std::atomic_init(3)

🌸 NAME 🌸

okay so bestie, this is std::atomic_init(3) from the C++ Standard Library — and yes, the manual name is literally std::atomic_init — std::atomic_init, iconic, no notes. 💅

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✨ Synopsis ✨

Defined in header <atomic>, and here’s the whole signature situation. Heads up: both overloads are (deprecated in C++20) 😭

Defined in header <atomic>
template< class T >
void atomic_init( std::atomic<T>* obj,
                  typename std::atomic<T>::value_type desired ) noexcept;

template< class T >
void atomic_init( volatile std::atomic<T>* obj,
                  typename std::atomic<T>::value_type desired ) noexcept;

• (1) — the std::atomic<T>* obj overload; it’s (since C++11) and (deprecated in C++20).
• (2) — the volatile std::atomic<T>* obj overload; also (since C++11) and (deprecated in C++20).

So what does it do? It initializes the default-constructed atomic object obj with the value desired. Slay. ✨

🚨 This function is not atomic. Concurrent access from another thread — even through an atomic operation — is a data race. Not a cute look, bestie. And if obj was not default-constructed, or if this function is called twice on the same obj, the behavior is undefined. Like, actually undefined. 🙈

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🦋 Parameters 🦋

• obj — pointer to an atomic object to initialize.
• desired — the value to initialize atomic object with.

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🎀 Return value 🎀

• (none) — literally nothing comes back. 💖

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🌈 Notes 🌈

This function is provided for compatibility with C. If that compatibility is not required, std::atomic may be initialized through their non-default constructors. iykyk. 🫶

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🧚 Example 🧚

This section is incomplete Reason: no example

not me crying at the missing example 😭

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💀 Defect reports 💀

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

• DR: P0558R1
• Applied to: C++11
• Behavior as published: exact type match was required because T is only deduced from obj
• Correct behavior: T was deduced from multiple arguments

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👑 See also 👑

• ATOMIC_VAR_INIT — constant initialization of an atomic variable of static storage duration. It’s a function macro, (C++11), (deprecated in C++20).
• constructor — constructs an atomic object; it’s a public member function of std::atomic<T>.
• C documentation for atomic_init — yes, C has its own docs for this one.

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🍓 Category 🍓

• * Todo no example

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Kisses and good vibes, your C++ bestie 💖 — source/version: http://cppreference.com, date: 2024.06.10, manual page: std::atomic_init(3). Periodt. 🌟