[stopcallback.inplace]

# 32 Concurrency support library [[thread]](./#thread)

## 32.3 Stop tokens [[thread.stoptoken]](thread.stoptoken#stopcallback.inplace)

### 32.3.10 Class template inplace_stop_callback [stopcallback.inplace]

#### [32.3.10.1](#general) General [[stopcallback.inplace.general]](stopcallback.inplace.general)

namespace std {template<class CallbackFn>class inplace_stop_callback {public:using callback_type = CallbackFn; // [[stopcallback.inplace.cons]](#cons "32.3.10.2 Constructors and destructor"), constructors and destructortemplate<class Initializer>explicit inplace_stop_callback(inplace_stop_token st, Initializer&& init)noexcept(is_nothrow_constructible_v<CallbackFn, Initializer>); ~inplace_stop_callback();

 inplace_stop_callback(inplace_stop_callback&&) = delete;
 inplace_stop_callback(const inplace_stop_callback&) = delete;
 inplace_stop_callback& operator=(inplace_stop_callback&&) = delete;
 inplace_stop_callback& operator=(const inplace_stop_callback&) = delete; private: CallbackFn *callback-fn*; // *exposition only*}; template<class CallbackFn> inplace_stop_callback(inplace_stop_token, CallbackFn)-> inplace_stop_callback<CallbackFn>;}

[1](#general-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1352)

*Mandates*: CallbackFn satisfies both[invocable](concept.invocable#concept:invocable "18.7.2 Concept invocable [concept.invocable]") and [destructible](concept.destructible#concept:destructible "18.4.10 Concept destructible [concept.destructible]")[.](#general-1.sentence-1)

[2](#general-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1357)

*Remarks*: For a type Initializer, if[*stoppable-callback-for*](stoptoken.concepts#concept:stoppable-callback-for "32.3.3 Stop token concepts [stoptoken.concepts]")<CallbackFn, inplace_stop_token, Initializer> is satisfied, then[*stoppable-callback-for*](stoptoken.concepts#concept:stoppable-callback-for "32.3.3 Stop token concepts [stoptoken.concepts]")<CallbackFn, inplace_stop_token, Initializer> is modeled[.](#general-2.sentence-1)

For an inplace_stop_callback<CallbackFn> object,
the exposition-only *callback-fn* member is
its associated callback function ([[stoptoken.concepts]](stoptoken.concepts "32.3.3 Stop token concepts"))[.](#general-2.sentence-2)

#### [32.3.10.2](#cons) Constructors and destructor [[stopcallback.inplace.cons]](stopcallback.inplace.cons)

[ð](#cons-itemdecl:1)

`template<class Initializer>
  explicit inplace_stop_callback(inplace_stop_token st, Initializer&& init)
    noexcept(is_nothrow_constructible_v<CallbackFn, Initializer>);
`

[1](#cons-1)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1381)

*Constraints*: [constructible_from](concept.constructible#concept:constructible_from "18.4.11 Concept constructible_­from [concept.constructible]")<CallbackFn, Initializer> is satisfied[.](#cons-1.sentence-1)

[2](#cons-2)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1385)

*Effects*: Initializes *callback-fn* with std​::​forward<Initializer>(init) and executes a stoppable callback registration ([[stoptoken.concepts]](stoptoken.concepts "32.3.3 Stop token concepts"))[.](#cons-2.sentence-1)

[ð](#cons-itemdecl:2)

`~inplace_stop_callback();
`

[3](#cons-3)

[#](http://github.com/Eelis/draft/tree/9adde4bc1c62ec234483e63ea3b70a59724c745a/source/threads.tex#L1396)

*Effects*: Executes a stoppable callback deregistration ([[stoptoken.concepts]](stoptoken.concepts "32.3.3 Stop token concepts"))[.](#cons-3.sentence-1)
