CMake/Source/cmCMakePolicyCommand.h

148 lines
5.7 KiB
C++

/*=========================================================================
Program: CMake - Cross-Platform Makefile Generator
Module: $RCSfile$
Language: C++
Date: $Date$
Version: $Revision$
Copyright (c) 2002 Kitware, Inc., Insight Consortium. All rights reserved.
See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notices for more information.
=========================================================================*/
#ifndef cmCMakePolicyCommand_h
#define cmCMakePolicyCommand_h
#include "cmCommand.h"
/** \class cmCMakePolicyCommand
* \brief Set how CMake should handle policies
*
* cmCMakePolicyCommand sets how CMake should deal with backwards
* compatibility policies.
*/
class cmCMakePolicyCommand : public cmCommand
{
public:
/**
* This is a virtual constructor for the command.
*/
virtual cmCommand* Clone()
{
return new cmCMakePolicyCommand;
}
/**
* 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() { return true; }
/**
* The name of the command as specified in CMakeList.txt.
*/
virtual const char* GetName() {return "cmake_policy";}
/**
* Succinct documentation.
*/
virtual const char* GetTerseDocumentation()
{
return "Manage CMake Policy settings.";
}
/**
* More documentation.
*/
virtual const char* GetFullDocumentation()
{
return
"As CMake evolves it is sometimes necessary to change existing "
"behavior in order to fix bugs or improve implementations of "
"existing features. "
"The CMake Policy mechanism is designed to help keep existing projects "
"building as new versions of CMake introduce changes in behavior. "
"Each new policy (behavioral change) is given an identifier of "
"the form \"CMP<NNNN>\" where \"<NNNN>\" is an integer index. "
"Documentation associated with each policy describes the OLD and NEW "
"behavior and the reason the policy was introduced. "
"Projects may set each policy to select the desired behavior. "
"When CMake needs to know which behavior to use it checks for "
"a setting specified by the project. "
"If no setting is available the OLD behavior is assumed and a warning "
"is produced requesting that the policy be set.\n"
"The cmake_policy command is used to set policies to OLD or NEW "
"behavior. "
"While setting policies individually is supported, we encourage "
"projects to set policies based on CMake versions.\n"
" cmake_policy(VERSION major.minor[.patch])\n"
"Specify that the current CMake list file is written for the "
"given version of CMake. "
"All policies introduced in the specified version or earlier "
"will be set to use NEW behavior. "
"All policies introduced after the specified version will be reset "
"to use OLD behavior with a warning. "
"This effectively requests behavior preferred as of a given CMake "
"version and tells newer CMake versions to warn about their new "
"policies. "
"The policy version specified must be at least 2.4 or the command "
"will report an error. "
"In order to get compatibility features supporting versions earlier "
"than 2.4 see documentation of policy CMP0001."
"\n"
" cmake_policy(SET CMP<NNNN> NEW)\n"
" cmake_policy(SET CMP<NNNN> OLD)\n"
"Tell CMake to use the OLD or NEW behavior for a given policy. "
"Projects depending on the old behavior of a given policy may "
"silence a policy warning by setting the policy state to OLD. "
"Alternatively one may fix the project to work with the new behavior "
"and set the policy state to NEW."
"\n"
" cmake_policy(GET CMP<NNNN> <variable>)\n"
"Check whether a given policy is set to OLD or NEW behavior. "
"The output variable value will be \"OLD\" or \"NEW\" if the "
"policy is set, and empty otherwise."
"\n"
"CMake keeps policy settings on a stack, so changes made by the "
"cmake_policy command affect only the top of the stack. "
"A new entry on the policy stack is managed automatically for each "
"subdirectory to protect its parents and siblings. "
"CMake also manages a new entry for scripts loaded by include() and "
"find_package() commands except when invoked with the NO_POLICY_SCOPE "
"option (see also policy CMP0011). "
"The cmake_policy command provides an interface to manage custom "
"entries on the policy stack:\n"
" cmake_policy(PUSH)\n"
" cmake_policy(POP)\n"
"Each PUSH must have a matching POP to erase any changes. "
"This is useful to make temporary changes to policy settings."
"\n"
"Functions and macros record policy settings when they are created "
"and use the pre-record policies when they are invoked. "
"If the function or macro implementation sets policies, the changes "
"automatically propagate up through callers until they reach the "
"closest nested policy stack entry."
;
}
cmTypeMacro(cmCMakePolicyCommand, cmCommand);
private:
bool HandleSetMode(std::vector<std::string> const& args);
bool HandleGetMode(std::vector<std::string> const& args);
bool HandleVersionMode(std::vector<std::string> const& args);
};
#endif