cmake configure_file() example

configure_file.CMakeLists.txt

cmake_minimum_required(VERSION 3.16.3)
project(configure-file-example)

# Configure file, export the environment variable.
set(FOO_DIR
    "${CMAKE_CURRENT_SOURCE_DIR}/${PATH_YOU_WANT}")
configure_file(config/foo.h.in foo.h @ONLY)

# Libraries or excutables
# ...
include_directories(
    ${CMAKE_CURRENT_BINARY_DIR})

foo.h

#ifndef FOO_H
#define FOO_H

#include <string>

#define FOO_DIR @FOO_DIR@

std::string GetFooDir() {
    std::string path = "@FOO_DIR@";
    return path;
}

#endif  // FOO_H