#include <Corrade/Containers/Pointer.h>
template<class T>
Corrade::Containers::Pointer class

Lightweight unique pointer.

An alternative to std::unique_ptr from C++11, provides an owning move-only wrapper over a pointer of type T, calling delete on it on destruction. The pointer() convenience function also provides an equivalent for C++14 std::make_unique(), but on C++11 as well. Can be also thought of as a heap-allocated counterpart to Optional.

Compared to std::unique_ptr, this class does proper const propagation as would be expected from any other owning container like Array or String — i.e., it's only possible to mutate the owned data if the instance is not const. There's no STL functionality with such behavior except for the proposed std::indirect_value.

Unlike std::unique_ptr, this class does not provide custom deleters, doesn't work with arrays and doesn't have a constexpr API. On the other hand that makes it fairly simple and lightweight. If you need a custom deleter, use either ScopeGuard or the standard std::unique_ptr. For owning array wrappers use Array, which maintains a size information and also supports custom deleters.

STL compatibility

Instances of Pointer are implicitly move-convertible to and from std::unique_ptr if you include Corrade/Containers/PointerStl.h. The conversion is provided in a separate header to avoid unconditional #include <memory>, which significantly affects compile times. Additionally, the pointer(T&&) overload also allows for such a conversion. Example:

#include <Corrade/Containers/PointerStl.h>

…

std::unique_ptr<int> a{new int{5}};
Containers::Pointer<int> b = std::move(a);

std::unique_ptr<int> c = Containers::pointer<int>(12);

auto d = Containers::pointer(std::unique_ptr<int>{new int{5}});
        // d is Containers::Pointer<int>

Public types

using Type = T new in Git master
Value type.

Constructors, destructors, conversion operators

Pointer(std::nullptr_t = nullptr) noexcept
Default constructor.
Pointer(T* pointer) explicit noexcept
Construct a unique pointer by value.
template<class ... Args>
Pointer(Corrade::InPlaceInitT, Args && ... args) explicit
Construct a unique pointer in-place.
template<class U, class = typename std::enable_if<std::is_base_of<T, U>::value>::type>
Pointer(Pointer<U>&& other) noexcept
Construct a unique pointer from another of a derived type.
template<class U, class = decltype(Implementation::PointerConverter<T, U>::from(std::declval<U && >()))>
Pointer(U&& other) noexcept
Construct a unique pointer from external representation.
Pointer(const Pointer<T>&) deleted
Copying is not allowed.
Pointer(Pointer<T>&& other) noexcept
Move constructor.
template<class U, class = decltype(Implementation::PointerConverter<T, U>::to(std::declval<Pointer<T> && >()))>
operator U() &&
Convert the unique pointer to external representation.
~Pointer()
Destructor.
operator bool() const explicit
Whether the pointer is non-null.

Public functions

auto operator=(const Pointer<T>&) -> Pointer<T>& deleted
Copying is not allowed.
auto operator=(Pointer<T>&& other) -> Pointer<T>& noexcept
Move assignment.
auto operator==(std::nullptr_t) const -> bool
Equality comparison to a null pointer.
auto operator!=(std::nullptr_t) const -> bool
Non-equality comparison to a null pointer.
auto get() -> T*
Underlying pointer value.
auto get() const -> const T*
auto operator->() -> T*
Access the underlying pointer.
auto operator->() const -> const T*
auto operator*() -> T&
Access the underlying pointer.
auto operator*() const -> const T&
void reset(T* pointer = nullptr)
Reset the pointer to a new value.
template<class ... Args>
auto emplace(Args && ... args) -> T&
Emplace a new value.
template<class U, class ... Args>
auto emplace(Args && ... args) -> U& new in Git master
Emplace a new value of a derived type.
auto release() -> T*
Release the pointer ownership.

Function documentation

template<class T>
Corrade::Containers::Pointer<T>::Pointer(std::nullptr_t = nullptr) noexcept

Default constructor.

Creates a nullptr unique pointer.

template<class T>
Corrade::Containers::Pointer<T>::Pointer(T* pointer) explicit noexcept

Construct a unique pointer by value.

Takes ownership of the passed pointer.

template<class T> template<class ... Args>
Corrade::Containers::Pointer<T>::Pointer(Corrade::InPlaceInitT, Args && ... args) explicit

Construct a unique pointer in-place.

Allocates a new object by passing args to its constructor.

template<class T> template<class U, class = typename std::enable_if<std::is_base_of<T, U>::value>::type>
Corrade::Containers::Pointer<T>::Pointer(Pointer<U>&& other) noexcept

Construct a unique pointer from another of a derived type.

