Define and document custom properties.

define_property(<GLOBAL | DIRECTORY | TARGET | SOURCE |
                 PROPERTY <name> [INHERITED]
                 BRIEF_DOCS <brief-doc> [docs...]
                 FULL_DOCS <full-doc> [docs...])

Define one property in a scope for use with the set_property() and get_property() commands. This is primarily useful to associate documentation with property names that may be retrieved with the get_property() command. The first argument determines the kind of scope in which the property should be used. It must be one of the following:

GLOBAL    = associated with the global namespace
DIRECTORY = associated with one directory
TARGET    = associated with one target
SOURCE    = associated with one source file
TEST      = associated with a test named with add_test
VARIABLE  = documents a CMake language variable
CACHED_VARIABLE = documents a CMake cache variable

Note that unlike set_property() and get_property() no actual scope needs to be given; only the kind of scope is important.

The required PROPERTY option is immediately followed by the name of the property being defined.

If the INHERITED option is given, then the get_property() command will chain up to the next higher scope when the requested property is not set in the scope given to the command.

  • DIRECTORY scope chains to its parent directory’s scope, continuing the walk up parent directories until a directory has the property set or there are no more parents. If still not found at the top level directory, it chains to the GLOBAL scope.

  • TARGET, SOURCE and TEST properties chain to DIRECTORY scope, including further chaining up the directories, etc. as needed.

Note that this scope chaining behavior only applies to calls to get_property(), get_directory_property(), get_target_property(), get_source_file_property() and get_test_property(). There is no inheriting behavior when setting properties, so using APPEND or APPEND_STRING with the set_property() command will not consider inherited values when working out the contents to append to.

The BRIEF_DOCS and FULL_DOCS options are followed by strings to be associated with the property as its brief and full documentation. Corresponding options to the get_property() command will retrieve the documentation.