Targets, Properties, And More#

Target Types #

Two basic types: add_executable() and add_library()
add_executable() is not relevant …
- Only entry point into dependency graph
- ⟶ does not propagate anything to dependers
- There are no dependers

add_library() …

Type	Description
Normal library	`STATIC` (default), `SHARED`, `MODULE`. Has sources to be built.
Object libraries	Technically much like normal libraries, but not an archive or shared object (only virtual, implemented by CMake)
Interface libraries	No sources; only there to propagate properties to dependers, and to have further dependencies on their own.

(For a complete list see add_library())

Target function	Property name	Description	Documentation
`target_compile_definitions()`	`COMPILE_DEFINITIONS`	Macros set on the compiler command line (`-Dname=value`)	target_compile_definitions()
`target_compile_options()`	`COMPILE_OPTIONS`	Non-macro compiler flags/options	TARGET_COMPILE_OPTIONS()
`target_include_directories()`	`INCLUDE_DIRECTORIES`	Include directories	target_include_directories()
`target_link_libraries()`	(Much more complicated, see documentation)	Dependencies, in the widest sense	target_link_libraries()
`set_target_properties()`	Any property, including custom properties	See documentation	set_target_properties()

PUBLIC propagated to dependers
- Dependency through #include <other.h> in a header file ⟶ all includers need to know
- blacklist availability in approach 2 (but only if blacklist has compiled code)
- PUBLIC only possible when target has compiled code
PRIVATE does not propagate
- For example, one might structure a target’s source code into src/, private-inc/, and public-inc/ ⟶ private-inc/ would be target_include_directories(... PRIVATE ...)
- For example, target_compile_definitions() for target-local compilation only
INTERFACE propagated to dependers
- Just like PUBLIC - except that PUBLIC is not possible on INTERFACE targets (e.g. header-only libraries)
- Asymmetric; smells like it does in many corners of CMake
- Documentation has no clear explanation. Exceptions, and paragraph-long explanations.