Are there other means of obtaining the properties of a target in cmake? - cmake

Question

I have created a C++ static library, and in order to make it searchable easily, I create the following cmake files:
lib.cmake
# The installation prefix configured by this project.
set(_IMPORT_PREFIX "C:/------/install/win32")
# Create imported target boost
add_library(lib STATIC IMPORTED)
set_target_properties(lib PROPERTIES
INTERFACE_COMPILE_DEFINITIONS "lib_define1;lib_define2"
INTERFACE_INCLUDE_DIRECTORIES "${_IMPORT_PREFIX}/../include"
)
# Load information for each installed configuration.
get_filename_component(_DIR "${CMAKE_CURRENT_LIST_FILE}" PATH)
file(GLOB CONFIG_FILES "${_DIR}/lib-*.cmake")
foreach(f ${CONFIG_FILES})
include(${f})
endforeach()
lib-debug.cmake
# Import target "boost" for configuration "Debug"
set_property(TARGET lib APPEND PROPERTY IMPORTED_CONFIGURATIONS DEBUG)
set_target_properties(boost PROPERTIES
IMPORTED_LINK_INTERFACE_LANGUAGES_DEBUG "CXX"
IMPORTED_LOCATION_DEBUG "${_IMPORT_PREFIX}/Debug/staticlib/lib.lib"
)
When I want to use this library in an executable, I can simply invoke it by calling find_package command:
find_package(lib REQUIRED)
if(lib_FOUND)
message("lib has been found")
else()
message("lib cannot be found")
endif(boost_FOUND)
It works and if I want to know the head file directory of the library, I will have to call it this way:
get_target_property(lib_dir lib INTERFACE_INCLUDE_DIRECTORIES)
I was just wondering whether there are other ways of obtaining the properties of an target. In this case I expect some variable like lib_INCLUDE_DIRECTORIES will exist.

Answer 1

No, CMake does not automatically define variables for the properties of a target (or of anything else). If you need the value of a property, you have to query it explicitly (using get_property or the specific getters like get_target_property etc.).
In your specific case, INTERFACE_INCLUDE_DIRECTORIES is a property which I would expect you would not need to query at all. The whole point of INTERFACE_* properties is to propagate usage requirements automatically; their propagation is implemented in CMake itself.