[CMake] FIND_PACKAGE, version check

[Pierre]

Hello,

On 1/9/07, Eric Noulard <eric.noulard at gmail.com> wrote:
> 2007/1/9, Pierre <pierre.php at gmail.com>:
> > Hello,
> >
> > Being new to this list and cmake, I first like to thank you for cmake,
> > it is a pleasure to work with it.
> >
> > In an attempt to use CMake in libgd (http://libgd.org), I was looking
> > for a way to use the versions argument in find_package. For example, I
> > have to do something like:
> >
> > FIND_PACKAGE(Freetype 2.2) or FIND_PACKAGE(Freetype 2.2.1)
> >
> > I checked the various Find* function in cmake (2.4.3) or the various
> > other projects like KDE but they don't seem to check the version
> > informations in the cmake Find* macros. My idea was to provide
> > FOO_VERSION(_(MAJOR|MINOR|PATH), is it the way to go?
>
> I  don't know the "WAY to go" but I did something similar
> for checking version.
>
> You may find it useful to know that if you
> SET(FOO_MINIMAL_VERSION "3.4.7")
> EXEC_PROGRAM(${FOO_CONFIG_PROGRAM}
>     ARGS "--version"
>     OUTPUT_VARIABLE FOO_VERSION)
>
> you may easily check for "sufficient" version with something like
>
> IF (FOO_VERSION STRGREATER FOO_MINIMAL_VERSION)
>     MESSAGE(STATUS "Be happy with foo ${FOO_VERSION})
> ELSE (FOO_VERSION STRGREATER FOO_MINIMAL_VERSION)
>     MESSAGE(ERROR "Unable to use version ${FOO_VERSION} of foo...")
> ENDIF

Yes, that's the idea (or using regexp for exotic versions scheme).
Hiding these tests insinde the FindFoo.cmake can be handy (and clean
:). I will try to provide a patch for the existing macros and post it
here (freetype, png, jpeg, etc. )

--Pierre