[cmake-developers] Adding MacroWriteBasicCMakeVersionFile.cmake file to cmake ?

[Alexander Neundorf]

On Sunday 31 July 2011, Brad King wrote:
> On 7/30/2011 3:33 AM, Rolf Eike Beer wrote:
> >> Another common scheme is to say that a version is compatible if the
> >> major version number matches and incompatible otherwise.   I'm not
> >> saying we have to try to include every common scheme.   I think just
> >> the basic one you proposed originally is sufficient.   However, I'd
> >> like to come up with a name for it that will distinguish it from
> >> other schemes added in the future.   Any ideas for a name?
> > 
> > NewerVersionMatches and MajorVersionMatches?
> 
> Those sound good, thanks!

Didn't know what the best way to do it would be, so there are now two branches 
on stage, WriteConfigVersionFile and ConfigVersionFile_2Templates.

Both have the same purpose, but one provides a macro, which wraps the 
configure_file() file call, and the other one provides two 
ConfigVersion.cmake.in files, which the user can then use as input for 
configure_file().

Usage with the macro is like this:

include(WriteBasicConfigVersionFile)
write_basic_config_version_file(${CMAKE_CURRENT_BINARY_DIR}/XyzConfigVersion.cmake
                                VERSION 2.3.4 COMPATIBILITY SameMajorVersion )

Alternatively "AnyNewerVersion" can be used instead of "SameMajorVersion".
With the two input files usage is like this:

set(PROJECT_VERSION 1.2.3)
configure_file(
    ${CMAKE_ROOT}/Modules/BasicConfigVersion-SameMajorVersion.cmake.in
    ${CMAKE_CURRENT_BINARY_DIR}/XyzConfigVersion.cmake @ONLY )


Also here, alternatively BasicConfigVersion-AnyNewerVersion.cmake.in can be 
used as input file.
And then in both cases:


install(FILES ${CMAKE_CURRENT_BINARY_DIR}/XyzConfigVersion.cmake
              ${CMAKE_SOURCE_DIR}/XyzConfig.cmake
        DESTINATION lib/cmake/xyz )



I'm not sure which syntax I like better. The one with the macro feels more 
high-level, but maybe hides too much what is actually going on (which is not 
much). The one where the user must use configure_file() directly feels more 
low-level, but doesn't try to make a secret of what's going on, which may be 
better to encourage users to write their own version files.

Which one would you prefer ?
I'll add tests for the one we decide to use.

Alex