173 lines
9.1 KiB
Plaintext
173 lines
9.1 KiB
Plaintext
For more information about how to contribute modules to CMake, see this page:
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http://www.itk.org/Wiki/CMake:Module_Maintainers
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Note to authors of FindXxx.cmake files
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We would like all FindXxx.cmake files to produce consistent variable names.
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Please use the following consistent variable names for general use.
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Xxx_INCLUDE_DIRS The final set of include directories listed in one variable for use by client code.
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This should not be a cache entry.
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Xxx_LIBRARIES The libraries to link against to use Xxx. These should include full paths.
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This should not be a cache entry.
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Xxx_DEFINITIONS Definitions to use when compiling code that uses Xxx. This really shouldn't include options such
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as (-DHAS_JPEG)that a client source-code file uses to decide whether to #include <jpeg.h>
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Xxx_EXECUTABLE Where to find the Xxx tool.
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Xxx_Yyy_EXECUTABLE Where to find the Yyy tool that comes with Xxx.
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Xxx_LIBRARY_DIRS Optionally, the final set of library directories listed in one variable for use by client code.
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This should not be a cache entry.
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Xxx_ROOT_DIR Where to find the base directory of Xxx.
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Xxx_VERSION_Yy Expect Version Yy if true. Make sure at most one of these is ever true.
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Xxx_WRAP_Yy If False, do not try to use the relevant CMake wrapping command.
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Xxx_Yy_FOUND If False, optional Yy part of Xxx sytem is not available.
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Xxx_FOUND Set to false, or undefined, if we haven't found, or don't want to use Xxx.
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Xxx_NOT_FOUND_MESSAGE Should be set by config-files in the case that it has set Xxx_FOUND to FALSE.
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The contained message will be printed by the find_package() command and by
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find_package_handle_standard_args() to inform the user about the problem.
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Xxx_RUNTIME_LIBRARY_DIRS Optionally, the runtime library search path for use when running an executable linked to
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shared libraries.
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The list should be used by user code to create the PATH on windows or LD_LIBRARY_PATH on unix.
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This should not be a cache entry.
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Xxx_VERSION_STRING A human-readable string containing the version of the package found, if any.
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Xxx_VERSION_MAJOR The major version of the package found, if any.
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Xxx_VERSION_MINOR The minor version of the package found, if any.
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Xxx_VERSION_PATCH The patch version of the package found, if any.
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You do not have to provide all of the above variables. You should provide Xxx_FOUND under most circumstances.
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If Xxx is a library, then Xxx_LIBRARIES, should also be defined, and Xxx_INCLUDE_DIRS should usually be
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defined (I guess libm.a might be an exception)
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The following names should not usually be used in CMakeLists.txt files, but they may be usefully modified in
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users' CMake Caches to control stuff.
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Xxx_LIBRARY Name of Xxx Library. A User may set this and Xxx_INCLUDE_DIR to ignore to force non-use of Xxx.
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Xxx_Yy_LIBRARY Name of Yy library that is part of the Xxx system. It may or may not be required to use Xxx.
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Xxx_INCLUDE_DIR Where to find xxx.h, etc. (Xxx_INCLUDE_PATH was considered bad because a path includes an
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actual filename.)
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Xxx_Yy_INCLUDE_DIR Where to find xxx_yy.h, etc.
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For tidiness's sake, try to keep as many options as possible out of the cache, leaving at least one option which can be
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used to disable use of the module, or locate a not-found library (e.g. Xxx_ROOT_DIR).
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For the same reason, mark most cache options as advanced.
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If you need other commands to do special things then it should still begin with Xxx_. This gives a sort of namespace
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effect and keeps things tidy for the user. You should put comments describing all the exported settings, plus
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descriptions of any the users can use to control stuff.
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You really should also provide backwards compatibility any old settings that were actually in use.
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Make sure you comment them as deprecated, so that no-one starts using them.
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To correctly document a module, create a comment block at the top with # comments.
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There are three types of comments that can be in the block:
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1. The brief description of the module, this is done by:
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# - a small description
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2. A paragraph of text. This is done with all text that has a single
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space between the # and the text. To create a new paragraph, just
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put a # with no text on the line.
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3. A verbatim line. This is done with two spaces between the # and the text.
