[CMake] Package installation conundrum

[Michael Wild]

On 09.05.2012, at 21:03, Alexander Neundorf <a.neundorf-work at gmx.net> wrote:

> On Wednesday 09 May 2012, Michael Wild wrote:
> > On 05/08/2012 11:13 PM, Dave Abrahams wrote:
> > > on Tue May 08 2012, Alexander Neundorf <a.neundorf-work-hi6Y0CQ0nG0-AT-public.gmane.org> wrote:
> > >> On Tuesday 08 May 2012, Dave Abrahams wrote:
> > >>> Here's another one!
> > >>>
> > >>> Scenario:
> > >>>
> > >>> * I am running CMake under 0install to build and install libraries
> > >>>
> > >>> * Each library builds a package SomePackage for the library binaries
> > >>> and another package SomePackage-dev for the library headers (and
> > >>> import libraries on Windows)
> > >>>
> > >>> * The FindSomePackage.cmake file is part of the -dev package
> > >>>
> > >>> * After building, 0install moves each package's build products into a
> > >>> mostly-unpredictable subdirectory of its otherwise-read-only "cache"
> > >>> (~/.cache/0install.net/). The subdirectory's name is determined by a
> > >>> hash of the files.
> > >>>
> > >>> * To get this working, I followed the scheme discussed here:
> > >>>
> > >>> http://news.gmane.org/find-root.php?message_id=%3cm2lil6s8jq.fsf%40plut
> > >>> o.l uannocracy.com%3e
> > >>>
> > >>> Summary:
> > >>>
> > >>> 1. Create a 0install "SomePackage-preinstall" package. Building this
> > >>> package involves CMake building and installing both SomePackage and
> > >>> SomePackage-dev into separate subdirectories (main/ and dev/) of
> > >>> some prefix. 0install thereafter moves the whole directory tree
> > >>> into its cache in a directory called sha1=someuglyhash
> > >>>
> > >>> 2. SomePackage's 0installation procedure is to copy
> > >>> sha1=someuglyhash/main/ into its distribution directory (which then
> > >>> ends up in
> > >>> ~/.cache/0install.net/sha1=otheruglyhash)
> > >>>
> > >>> 3. SomePackage-dev's 0installation procedure is to copy
> > >>> sha1=someuglyhash/dev/ into its distribution directory
> > >>>
> > >>> Problem: FindSomePackageConfig.cmake now has the wrong path to the
> > >>> library binaries.
> > >>>
> > >>> Any help most appreciated.
> > >>
> > >> Can you please summarize what you actually want to achieve ?
> > >
> > > Well, I tried to, above.
> > >
> > > In short, I want to create separate main and -dev packages without
> > > building twice, under the constraints imposed by 0install.
> > >
> > >> Do you say that libFoo installs a FindFoo.cmake as part of libFoo-devel
> > >> ?
> > >>
> > >> If that's the case, then this is wrong.
> > >
> > > I'm sorry, that *is* wrong. It installs a FooConfig.cmake as part of
> > > libFoo.devel
> > >
> > >> FindFoo.cmake must be part of the using software, not of the software to
> > >> be searched.
> > >>
> > >> Why do you have to find the installed library in this cache directory
> > >> ?
> > >
> > > Because, in a 0install world, that's where things go when you "install"
> > > them.
> >
> > Ok, how you do it along these lines:
> >
> > CMakeLists.txt:
> > #-------------- BOF
> >
> > cmake_minimum_required(VERSION 2.8 FATAL_ERROR)
> > project(Foo)
> >
> > set(FOO_VERSION 1.2.3)
> >
> > # initialize (absolute) installation directory variables
> > set(INSTALL_BIN_DIR bin CACHE PATH "Install path for binaries")
> > set(INSTALL_LIB_DIR lib CACHE PATH "Install path for libraries")
> > set(INSTALL_INCLUDE_DIR include CACHE PATH "Install path for headers")
> > # this is for UNIX systems, see docs of find_package() for the search
> > # paths on APPLE and WIN32
> > set(INSTALL_CMAKE_DIR lib/foo-${FOO_VERSION}/cmake CACHE PATH
> > "Install path for CMake files")
> > foreach(t BIN LIB INCLUDE CMAKE)
> > if(NOT IS_ABSOLUTE ${INSTALL_${t}_DIR})
> > set(INSTALL_${t}_DIR ${CMAKE_INSTALL_PREFIX}/${INSTALL_${t}_DIR})
> > endif()
> > mark_as_advanced(INSTALL_${t}_DIR)
> > endforeach()
> >
> > # configure FooConfig.cmake and friends. FooConfig.cmake must be able
> > # to locate FooExports.cmake and FOO_INCLUDE_DIR relative to its own
> > # directory without using absolute paths.
> > configure_file(cmake/FooConfig.cmake.in
> > ${PROJECT_BINARY_DIR}/FooConfig.cmake @ONLY)
> Please have a lokok at the new macro configure_package_config_file() which is in cmake 2.8.8.
> This helps a lot with writing config files which are relocatable.
> The Config.cmake.in file has to contains a few special variables/macros:
> @PACKAGE_INIT@
> set(FOO_INCLUDE_DIR "@PACKAGE_INSTALL_INCLUDE_DIR@" )
> set(FOO_BIN_DIR "@PACKAGE_INSTALL_BIN_DIR@" )
> i.e. for every FOO_XYZ variable use a @PACKAGE_FOO_XYZ@ variable, and the configure_package_config_file() will replace this with the help of the @PACKAGE_INIT@ macro with a relocatable version.
> http://www.cmake.org/cmake/help/v2.8.8/cmake.html#module:CMakePackageConfigHelpers
> > configure_file(cmake/FooConfigVersion.cmake.in
> > ${PROJECT_BINARY_DIR}/FooConfigVersion.cmake @ONLY)
> >
> > # configure the headers into the build tree so the package can be used
> > # without installing it and not hard-coding the source/build directory
> > # information into FooConfig.cmake
> > configure_file(include/foo.h
> > ${PROJECT_BINARY_DIR}/include/foo.h COPYONLY)
> The input file should have a suffix which indicates it is a file which is intended to be configured, usually foo.h.in.
> Alex

I don't agree, since it's COPYONLY. Besides, with a little more work in FooConfig.cmake you can skip that step...

Michael