[CMake] How to make a ProjectConfig.cmake

[Michael Hertling]

On 12/30/2010 11:33 AM, Ian Monroe wrote:
> To create my QyotoConfig.cmake I need to know the full path of a
> library so that I can set a variable like QYOTO_LIBRARY.
> 
> This is pretty standard requirement right? Its what we're supposed to
> do in *Config.cmake's?

Yes.

> So anyways, how do I that? The only target property that hasn't
> returned NOTFOUND is LOCATION, which unhelpfully returns the location
> of the library in the build directory. I could parse this to get the
> file name, and then append it to the library install location... but
> that seems like such a hack. Feels like I'm doing something wrong if I
> need to use a hack to do something standard.

Usually, I'd have a template QyotoConfig.cmake.in which contains

FIND_LIBRARY(QYOTO_LIBRARY qyoto
    PATHS @CMAKE_INSTALL_PREFIX@/lib
    NO_DEFAULT_PATH
)

and is processed by CONFIGURE_FILE(). If the library is installed with

INSTALL(TARGETS qyoto
    RUNTIME DESTINATION bin
    LIBRARY DESTINATION lib
    ARCHIVE DESTINATION lib
)

the FIND_LIBRARY() in the resulting QyotoConfig.cmake file will find
the library right at the installation location but nowhere else, and
the platform-dependent file names, e.g. libqyoto.so versus qyoto.dll,
are also handled correctly.

> I looked at install(EXPORT which could work, but it seems to include a
> lot more information then is needed. I just want to set a variable
> with the full path to a library.

Nevertheless, the imported-targets approach, i.e. the combination of
INSTALL(TARGETS ... EXPORT ...) and INSTALL(EXPORT ...) along with an
appropriately set up config file, is much more powerful and should be
preferred, IMO; see [1] for more information. BTW, as the export file
defines the imported targets, its inclusion in the config file should
possibly be protected in a suitable way to avoid fatal redefinitions.

Regards,

Michael

[1] http://www.cmake.org/Wiki/CMake_2.6_Notes#Packaging_and_Exporting