Expects that T is a base of U. For downcasting (base to derived) use pointerCast(). Calls release() on other.

template<class T> template<class U, class = decltype(Implementation::PointerConverter<T, U>::from(std::declval<U && >()))>
Corrade::Containers::Pointer<T>::Pointer(U&& other) noexcept

Construct a unique pointer from external representation.

template<class T> template<class U, class = decltype(Implementation::PointerConverter<T, U>::to(std::declval<Pointer<T> && >()))>
Corrade::Containers::Pointer<T>::operator U() &&

Convert the unique pointer to external representation.

template<class T>
Corrade::Containers::Pointer<T>::~Pointer()

Destructor.

Calls delete on the stored pointer.

template<class T>
Corrade::Containers::Pointer<T>::operator bool() const explicit

Whether the pointer is non-null.

Returns false if stored pointer is nullptr, true otherwise.

template<class T>
bool Corrade::Containers::Pointer<T>::operator==(std::nullptr_t) const

Equality comparison to a null pointer.

Returns true if the poiner is nullptr, false otherwise.

template<class T>
bool Corrade::Containers::Pointer<T>::operator!=(std::nullptr_t) const

Non-equality comparison to a null pointer.

Returns false if the pointer is nullptr, false otherwise.

template<class T>
T* Corrade::Containers::Pointer<T>::get()

Underlying pointer value.

template<class T>
const T* Corrade::Containers::Pointer<T>::get() const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<class T>
T* Corrade::Containers::Pointer<T>::operator->()

Access the underlying pointer.

Expects that the pointer is not nullptr.

template<class T>
const T* Corrade::Containers::Pointer<T>::operator->() const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<class T>
T& Corrade::Containers::Pointer<T>::operator*()

Access the underlying pointer.

Expects that the pointer is not nullptr.

template<class T>
const T& Corrade::Containers::Pointer<T>::operator*() const

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

template<class T>
void Corrade::Containers::Pointer<T>::reset(T* pointer = nullptr)

Reset the pointer to a new value.

Calls delete on the previously stored pointer and replaces it with pointer.

template<class T> template<class ... Args>
T& Corrade::Containers::Pointer<T>::emplace(Args && ... args)

Emplace a new value.

Calls delete on the previously stored pointer and allocates a new object by passing args to its constructor.

template<class T> template<class U, class ... Args>
U& Corrade::Containers::Pointer<T>::emplace(Args && ... args) new in Git master

Emplace a new value of a derived type.

Calls delete on the previously stored pointer and allocates a new object of type U by passing args to its constructor.

template<class T>
T* Corrade::Containers::Pointer<T>::release()

Release the pointer ownership.

Resets the stored pointer to nullptr, returning the previous value.

template<class T> template<class T>
bool operator==(std::nullptr_t, const Pointer<T>& b)

Equality comparison of a null pointer and an unique pointer.

See Pointer::operator==(std::nullptr_t) const for more information.

template<class T> template<class T>
bool operator!=(std::nullptr_t, const Pointer<T>& b)

Non-euality comparison of a null pointer and an unique pointer.

See Pointer::operator!=(std::nullptr_t) const for more information.

template<class T> template<class T>
Pointer<T> pointer(T* pointer)

Make a unique pointer.

Convenience alternative to Pointer::Pointer(T*). The following two lines are equivalent:

std::string* ptr = …;

auto a = Containers::Pointer<std::string>{ptr};
auto b = Containers::pointer(ptr);

template<class T> template<class T>
auto pointer(T&& other)

Make a unique pointer from external representation.

template<class T> template<class U, class T>
Pointer<U> pointerCast(Pointer<T>&& pointer)

Downcast a pointer.

While upcasting (derived to base) is handled implicitly with Pointer::Pointer(Pointer<U>&&), downcasting needs to be done explicitly. Performs static_cast<U>(), calling Pointer::release() on pointer. You have to ensure the pointer is actually of type U, as only the inheritance relation between T and U is checked at compile time, not the actual type stored in pointer.

Casting with dynamic_cast<U>() is not supported, as it would lead to a destructive behavior in case the instance is not of type U. The standard library provides std::dynamic_pointer_cast() and friends for this case, but they return a std::shared_ptr in order to behave non-destructively.

template<class T> template<class T, class ... Args>
Pointer<T> pointer(Args && ... args)

Make a unique pointer.

Convenience alternative to Pointer::Pointer(InPlaceInitT, Args&&... args), similar to std::make_unique() from C++14. The following two lines are equivalent:

auto a = Containers::Pointer<std::string>{InPlaceInit, 'a', 'b'};
auto b = Containers::pointer<std::string>('a', 'b');

template<class T> template<class T>
Utility::Debug& operator<<(Utility::Debug& debug, const Pointer<T>& value)

Debug output operator.