[CMake] Cache variables from module

[Florian Lindner]

Hello,

I have a third party FindPETSc.cmake module:

https://github.com/jedbrown/cmake-modules/blob/master/FindPETSc.cmake

The problem I have, is that variable PETSC_VERSION is not set when cmake is run for a second time

https://github.com/jedbrown/cmake-modules/issues/28

What is best way to deal with that?

Can an entire function be cached, e.g. petsc_get_version or is adding CACHE to the set calls of PETSC_VERSION the best way?

Adding CACHE INTERNAL gives me error messages:

set (PETSC_VERSION "${PETSC_VERSION_MAJOR}.${PETSC_VERSION_MINOR}.${PETSC_VERSION_SUBMINOR}" CACHE INTERNAL "PETSc
version" PARENT_SCOPE)


CMake Error at tools/cmake-modules/FindPETSc.cmake:314 (if):
  if given arguments:

    "3.8.4" "CACHE" "INTERNAL" "PETSc version" "VERSION_LESS" "3.1"

  Unknown arguments specified



Thanks!
Florian