Stores a pointer to a potentially shared object. More...

Inheritance diagram for QSharedPointer< T >:

Public Typedefs
using	element_type = typename std::shared_ptr< T >::element_type

using	ElementType = element_type

using	pointer = element_type *

using	Pointer = pointer

using	weak_type = QWeakPointer< T >

using	WeakType = weak_type

Public Methods
constexpr	QSharedPointer () noexcept

	QSharedPointer (const QSharedPointer< T > &other) = default

template<typename U >
	QSharedPointer (const QSharedPointer< U > &p) noexcept

template<typename U >
	QSharedPointer (const QSharedPointer< U > &p1, element_type *p2) noexcept

template<typename U >
	QSharedPointer (const QWeakPointer< U > &p)

template<typename U >
	QSharedPointer (const std::shared_ptr< U > &p) noexcept

	QSharedPointer (QSharedPointer< T > &&other) = default

template<typename U >
	QSharedPointer (QSharedPointer< U > &&p) noexcept

template<typename U >
	QSharedPointer (QSharedPointer< U > &&p1, element_type *p2) noexcept

template<typename U , typename Deleter >
	QSharedPointer (QUniquePointer< U, Deleter > &&p)

constexpr	QSharedPointer (std::nullptr_t) noexcept

template<typename Deleter >
	QSharedPointer (std::nullptr_t, Deleter d)

template<typename Deleter , typename Alloc >
	QSharedPointer (std::nullptr_t, Deleter d, Alloc a)

template<typename U >
	QSharedPointer (std::shared_ptr< U > &&p) noexcept

template<typename U >
	QSharedPointer (U *p)

template<typename U , typename Deleter >
	QSharedPointer (U *p, Deleter d)

template<typename U , typename Deleter , typename Alloc >
	QSharedPointer (U *p, Deleter d, Alloc a)

	~QSharedPointer ()

void	clear ()

template<typename U >
QSharedPointer< U >	constCast () const

QSharedPointer< T >	create (Args &&...args)

T *	data () const

template<typename U >
QSharedPointer< U >	dynamicCast () const

bool	isNull () const

template<typename U >
QSharedPointer< U >	objectCast () const

	operator bool () const

bool	operator! () const

bool	operator!= (const QSharedPointer< T > &other) const

bool	operator!= (const T *ptr) const

bool	operator!= (std::nullptr_t) const

T &	operator* () const

T *	operator-> () const

bool	operator< (const QSharedPointer< T > &other) const

bool	operator< (const T *ptr) const

bool	operator< (std::nullptr_t) const

bool	operator<= (const QSharedPointer< T > &other) const

bool	operator<= (const T *ptr) const

bool	operator<= (std::nullptr_t) const

QSharedPointer &	operator= (const QSharedPointer< T > &other) = default

template<typename U >
QSharedPointer &	operator= (const QSharedPointer< U > &p) noexcept

template<typename U >
QSharedPointer &	operator= (const QWeakPointer< U > &p)

QSharedPointer &	operator= (QSharedPointer< T > &&other) = default

template<typename U >
QSharedPointer &	operator= (QSharedPointer< U > &&p) noexcept

bool	operator== (const QSharedPointer< T > &other) const

bool	operator== (const T *ptr) const

bool	operator== (std::nullptr_t) const

bool	operator> (const QSharedPointer< T > &other) const

bool	operator> (const T *ptr) const

bool	operator> (std::nullptr_t) const

bool	operator>= (const QSharedPointer< T > &other) const

bool	operator>= (const T *ptr) const

bool	operator>= (std::nullptr_t) const

void	reset ()

void	reset (U *value)

void	reset (U *value, Deleter d)

void	reset (U *value, Deleter d, Alloc a)

template<typename U >
QSharedPointer< U >	staticCast () const

void	swap (QSharedPointer &other)

QWeakPointer< T >	toWeakRef () const

long	use_count () const noexcept

Related Functions
These are not member functions
QSharedPointer< T >	QMakeShared (Args &&...args)

QSharedPointer< U >	qSharedPointerConstCast (const QSharedPointer< T > &other)

QSharedPointer< U >	qSharedPointerDynamicCast (const QSharedPointer< T > &other)

QSharedPointer< U >	qSharedPointerObjectCast (const QSharedPointer< T > &other)

QSharedPointer< U >	qSharedPointerStaticCast (const QSharedPointer< T > &other)

Detailed Description

template<typename T>
class QSharedPointer< T >

The QSharedPointer class stores a pointer to a potentially shared object. This class maintains a shared reference count which indicates how many shared pointers are pointing to the current object. Any pointer class which takes responsibility for the lifetime of the object it points to is considered a smart pointer.

