我如何在CMakeLists.txt中知道它是否与add_subdirectory()一起使用? [英] How can I tell, within a CMakeLists.txt, whether it's used with add_subdirectory()?
问题描述
我有这个代码项目,可以独立构建,也可以作为较大存储库的子项目构建(将其作为子存储库检查)。在后一种情况下,我为主要项目有一个顶级 CMakeLists.txt
I have this code project can be built either independently or as a subproject of a larger repository (checking it our as a sub-repository). In the latter case, I have a top-level CMakeLists.txt
for the main project which has
add_subdirectory(${MY_SUBPROJ_SUBDIR})
现在,我希望该子项目如果通过 add_directory()
使用它,其行为会有所不同。显然,我将使用大型 if
指令。但是我要检查什么情况?在运行某些 CMakeLists.txt
时,CMake如何告诉它是子目录文件还是主文件?
now, I want the subproject to behave somewhat differently in case it's used via the add_directory()
. Obviously, I would be using a large if
instruction. But what condition do I check? How can CMake "tell", when running for some CMakeLists.txt
, whether it's a subdir file or the main file?
推荐答案
-
之后在
project()
调用中项目的CMakeLists.txt
,并且可以在项目的子目录中使用:
After the
project()
call in project'sCMakeLists.txt
and in the project's subdirectories you may use:
if(CMAKE_SOURCE_DIR STREQUAL PROJECT_SOURCE_DIR)
# I am top-level project.
else()
# I am called from other project with add_subdirectory().
endif()
注意:如评论中所述,此方法可能不能在Windows上运行,其中 CMAKE_SOURCE_DIR
包含小写版本的 PROJECT_SOURCE_DIR
,因此无法直接比较相等性。对于这种情况,请检查 PARENT_DIRECTORY
属性,如该答案所述对于重复的问题,似乎更可靠。
NOTE: As stated in the comments, this approach may to not work on Windows, where CMAKE_SOURCE_DIR
contains lower-case version of PROJECT_SOURCE_DIR
and thus cannot be compared directly for equality. For that case approach with checking PARENT_DIRECTORY
property, as described in that answer to the duplicate question, seems to be more robust.
在<$ c $之前之前 c> project()调用:
Alternative for use before the project()
call:
if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
# I am top-level project.
else()
# I am called from other project with add_subdirectory().
endif()
此替代方案也可以在项目 CMakeLists.txt中的任何位置使用
(但不在子目录中)。
This alternative can also be used anywhere in project's CMakeLists.txt
(but not in subdirectories).
您有一个项目 A ,其中有两个 CMakeLists.txt
:一个在项目目录中,另一个在子目录 src /
。上述使用方法的方案:
Assume you have a project A with two CMakeLists.txt
: one in the project's directory, and one in subdirectory src/
. Scheme for use approaches described above:
CMakeLists.txt :
cmake_minimum_required(...)
...
<only approach *2* can be used there>
...
project(A)
...
<approach *1* or *2* can be used there>
...
add_subdirectory(src)
...
src / CMakeLists.txt :
...
<only approach *1* can be used there>
...
在给定的方案下,项目 A 可以检测到内置的独立项目(顶级项目)或作为另一个项目 B 的一部分。
With given scheme project A may detect, whether it is built standalone (top-level project) or as a part of another project B.
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