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| __TOC__
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| This page documents creation and use of packages that help projects locate each other. | | This page has moved [https://gitlab.kitware.com/cmake/community/wikis/doc/tutorials/Packaging here]. |
| These features are distinct from CPack which is meant for creating source and binary distributions and installers.
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| The <code>find_package</code> command has been enhanced with features to help find packages without the use of "find" modules (FindXXX.cmake files).
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| Projects that are aware of CMake may provide a "package configuration file" inside their installation trees.
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| Naming the file correctly and installing it in a suitable location will allow the <code>find_package</code> command to find it easily.
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| See also the CMake [[CMake/Tutorials/Package_Registry|Package Registry]] to help <code>find_package</code> find packages in arbitrary locations.
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| =Package Configuration Files=
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| Consider a project "Foo" that installs the following files:
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| <pre>
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| <prefix>/include/foo-1.2/foo.h
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| <prefix>/lib/foo-1.2/libfoo.a
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| </pre>
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| It may also provide a CMake package configuration file
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| <pre>
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| <prefix>/lib/foo-1.2/foo-config.cmake
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| </pre>
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| with content such as
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| <pre>
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| # ...
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| # (compute PREFIX relative to file location)
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| # ...
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| set(foo_INCLUDE_DIRS ${PREFIX}/include/foo-1.2)
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| set(foo_LIBRARY ${PREFIX}/lib/foo-1.2/libfoo.a)
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| </pre>
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| If another project wishes to use Foo it need only to locate the <code>foo-config.cmake</code> file and load it to get all the information it needs about package content locations.
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| Since the package configuration file is provided by the package installation it already knows all the file locations.
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| The <code>find_package</code> command may be used to search for the configuration file:
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| <pre>
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| find_package(Foo)
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| </pre>
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| This command (assuming no <code>FindFoo.cmake</code> module exists) constructs a set of installation prefixes and searches under each prefix in several locations.
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| Given the name "Foo", it looks for a file called "<code>FooConfig.cmake</code>" or "<code>foo-config.cmake</code>".
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| The full set of locations is specified in the <code>find_package</code> command documentation, but one place it looks is
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| <pre>
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| <prefix>/lib/Foo*/
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| </pre>
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| where "<code>Foo*</code>" is a case-insensitive globbing expression.
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| In our example the globbing expression will match "<code><prefix>/lib/foo-1.2</code>" and the configuration file will be found.
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| '''Note:''' If your project does not already have a <code><prefix>/lib/Foo*/</code> directory you may prefer to put the package file in <code><prefix>/lib/cmake/Foo*/</code> to keep the <code>lib</code> directory clean. However, CMake 2.6.2 and lower do not search there. CMake 2.6.3 and above do.
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| Once found, a package configuration file is immediately loaded. It contains all the information the project needs to use the package.
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| ==Packaging and Exporting==
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| Package configuration files may also work in conjunction with [[CMake/Tutorials/Exporting_and_Importing_Targets|Exporting and Importing Targets]].
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| For example, a project might write
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| <pre>
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| add_library(mylib STATIC mylib.c mylib.h)
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| install(FILES mylib.h DESTINATION include/myproj)
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| install(TARGETS mylib EXPORT mylib-targets DESTINATION lib/myproj)
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| install(EXPORT mylib-targets DESTINATION lib/myproj)
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| install(FILES myproj-config.cmake DESTINATION lib/myproj)
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| </pre>
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| where <code>myproj-config.cmake</code> contains something like
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| <pre>
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| get_filename_component(SELF_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
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| include(${SELF_DIR}/mylib-targets.cmake)
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| get_filename_component(myproj_INCLUDE_DIRS "${SELF_DIR}/../../include/myproj" ABSOLUTE)
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| </pre>
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| After the project is built and installed, an outside project may use it by writing
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| <pre>
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| find_package(myproj REQUIRED)
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| include_directories(${myproj_INCLUDE_DIRS})
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| add_executable(myexe myexe.c)
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| target_link_libraries(myexe mylib)
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| </pre>
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| =Package Version Files=
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| The <code>find_package</code> command offers a version request argument. One might write
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| <pre>
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| find_package(Foo 1.2)
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| find_package(Bar 4.2 EXACT)
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| </pre>
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| in order to get a version of package <code>Foo</code> that is compatible with version 1.2 and exactly package <code>Bar</code> version 4.2.
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| CMake does not attempt to define any convention for the compatibility or exactness of version numbers for a package.
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| It also does not try to map the version number to a directory or file name.
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| Instead packages must provide "version" files next to their package configuration files.
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| This allows maximum flexibility for project authors and package maintainers.
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| A package version file is placed next to the package configuration file.
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| Its name matches that of the configuration file but has either "<code>-version</code>" or "<code>Version</code>" appended to the name before the "<code>.cmake</code>" extension.
