CMake: Creating a Library

Introduction

In software development, creating a library is a common practice that allows for code reuse and modularity. One of the tools we can use to facilitate this process is CMake, a cross-platform free and open-source software for managing the build process of software using a compiler-independent method. This blog post will guide you through the process of creating a library using CMake, covering the basics of using CMake, setting up a project in CMake, and ultimately creating a library.

Understanding CMake

CMake is an extensible, open-source system that manages the build process in an operating system and in a compiler-independent manner. Unlike many cross-platform systems, CMake is designed to be used in conjunction with the native build environment. Simple configuration files placed in each source directory (called CMakeLists.txt files) are used to generate standard build files (e.g., makefiles on Unix and projects/workspaces in Windows MSVC) which are used in the usual way.

Setting up a Project in CMake

To set up a project in CMake, you first need to install CMake on your system. Once you have CMake installed, you can create a new directory for your project and add a CMakeLists.txt file to it. This file is where you’ll specify how your project should be built. The most basic CMakeLists.txt file for creating a library could look something like this:

cmake_minimum_required(VERSION 3.10)
project(MyLibrary)
add_library(MyLibrary STATIC src/my_library.cpp)

In this example, we’re specifying that we require at least version 3.10 of CMake, naming our project “MyLibrary”, and adding a static library that’s built from the source file “src/my_library.cpp”.

Creating a Library in CMake

Now that you’ve set up your project, you can create a library. In the example CMakeLists.txt file above, the add_library function is what’s actually creating the library. The first argument to this function is the name of the library, and the second argument is whether the library is STATIC (i.e., the library is linked at compile-time) or SHARED (i.e., the library is linked at runtime). The remaining arguments are the source files for the library.

To build your project and create the library, you would navigate to your project directory in a terminal and run the following commands:

mkdir build
cd build
cmake ..
make

This will create a build directory, navigate into it, generate the necessary build files with CMake, and then build your project with make.

Conclusion

CMake is a powerful tool for managing the build process of software. Its ability to work across platforms and with various compilers makes it a valuable tool for any developer’s toolkit. By understanding the basics of CMake and how to set up a project and create a library, you can increase the modularity and reusability of your code, making your software more efficient and easier to maintain.