问题描述

我想要以下结构 A ->B->C，其中:

I would like to have the following structure A -> B -> C, where:

• C 是样板代码，第三方库的包装器，非常基本代码等
• B 是常用的类、函数和数据特定于项目领域的结构.
• A 是项目本身.

• C is boilerplate code, wrappers for third-party libraries, very basic code etc.
• B is the common classes, functions and data structures specific to the project's domain.
• A is the project itself.

我希望以后在我的其他项目中可以轻松地重用 C 或 B(+C).另外，我还有以下要求:

I would like to make it easy to reuse C or B(+C) in future in my other projects. In addition, I have the following requirements:

1. 由于这三个项目都在进行中，我希望能够构建C、C+B 和C+B+A 一次性完成.
2. 我更喜欢静态链接而不是动态链接，因此 C 和 C+B 将是静态库，而 C+B+A> 将是可执行文件
3. 我想让 cmake 列表和配置文件保持简单和干净.我在官方 wiki 和互联网上找到的例子非常庞大和可怕.
4. 如果我更改A、B 或C 的位置，如果不需要更改多于几行，那就太好了 在文件系统中.
5. 这三个组件都在使用 google-test，但我不确定它对项目布局是否重要.

1. As all three projects are in-progress, I would like to have an ability to build C, C+B and C+B+A in one shot.
2. I would prefer the static linkage over dynamic, so that C and C+B would be static libraries, and C+B+A would be the executable
3. I would like to keep cmake lists and config files simple and clean. Examples which I found in the official wiki and over the internet are pretty big and monstrous.
4. It would be great if it won't require changing more than a couple of lines if I'd change the locations of A, B or C in the filesystem.
5. All these three components are using google-test, but I'm not sure if it is important for the project layout.

我对 cmake 很陌生，我什至不明白编写 XXXConfig.cmake 或 FindXXX.cmake 文件更好.另外，我不确定，我应该如何使用 X_INCLUDE_DIRS 将相对路径从子组件传递到父组件.

I am pretty new to cmake and I don't even understand is it better to write XXXConfig.cmake or FindXXX.cmake files. Also, I am not sure, how should I pass relative paths from subcomponent to the parent component using X_INCLUDE_DIRS.

推荐答案

首先我必须承认我同意 @Tsyvarev.您的 CMake 环境应适合您的流程/工作流程，并应考虑项目规模和团队结构.或者一般来说 CMake 将在其中使用的环境.这往往 - 从积极的方面 - 非常活跃.

First I have to admit that I agree with @Tsyvarev. Your CMake environment should fit to your processes/workflow and should take project sizes and team structure into account. Or generally speaking the environment CMake will be used in. And this tends to be - in a positive way - very alive.

所以你的这部分问题很难回答，我将专注于技术部分:

So this part of your question is difficult to answer and I'll concentrate on the technical part:

1. CMake 必须知道依赖项的位置 - 相对或绝对 - 通过
   • 拥有一个单一的源代码树(你不再想要的那个)
     • 具有多个可执行文件的 CMake 共享库
     • CMake:如何设置源、库和CMakeLists.txt 依赖项?

• CMake 库输出的自定义目录
• cmake install 不在 Windows 上安装库

• 如何让 cmake 找到我的替代方案提升安装?
• 如何为CMake 构建过程本身?

• 使其他 cmake 包自动访问 cmake 库
• cmake 不会在 ExternalProject_Add 中正确运行 build_command

• 优先使用工具链文件而不是 if(SomeCompiler) 语句
• 将常见/重复代码部分作为 function() 主体移动到共享的 CMake 包含文件中
• 将复杂的非目标特定代码部分移动到它们自己的 (CMake) 脚本文件中

• Prefer toolchain files over if(SomeCompiler) statements
• Move common/repeating code parts as function() bodies into a shared CMake include file
• Move complex non-target specific code parts into their own (CMake) script files

示例代码

由于您特别要求 find_package() 变体，因此采用 在您的 CMake 项目中使用支持 CMake 的库 以及上面列出的内容:

Example Code

Since you have specifically asked for the find_package() variant, taking Use CMake-enabled libraries in your CMake project and the things listed above:

MyCommonCode.cmake

cmake_policy(SET CMP0022 NEW)

function(my_export_target _target _include_dir)
    file(
        WRITE "${CMAKE_CURRENT_BINARY_DIR}/${_target}Config.cmake"
        "
            include("${CMAKE_CURRENT_LIST_DIR}/${_target}Targets.cmake")
            set_property(
                TARGET ${_target} 
                APPEND PROPERTY 
                    INTERFACE_INCLUDE_DIRECTORIES "${_include_dir}"
            )
        "
    )

    export(
        TARGETS ${_target} 
        FILE "${CMAKE_CURRENT_BINARY_DIR}/${_target}Targets.cmake"
        EXPORT_LINK_INTERFACE_LIBRARIES
    )
    export(PACKAGE ${_target}) 
endfunction(my_export_target)

C/CMakeLists.txt

include(MyCommonCode.cmake)
...
my_export_target(C "${CMAKE_CURRENT_SOURCE_DIR}/include")

B/CMakeLists.txt

include(MyCommonCode.cmake)

find_package(C REQUIRED)
...
target_link_libraries(B C)
my_export_target(B "${CMAKE_CURRENT_SOURCE_DIR}/include")

A/CMakeLists.txt

include(MyCommonCode.cmake)

find_package(B REQUIRED)
...
target_link_libraries(A B)

这将所有 3 个构建环境分开，仅共享相对静态的 MyCommonCode.cmake 文件.因此，在这种方法中，到目前为止我还没有涵盖您的第一点，但建议使用外部脚本来链接/触发 A/B/C 的构建步骤.

This keeps all 3 build environments separate, only sharing the relatively static MyCommonCode.cmake file. So in this approach I have so far not covered your first point, but would recommend the use of a external script to chain/trigger your build steps for A/B/C.

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