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| For example, the files
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| <pre>
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| <prefix>/lib/foo-1.3/foo-config.cmake
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| <prefix>/lib/foo-1.3/foo-config-version.cmake
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| </pre>
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| and
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| <pre>
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| <prefix>/lib/bar-4.2/BarConfig.cmake
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| <prefix>/lib/bar-4.2/BarConfigVersion.cmake
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| </pre>
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| are each pairs of package configuration files and corresponding version files.
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| When the <code>find_package</code> command finds a candidate package configuration file it looks next to it for a version file.
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| The version file is loaded to test whether the package version is an acceptable match for the version requested.
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| If the version file claims compatibility the configuration file is accepted. Otherwise it is ignored.
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| When the <code>find_package</code> command loads a version file it first sets the following variables:
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| {| border=1
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| ! CMake 2.6.2 and Above !! CMake 2.6.0 and 2.6.1
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| |-valign="top"
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| |<pre>
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| PACKAGE_FIND_NAME = the <package> name
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| PACKAGE_FIND_VERSION = full requested version string
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| PACKAGE_FIND_VERSION_MAJOR = major version if requested, else 0
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| PACKAGE_FIND_VERSION_MINOR = minor version if requested, else 0
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| PACKAGE_FIND_VERSION_PATCH = patch version if requested, else 0
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| PACKAGE_FIND_VERSION_TWEAK = tweak version if requested, else 0
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| PACKAGE_FIND_VERSION_COUNT = number of version components, 0 to 4
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| </pre>
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| ||<pre>
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| PACKAGE_FIND_NAME = the <package> name
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| PACKAGE_FIND_VERSION = full requested version string
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| PACKAGE_FIND_VERSION_MAJOR = requested major version, if any
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| PACKAGE_FIND_VERSION_MINOR = requested minor version, if any
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| PACKAGE_FIND_VERSION_PATCH = requested patch version, if any
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| </pre>
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| |}
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| The version file must use these variables to check whether it is compatible or an exact match for the requested version.
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| It sets the following variables with results:
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| <pre>
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| PACKAGE_VERSION = full provided version string
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| PACKAGE_VERSION_EXACT = true if version is exact match
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| PACKAGE_VERSION_COMPATIBLE = true if version is compatible
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| PACKAGE_VERSION_UNSUITABLE = true if unsuitable as any version (CMake >= 2.6.3)
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| </pre>
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| For example, <code>foo-config-version.cmake</code> might contain
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| <pre>
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| set(PACKAGE_VERSION 1.3)
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| if("${PACKAGE_FIND_VERSION_MAJOR}" EQUAL 1)
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| set(PACKAGE_VERSION_COMPATIBLE 1) # compatible with any version 1.x
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| if("${PACKAGE_FIND_VERSION_MINOR}" EQUAL 3)
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| set(PACKAGE_VERSION_EXACT 1) # exact match for version 1.3
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| endif("${PACKAGE_FIND_VERSION_MINOR}" EQUAL 3)
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| endif("${PACKAGE_FIND_VERSION_MAJOR}" EQUAL 1)
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| </pre>
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| if it is compatible with all "<code>1.x</code>" versions of Foo and exactly matches version "<code>1.3</code>".
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| Note that the input variable names all start in "<code>PACKAGE_FIND_</code>" and the output variable names all start in "<code>PACKAGE_</code>".
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| The names are fixed and do not vary with the package name.
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| Version files are loaded in a nested scope so they are free to set any variables they wish as part of their computation.
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| The <code>find_package</code> command wipes out the scope when the version file has completed and it has checked the output variables.
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| When the version file claims to be an acceptable match for the requested version the <code>find_package</code> command sets the following variables for use by the project:
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| {| border=1
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| ! CMake 2.6.2 and Above !! CMake 2.6.0 and 2.6.1
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| |-valign="top"
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| |<pre>
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| <package>_VERSION = full provided version string
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| <package>_VERSION_MAJOR = major version if provided, else 0
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| <package>_VERSION_MINOR = minor version if provided, else 0
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| <package>_VERSION_PATCH = patch version if provided, else 0
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| <package>_VERSION_TWEAK = tweak version if provided, else 0
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| <package>_VERSION_COUNT = number of version components, 0 to 4
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| </pre>
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| ||<pre>
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| <package>_VERSION = package version (major[.minor[.patch]])
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| <package>_VERSION_MAJOR = major from major[.minor[.patch]], if any
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| <package>_VERSION_MINOR = minor from major[.minor[.patch]], if any
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| <package>_VERSION_PATCH = patch from major[.minor[.patch]], if any
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| </pre>
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| |}
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| The variables report the version of the package that was actually found.
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| The "<code><package></code>" part of their name matches the argument given to the <code>find_package</code> command.
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| {{CMake/Template/Footer}}
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