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)
calls the exit function when the scope is exited if the scope_exit is
destructor 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

wraps a function object and invokes it on exiting the scope through
scope_fail 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)