[CMake] Please critique my "hello world" CMakeLists.txt and Config.cmake

[Alexander Neundorf]

On Sunday 24 February 2013, Chris Stankevitz wrote:
> On Sun, Feb 24, 2013 at 12:37 PM, Alexander Neundorf
> 
> <a.neundorf-work at gmx.net> wrote:
> >> github links:
> >> https://github.com/chrisstankevitz/hello
> >> https://github.com/chrisstankevitz/hello-client
> > 
> > Maybe we'll start with the old way and get to the new way.
> 
> Alex,
> 
> Thank you again.  I updated the projects per your teaching.  The only
> place I had to guess was here:
> 
> INSTALL(
>   FILES
>     ${CMAKE_CURRENT_BINARY_DIR}/helloConfig.cmake
>   DESTINATION
>     ${hello_DIRNAME_lib}
>   )
> 
> With respect to this INSTALL directive, I have three questions:
> 
> 1. Is it needed?  [Apparently the answer is yes]

Yes, this installs the Config.cmake file to a place where it will be found by 
find_package().
If you would only install(EXPORT ... FILE helloConfig.cmake) , i.e. name the 
exported target file Config.cmake, then you wouldn't have a place where you 
can set the include directory variables or other information.

> 2. Is ${CMAKE_CURRENT_BINARY_DIR}/helloConfig.cmake the appropriate
> way for me to reference this file?  I got this from kdelibs.git.

Yes. configure_file() creates the output files in CMAKE_CURRENT_BINARY_DIR if 
you don't tell it to put it somewhere else.

> 3. Is ${hello_DIRNAME_lib} (aka
> /usr/local/lib/hello-1.1/helloConfig.cmake) the correct place to
> install helloConfig.cmake?  kdelibs.git puts it somewhere else
> ("${CMAKECONFIG_INSTALL_DIR}" which I guessed corresponds to the weird
> location /usr/local/hello/).

See the documentation for find_package(), for the locations where it searches 
Config.cmake files.
lib/hello-1.1/helloConfig.cmake sounds good, this should be the 
"<prefix>/(lib/<arch>|lib|share)/<name>*/"  case from the docs.
kdelibs puts it into lib/cmake/<name>/

Alex