std::once_flag

 

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Defined in header <mutex>
class once_flag;		(since C++11)

The class std::once_flag is a helper structure passed to std::call_once to group invocations of that function so that only one invocation results in execution of one of the functions passed to std::call_once.

Noncopyable.

Member functions

std::once_flag::once_flag

once_flag();

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

Parameters

(none)

Exceptions

noexcept specification:  

noexcept

  (since C++11)

See also

call_once (C++11)	invokes a function only once even if called from multiple threads (function template)