Cmake在变量更改时重新生成
Cmake Regenerate on variable change
Y部件：
我有一个CMake宏，它运行一个外部程序并创建特定于项目的变量。我想让CMake在每次生成时运行此脚本，检查变量是否发生了更改，如果发生了更改（以防止在没有发生更改时重新生成完整的项目），则重新生成CONFIGURE_FILE标头。。。不过我真的不知道该怎么做。（添加自定义目标每次都会重建头文件，并且不能调用宏，与添加自定义命令相同）。
X部分：
因此，我编写了以下脚本，用于提取hg版本信息，以便在c++项目中使用：
macro (ReadProjectRevisionStatus)
exec_program(hg ${PROJECT_SOURCE_DIR} ARGS paths OUTPUT_VARIABLE ${PROJECT_NAME}_HGPATHS)
message(STATUS "${PROJECT_NAME}_HGPATHS=${${PROJECT_NAME}_HGPATHS}}")
if (NOT(${PROJECT_NAME}_HGPATHS STREQUAL ""))
string(REPLACE "n" ";" ${PROJECT_NAME}_HGPATHS ${${PROJECT_NAME}_HGPATHS})
foreach(HGPATH ${${PROJECT_NAME}_HGPATHS})
string(SUBSTRING "${HGPATH}" 0 10 HGPATHSTART)
if (HGPATHSTART MATCHES "default = ")
string(LENGTH "${HGPATH}" HGPATHLENGTH)
math(EXPR HGSUBLEN "${HGPATHLENGTH}-10")
string(SUBSTRING "${HGPATH}" 10 ${HGSUBLEN} ${PROJECT_NAME}_HGREMOTEDIR)
endif()
endforeach()
endif()
if (NOT ${PROJECT_NAME}_HGREMOTEDIR)
message(WARNING "No remote repository set. Will use current direcoty for build number, but this value may be inaccurate.")
set(${PROJECT_NAME}_HGREMOTEDIR ${PROJECT_SOURCE_DIR})
else()
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR} ARGS status RETURN_VALUE HGREMOTESTATUSVALUE OUTPUT_VARIABLE NUL)
if (NOT HGREMOTESTATUSVALUE EQUAL 0)
message(WARNING "Cannot connect to remote repository at ${${PROJECT_NAME}_HGREMOTEDIR}. Will use current direcoty for build number, but this value may be inaccurate.")
set(${PROJECT_NAME}_HGREMOTEDIR ${PROJECT_SOURCE_DIR})
endif()
endif()
#Identify changeset
exec_program(hg ${PROJECT_SOURCE_DIR} ARGS "id" "-i" OUTPUT_VARIABLE OUTPUT_VARIABLE ${PROJECT_NAME}_HGHASHCODE)
if (${PROJECT_NAME}_HGHASHCODE MATCHES ".*\+")
MESSAGE(STATUS "Node is dirty. Will generate temporary version number...")
set (${PROJECT_NAME}_HGDIRTY 1)
string(LENGTH ${${PROJECT_NAME}_HGHASHCODE} HGHASHLEN)
MATH(EXPR HGHASHLEN "${HGHASHLEN}-1")
string(SUBSTRING ${${PROJECT_NAME}_HGHASHCODE} 0 ${HGHASHLEN} ${PROJECT_NAME}_HGHASHCODE)
endif()
#check if remote repository contains changeset
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR}
ARGS "log" "-r" "${${PROJECT_NAME}_HGHASHCODE}"
RETURN_VALUE HGREMOTEHASCHANGESET
OUTPUT_VARIABLE NUL)
if (NOT HGREMOTEHASCHANGESET EQUAL 0)
message(WARNING "Remote repository ${${PROJECT_NAME}_HGREMOTEDIR} does not have changeset ${${PROJECT_NAME}_HGHASHCODE}. Will use current direcoty for build number, but this value may be inaccurate.")
