Commit f3dd116c authored by Daniele E. Domenichelli's avatar Daniele E. Domenichelli Committed by Brad King
Browse files

CMakePackageConfigHelpers: restructure documentation and document commands

parent 64eca30d
......@@ -2,29 +2,35 @@
# CMakePackageConfigHelpers
# -------------------------
#
# CONFIGURE_PACKAGE_CONFIG_FILE(), WRITE_BASIC_PACKAGE_VERSION_FILE()
# Helpers functions for creating config files that can be included by other
# projects to find and use a package.
#
# Adds the :command:`configure_package_config_file()` and
# :command:`write_basic_package_version_file()` commands.
#
# Generating a Package Configuration File
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#
# ::
# .. command:: configure_package_config_file
#
# CONFIGURE_PACKAGE_CONFIG_FILE(<input> <output> INSTALL_DESTINATION <path>
# Create a config file for a project::
#
# configure_package_config_file(<input> <output> INSTALL_DESTINATION <path>
# [PATH_VARS <var1> <var2> ... <varN>]
# [NO_SET_AND_CHECK_MACRO]
# [NO_CHECK_REQUIRED_COMPONENTS_MACRO])
#
#
# ``configure_package_config_file()`` should be used instead of the plain
# :command:`configure_file()` command when creating the ``<Name>Config.cmake``
# or ``<Name>-config.cmake`` file for installing a project or library. It helps
# making the resulting package relocatable by avoiding hardcoded paths in the
# installed ``Config.cmake`` file.
#
# CONFIGURE_PACKAGE_CONFIG_FILE() should be used instead of the plain
# configure_file() command when creating the <Name>Config.cmake or
# <Name>-config.cmake file for installing a project or library. It
# helps making the resulting package relocatable by avoiding hardcoded
# paths in the installed Config.cmake file.
#
# In a FooConfig.cmake file there may be code like this to make the
# install destinations know to the using project:
# In a ``FooConfig.cmake`` file there may be code like this to make the install
# destinations know to the using project:
#
# ::
# .. code-block:: cmake
#
# set(FOO_INCLUDE_DIR "@CMAKE_INSTALL_FULL_INCLUDEDIR@" )
# set(FOO_DATA_DIR "@CMAKE_INSTALL_PREFIX@/@RELATIVE_DATA_INSTALL_DIR@" )
......@@ -32,121 +38,126 @@
# ...logic to determine installedPrefix from the own location...
# set(FOO_CONFIG_DIR "${installedPrefix}/@CONFIG_INSTALL_DIR@" )
#
# All 4 options shown above are not sufficient, since the first 3
# hardcode the absolute directory locations, and the 4th case works only
# if the logic to determine the installedPrefix is correct, and if
# CONFIG_INSTALL_DIR contains a relative path, which in general cannot
# be guaranteed. This has the effect that the resulting FooConfig.cmake
# file would work poorly under Windows and OSX, where users are used to
# choose the install location of a binary package at install time,
# independent from how CMAKE_INSTALL_PREFIX was set at build/cmake time.
#
# Using CONFIGURE_PACKAGE_CONFIG_FILE() helps. If used correctly, it
# makes the resulting FooConfig.cmake file relocatable. Usage:
# All 4 options shown above are not sufficient, since the first 3 hardcode the
# absolute directory locations, and the 4th case works only if the logic to
# determine the ``installedPrefix`` is correct, and if ``CONFIG_INSTALL_DIR``
# contains a relative path, which in general cannot be guaranteed. This has the
# effect that the resulting ``FooConfig.cmake`` file would work poorly under
# Windows and OSX, where users are used to choose the install location of a
# binary package at install time, independent from how
# :variable:`CMAKE_INSTALL_PREFIX` was set at build/cmake time.
#
# ::
# Using ``configure_package_config_file`` helps. If used correctly, it makes
# the resulting ``FooConfig.cmake`` file relocatable. Usage:
#
# 1. write a FooConfig.cmake.in file as you are used to
# 2. insert a line containing only the string "@PACKAGE_INIT@"
# 3. instead of set(FOO_DIR "@SOME_INSTALL_DIR@"), use set(FOO_DIR "@PACKAGE_SOME_INSTALL_DIR@")
# (this must be after the @PACKAGE_INIT@ line)
# 4. instead of using the normal configure_file(), use CONFIGURE_PACKAGE_CONFIG_FILE()
# 1. write a ``FooConfig.cmake.in`` file as you are used to
# 2. insert a line containing only the string ``@PACKAGE_INIT@``
# 3. instead of ``set(FOO_DIR "@SOME_INSTALL_DIR@")``, use
# ``set(FOO_DIR "@PACKAGE_SOME_INSTALL_DIR@")`` (this must be after the
# ``@PACKAGE_INIT@`` line)
# 4. instead of using the normal :command:`configure_file()`, use
# ``configure_package_config_file()``
#
#
#
# The <input> and <output> arguments are the input and output file, the
# same way as in configure_file().
# The ``<input>`` and ``<output>`` arguments are the input and output file, the
# same way as in :command:`configure_file()`.
#
# The <path> given to INSTALL_DESTINATION must be the destination where
# the FooConfig.cmake file will be installed to. This can either be a
# The ``<path>`` given to ``INSTALL_DESTINATION`` must be the destination where
# the ``FooConfig.cmake`` file will be installed to. This can either be a
# relative or absolute path, both work.
#
# The variables <var1> to <varN> given as PATH_VARS are the variables
# which contain install destinations. For each of them the macro will
# create a helper variable PACKAGE_<var...>. These helper variables
# must be used in the FooConfig.cmake.in file for setting the installed
# location. They are calculated by CONFIGURE_PACKAGE_CONFIG_FILE() so
# that they are always relative to the installed location of the
# package. This works both for relative and also for absolute
# locations. For absolute locations it works only if the absolute
# location is a subdirectory of CMAKE_INSTALL_PREFIX.
#
# By default configure_package_config_file() also generates two helper
# macros, set_and_check() and check_required_components() into the
# FooConfig.cmake file.
#
# set_and_check() should be used instead of the normal set() command for
# setting directories and file locations. Additionally to setting the
# variable it also checks that the referenced file or directory actually
# exists and fails with a FATAL_ERROR otherwise. This makes sure that
# the created FooConfig.cmake file does not contain wrong references.
# When using the NO_SET_AND_CHECK_MACRO, this macro is not generated
# into the FooConfig.cmake file.
#
# check_required_components(<package_name>) should be called at the end
# of the FooConfig.cmake file if the package supports components. This
# macro checks whether all requested, non-optional components have been
# found, and if this is not the case, sets the Foo_FOUND variable to
# FALSE, so that the package is considered to be not found. It does
# that by testing the Foo_<Component>_FOUND variables for all requested
# required components. When using the NO_CHECK_REQUIRED_COMPONENTS
# option, this macro is not generated into the FooConfig.cmake file.
# The variables ``<var1>`` to ``<varN>`` given as ``PATH_VARS`` are the
# variables which contain install destinations. For each of them the macro will
# create a helper variable ``PACKAGE_<var...>``. These helper variables must be
# used in the ``FooConfig.cmake.in`` file for setting the installed location.
# They are calculated by ``configure_package_config_file`` so that they are
# always relative to the installed location of the package. This works both for
# relative and also for absolute locations. For absolute locations it works
# only if the absolute location is a subdirectory of
# :variable:`CMAKE_INSTALL_PREFIX`.
#
# By default ``configure_package_config_file`` also generates two helper macros,
# ``set_and_check()`` and ``check_required_components()`` into the
# ``FooConfig.cmake`` file.
#
# ``set_and_check()`` should be used instead of the normal ``set()`` command for
# setting directories and file locations. Additionally to setting the variable
# it also checks that the referenced file or directory actually exists and fails
# with a ``FATAL_ERROR`` otherwise. This makes sure that the created
# ``FooConfig.cmake`` file does not contain wrong references.
# When using the ``NO_SET_AND_CHECK_MACRO``, this macro is not generated
# into the ``FooConfig.cmake`` file.
#
# ``check_required_components(<package_name>)`` should be called at the end of
# the ``FooConfig.cmake`` file if the package supports components. This macro
# checks whether all requested, non-optional components have been found, and if
# this is not the case, sets the ``Foo_FOUND`` variable to ``FALSE``, so that
# the package is considered to be not found. It does that by testing the
# ``Foo_<Component>_FOUND`` variables for all requested required components.
# When using the ``NO_CHECK_REQUIRED_COMPONENTS_MACRO`` option, this macro is
# not generated into the ``FooConfig.cmake`` file.
#
# For an example see below the documentation for
# WRITE_BASIC_PACKAGE_VERSION_FILE().
#
#
#
# ::
#
# WRITE_BASIC_PACKAGE_VERSION_FILE( filename [VERSION major.minor.patch] COMPATIBILITY (AnyNewerVersion|SameMajorVersion|ExactVersion) )
