This recipe will build a simple executable linking against the message library. The layout of the project is as follows:

├── cmake
│   ├── install_hook.cmake.in
│   └── print_rpath.py
├── CMakeLists.txt
├── external
│   └── upstream
│       ├── CMakeLists.txt
│       └── message
│           └── CMakeLists.txt
└── src
    ├── CMakeLists.txt
    └── use_message.cpp

The main CMakeLists.txt file coordinates the superbuild. The external subdirectory contains CMake instructions to handle the dependencies. The cmake subdirectory contains a Python script and a template CMake script. These will be used to fine-tune the installation, the CMake script being first configured and then executed to call the Python script to print the RPATH for the installed use_message executable:

import shlex
import subprocess
import sys


def main():
    patcher = sys.argv[1]
    elfobj = sys.argv[2]

    tools = {'patchelf': '--print-rpath', 'chrpath': '--list', 'otool': '-L'}
    if patcher not in tools.keys():
        raise RuntimeError('Unknown tool {}'.format(patcher))
    cmd = shlex.split('{:s} {:s} {:s}'.format(patcher, tools[patcher], elfobj))
    rpath = subprocess.run(
        cmd,
        bufsize=1,
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        universal_newlines=True)
    print(rpath.stdout)


if __name__ == "__main__":
    main()

Printing the RPATH can easily be done with platform-native tools that we will discuss later on in this recipe.

Finally, the src subdirectory contains the CMakeLists.txt and source file for the actual project we want to compile. The use_message.cpp source file contains the following:

#include <cstdlib>
#include <iostream>

#ifdef USING_message
#include <message/Message.hpp>
void messaging() {
  Message say_hello("Hello, World! From a client of yours!");
  std::cout << say_hello << std::endl;

  Message say_goodbye("Goodbye, World! From a client of yours!");
  std::cout << say_goodbye << std::endl;
}
#else
void messaging() {
  std::cout << "Hello, World! From a client of yours!" << std::endl;

  std::cout << "Goodbye, World! From a client of yours!" << std::endl;
}
#endif

int main() {
  messaging();
  return EXIT_SUCCESS;
}