std::experimental:: scope_fail

Defined in header <experimental/scope>
template < class EF > class scope_fail ;		(library fundamentals TS v3)

The class template scope_fail is a general-purpose scope guard intended to call its exit function when a scope is exited via an exception.

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

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

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

A scope_fail effectively holds an EF and a bool flag indicating if it is active, alongwith a counter of uncaught exceptions used for detecting whether the destructor is called during stack unwinding.

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_fail (public member function)
(destructor)	calls the exit function when the scope is exited via an exception if the scope_fail is active, then destroys the scope_fail (public member function)
operator= [deleted]	scope_fail is not assignable (public member function)
Modifiers
release	makes the scope_fail inactive (public member function)

Deduction guides

Notes

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

Constructing a scope_fail is constructed from another scope_fail created in a different thread might also lead to unexpected behavior since the count of uncaught exceptions obtained in different threads may be compared during the destruction.

Example

This section is incomplete Reason: no example

See also

scope_exit	wraps a function object and invokes it on exiting the scope (class template)
scope_success	wraps a function object and invokes it on exiting the scope normally (class template)
default_delete (C++11)	default deleter for unique_ptr (class template)