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

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Great thanks to free_coffe i managed this to work. Posting solution for my case, possibly someone need it.

template 
RequestResult async_foo(Packet &pkt, CompletionToken&& token) {
   typename boost::asio::handler_type< CompletionToken, void(RequestResult) >::type handler( std::forward(token) );
  boost::asio::async_result result(handler);
  storage_api->writePacket(pkt, handler);
  return result.get();
}

Later we can use this proxy:

RequestResult res = async_foo(pkt, std::forward(yield) );