[vtk-developers] VTK module system uplift to CMake 3.0 features

[Ben Boeckel]

On Mon, Mar 02, 2015 at 17:49:42 -0500, Marcus D. Hanwell wrote:
> Perhaps because removing/deprecating vtkMPI.cmake etc would change the
> build system interface. Traditionally the VTK build system has been
> fairly static, and people come to rely on CMake code. Not sure that is
> a major consideration at this stage, but it should be considered. I
> know we have had a number of people ask about the instantiator CMake
> code...

My plan was to keep all changes, to start, local to
vtkModuleMacros.cmake. This would ensure that code written for the old
API would still work (well, as far as CMake uses the API at least). Any
functions which would now be unnecessary would cause warning messages
based on a flag so that users/developers would have an upgrade path
(though whether to default to ON or OFF is a valid question).

> My main objection is that Ubuntu LTS 14.04 has CMake 2.8.12.2, and
> that is the most recent LTS (next is out next year I believe). CMake
> is reasonably easy to obtain/install locally updated versions, but
> LTS/distro CMake versions present an additional barrier. If people
> agree it is worth it then we should go with it, but a number of people
> tend to use LTS/enterprise versions to simplify upgrade cycles (3.0
> was tagged June 10 from the looks of it).

I think a PPA is fine for developers. I don't expect VTK 6.3 or whatever
version it ends up in to even be a thought for LTS.

--Ben