The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <thread>
#include <future>
#include <iostream>
#include <string>
#include <exception>
#include <stdexcept>
#include <functional>
#include <utility>
void doSomething (std::promise<std::string>& p)
{
try {
// read character and throw exception if 'x'
std::cout << "read char ('x' for exception): ";
char c = std::cin.get();
if (c == 'x') {
throw std::runtime_error(std::string("char ")+c+" read");
}
//...
std::string s = std::string("char ") + c + " processed";
p.set_value_at_thread_exit(std::move(s)); // store result
}
catch (...) {
p.set_exception_at_thread_exit(std::current_exception()); // store exception
}
}
int main()
{
try {
// create a promise to store the outcome
std::promise<std::string> p;
// create a future to process the outcome
std::future<std::string> f(p.get_future());
// start a thread using the promise to store the outcome
std::thread t(doSomething,std::ref(p));
t.detach();
//...
// process the outcome
std::cout << "result: " << f.get() << std::endl;
}
catch (const std::exception& e) {
std::cerr << "EXCEPTION: " << e.what() << std::endl;
}
catch (...) {
std::cerr << "EXCEPTION " << std::endl;
}
}