std::experi...::scope_exit(3)

💖 std::experimental::scope_exit 💖

Okay bestie, this is the std::experi...::scope_exit(3) page from the C++ Standard Libary (that's how the header spells it, keeping the lore 💀) — and it's giving tiny scope guard with main character energy ✨.

🌸 NAME 🌸

std::experimental::scope_exit — std::experimental::scope_exit

✨ Synopsis ✨

Defined in header <experimental/scope>.

template< class EF >                    (library fundamentals TS v3)
class scope_exit;

The class template scope_exit is a general-purpose scope guard intended to call its exit function when a scope is exited. 🫶

scope_exit is not CopyConstructible, CopyAssignable or MoveAssignable, however, it may be MoveConstructible if EF meets some requirements, which permits wrapping a scope_exit into another object. 💅

A scope_exit may be either active, i.e. calls its exit function on destruction, or inactive, i.e. does nothing on destruction. A scope_exit is active after constructed from an exit function. ✨

A scope_exit can become inactive by calling release() on it either manually or automatically (by the move constructor). An inactive scope_exit may also be obtained by initializing with another inactive scope_exit. Once a scope_exit is inactive, it cannot become active again. 🎀

A scope_exit effectively holds an EF and a bool flag indicating if it is active. 👑

🦋 Template parameters 🦋

• EF — type of stored exit function

🌈 Type requirements 🌈

• EF shall be either:
  • a Destructible FunctionObject type,
  • an lvalue reference to FunctionObject,
  • an lvalue reference to function.
• Calling an lvalue of std::remove_reference_t<EF> with no argument shall be well-formed.

🎀 Member functions 🎀

• constructor — constructs a new scope_exit (public member function)
• destructor — calls the exit function when the scope is exited if the scope_exit is active, then destroys the scope_exit (public member function)
• operator= — scope_exit is not assignable [deleted] (public member function)

💜 Modifiers 💜

• release — makes the scope_exit inactive (public member function)

🧚 Deduction guides 🧚

🔥 Notes 🔥

Constructing a scope_exit of dynamic storage duration might lead to unexpected behavior.

If the EF stored in a scope_exit object refers to a local variable of the function where it is defined, e.g., as a lambda capturing the variable by reference, and that variable is used as a return operand in that function, that variable might have already been returned when the scope_exit's destructor executes, calling the exit function. This can lead to surprising behavior. 😭

🍓 Example 🍓

This section is incomplete Reason: no example

⭐ See also ⭐

• scope_fail — wraps a function object and invokes it on exiting the scope through an exception (class template)
• scope_success — wraps a function object and invokes it on exiting the scope normally (class template)
• default_delete — default deleter for unique_ptr (C++11) (class template)

🦋 Category 🦋

• Todo no example

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And that's the whole page, bestie! 🫶 Source: http://cppreference.com, version/date: 2024.06.10, page: std::experi...::scope_exit(3). Periodt. 💅