[vtk-developers] [ANNOUNCE] New module system landing

[Ben Boeckel]

On Mon, Feb 04, 2019 at 15:31:22 +0000, Andras Lasso wrote:
> I just wanted to clarify that application developers only need YES and
> DONT_WANT states for VTK modules. If the other states are required
> internally in VTK (for example, for VTK automatic tests) then it's
> fine, but please try to keep the VTK's public CMake configuration API
> simple.

That can be provided. An option to `vtk_module_scan` to provide a
limited set of values for the `STRINGS` property can be done.

> > Right now it says "X requires disabled module Y". What's missing is
> > information of the link between X and Y for figuring out how to fix
> > it.
> 
> Dependency graph printing feature of CTK fixes this. See an example
> below how external project dependency graph is printed during
> application configuration. @jcfr can give you more details on how this
> works and could be adapted to VTK modules.

One difference is that it will be provided on-demand only. I personally
find such configure output to be noise for general reconfigures and can
take up a substantial amount of configure time to format and write. VTK
now re-configures in under 10 seconds on my machine; I'd like to avoid
having that start to creep up for information useful only sometimes.

For anyone interested in implementing it, the dependency logic is all in
`vtk_module_scan` after the topological sort into
`_vtk_scan_all_modules`.

--Ben