[CMake] Create an XXXConfig.cmake file

[Michael Jackson]

Thanks to everyone for the help. I'll start taking a look around. Just  
for the record, John Biddiscombe is also helping in this effort and  
there is also initial "buy-in" from The HDFGroup to switch their HDF5  
windows builds over to CMake in the future when the CMake version  
stabilizes.

There was some discussion on the boost-cmake mailing list about this  
subject and the reason I didn't really go for the HDF5Exports approach  
was that I need to know "a-priori" what hdf5 libraries were installed  
and the names of those targets, at least as I understood it then.  
Maybe I was misunderstanding something.

When the HDF5-CMake sources get to that point some one will start  
investigating it more.

The project is at www.gitorious.com/hdf5/hdf5-v18 if anyone wants to  
contribute or just monitor the situation..
--
Mike Jackson <www.bluequartz.net>

On Nov 19, 2009, at 11:14 AM, Michael Wild wrote:

>
> On 19. Nov, 2009, at 16:24 , Michael Jackson wrote:
>
>> So, there are a few of us quickly port the HDF5 1.8 code to CMake.  
>> I'm thinking that we should put in an HDF5Config.cmake file for  
>> other projects use. Simple question:
>>
>> What goes in one of those? Is there a tutorial somewhere? Where  
>> does the file get installed into? What does the consumer of the  
>> file need to put into their cmake files?
>>
>> And what version of CMake does all that apply to?
>>
>> Thanks
>>
>
> That depends on how complicated your stuff is. Most likely it will  
> be something like this:
>
> # Tell the user project where to find our headers and libraries
> set( HDF5_INCLUDE_DIRS "@CMAKE_INSTALL_PREFIX@/include" )
> set( HDF5_LIBRARIES "@CMAKE_INSTALL_PREFIX@/lib")
>
> # Our build settings and library dependencies
> include( "@CMAKE_INSTALL_PREFIX@/share/cmake/ 
> HDF5LibraryDepends.cmake" )
> include( CMakeImportBuildSettings )
> cmake_import_build_settings( "@CMAKE_INSTALL_PREFIX@/share/cmake/ 
> HDF5MBuildSettings.cmake" )
>
>
> Of course, you must create the HDF5LibraryDepends.cmake and the  
> HDF5BuildSettings.cmake using install(EXPORT ...) and  
> cmake_export_build_settings, respectively. For the former to work,  
> you have to install the libraries using an export-set, e.g:
>
> # install target HDF5 (supposedly the library)
> install(
>  TARGETS HDF5
>  EXPORT HDF5LibraryDepends   # this is the name of the export-set
>  LIBRARY DESTINATION lib COMPONENT shlibs
>  ARCHIVE DESTINATION lib COMPONENT dev
>  RUNTIME DESTINATION bin COMPONENT bin
>  PUBLIC_HEADER DESTINATION include COMPONENT dev
>  )
>
> # install the export-set
> install(
>  EXPORT HDF5LibraryDepends # again, the name of the export-set
>  DESTINATION "@CMAKE_INSTALL_PREFIX@/share/cmake"
>  COMPONENT dev
>  )
>
>
> If you carefully read the man-page about find_package, there's a  
> whole section detailing where CMake finds XXXConfig.cmake files. The  
> path <prefix>/share/cmake is only one example that works on *NIX  
> platforms. Probably you'll want to use something else on Windows (or  
> Mac if you're building a framework). Also if your package requires  
> the user to do add_definition and similar stuff, or you want to  
> provide him helper-functions, you should put that stuff in a  
> HDF5Use.cmake and in the HDF5Config.cmake set the variable  
> HDF5_USE_FILE to the path of this file. If the user then wants to  
> make use of these add_definitions and functions, he should then  
> include ${HDF5_USE_FILE}. If you decide to provide a HDF5Use.cmake,  
> the cmake_import_build_settings code should also be moved there.
>
> Essentially, XXXConfig.cmake should act like a FindXXX.cmake (define  
> XXX_LIBRARIES and XXX_INCLUDE_DIRS and related) plus include the  
> XXXLibraryDepends.cmake file and perhaps also import the build  
> settings (or define XXX_USE_FILE).
>
> HTH
>
> Michael