cmake 与 Qt 共享库

Question

I created two default projects with QtCreator v6.0.1: MyApp and MyLib for Linux(Ubuntu). I changed the folders structure to

MyApp
├──build
│   ├──Debug
|   └──Release
├──src
├──libs
|   └──MyLib
|        ├──build
|        ├──src
|        ├──include
|        └──CMakeLists.txt
├──include
├──src
└──CMakeLists.txt

What kind of changes I need to make with both of CMakeLists.txt to make MyLib as shared library and use it in MyApp?

Answer 1

First of all, as already mentioned, you'll need to add the MyLib directory with add_subdirectory in the top-level CMakeLists.txt:

    ...
    add_subdirectory(libs/MyLib)
    ...

Then, defining a shared/dynamic library with CMake is pretty straight forward. You use add_library providing the name of the library, the source files and some flags. By default it will create a static library, but with the keyword SHARED you can change that:

    add_library(MyLib SHARED
                MySource1.cpp
                MySource2.cpp
                ...
                )

Have a look here: https://cmake.org/cmake/help/latest/command/add_library.html

By the way, all generated code (including the library) will end up in the one and only build directory (which you either specify with cmake -B $BUILD_DIR or which is the working directory for running cmake). So you won't have an additional one in your libs/MyLib folder.