[vtk-developers] python install prefix in setup.py

[David Gobbi]

The default install location for the VTK python wrappers in VTKcvs 
doesn't make sense to me.
If the VTK install prefix is /usr/local, then the python wrappers will 
be installed here:

  /usr/local/python2.3/site-packages/

If python is installed somewhere else, (e.g. /usr/ is a common location) 
then installing
the wrappers in /usr/local isn't very useful.

The default behaviour of setup.py is to query the python executable to 
find out where it is
installed.  This behaviour is explicitly overridden by 
VTK/Wrapping/Python/CMakeList.txt:

  SET(VTK_PYTHON_SETUP_ARGS "--prefix=\"${DOLLAR}{CMAKE_INSTALL_PREFIX}\""
      CACHE STRING "Arguments passed to \"python setup.py install ...\" 
during installation.")

I think that having a customizable VTK_PYTHON_SETUP_ARGS is a good idea, 
but the default
value of this variable is not going to work for most people.

The best option is to query the PYTHON_EXECUTABLE to see where it was 
installed, and use that
as the wrapper install prefix instead of using CMAKE_INSTALL_PREFIX.

The python install prefix can be queried by running 'python -c "import 
sys; print sys.prefix"',
where 'python' is whatever PYTHON_EXECUTABLE has been set by cmake.

Does this make sense to anyone else?

 - David