Async types

async.cpp

#include <chrono>
using std::chrono::duration;
using std::chrono::system_clock;

#include <future>
using std::async;
using std::launch;

#include <iostream>
using std::cout;
using std::endl;


int main()
{
	auto start_lazy = system_clock::now();
	auto future_lazy = async(launch::deferred, [](){return 42 + 1337;});
	cout << future_lazy.get() << endl;
	cout << "lazy: " << duration<double>(system_clock::now() - start_lazy).count() << endl;
	
	auto start_eager = system_clock::now();
	auto future_eager = async(launch::async, [](){return 42 + 1337;});
	cout << future_eager.get() << endl;
	cout << "eager: " << duration<double>(system_clock::now() - start_eager).count() << endl;
	
	auto start_auto = system_clock::now();
	auto future_auto = async([](){return 42 + 1337;});
	cout << future_auto.get() << endl;
	cout << "auto: " << duration<double>(system_clock::now() - start_auto).count() << endl;
	
	return 0;
}