Commit 1c0e1702 authored by Brad King's avatar Brad King
Browse files

ENH: Improve documentation of cmake_policy command.

  - Add a paragraph introducing the policy mechanism
  - Explicitly introduce the CMP<NNNN>, OLD, and NEW notation
  - Note that setting policies by CMake version is preferred
  - Fix SET signature to use CMP<NNNN> notation
  - Add more details about the policy stack
parent 33c84b50
......@@ -58,7 +58,7 @@ public:
virtual const char* GetTerseDocumentation()
return "Manage CMake policy settings.";
return "Manage CMake Policy settings.";
......@@ -67,13 +67,31 @@ public:
virtual const char* GetFullDocumentation()
"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 NEW. "
"All policies introduced after the specified version will be set "
"to WARN, which is like OLD but also produces a warning. "
"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. "
......@@ -82,8 +100,8 @@ public:
"In order to get compatibility features supporting versions earlier "
"than 2.4 see documentation of policy CMP0001."
" cmake_policy(SET <CMPNNNN> NEW)\n"
" cmake_policy(SET <CMPNNNN> OLD)\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. "
......@@ -96,8 +114,10 @@ public:
"Each PUSH must have a matching POP. "
"This is useful when mixing multiple projects, subprojects, and "
"files included from external projects that may each have been "
"written for a different version of CMake."
"written for a different version of CMake. "
"Each subdirectory entered by the project automatically pushes "
"a new level on the stack to isolate the subdirectories from "
"their parents.";
cmTypeMacro(cmCMakePolicyCommand, cmCommand);
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment