class
<mutex>
std::once_flag
Flag argument type for call_once
Object of this type are used as arguments for call_once.
Using the same object on different calls to call_once in different threads causes a single execution if called concurrently.
It is a non-copyable, non-movable, default-constructible class, declared in <mutex> with the following prototype:
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struct once_flag {
constexpr once_flag() noexcept;
once_flag (const once_flag&) = delete;
once_flag& operator= (const once_flag&) = delete;
};
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See also
- call_once
- Call function once (public member function
)