set(${PROJECT_NAME}_HGREMOTEDIR ${PROJECT_SOURCE_DIR})
endif()
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR}
ARGS "log" "-r" ${${PROJECT_NAME}_HGHASHCODE} "--template" "{latesttag}"
OUTPUT_VARIABLE ${PROJECT_NAME}_HGMAJORMINORVERSION)
MESSAGE(STATUS "${PROJECT_NAME}_HGMAJORMINORVERSION=${${PROJECT_NAME}_HGMAJORMINORVERSION}")
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR}
ARGS "log" "-r" ${${PROJECT_NAME}_HGHASHCODE} "--template" "{latesttagdistance}"
OUTPUT_VARIABLE ${PROJECT_NAME}_HGBUILDNUMBER)
if (${PROJECT_NAME}_HGDIRTY)
MATH(EXPR ${PROJECT_NAME}_HGBUILDNUMBER "${${PROJECT_NAME}_HGBUILDNUMBER}+1")
set(${PROJECT_NAME}_HGHASHCODE "${${PROJECT_NAME}_HGHASHCODE}+")
endif()
MESSAGE(STATUS "Version=${${PROJECT_NAME}_HGMAJORMINORVERSION}.${${PROJECT_NAME}_HGBUILDNUMBER}.${${PROJECT_NAME}_HGHASHCODE}")
endmacro()
我现在这样称呼它。
ReadProjectRevisionStatus()
CONFIGURE_FILE(${CMAKE_CURRENT_SOURCE_DIR}/main.h.in ${CMAKE_CURRENT_BINARY_DIR}/main.h)
main.h.in所在位置：
#ifndef MAIN_H
#define MAIN_H
#include <string>
const std::string ${PROJECT_NAME}_HGMAJORMINORVERSION = "${${PROJECT_NAME}_HGMAJORMINORVERSION}";
const std::string ${PROJECT_NAME}_HGBUILDNUMBER = "${${PROJECT_NAME}_HGBUILDNUMBER}";
const std::string ${PROJECT_NAME}_HGHASHCODE = "${${PROJECT_NAME}_HGHASHCODE}";
const std::string ${PROJECT_NAME}_HG_SHORT_VERSION =
${PROJECT_NAME}_HGMAJORMINORVERSION+"."+
${PROJECT_NAME}_HGBUILDNUMBER;
const std::string ${PROJECT_NAME}_HG_VERSION =
${PROJECT_NAME}_HG_SHORT_VERSION + "." +
${PROJECT_NAME}_HGHASHCODE;
#endif
我想做的是在每个构建命令上运行这个宏（我可以使用ADD_CUSTOM_TARGET，然后设置变量，而不是从项目中读取它们），但我只想在变量发生更改时重新生成main.h（以防止不必要的重新编译）。
编辑：工作解决方案
制作HGVersion.CMake
cmake_minimum_required (VERSION 2.8)
macro (ReadProjectRevisionStatus)
message(STATUS PROJECT_SOURCE_DIR=${PROJECT_SOURCE_DIR})
exec_program(hg ${PROJECT_SOURCE_DIR} ARGS paths OUTPUT_VARIABLE ${PROJECT_NAME}_HGPATHS)
message(STATUS "${PROJECT_NAME}_HGPATHS=${${PROJECT_NAME}_HGPATHS}}")
if (NOT(${PROJECT_NAME}_HGPATHS STREQUAL ""))
string(REPLACE "n" ";" ${PROJECT_NAME}_HGPATHS ${${PROJECT_NAME}_HGPATHS})
foreach(HGPATH ${${PROJECT_NAME}_HGPATHS})
string(SUBSTRING "${HGPATH}" 0 10 HGPATHSTART)
if (HGPATHSTART MATCHES "default = ")
string(LENGTH "${HGPATH}" HGPATHLENGTH)
math(EXPR HGSUBLEN "${HGPATHLENGTH}-10")
string(SUBSTRING "${HGPATH}" 10 ${HGSUBLEN} ${PROJECT_NAME}_HGREMOTEDIR)
endif()
endforeach()
endif()
if (NOT ${PROJECT_NAME}_HGREMOTEDIR)
message(WARNING "No remote repository set. Will use current direcoty for build number, but this value may be inaccurate.")
set(${PROJECT_NAME}_HGREMOTEDIR ${PROJECT_SOURCE_DIR})
else()
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR} ARGS status RETURN_VALUE HGREMOTESTATUSVALUE OUTPUT_VARIABLE NUL)
if (NOT HGREMOTESTATUSVALUE EQUAL 0)
message(WARNING "Cannot connect to remote repository at ${${PROJECT_NAME}_HGREMOTEDIR}. Will use current direcoty for build number, but this value may be inaccurate.")
set(${PROJECT_NAME}_HGREMOTEDIR ${PROJECT_SOURCE_DIR})
endif()
endif()
#Identify changeset
exec_program(hg ${PROJECT_SOURCE_DIR} ARGS "id" "-i" OUTPUT_VARIABLE OUTPUT_VARIABLE ${PROJECT_NAME}_HGHASHCODE)
if (${PROJECT_NAME}_HGHASHCODE MATCHES ".*\+")
MESSAGE(STATUS "Node is dirty. Will generate temporary version number...")
