading data from VTK/pVTK/Exodus/... files, is there any way to
determine the file format before calling Update() on the reader (and
error out)?
What I've currently got is

    if extension == '.vtu':
        # Set up VTU reader
    elif extension == '.vtk':
        # Set up VTK reader
    elif extension in [ '.ex2', '.exo', '.e' ]:
        # Set up exodus reader
    else:
        raise RuntimeError( 'Unknown file type \'%s\'.' % filename )

but this is going wrong if the extension doesn't coincide with the
file type, and is getting messy for parallel file format.

Any hints?

Cheers,
Nico