Where to define a macro when compiling a shared library that contains multiple files

Question

I want to #define BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG so as to use nanosecond resolution in boost datetime.

I want to use this nanosecond across the whole shared library I'm going to compile.

So where should I put this line, #define BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG?

I previously wanted to define it in the CMakeLists.txt file with add_compile_definitions(BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG).

However, it does not take effect. This is because within the library, cout << "nanoseconds per unit: " << pt::time_duration(0, 0, 0, 1).total_nanoseconds() << endl; still gives nanoseconds per unit: 1000

Here's the CMakeLists.txt,

cmake_minimum_required(VERSION 3.22)
project(project_name)

set(CMAKE_CXX_STANDARD 17)

add_compile_definitions(BOOST_DATE_TIME_POSIX_TIME_STD_CONFIG)

find_package( Boost COMPONENTS filesystem iostreams REQUIRED )

include_directories( ${Boost_INCLUDE_DIR} )

include_directories( include )

file(GLOB SOURCES include/*.h src/*.cpp)

add_library(project_name SHARED library.cpp ${SOURCES})

set_target_properties(project_name PROPERTIES LINKER_LANGUAGE CXX)

target_link_libraries(project_name ${Boost_LIBRARIES})

Answer 1

Try:

add_compile_definitions(-DBOOST_DATE_TIME_POSIX_TIME_STD_CONFIG)

or

add_definitions(-DBOOST_DATE_TIME_POSIX_TIME_STD_CONFIG)