c++11 - Is there a packaged_task::set_exception equivalent? -

my assumption packaged_task has promise underneath. if task throws exception, how route associated future? promise call set_exception – how do same packaged_task?

an std::packaged_task has associated std::future object hold exception (or result of task). can retrieve future calling get_future() member function of std::packaged_task.

this means enough throw exception inside function associated packaged task in order exception caught task's future (and re-thrown when get() called on future object).

for instance:

#include <thread> #include <future> #include <iostream>  int main() {     std::packaged_task<void()> pt([] () {          std::cout << "hello, ";          throw 42; // <== throw exception...     });      // retrieve associated future...     auto f = pt.get_future();      // start task (here, in separate thread)     std::thread t(std::move(pt));      try     {         // throw exception thrown inside         // packaged task's function...         f.get();     }     catch (int e)     {         // ...and here have exception         std::cout << e;     }      t.join(); }