FindPackagecmake

FindPackagecmake is a command within the CMake build system used to locate and load modules and packages required for a project. Its primary function is to search for and import settings and definitions from external libraries or components that a project depends on. When CMake encounters a FindPackagecmake command, it looks for a file named Find<PackageName>.cmake in predefined search paths. These search paths typically include the CMake installation's module directory, as well as directories specified by the user via the CMAKE_MODULE_PATH variable.

If a Find<PackageName>.cmake file is found, CMake executes the script within it. This script is responsible for determining if the package is installed on the system, finding its include directories, libraries, and any other necessary configuration information. Upon successful discovery, the script will define CMake variables and imported targets that the project can then use to link against the found package. For instance, it might define variables like <PackageName>_INCLUDE_DIRS and <PackageName>_LIBRARIES, or create an imported target like Pkg::<PackageName>.

If the package is not found, the FindPackagecmake command typically sets certain variables to indicate failure, such as <PackageName>_FOUND to false. This allows the project to handle cases where a dependency is missing, often by displaying an error message to the user and disabling features that rely on that package. Many common libraries and packages provide their own Find<PackageName>.cmake scripts, which are distributed with CMake itself or with the respective libraries. Developers can also write their own custom Find<PackageName>.cmake scripts for less common or project-specific dependencies.