std::experimental::observer_ptr

 

C++

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Feature test macros (C++20)

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Technical specifications

Symbols index

External libraries

 

Experimental

Technical Specification

Filesystem library (filesystem TS)

Library fundamentals (library fundamentals TS)

Library fundamentals 2 (library fundamentals TS v2)

Library fundamentals 3 (library fundamentals TS v3)

Extensions for parallelism (parallelism TS)

Extensions for parallelism 2 (parallelism TS v2)

Extensions for concurrency (concurrency TS)

Extensions for concurrency 2 (concurrency TS v2)

Concepts (concepts TS)

Ranges (ranges TS)

Reflection (reflection TS)

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Pattern Matching

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Library fundamentals v2

experimental::propagate_const

experimental::not_fn

experimental::observer_ptr

experimental::make_array

experimental::to_array

experimental::ostream_joiner

experimental::gcd

experimental::lcm

experimental::source_location

experimental::randint

detection idiom

uniform container erasure

logical operator type traits

 

std::experimental::observer_ptr

Member functions

observer_ptr::observer_ptr

Modifiers

observer_ptr::release

observer_ptr::reset

observer_ptr::swap

Observers

observer_ptr::get

observer_ptr::operator bool

observer_ptr::operator*observer_ptr::operator->

Conversions

observer_ptr::operator element_type*

Non-member functions

make_observer

operator==operator!=operator<operator>operator<=operator>operator>=

swap

std::hash

 

Defined in header <experimental/memory>
template< class W > class observer_ptr;		(library fundamentals TS v2)

std::experimental::observer_ptr is a non-owning pointer, or observer. The observer stores a pointer to a second object, known as the watched object. An observer_ptr may also have no watched object.

An observer is not responsible in any way for the watched object; there is no inherent relationship between an observer and the object it watches.

It is intended as a near drop-in replacement for raw pointer types, with the advantage that, as a vocabulary type, it indicates its intended use without need for detailed analysis by code readers.

Specializations of observer_ptr satisfy the requirements of CopyConstructible and CopyAssignable.

Type requirements

- W shall not be a reference type, but may be an incomplete type.

Member types

Member type	Definition
element_type	W, the type of the object watched by this observer_ptr

Member functions

(constructor)	constructs a new observer_ptr (public member function)
(destructor) (implicitly declared)	destructs an observer_ptr (public member function)
operator= (implicitly declared)	implicitly declared copy and move assignment operators that assign the stored pointer (public member function)
Modifiers
release	returns a pointer to the watched object and stops watching the object (public member function)
reset	replaces the watched object (public member function)
swap	swaps the watched objects (public member function)
Observers
get	returns a pointer to the watched object (public member function)
operator bool	checks if there is an associated watched object (public member function)
operator*operator->	dereferences pointer to the watched object (public member function)
Conversions
operator element_type*	explicit conversion function to the stored pointer (public member function)

Non-member functions

make_observer	creates an observer_ptr that watches an object (function template)
operator==operator!=operator<operator<=operator>operator>=	compares to another observer_ptr or with nullptr (function template)
std::experimental::swap(std::experimental::observer_ptr)	specializes the swap algorithm (function template)

Helper classes

std::hash<std::experimental::observer_ptr>

hash support for observer_ptr (class template specialization)

Example

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