Exporting and Installing

There are three good ways and one bad way to allow others use your library:

Find module (the bad way)

If you are the library author, don’t make a Find<mypackage>.cmake script! These were designed for libraries whose authors did not support CMake. Use a Config<mypackage>.cmake instead as listed below.

Add Subproject

A package can include your project in a subdirectory, and then use add_subdirectory on the subdirectory. This useful for header-only and quick-to-compile libraries. Note that the install commands may interfere with the parent project, so you can add EXCLUDE_FROM_ALL to the add_subdirectory command; the targets you explicitly use will still be built.

In order to support this as a library author, make sure you use CMAKE_CURRENT_SOURCE_DIR instead of PROJECT_SOURCE_DIR (and likewise for other variables, like binary dirs). You can check CMAKE_PROJECT_NAME STREQUAL PROJECT_NAME to only add options or defaults that make sense if this is a project.

Also, since namespaces are a good idea, and the usage of your library should be consistent with the other methods below, you should add

add_library(MyLib::MyLib ALIAS MyLib)

to standardise the usage across all methods. This ALIAS target will not be exported below.

Exporting

The third way is *Config.cmake scripts; that will be the topic of the next chapter in this session.