std::promise::set_exception
From cppreference.com
void set_exception( std::exception_ptr p ); |
(since C++11) | |
Atomically stores the exception pointer p
into the shared state and makes the state ready.
The operation behaves as though set_value, set_exception
, set_value_at_thread_exit, and set_exception_at_thread_exit acquire a single mutex associated with the promise object while updating the promise object.
An exception is thrown if there is no shared state or the shared state already stores a value or exception.
Parameters
p | - | exception pointer to store. The behavior is undefined if p is null.
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Return value
(none)
Exceptions
std::future_error on the following conditions:
- *this has no shared state. The error category is set to no_state.
- The shared state already stores a value or exception. The error category is set to promise_already_satisfied.
Example
Run this code
#include <thread> #include <iostream> #include <future> int main() { std::promise<int> p; std::future<int> f = p.get_future(); std::thread t([&p]{ try { // code that may throw throw std::runtime_error("Example"); } catch(...) { try { // store anything thrown in the promise p.set_exception(std::current_exception()); } catch(...) {} // set_exception() may throw too } }); try { std::cout << f.get(); } catch(const std::exception& e) { std::cout << "Exception from the thread: " << e.what() << '\n'; } t.join(); }
Output:
Exception from the thread: Example
See also
sets the result to indicate an exception while delivering the notification only at thread exit (public member function) |