std::once_flag(3)

💖 std::once_flag(3) 💖

okay bestie, welcome to the std::once_flag page — it lives in the Library Functions Manual and it's literally just a flag type, but it's a flag type that matters, so let's get into it 🎀

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✨ NAME ✨

std::once_flag — the flag type that std::call_once uses. that's it, that's the whole job, and she does it flawlessly 💅

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🌸 SYNOPSIS 🌸

#include <mutex>

🦋 Public Member Functions

• once_flag(const once_flag &) = delete — deleted copy constructor. no copies, bestie, she's one of a kind 👑
• once_flag &operator=(const once_flag &) = delete — deleted assignment operator. and no reassigning either. she does not do hand-me-downs 💀

🫶 Friends

• template<typename _Callable, typename... _Args> void call_once(once_flag &__once, _Callable &&__f, _Args &&... __args) — invokes a callable and syncs up with every other call that's using the same flag. it's giving coordinated group chat energy ✨

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🌈 Detailed Description 🌈

Flag type used by std::call_once.

lowkey that's the entire description and honestly? iconic. she's a flag, she's used by std::call_once, she contains multitudes 🎀

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🧚 Constructor & Destructor Documentation 🧚

std::once_flag::once_flag(const once_flag &) [delete]

Deleted copy constructor.

you cannot copy her. periodt. the compiler will simply say no and you will simply have to deal with that 😭

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⭐ Member Function Documentation ⭐

once_flag &std::once_flag::operator=(const once_flag &) [delete]

Deleted assignment operator.

you also cannot assign to her. no takebacks, no swapsies, no nothing. she's immutable in spirit and also literally, fr fr 💅

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💜 Friends And Related Symbol Documentation 💜

template<typename _Callable, typename... _Args> void call_once(once_flag &__once, _Callable &&__f, _Args &&... __args) [friend]

Invoke a callable and synchronize with other calls using the same flag.

References std::__invoke(), and std::forward(). those two are doing the heavy lifting behind the scenes and we love them for it 🫶

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👑 Author 👑

Generated automatically by Doxygen for libstdc++ from the source code.

so like, nobody wrote this, a robot did, and honestly? she ate 🤖✨

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bestie reminder: this whole page is libstdc++ business, and it's page std::once_flag(3) — the flag that makes std::call_once behave. treat her with respect 🎀💖