kicad-developers team mailing list archive

[Wayne Stambaugh <stambaughw@xxxxxxxxxxx>]

On 4/12/2013 4:17 PM, Adam Wolf wrote:
> Hi Wayne,
>
> It looks like CMake doesn't extract the library version number from
> the interpreter--it just finds the highest python version libraries
> installed.  Someone wrote up a new FindPythonLibs.cmake that does look
> at the running interpreter, and it was rejected in 2011.  This may be
> part of why the team has such a hard time with Python and cmake!

The reason for the rejection is that it failed on cross-platform builds 
but it could have be modified to check for a cross build and use the 
version pulled from the default interpreter on non-cross builds.

> The patch to do this would be extremely minimal--check if
> PYTHON_VERSION_MAJOR and PYTHON_VERSION_MINOR were set (by
> FindPythonInterp) and then replace the version list creation with
>
> set(_FOUND_PYTHON_MAJ_MIN ${PYTHON_VERSION_MAJOR}.${PYTHON_VERSION_MINOR})
>
> set(_Python_VERSIONS
>     ${Python_ADDITIONAL_VERSIONS}\
>     ${_FOUND_PYTHON_MAJ_MIN}\
>     ${_PYTHON_FIND_OTHER_VERSIONS}
>     )
>
> This would make it search for user specified versions first, then the
> detected version, and then the standard Python version list.
>
> Since CMake's Python version detection is currently broken with cmake
> on any system where there are installed headers of a newer version
> than the default interpreter, which includes Fedora and Ubuntu, do you
> think I should write and test this patch, and send it over to the
> CMake folks, or do you think that'd be a waste given the fact that
> since at least 2011, they've been wanting to first rewrite Python
> version detection with FindPython.cmake?
> (http://www.cmake.org/pipermail/cmake/2011-November/047799.html)
>
> Adam Wolf
> Wayne and Layne, LLC

I don't know if you'll get anywhere sending the patch to the CMake folks 
but for our purposes we could use the default interpreter version on 
non-cross builds which should solve part of the problem.  To prevent 
python 3 from being used, you would have to remove the all of the python 
3 paths from the path search lists of both FindPythonInter and 
FindPythonLib.