32 Concurrency support library [thread]

32.3 Stop tokens [thread.stoptoken]

32.3.6 Class template stop_callback [stopcallback]

32.3.6.1 General [stopcallback.general]

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namespace std { template<class CallbackFn> class stop_callback { public: using callback_type = CallbackFn; // [stopcallback.cons], constructors and destructor template<class Initializer> explicit stop_callback(const stop_token& st, Initializer&& init) noexcept(is_nothrow_constructible_v<CallbackFn, Initializer>); template<class Initializer> explicit stop_callback(stop_token&& st, Initializer&& init) noexcept(is_nothrow_constructible_v<CallbackFn, Initializer>); ~stop_callback(); stop_callback(const stop_callback&) = delete; stop_callback(stop_callback&&) = delete; stop_callback& operator=(const stop_callback&) = delete; stop_callback& operator=(stop_callback&&) = delete; private: CallbackFn callback-fn; // exposition only }; template<class CallbackFn> stop_callback(stop_token, CallbackFn) -> stop_callback<CallbackFn>; }
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Mandates: stop_callback is instantiated with an argument for the template parameter CallbackFn that satisfies both invocable and destructible.
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Remarks: For a type Initializer, if stoppable-callback-for<CallbackFn, stop_token, Initializer> is satisfied, then stoppable-callback-for<CallbackFn, stop_token, Initializer> is modeled.
The exposition-only callback-fn member is the associated callback function ([stoptoken.concepts]) of stop_callback<
CallbackFn> objects.

32.3.6.2 Constructors and destructor [stopcallback.cons]

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template<class Initializer> explicit stop_callback(const stop_token& st, Initializer&& init) noexcept(is_nothrow_constructible_v<CallbackFn, Initializer>); template<class Initializer> explicit stop_callback(stop_token&& st, Initializer&& init) noexcept(is_nothrow_constructible_v<CallbackFn, Initializer>);
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Constraints: CallbackFn and Initializer satisfy constructible_from<CallbackFn, Initializer>.
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Effects: Initializes callback-fn with std​::​forward<Initializer>(init) and executes a stoppable callback registration ([stoptoken.concepts]).
If a callback is registered with st's shared stop state, then *this acquires shared ownership of that stop state.
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~stop_callback();
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Effects: Executes a stoppable callback deregistration ([stoptoken.concepts]) and releases ownership of the stop state, if any.