std::barrier::barrier(3)

💖 std::barrier::barrier(3) 💖

okay so we’re in the C++ Standard Libary manual, section 3, and this page is literally all about std::barrier::barrier. Bestie, it’s giving constructor lore, and we are keeping every single detail, fr fr. ✨

🌸 NAME 🌸

std::barrier::barrier — and yes, the name line is std::barrier::barrier - std::barrier::barrier. No cap, that’s the whole vibe. 💅

✨ Synopsis ✨

Here’s the synopsis, bestie:

(1) (since C++20)
constexpr explicit barrier( std::ptrdiff_t expected,
                            CompletionFunction f = CompletionFunction());

(2) (since C++20)
barrier( const barrier& ) = delete;

1. Constructor (1) sets both the initial expected count for each phase and the current expected count for the first phase to expected. It initializes the completion function object with std::move(f), and then starts the first phase. The behavior is undefined if expected is negative or greater than max(). 😭
2. Constructor (2) is the copy constructor, and it is deleted. barrier is neither copyable nor movable. Periodt. 🫶

🎀 Parameters 🎀

• expected — initial value of the expected count. 💖
• f — completion function object to be called on phase completion step. 🌟

🔥 Exceptions 🔥

1. Constructor (1) can throw any exception thrown by CompletionFunction's move constructor. 😭

🦋 Notes 🦋

expected is permitted to be zero. However, calling any non-static member function other than the destructor on such barrier results in undefined behavior. In other words, such barrier can only be destroyed. 💀

⚠️ Warning, bestie: zero is allowed, but a zero-expected barrier is basically “look, don’t touch” — only the destructor is safe. No cap. 🙈

source/version/date check: http://cppreference.com • 2024.06.10 • std::barrier::barrier(3) slay and goodbye 💖✨