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std::promise::set_exception(3) | C++ Standard Libary | std::promise::set_exception(3) |
NAME¶
std::promise::set_exception - std::promise::set_exception
Synopsis¶
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.
Calls to this function do not introduce data races with calls to get_future
(therefore they need not synchronize with each other).
Parameters¶
p - exception pointer to store. The behavior is undefined if p is null
Return value¶
(none)
Exceptions¶
std::future_error on the following conditions:
* *this has no shared state. The error code is set to no_state.
* The shared state already stores a value or exception. The error code is set
to
promise_already_satisfied.
Example¶
// Run this code
#include <future>
#include <iostream>
#include <thread>
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());
// or throw a custom exception instead
// p.set_exception(std::make_exception_ptr(MyException("mine")));
}
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
set_exception_at_thread_exit delivering the notification only at thread exit
(public member function)
2024.06.10 | http://cppreference.com |