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std::experimental::scope_success

From cppreference.com
Defined in header <experimental/scope>
template<class EF>
class scope_success;
(library fundamentals TS v3)

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

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

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

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

A scope_success 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.

Contents

[edit] 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.

[edit] Member functions

constructs a new scope_success
(public member function) [edit]
calls the exit function when the scope is exited normally if the scope_success is active, then destroys the scope_success
(public member function) [edit]
operator=
[deleted]
scope_success is not assignable
(public member function)
Modifiers
makes the scope_success inactive
(public member function) [edit]

[edit] Deduction guides

[edit] Notes

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

Constructing a scope_success is constructed from another scope_success 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.

If the EF stored in a scope_success 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_success's destructor executes, calling the exit function. This can lead to surprising behavior.

[edit] Example

[edit] See also

wraps a function object and invokes it on exiting the scope
(class template) [edit]
wraps a function object and invokes it on exiting the scope through an exception
(class template) [edit]
default deleter for unique_ptr
(class template) [edit]