CMake is a powerful open-source, cross-platform family of tools designed to build, test and package software. A core component of CMake's functionality lies within its generators. This article dives into the world of CMake generators, explaining their purpose, types, and how to use them effectively. Understanding CMake generators is crucial for anyone looking to streamline their build process across different platforms and IDEs.
At its heart, a CMake generator is responsible for creating the necessary input files for a native build system. Think of it as a translator, taking CMake's platform-agnostic instructions and converting them into the specific language that your chosen build tool understands. The selection of a CMake generator determines which native build system will be employed for the project.
CMake generators are platform-specific, meaning that availability may vary depending on your operating system.
To see a list of generators available on your current platform, use the following command:
cmake --help
You can then specify the generator when creating a new build tree using the -G option:
cmake -G "Your Generator" <path_to_source>
For a more interactive approach, the cmake-gui tool allows you to select a generator through a graphical interface.
CMake generators can be broadly categorized into the following types:
Let's take a closer look at some of the most commonly used generators:
Makefile generators produce Makefiles which are then used by the make build system. Several variations exist to support different environments:
Ninja is a small build system with a focus on speed. CMake's Ninja generators are popular for their efficiency:
CMake provides extensive support for Microsoft Visual Studio, with generators available for various versions:
Selecting the correct Visual Studio generator is crucial for ensuring compatibility with your development environment.
Beyond Makefiles, Ninja, and Visual Studio, CMake supports other specialized generators:
Older versions of CMake had the concept of "Extra Generators" used to generate project files for auxiliary IDE tools alongside a main generator. These are now deprecated in favor of the more modern cmake-file-api(7). Examples of these included:
These generators are deprecated as of CMake 3.27 and will be removed in a future version. IDEs should now use the cmake-file-api to view CMake-generated project build trees.
Selecting the appropriate CMake generator depends on several factors:
make, Ninja generators require ninja, etc.CMake generators are the bridge between CMake's configuration and the actual build process. By understanding the different types of generators and their specific characteristics, you can optimize your build workflow for efficiency, cross-platform compatibility, and integration with your preferred development tools. While the landscape of build systems continues to evolve (with tools like build2 gaining traction), CMake remains a cornerstone of modern software development, and mastering its generators is an invaluable skill.