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For example:
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# - This is a cool module
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# This module does really cool stuff.
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# It can do even more than you think.
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#
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# It even needs to paragraphs to tell you about it.
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# And it defines the following variables:
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# VAR_COOL - this is great isn't it?
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# VAR_REALLY_COOL - cool right?
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#
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Test the documentation formatting by running "cmake --help-module FindXxx".
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Edit the comments until the output of this command looks satisfactory.
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To have a .cmake file in this directory NOT show up in the
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modules documentation, you should start the file with a blank
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line.
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After the documentation, leave a *BLANK* line, and then add a
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copyright and licence notice block like this one:
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#=============================================================================
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# Copyright 2009-2011 Your Name
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#
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# Distributed under the OSI-approved BSD License (the "License");
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# see accompanying file Copyright.txt for details.
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#
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# This software is distributed WITHOUT ANY WARRANTY; without even the
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# implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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# See the License for more information.
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#=============================================================================
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# (To distribute this file outside of CMake, substitute the full
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# License text for the above reference.)
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The layout of the notice block is strictly enforced by the ModuleNotices test.
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Only the year range and name may be changed freely.
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A FindXxx.cmake module will typically be loaded by the command
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FIND_PACKAGE(Xxx [major[.minor[.patch[.tweak]]]] [EXACT]
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[QUIET] [[REQUIRED|COMPONENTS] [components...]])
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If any version numbers are given to the command it will set the
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following variables before loading the module:
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Xxx_FIND_VERSION = full requested version string
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Xxx_FIND_VERSION_MAJOR = major version if requested, else 0
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Xxx_FIND_VERSION_MINOR = minor version if requested, else 0
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Xxx_FIND_VERSION_PATCH = patch version if requested, else 0
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Xxx_FIND_VERSION_TWEAK = tweak version if requested, else 0
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Xxx_FIND_VERSION_COUNT = number of version components, 0 to 4
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Xxx_FIND_VERSION_EXACT = true if EXACT option was given
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If the find module supports versioning it should locate a version of
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the package that is compatible with the version requested. If a
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compatible version of the package cannot be found the module should
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not report success. The version of the package found should be stored
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in "Xxx_VERSION..." version variables documented by the module.
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If the QUIET option is given to the command it will set the variable
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Xxx_FIND_QUIETLY to true before loading the FindXxx.cmake module. If
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this variable is set the module should not complain about not being
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able to find the package. If the
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REQUIRED option is given to the command it will set the variable
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Xxx_FIND_REQUIRED to true before loading the FindXxx.cmake module. If
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this variable is set the module should issue a FATAL_ERROR if the
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package cannot be found.
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If neither the QUIET nor REQUIRED options are given then the
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FindXxx.cmake module should look for the package and complain without
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error if the module is not found.
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FIND_PACKAGE() will set the variable CMAKE_FIND_PACKAGE_NAME to
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contain the actual name of the package.
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A package can provide sub-components.
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Those components can be listed after the COMPONENTS (or REQUIRED)
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or OPTIONAL_COMPONENTS keywords. The set of all listed components will be
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specified in a Xxx_FIND_COMPONENTS variable.
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For each package-specific component, say Yyy, a variable Xxx_FIND_REQUIRED_Yyy
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will be set to true if it listed after COMPONENTS and it will be set to false
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if it was listed after OPTIONAL_COMPONENTS.
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Using those variables a FindXxx.cmake module and also a XxxConfig.cmake package
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configuration file can determine whether and which components have been requested,
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and whether they were requested as required or as optional.
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For each of the requested components a Xxx_Yyy_FOUND variable should be set
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accordingly.
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The per-package Xxx_FOUND variable should be only set to true if all requested
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required components have been found. A missing optional component should not
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keep the Xxx_FOUND variable from being set to true.
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If the package provides Xxx_INCLUDE_DIRS and Xxx_LIBRARIES variables, the include
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dirs and libraries for all components which were requested and which have been
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found should be added to those two variables.
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To get this behaviour you can use the FIND_PACKAGE_HANDLE_STANDARD_ARGS()
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macro, as an example see FindJPEG.cmake.
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For internal implementation, it's a generally accepted convention that variables starting with
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underscore are for temporary use only. (variable starting with an underscore
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are not intended as a reserved prefix).
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