#
#
#
# Writes a file for use as <package>ConfigVersion.cmake file to
# <filename>. See the documentation of find_package() for details on
# this.
#
# ::
#
# filename is the output filename, it should be in the build tree.
# major.minor.patch is the version number of the project to be installed
#
# If no ``VERSION`` is given, the :variable:`PROJECT_VERSION` variable
# is used. If this hasn't been set, it errors out.
#
# The COMPATIBILITY mode AnyNewerVersion means that the installed
# package version will be considered compatible if it is newer or
# exactly the same as the requested version. This mode should be used
# for packages which are fully backward compatible, also across major
# versions. If SameMajorVersion is used instead, then the behaviour
# differs from AnyNewerVersion in that the major version number must be
# the same as requested, e.g. version 2.0 will not be considered
# compatible if 1.0 is requested. This mode should be used for packages
# which guarantee backward compatibility within the same major version.
# If ExactVersion is used, then the package is only considered
# compatible if the requested version matches exactly its own version
# number (not considering the tweak version). For example, version
# 1.2.3 of a package is only considered compatible to requested version
# 1.2.3. This mode is for packages without compatibility guarantees.
# If your project has more elaborated version matching rules, you will
# need to write your own custom ConfigVersion.cmake file instead of
# using this macro.
#
# Internally, this macro executes configure_file() to create the
# resulting version file. Depending on the COMPATIBLITY, either the
# file BasicConfigVersion-SameMajorVersion.cmake.in or
# BasicConfigVersion-AnyNewerVersion.cmake.in is used. Please note that
# :command:`write_basic_package_version_file()`.
#
# Generating a Package Version File
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#
# .. command:: write_basic_package_version_file
#
# Create a version file for a project::
#
# write_basic_package_version_file(<filename>
# [VERSION <major.minor.patch>]
# COMPATIBILITY <AnyNewerVersion|SameMajorVersion|ExactVersion> )
#
#
# Writes a file for use as ``<package>ConfigVersion.cmake`` file to
# ``<filename>``. See the documentation of :command:`find_package()` for
# details on this.
#
# ``<filename>`` is the output filename, it should be in the build tree.
# ``<major.minor.patch>`` is the version number of the project to be installed.
#
# If no ``VERSION`` is given, the :variable:`PROJECT_VERSION` variable is used.
# If this hasn't been set, it errors out.
#
# The ``COMPATIBILITY`` mode ``AnyNewerVersion`` means that the installed
# package version will be considered compatible if it is newer or exactly the
# same as the requested version. This mode should be used for packages which
# are fully backward compatible, also across major versions.
# If ``SameMajorVersion`` is used instead, then the behaviour differs from
# ``AnyNewerVersion`` in that the major version number must be the same as
# requested, e.g. version 2.0 will not be considered compatible if 1.0 is
# requested. This mode should be used for packages which guarantee backward
# compatibility within the same major version.
# If ``ExactVersion`` is used, then the package is only considered compatible if
# the requested version matches exactly its own version number (not considering
# the tweak version). For example, version 1.2.3 of a package is only
# considered compatible to requested version 1.2.3. This mode is for packages
# without compatibility guarantees.
# If your project has more elaborated version matching rules, you will need to
# write your own custom ``ConfigVersion.cmake`` file instead of using this
# macro.
#
# Internally, this macro executes :command:`configure_file()` to create the
# resulting version file. Depending on the ``COMPATIBLITY``, either the file
# ``BasicConfigVersion-SameMajorVersion.cmake.in`` or
# ``BasicConfigVersion-AnyNewerVersion.cmake.in`` is used. Please note that
# these two files are internal to CMake and you should not call
# configure_file() on them yourself, but they can be used as starting
# point to create more sophisticted custom ConfigVersion.cmake files.
# :command:`configure_file()` on them yourself, but they can be used as starting
# point to create more sophisticted custom ``ConfigVersion.cmake`` files.
#
# Example Generating Package Files
# ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
#
# Example using both :command:`configure_package_config_file` and
# ``write_basic_package_version_file()``:
#
# Example using both configure_package_config_file() and
# write_basic_package_version_file(): CMakeLists.txt:
# ``CMakeLists.txt``:
#
# ::
# .. code-block:: cmake
#
# set(INCLUDE_INSTALL_DIR include/ ... CACHE )
# set(LIB_INSTALL_DIR lib/ ... CACHE )
......@@ -162,11 +173,9 @@
# install(FILES ${CMAKE_CURRENT_BINARY_DIR}/FooConfig.cmake ${CMAKE_CURRENT_BINARY_DIR}/FooConfigVersion.cmake
# DESTINATION ${LIB_INSTALL_DIR}/Foo/cmake )
#
# ``FooConfig.cmake.in``:
#
#
# With a FooConfig.cmake.in:
#
# ::
# .. code-block:: cmake
#
# set(FOO_VERSION x.y.z)
# ...
......@@ -175,10 +184,6 @@
# set_and_check(FOO_INCLUDE_DIR "@PACKAGE_INCLUDE_INSTALL_DIR@")
# set_and_check(FOO_SYSCONFIG_DIR "@PACKAGE_SYSCONFIG_INSTALL_DIR@")
#
#
#
# ::
#
# check_required_components(Foo)
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment