How to use v2 initializers

Start with the Boost.Process v2 process initializer API, especially the CustomInit hook methods and the async_execute entry point shown in the example. Determine whether the hooks are expected to run in this usage, then document the correct initializer pattern and a working example; no specific file or test is named in the issue.

Hello,

I am excited to use process v2 in my projects. Unfortunately I am having a bit of a hard time understanding the API. If this is not the correct place to post such questions I apologize.

Please see my following example. I cannot get the on_* functions to run. I am sure I am doing something wrong:

namespace asio = boost::asio;
namespace bp = boost::process::v2;
using namespace std::chrono_literals;

struct CustomInit
{
   template <typename Launcher>
   std::error_code on_setup(Launcher&, const std::filesystem::path&, const char * const *&)
   {
      std::cout << "on_setup" << std::endl;
      return {};
   }

   template <typename Launcher>
   std::error_code on_error(Launcher&, const std::filesystem::path&, const char * const *&)
   {
      std::cout << "on_error" << std::endl;
      return {};
   }

   template <typename Launcher>
   std::error_code on_success(Launcher&, const std::filesystem::path&, const char * const *&)
   {
      std::cout << "on_success" << std::endl;
      return {};
   }

   template <typename Launcher>
   std::error_code on_fork_error(Launcher&, const std::filesystem::path&, const char * const *&)
   {
      std::cout << "on_fork_error" << std::endl;
      return {};
   }

   template <typename Launcher>
   std::error_code on_exec_setup(Launcher&, const std::filesystem::path&, const char * const *&)
   {
      std::cout << "on_exec_setup" << std::endl;
      return {};
   }

   template <typename Launcher>
   std::error_code on_exec_error(Launcher&, const std::filesystem::path&, const char * const *&)
   {
      std::cout << "on_exec_error" << std::endl;
      return {};
   }
};

int
main(void)
{
   asio::io_context io;
   
   try {
      auto p = bp::process(io, "/usr/bin/sleep", {"1"}, CustomInit{});

      bp::async_execute(std::move(p),
      [] (const boost::system::error_code &, const int exitCode) {
         std::cout << exitCode << std::endl;
      });

      io.run();
   }
   catch (const std::exception &e) {
      std::cerr << e.what() << std::endl;
   }

   return 0;
}

Thanks in advance for any assistance you can provide.