std::once_flag - cppreference.com (original) (raw)

| | | | | ----------------- | | ------------- | | class once_flag; | | (since C++11) |

The class std::once_flag is a helper structure for std::call_once.

An object of type std::once_flag that is passed to multiple calls to std::call_once allows those calls to coordinate with each other such that only one of the calls will actually run to completion.

std::once_flag is neither copyable nor movable.

Contents

[edit] Member functions

std::once_flag::once_flag

| constexpr once_flag() noexcept; | | | | -------------------------------- | | |

Constructs an once_flag object. The internal state is set to indicate that no function has been called yet.

Parameters

(none)

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