| /*============================================================================ |
| CMake - Cross Platform Makefile Generator |
| Copyright 2000-2009 Kitware, Inc., Insight Software Consortium |
| |
| Distributed under the OSI-approved BSD License (the "License"); |
| see accompanying file Copyright.txt for details. |
| |
| This software is distributed WITHOUT ANY WARRANTY; without even the |
| implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
| See the License for more information. |
| ============================================================================*/ |
| #ifndef cmSetCommand_h |
| #define cmSetCommand_h |
| |
| #include "cmCommand.h" |
| |
| /** \class cmSetCommand |
| * \brief Set a CMAKE variable |
| * |
| * cmSetCommand sets a variable to a value with expansion. |
| */ |
| class cmSetCommand : public cmCommand |
| { |
| public: |
| /** |
| * This is a virtual constructor for the command. |
| */ |
| virtual cmCommand* Clone() |
| { |
| return new cmSetCommand; |
| } |
| |
| /** |
| * This is called when the command is first encountered in |
| * the CMakeLists.txt file. |
| */ |
| virtual bool InitialPass(std::vector<std::string> const& args, |
| cmExecutionStatus &status); |
| |
| /** |
| * This determines if the command is invoked when in script mode. |
| */ |
| virtual bool IsScriptable() const { return true; } |
| |
| /** |
| * The name of the command as specified in CMakeList.txt. |
| */ |
| virtual const char* GetName() const {return "set";} |
| |
| /** |
| * Succinct documentation. |
| */ |
| virtual const char* GetTerseDocumentation() const |
| { |
| return "Set a CMake, cache or environment variable to a given value."; |
| } |
| |
| /** |
| * More documentation. |
| */ |
| virtual const char* GetFullDocumentation() const |
| { |
| return |
| " set(<variable> <value>\n" |
| " [[CACHE <type> <docstring> [FORCE]] | PARENT_SCOPE])\n" |
| "Within CMake sets <variable> to the value <value>. " |
| "<value> is expanded before <variable> is set to it. " |
| "Normally, set will set a regular CMake variable. " |
| "If CACHE is present, then the <variable> is put in the cache " |
| "instead, unless it is already in the cache. " |
| "See section 'Variable types in CMake' below for details of " |
| "regular and cache variables and their interactions. " |
| "If CACHE is used, <type> and <docstring> are required. <type> is used " |
| "by the CMake GUI to choose a widget with which the user sets a value. " |
| "The value for <type> may be one of\n" |
| " FILEPATH = File chooser dialog.\n" |
| " PATH = Directory chooser dialog.\n" |
| " STRING = Arbitrary string.\n" |
| " BOOL = Boolean ON/OFF checkbox.\n" |
| " INTERNAL = No GUI entry (used for persistent variables).\n" |
| "If <type> is INTERNAL, the cache variable is marked as internal, " |
| "and will not be shown to the user in tools like cmake-gui. " |
| "This is intended for values that should be persisted in the cache, " |
| "but which users should not normally change. INTERNAL implies FORCE." |
| "\n" |
| "Normally, set(...CACHE...) creates cache variables, but does not " |
| "modify them. " |
| "If FORCE is specified, the value of the cache variable is set, even " |
| "if the variable is already in the cache. This should normally be " |
| "avoided, as it will remove any changes to the cache variable's value " |
| "by the user.\n" |
| "If PARENT_SCOPE is present, the variable will be set in the scope " |
| "above the current scope. Each new directory or function creates a new " |
| "scope. This command will set the value of a variable into the parent " |
| "directory or calling function (whichever is applicable to the case at " |
| "hand). PARENT_SCOPE cannot be combined with CACHE.\n" |
| "If <value> is not specified then the variable is removed " |
| "instead of set. See also: the unset() command.\n" |
| " set(<variable> <value1> ... <valueN>)\n" |
| "In this case <variable> is set to a semicolon separated list of " |
| "values.\n" |
| "<variable> can be an environment variable such as:\n" |
| " set( ENV{PATH} /home/martink )\n" |
| "in which case the environment variable will be set.\n" |
| "*** Variable types in CMake ***\n" |
| "In CMake there are two types of variables: normal variables and cache " |
| "variables. Normal variables are meant for the internal use of the " |
| "script (just like variables in most programming languages); they are " |
| "not persisted across CMake runs. " |
| "Cache variables (unless set with INTERNAL) are mostly intended for " |
| "configuration settings where the first CMake run determines a " |
| "suitable default value, which the user can then override, by editing " |
| "the cache with tools such as ccmake or cmake-gui. " |
| "Cache variables are stored in the CMake cache file, and " |
| "are persisted across CMake runs. \n" |
| "Both types can exist at the same time with the same name " |
| "but different values. " |
| "When ${FOO} is evaluated, CMake first looks for " |
| "a normal variable 'FOO' in scope and uses it if set. " |
| "If and only if no normal variable exists then it falls back to the " |
| "cache variable 'FOO'.\n" |
| "Some examples:\n" |
| "The code 'set(FOO \"x\")' sets the normal variable 'FOO'. It does not " |
| "touch the cache, but it will hide any existing cache value 'FOO'.\n" |
| "The code 'set(FOO \"x\" CACHE ...)' checks for 'FOO' in the cache, " |
| "ignoring any normal variable of the same name. If 'FOO' is in the " |
| "cache then nothing happens to either the normal variable or the cache " |
| "variable. If 'FOO' is not in the cache, then it is added to the " |
| "cache.\n" |
| "Finally, whenever a cache variable is added or modified by a command, " |
| "CMake also *removes* the normal variable of the same name from the " |
| "current scope so that an immediately following evaluation of " |
| "it will expose the newly cached value.\n" |
| "Normally projects should avoid using normal and cache variables of " |
| "the same name, as this interaction can be hard to follow. " |
| "However, in some situations it can be useful. " |
| "One example (used by some projects):" |
| "\n" |
| "A project has a subproject in its source tree. The child project has " |
| "its own CMakeLists.txt, which is included from the parent " |
| "CMakeLists.txt using add_subdirectory(). " |
| "Now, if the parent and the child project provide the same option " |
| "(for example a compiler option), the parent gets the first chance " |
| "to add a user-editable option to the cache. " |
| "Normally, the child would then use the same value " |
| "that the parent uses. " |
| "However, it may be necessary to hard-code the value for the child " |
| "project's option while still allowing the user to edit the value used " |
| "by the parent project. The parent project can achieve this simply by " |
| "setting a normal variable with the same name as the option in a scope " |
| "sufficient to hide the option's cache variable from the child " |
| "completely. The parent has already set the cache variable, so the " |
| "child's set(...CACHE...) will do nothing, and evaluating the option " |
| "variable will use the value from the normal variable, which hides the " |
| "cache variable."; |
| } |
| |
| cmTypeMacro(cmSetCommand, cmCommand); |
| }; |
| |
| |
| |
| #endif |
