std::expected::value_or(3)

🌸 NAME 🌸

std::expected::value_or — okay bestie, the name is literally std::expected::value_or, and this is the C++ Standard Libary manual page for std::expected::value_or(3) (yes, “Libary” is spelled like that in the source, no cap). It’s giving “fallback value when your expected doesn’t have the goods” energy. 🫶

✨ Synopsis ✨

template< class U >                               (1) (since C++23)
constexpr T value_or( U&& default_value ) const&;
template< class U >                               (2) (since C++23)
constexpr T value_or( U&& default_value ) &&;

Returns the contained value if *this contains an expected value, otherwise returns default_value. Slay. 💅

1. Returns bool(*this) ? **this : static_cast<T>(std::forward<U>(default_value))
2. Returns bool(*this) ? std::move(**this) : static_cast<T>(std::forward<U>(default_value))

🎀 Parameters 🎀

• default_value — the value to use in case *this does not contain an expected value. That’s your fallback bestie, the one who shows up when the value doesn’t. 💖

🧚 Type requirements 🧚

• T must meet the requirements of CopyConstructible in order to use overload (1).
• T must meet the requirements of MoveConstructible in order to use overload (2).
• U&& must be convertible to T.

🌈 Return value 🌈

The currently contained value if *this contains an expected value, or default_value otherwise. That’s it, that’s the tea. ☕

🔥 Exceptions 🔥

Any exception thrown by the selected constructor of the return value T. So yeah, if T’s constructor decides to throw, that energy comes straight through. 😭

💅 Notes 💅

If T is (possibly cv-qualified) void, this member is not declared. Periodt. 🫶

💀 Example 💀

This section is incomplete.

Reason: no example.

👀 See also 👀

• value — returns the expected value (public member function). lowkey the main character version of this. ✨

🏷️ Category 🏷️

• Todo no example

made with 💖 by http://cppreference.com — 2024.06.10 💅