Source/cmCMakePolicyCommand.h

   1 /*=========================================================================
   2
   3   Program:   CMake - Cross-Platform Makefile Generator
   4   Module:    $RCSfile: cmCMakePolicyCommand.h,v $
   5   Language:  C++
   6   Date:      $Date: 2009-02-06 13:15:05 $
   7   Version:   $Revision: 1.10 $
   8
   9   Copyright (c) 2002 Kitware, Inc., Insight Consortium.  All rights reserved.
  10   See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
  11
  12      This software is distributed WITHOUT ANY WARRANTY; without even
  13      the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
  14      PURPOSE.  See the above copyright notices for more information.
  15
  16 =========================================================================*/
  17 #ifndef cmCMakePolicyCommand_h
  18 #define cmCMakePolicyCommand_h
  19
  20 #include "cmCommand.h"
  21
  22 /** \class cmCMakePolicyCommand
  23  * \brief Set how CMake should handle policies
  24  *
  25  * cmCMakePolicyCommand sets how CMake should deal with backwards
  26  * compatibility policies.
  27  */
  28 class cmCMakePolicyCommand : public cmCommand
  29 {
  30 public:
  31   /**
  32    * This is a virtual constructor for the command.
  33    */
  34   virtual cmCommand* Clone()
  35     {
  36     return new cmCMakePolicyCommand;
  37     }
  38
  39   /**
  40    * This is called when the command is first encountered in
  41    * the CMakeLists.txt file.
  42    */
  43   virtual bool InitialPass(std::vector<std::string> const& args,
  44                            cmExecutionStatus &status);
  45
  46  /**
  47    * This determines if the command is invoked when in script mode.
  48    */
  49   virtual bool IsScriptable() { return true; }
  50
  51  /**
  52    * The name of the command as specified in CMakeList.txt.
  53    */
  54   virtual const char* GetName() {return "cmake_policy";}
  55
  56  /**
  57    * Succinct documentation.
  58    */
  59   virtual const char* GetTerseDocumentation()
  60     {
  61     return "Manage CMake Policy settings.";
  62     }
  63
  64   /**
  65    * More documentation.
  66    */
  67   virtual const char* GetFullDocumentation()
  68     {
  69     return
  70       "As CMake evolves it is sometimes necessary to change existing "
  71       "behavior in order to fix bugs or improve implementations of "
  72       "existing features.  "
  73       "The CMake Policy mechanism is designed to help keep existing projects "
  74       "building as new versions of CMake introduce changes in behavior.  "
  75       "Each new policy (behavioral change) is given an identifier of "
  76       "the form \"CMP<NNNN>\" where \"<NNNN>\" is an integer index.  "
  77       "Documentation associated with each policy describes the OLD and NEW "
  78       "behavior and the reason the policy was introduced.  "
  79       "Projects may set each policy to select the desired behavior.  "
  80       "When CMake needs to know which behavior to use it checks for "
  81       "a setting specified by the project.  "
  82       "If no setting is available the OLD behavior is assumed and a warning "
  83       "is produced requesting that the policy be set.\n"
  84       "The cmake_policy command is used to set policies to OLD or NEW "
  85       "behavior.  "
  86       "While setting policies individually is supported, we encourage "
  87       "projects to set policies based on CMake versions.\n"
  88       "  cmake_policy(VERSION major.minor[.patch])\n"
  89       "Specify that the current CMake list file is written for the "
  90       "given version of CMake.  "
  91       "All policies introduced in the specified version or earlier "
  92       "will be set to use NEW behavior.  "
  93       "All policies introduced after the specified version will be unset.  "
  94       "This effectively requests behavior preferred as of a given CMake "
  95       "version and tells newer CMake versions to warn about their new "
  96       "policies.  "
  97       "The policy version specified must be at least 2.4 or the command "
  98       "will report an error.  "
  99       "In order to get compatibility features supporting versions earlier "
 100       "than 2.4 see documentation of policy CMP0001."
 101       "\n"
 102       "  cmake_policy(SET CMP<NNNN> NEW)\n"
 103       "  cmake_policy(SET CMP<NNNN> OLD)\n"
 104       "Tell CMake to use the OLD or NEW behavior for a given policy.  "
 105       "Projects depending on the old behavior of a given policy may "
 106       "silence a policy warning by setting the policy state to OLD.  "
 107       "Alternatively one may fix the project to work with the new behavior "
 108       "and set the policy state to NEW."
 109       "\n"
 110       "  cmake_policy(GET CMP<NNNN> <variable>)\n"
 111       "Check whether a given policy is set to OLD or NEW behavior.  "
 112       "The output variable value will be \"OLD\" or \"NEW\" if the "
 113       "policy is set, and empty otherwise."
 114       "\n"
 115       "CMake keeps policy settings on a stack, so changes made by the "
 116       "cmake_policy command affect only the top of the stack.  "
 117       "A new entry on the policy stack is managed automatically for each "
 118       "subdirectory to protect its parents and siblings.  "
 119       "CMake also manages a new entry for scripts loaded by include() and "
 120       "find_package() commands except when invoked with the NO_POLICY_SCOPE "
 121       "option (see also policy CMP0011).  "
 122       "The cmake_policy command provides an interface to manage custom "
 123       "entries on the policy stack:\n"
 124       "  cmake_policy(PUSH)\n"
 125       "  cmake_policy(POP)\n"
 126       "Each PUSH must have a matching POP to erase any changes.  "
 127       "This is useful to make temporary changes to policy settings."
 128       "\n"
 129       "Functions and macros record policy settings when they are created "
 130       "and use the pre-record policies when they are invoked.  "
 131       "If the function or macro implementation sets policies, the changes "
 132       "automatically propagate up through callers until they reach the "
 133       "closest nested policy stack entry."
 134       ;
 135     }
 136
 137   cmTypeMacro(cmCMakePolicyCommand, cmCommand);
 138 private:
 139   bool HandleSetMode(std::vector<std::string> const& args);
 140   bool HandleGetMode(std::vector<std::string> const& args);
 141   bool HandleVersionMode(std::vector<std::string> const& args);
 142 };
 143
 144
 145
 146 #endif