gistfile1.cpp

#include <iostream>
#include <vector>
 
#define BOOST_THREAD_PROVIDES_FUTURE
#define BOOST_THREAD_PROVIDES_FUTURE_CONTINUATION
#define BOOST_THREAD_PROVIDES_FUTURE_WHEN_ALL_WHEN_ANY
#include <boost/thread/future.hpp>
 
using namespace boost;
 
int main() {
   std::vector<future<int>> futures = {
      async([]() { return 1; }),
      async([]() { return 2; })
   };

   future<std::vector<future<int>>> f3 = when_all(std::begin(futures), std::end(futures));

   auto f4 = f3.then([](decltype(f3)) {
      std::cout << "done" << std::endl;
   });

   f4.get();
}