std::coroutine_handle<Promise>::operator(), std::coroutine_handle<Promise>::resume

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

Utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Utilities library

Language support Type support (basic types, RTTI, type traits) Library feature-test macros (C++20) Dynamic memory management Program utilities Error handling Coroutine support (C++20) Variadic functions launder (C++17) initializer_list (C++11) source_location (C++20) Three-way comparison (C++20) three_way_comparablethree_way_comparable_with (C++20)(C++20) strong_ordering (C++20) weak_ordering (C++20) partial_ordering (C++20) common_comparison_category (C++20) compare_three_way_result (C++20) compare_three_way (C++20) strong_order (C++20) weak_order (C++20) partial_order (C++20) compare_strong_order_fallback (C++20) compare_weak_order_fallback (C++20) compare_partial_order_fallback (C++20) is_eqis_neqis_ltis_lteqis_gtis_gteq (C++20)(C++20)(C++20)(C++20)(C++20)(C++20)

General utilities Date and time Function objects Formatting library (C++20) bitset hash (C++11) integer_sequence (C++14) Relational operators (deprecated in C++20) rel_ops::operator!=rel_ops::operator>rel_ops::operator<=rel_ops::operator>= Integer comparison functions cmp_equalcmp_not_equalcmp_lesscmp_greatercmp_less_thancmp_greater_than (C++20)(C++20)(C++20)(C++20)(C++20)(C++20) in_range (C++20) Swap and type operations swap ranges::swap (C++20) exchange (C++14) declval (C++11) forward (C++11) move (C++11) move_if_noexcept (C++11) as_const (C++17) Common vocabulary types pair tuple (C++11) apply (C++17) make_from_tuple (C++17) optional (C++17) any (C++17) variant (C++17) Elementary string conversions to_chars (C++17) from_chars (C++17) chars_format (C++17)

 

Coroutine support

Coroutine traits

coroutine_traits (C++20)

Coroutine handle

coroutine_handle (C++20)

No-op coroutines

noop_coroutine_promise (C++20)

noop_coroutine (C++20)

Trivial awaitables

suspend_never (C++20)

suspend_always (C++20)

 

std::coroutine_handle

Member functions

coroutine_handle::coroutine_handle (C++20)

coroutine_handle::operator= (C++20)

coroutine_handle::from_promise (C++20)

Observers

coroutine_handle::done (C++20)

coroutine_handle::operator bool (C++20)

Control

coroutine_handle::operator()coroutine_handle::resume (C++20)(C++20)

coroutine_handle::destroy (C++20)

Promise access

coroutine_handle::promise (C++20)

Export/import

coroutine_handle::address (C++20)

coroutine_handle::from_address (C++20)

Non-member functions

operator==operator<=> (C++20)(C++20)

Helper classes

std::hash<std::coroutine_handle> (C++20)

 

Member of other specializations
void operator()() const; void resume() const;	(1)	(since C++20)
Member of specialization std::coroutine_handle<std::noop_coroutine_promise>
constexpr void operator()() const noexcept; constexpr void resume() const noexcept;	(2)	(since C++20)

1) Resumes the execution of the coroutine to which *this refers, or does nothing if the coroutine is a no-op coroutine.

2) Does nothing.

The behavior is undefined if the resumption is needed, and *this does not refer to suspended coroutine or the coroutine is suspended at its final suspend point. A concurrent resumption of the coroutine may result in a data race.

Resumption of a coroutine on an execution agent other than the one on which it was suspended has implementation-defined behavior unless each execution agent either is a thread represented by std::thread or std::jthread, or is the thread executing main.

Parameters

(none)

Return value

(none)

Notes

A coroutine that is resumed on a different execution agent should avoid relying on consistent thread identity throughout, such as holding a mutex object across a suspend point.

N4861 (C++20 final working draft) requires that a call to operator() or resume on a std::coroutine_handle<> converted from a std::noop_coroutine_handle is also no-op, which is unimplementable because a std::noop_coroutine_handle may refer to a coroutine that is not no-op, or may not refer to a coroutine. This is LWG issue 3460.

See also

destroy (C++20)

destroys a coroutine (public member function)