set (${PROJECT_NAME}_HGDIRTY 1)
string(LENGTH ${${PROJECT_NAME}_HGHASHCODE} HGHASHLEN)
MATH(EXPR HGHASHLEN "${HGHASHLEN}-1")
string(SUBSTRING ${${PROJECT_NAME}_HGHASHCODE} 0 ${HGHASHLEN} ${PROJECT_NAME}_HGHASHCODE)
endif()
#check if remote repository contains changeset
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR}
ARGS "log" "-r" "${${PROJECT_NAME}_HGHASHCODE}"
RETURN_VALUE HGREMOTEHASCHANGESET
OUTPUT_VARIABLE NUL)
if (NOT HGREMOTEHASCHANGESET EQUAL 0)
message(WARNING "Remote repository ${${PROJECT_NAME}_HGREMOTEDIR} does not have changeset ${${PROJECT_NAME}_HGHASHCODE}. Will use current direcoty for build number, but this value may be inaccurate.")
set(${PROJECT_NAME}_HGREMOTEDIR ${PROJECT_SOURCE_DIR})
endif()
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR}
ARGS "log" "-r" ${${PROJECT_NAME}_HGHASHCODE} "--template" "{latesttag}"
OUTPUT_VARIABLE ${PROJECT_NAME}_HGMAJORMINORVERSION)
MESSAGE(STATUS "${PROJECT_NAME}_HGMAJORMINORVERSION=${${PROJECT_NAME}_HGMAJORMINORVERSION}")
exec_program(hg ${${PROJECT_NAME}_HGREMOTEDIR}
ARGS "log" "-r" ${${PROJECT_NAME}_HGHASHCODE} "--template" "{latesttagdistance}"
OUTPUT_VARIABLE ${PROJECT_NAME}_HGBUILDNUMBER)
if (${PROJECT_NAME}_HGDIRTY)
MATH(EXPR ${PROJECT_NAME}_HGBUILDNUMBER "${${PROJECT_NAME}_HGBUILDNUMBER}+1")
set(${PROJECT_NAME}_HGHASHCODE "${${PROJECT_NAME}_HGHASHCODE}+")
endif()
MESSAGE(STATUS "Version=${${PROJECT_NAME}_HGMAJORMINORVERSION}.${${PROJECT_NAME}_HGBUILDNUMBER}.${${PROJECT_NAME}_HGHASHCODE}")
endmacro()
message(STATUS "GETTING HG VERSION")
ReadProjectRevisionStatus()
CONFIGURE_FILE(${PROJECT_SOURCE_DIR}/main.h.in ${PROJECT_BINARY_DIR}/main.h)
在主cmake文件中
add_custom_target(
${PROJECT_NAME}_hg_version_target
DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/main.h.in
COMMAND ${CMAKE_COMMAND}
ARGS -DPROJECT_SOURCE_DIR=${PROJECT_SOURCE_DIR}
-DPROJECT_NAME=${PROJECT_NAME}
-DPROJECT_BINARY_DIR=${PROJECT_BINARY_DIR}
-P "${CMAKE_CURRENT_SOURCE_DIR}/HGVersion.CMake")
和
add_dependences（$｛PROJECT_NAME｝${PROJECT_NAME}_hg_version_target)
有效，但似乎。。。真是一团糟。有人有更好的东西吗？
如果生成过程中的某些内容决定了要生成的文件的内容，则不能使用config_file生成该文件，因为config_file在配置阶段而不是在生成时运行。这是CMake的设计选择。
在您的情况下，您确实必须在构建过程中使用add_custom_command和add_custom_target来生成该文件，正如您已经发现的那样。
对于您提出的解决方案，可能有机会稍微简化一下。当您生成C/C++头文件时，CMake内部解析器应该能够自动发现哪些常见的源代码文件依赖于main.h。因此，提供一个带有add_custom_command的自定义命令就足够了，该命令将要生成的main.h文件声明为其OUTPUT。一旦CMake试图构建一个C/C++文件依赖的目标，它就应该自动调用这个命令。因此，您可能不需要自定义目标和手动声明的依赖关系。
相关文章：
- 如何创建一个CMake变量，除非显式重写，否则使用默认值
- 将成员变量添加到共享库中的类中，不会破坏二进制兼容性吗
- 将数组的地址分配给变量并删除
- 为"adjacent"变量赋值时出现问题
- enum是C++中的宏变量还是整数变量
- 在全局变量中保存类的实例以重新创建类(创建"backup")
- 用C++中的一个变量定义一个常量
- 具有奇怪重复模板模式的派生类中的成员变量已损坏
- 你能重载对象变量名本身返回的内容吗
- 内置函数可查看CPP中的成员变量
- 是否可以初始化不可复制类型的成员变量(或基类）
- 尝试通过多个向量访问变量时，向量下标超出范围
- 试图让变量检查数组中的某些内容
- Cpp-Tuple使用带有变量的get
- 将包含C样式数组的对象初始化为成员变量(C++）
- 当vector是tje全局变量时，c++中vector的内存管理
- 通过多个头文件使用常量变量
- std::threads可以从Windows DLL中的全局变量创建/销毁吗?
- 执行函数时导致崩溃的变量
- 变量没有改变?通过向量的函数调用
