CODEWITHSUNDEEP
c++cmake
Learning Lin
Learning Lin

Reputation: 157

Build many subproject that can be built independently and use common CMake variable by CMake?

I want to give examples to some users of my project. The exmaple is to be used CMake. And It's like:

- top level
CMakeLists.txt
-- example A
A.cpp
CMakeLists.txt
-- example B
B.cpp
CMakeLists.txt
-- example C
C.cpp
CMakeLists.txt

I want to set some common CMake options in the top CMakeLists.txt, like:

set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -stdlib=libc++ -fexperimental-library")
set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -lc++abi -fuse-ld=lld")
set(CMAKE_MODULE_LINKER_FLAGS "${CMAKE_MODULE_LINKER_FLAGS} -lc++abi -fuse-ld=lld")
set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -lc++abi -fuse-ld=lld")
set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

And I want that the example project can be built one time and the sub example can be built independently.

#A.cpp
cmake_minimum_required(VERSION 3.24)

# Something to be added

project(A)
add_executable(${PROJECT_NAME} A.cpp)

But I wish that I can do it without copy the common options into each CMakeLists.txt. I don't find a simple answer on StackOverflow or throughout Google. I think it should be a question may be met frequently in the fact. It's helpful to provide a tutorial even just a tutorial url.

Upvotes: 1

Views: 241

Answers (1)

laht
laht

Reputation: 96

Simply use add_subdirectory? Would simplify things and should still meet your requirement?

option(MYPROJECT_BUILD_EXAMPLES "Build examples" OFF/ON)

...

if (MYPROJECT_BUILD_EXAMPLES)
  add_subdirectory(examples)
endif()

Upvotes: 2

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