[cmake-developers] Using cmake pkg-config-like in non-cmake builds

[Alexander Neundorf]

Hi,

there can be the case that a package which has been built with cmake, should 
be used in a project which doesn't use cmake.
There is a feature request that cmake should help with generating pkg-config 
pc-files: http://public.kitware.com/Bug/view.php?id=11446

I don't like that idea, because a) this means duplicating information, and b) 
doing that in a less powerful format.

I have a slightly different idea: instead of having cmake generate pc-files, 
modify/extend cmake so that it can be used similar to pkg-config by projects 
which don't use cmake as their buildsystem.
I attached a first very quick try to that bug report.
It's a small cmake script which can be executed by cmake with -P, and which 
basically contains one find_package() call and prints the results, so they 
can be fed into a compiler invocation in a makefile.

It already somewhat works:
$ cmake -DMODE=COMPILE -DCOMPILER_ID=GNU -DPACKAGE=PNG -P cmake-config.cmake
 -I/usr/include -I/usr/include
 
 $ cmake -DMODE=LINK -DCOMPILER_ID=GNU -DPACKAGE=PNG -P cmake-config.cmake
 /usr/lib/libpng.so /usr/lib/libz.so
 

Do you think this makes sense ?

Current issues:
* the output goes to stderr instead stdout
* the output has line breaks
* actual problem: currently it's not possible to use commands which deal with 
targets in script-mode (I disabled that in 2007 since at least back then it 
didn't make sense). This means that find-modules which use try_compile() 
internally fail, and also those which create imported targets.

Do you think it is worth to put some effort into this ?

Alex