std::experi...al::emplace(3)

💅 NAME 💅

bestie, welcome to the std::experi...al::emplace page from the C++ Standard Libary manual 💖 this is your group-chat crash course, and yes we are keeping every detail.

std::experimental::optional::emplace — std::experimental::optional::emplace

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✨ Synopsis ✨

okay so here are the two overloads, and they are giving “in-place construction” energy:

template< class... Args >                                  (library
fundamentals TS)
void emplace( Args&&... args );
template< class U, class... Args >
void emplace( std::initializer_list<U> ilist, Args&&...    (library
fundamentals TS)
args );

So the vibe is: this constructs the contained value in-place. If *this already contains a value before the call, that contained value is destroyed by calling its destructor. no cap, it really said that.

1. Initializes the contained value by direct-initializing (but not direct-list-initializing) with std::forward<Args>(args)... as parameters.
2. Initializes the contained value by calling its constructor with ilist, std::forward<Args>(args)... as parameters. This overload participates in overload resolution only if std::is_constructible<T, std::initializer_list<U>&, Args&&...>::value is true.

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🌸 Parameters 🌸

• args... — the arguments to pass to the constructor
• ilist — the initializer list to pass to the constructor

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🦋 Type requirements 🦋

• T must be constructible from Args...
• T must be constructible from std::initializer_list and Args...

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🎀 Return value 🎀

(none) — literally nothing, bestie. it's giving void energy 💅

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💀 Exceptions 💀

Any exception thrown by the selected constructor of T. If an exception is thrown, *this does not contain a value after this call — and the previously contained value, if any, had been destroyed.

🫶 this is the important part: if it throws, the old value is already gone. not a drill.

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👑 See also 👑

• operator= — assigns contents (public member function)

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🍓 Category 🍓

• * Noindexed pages

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okay bye bestie, that’s the whole page — source/version: http://cppreference.com, date: 2024.06.10, page: std::experi...al::emplace(3). mwah 💋✨