summaryrefslogtreecommitdiffstats
path: root/Source/cmCMakePolicyCommand.h
blob: 4f1ed36ad3091c2e7605cf9f1839dec49f049532 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
/*============================================================================
  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 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() const { return true; }

 /**
   * The name of the command as specified in CMakeList.txt.
   */
  virtual const char* GetName() const {return "cmake_policy";}
  
 /**
   * Succinct documentation.
   */
  virtual const char* GetTerseDocumentation() const
    {
    return "Manage CMake Policy settings.";
    }
  
  /**
   * More documentation.
   */
  virtual const char* GetFullDocumentation() const
    {
    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[.tweak]])\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 unset "
      "(unless variable CMAKE_POLICY_DEFAULT_CMP<NNNN> sets a default).  "
      "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