boost::asio::spawn yield as callback

Question

I\'m trying to rewrite a project using boost::asio::spawn coroutines. Some parts of the project cannot be changed. For example, the storage protocol library is

Answer 1

Thanks to @PSIAlt and @free_coffee I know how to use callback functions in stackful coroutine.

Here is a simple example just for asio newbies(like me :D)

https://gist.github.com/chenfengyuan/4d764b0bca82a42c05a9

#include 
#include 
#include 
#include 
#include 

void bar(boost::asio::io_service &io, std::function cb){
    auto ptr = std::make_shared(io, boost::posix_time::seconds(1));
    ptr->async_wait([ptr, cb](const boost::system::error_code&){cb();});
}

template
void foo(boost::asio::io_service &io, Handler && handler){
    typename boost::asio::handler_type::type handler_(std::forward(handler));
    boost::asio::async_result result(handler_);
    bar(io, handler_);
    result.get();
    return;
}

int main()
{
  boost::asio::io_service io;
  boost::asio::spawn(io, [&io](boost::asio::yield_context yield){
      foo(io, yield);
      std::cout << "hello, world!\n";
  });

  io.run();

  return 0;
}