[CMake] How to make a ProjectConfig.cmake

[Michael Wild]

On 01/19/2011 07:24 PM, Alexander Neundorf wrote:
> On Thursday 30 December 2010, Michael Wild wrote:
>> 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?
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> Ian
>>
>> That's not how *Config.cmake modules work. They're NOT Find*.cmake
>> modules. You should:
>>
>> - add the targets to an export-set for usage from the build tree:
>>
>>   export(TARGETS ...
>>     FILE ${CMAKE_BINARY_DIR}/${PROJECT_NAME}LibraryDepends.cmake)
>>
>> - add the targets to an export-set for installation:
>>
>>   install(TARGETS ... EXPORT ${CMAKE_PROJECT_NAME}LibraryDepends ...)
>>
>> - export the package for usage from the build tree (enter into some
>> global registry):
>>
>>   export(PACKAGE ${PROJECT_NAME})
>>
>> - create a *Config.cmake file for the use from the build tree:
>>
>>   set(QYOTO_INCLUDE_DIR ${CMAKE_SOURCE_DIR})
>>   set(QYOTO_LIB_DIR ${CMAKE_BINARY_DIR}/lib)
>>   set(QYOTO_CMAKE_DIR ${CMAKE_BINARY_DIR})
>>   configure_file(${CMAKE_PROJECT_NAME}Config.cmake.in
>>     ${CMAKE_BINARY_DIR}/${CMAKE_PROJECT_NAME}Config.cmake @ONLY)
>>
>> - install the export set:
>>
>>   install(EXPORT ${CMAKE_PROJECT_NAME}LibraryDepends DESTINATION
>>     share/${CMAKE_PROJECT_NAME}/CMake)
>>
>>
>> - create a *Config.cmake file for the use from the install tree and
>> install it:
>>
>>   set(QYOTO_INCLUDE_DIR ${CMAKE_INSTALL_PREFIX}/include)
>>   set(QYOTO_LIB_DIR ${CMAKE_INSTALL_PREFIX}/lib)
>>   set(QYOTO_CMAKE_DIR
>>     ${CMAKE_INSTALL_PREFIX}/share/${CMAKE_PROJECT_NAME}/CMake)
>>   configure_file(${CMAKE_PROJECT_NAME}Config.cmake.in
>>     ${CMAKE_BINARY_DIR}/InstallFiles/${CMAKE_PROJECT_NAME}Config.cmake
>>     @ONLY)
>>   install(FILES
>>     ${CMAKE_BINARY_DIR}/InstallFiles/${CMAKE_PROJECT_NAME}Config.cmake
>>     DESTINATION share/${CMAKE_PROJECT_NAME}/CMake)
>>
>> - The *Config.cmake.in could look like this:
>>
>> #######################################################################
>> # Tell the user project where to find our headers and libraries
>> set(QYOTO_INCLUDE_DIR "@QYOTO_INCLUDE_DIR@")
>> set(QYOTO_INCLUDE_DIRS "${QYOTO_INCLUDE_DIR}")
>> set(QYOTO_LIBRARY_DIRS "@QYOTO_LIB_DIR@")
>>
>> # Our library dependencies (contains definitions for IMPORTED targets)
>> include("@QYOTO_CMAKE_DIR@/@PROJECT_NAME at LibraryDepends.cmake")
>>
>> # Defines (if required)
>> set(QYOTO_DEFINITIONS "@QYOTO_COMPILE_DEFINITIONS@")
>>
>> # USE file (if you have one)
>> set(QYOTO_USE_FILE
>>   "@QYOTO_CMAKE_DIR@/@PROJECT_NAME at Use.cmake"
>>   )
>> #######################################################################
>>
>> As you can see, the QYOTO_INCLUDE_DIR, QYOTO_LIB_DIR and QYOTO_CMAKE_DIR
>> values will differ between build and install tree, which is why you
>> should configure it twice, once for installation and once for the use
>> from the build tree.
>>
>> - If you want to get fancy, you can also provide a *ConfigVersion.cmake
>> file. This file should set the following variables, depending on the
>> variables PACKAGE_FIND_NAME, PACKAGE_FIND_VERSION,
>> PACKAGE_FIND_VERSION_{MAJOR,MINOR,PATCH,TWEAK,COUNT}:
>>
>>   - PACKAGE_VERSION (version string)
>>   - PACKAGE_VERSION_EXACT (TRUE or FALSE)
>>   - PACKAGE_VERSION_COMPATIBLE (TRUE or FALSE)
>>   - PACKAGE_VERSION_UNSUITABLE (TRUE or FALSE)
> 
> Wow, good summary.
> 
> Can you please put that in a wiki page on http://www.cmake.org/Wiki/CMake ?
> 
> Thanks :-)
> Alex

http://www.cmake.org/Wiki/CMake:How_to_create_a_ProjectConfig.cmake_file

What do you think? Text is pretty terse, but the code should cover it...

Michael