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:
Calling an lvalue of std::remove_reference_t<EF> with no argument shall be well-formed.

Member functions

constructs a new scope_fail
(public member function)
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)
scope_fail is not assignable
(public member function)
makes the scope_fail inactive
(public member function)

Deduction guides


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.


See also

wraps a function object and invokes it on exiting the scope
(class template)
wraps a function object and invokes it on exiting the scope normally
(class template)
default deleter for unique_ptr
(class template)