A QSharedPointer can be constructed from a raw pointer, another QSharedPointer, or by a QWeakPointer. When a QSharedPointer is destroyed the object it points to will be deleted if no other shared pointers are pointing to the given object.

Thread Safety

QSharedPointer and QWeakPointer are thread safe which means the internal pointer is updated atomically. Different threads can access the QSharedPointer or QWeakPointer pointing to the same object at the same time without a locking mechanism. While this shared pointer class is thread safe it can not provide a guarantee about the object it points to.

See also: QScopedPointer, QScopedArrayPointer, QSharedArrayPointer, QSharedDataPointer, QWeakPointer

Member Typedef Documentation

template<typename T >

QSharedPointer< T >::element_type

Typedef for std::shared_ptr<T>::element_type.

template<typename T >

QSharedPointer< T >::ElementType

Typedef for element_type.

template<typename T >

QSharedPointer< T >::pointer

Typedef for element_type *.

template<typename T >

QSharedPointer< T >::Pointer

Typedef for pointer.

template<typename T >

QSharedPointer< T >::weak_type

Typedef for QWeakPointer<T>.

template<typename T >

QSharedPointer< T >::WeakType

Typedef for weak_type.

Constructor & Destructor Documentation

template<typename T >

constexpr QSharedPointer< T >::QSharedPointer ( )

constexprnoexcept

Creates a new QSharedPointer which contains a nullptr.

template<typename T >

constexpr QSharedPointer< T >::QSharedPointer ( std::nullptr_t )

constexprnoexcept

Creates a new QSharedPointer which contains a nullptr.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer ( U * p )

explicit

Creates a new QSharedPointer which points to p. Ownership of the object is transferred to the new QSharedPointer.

template<typename T >

template<typename U , typename Deleter >

QSharedPointer< T >::QSharedPointer	(	U *	p,
		Deleter	d
	)

Creates a new QSharedPointer which points to the given raw pointer p. Ownership of the object is transferred to the new QSharedPointer. The value for d is a deleter object and will be used when QSharedPointer is being destroyed.

template<typename T >

template<typename Deleter >

QSharedPointer< T >::QSharedPointer	(	std::nullptr_t	,
		Deleter	d
	)

Creates a new QSharedPointer which contains a nullptr. The value for d is a deleter object and will be used when QSharedPointer is being destroyed.

template<typename T >

template<typename U , typename Deleter , typename Alloc >

QSharedPointer< T >::QSharedPointer	(	U *	p,
		Deleter	d,
		Alloc	a
	)

Creates a new QSharedPointer which points to p. Ownership of the object is transferred to the new QSharedPointer. The value for d is a deleter object and will be used when QSharedPointer is being destroyed. The value for a is an allocator object and will be used when QSharedPointer needs to allocate memory.

template<typename T >

template<typename Deleter , typename Alloc >

QSharedPointer< T >::QSharedPointer	(	std::nullptr_t	,
		Deleter	d,
		Alloc	a
	)

Creates a new QSharedPointer which contains a nullptr. The value for d is a deleter object and will be used when QSharedPointer is being destroyed. The value for a is an allocator object and will be used when QSharedPointer needs to allocate memory.

template<typename T >

template<typename U , typename Deleter >

QSharedPointer< T >::QSharedPointer ( QUniquePointer< U, Deleter > && p )

Creates a new QSharedPointer using the given unique pointer p. The unique pointer will be set to a nullptr.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer ( const std::shared_ptr & p )

noexcept

Creates a new QSharedPointer using the given C++ Standard Library shared pointer p.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer ( std::shared_ptr && p )

noexcept

Creates a new QSharedPointer by moving from the given C++ Standard Library shared pointer p.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer	(	const QSharedPointer< U > &	p1,
		element_type *	p2
	)

noexcept

Creates a new QSharedPointer which points to p2 and used the reference count from p1.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer	(	QSharedPointer< U > &&	p1,
		element_type *	p2
	)

noexcept

Creates a new QSharedPointer which points to p2 and used the reference count from p1.

template<typename T >

QSharedPointer< T >::~QSharedPointer ( )

Destroys this QSharedPointer.

If the current QSharedPointer is not a nullptr, then the internal reference count is decremented. If the reference count is zero then the object it is pointing to will be destroyed.

template<typename T >

QSharedPointer< T >::QSharedPointer ( const QSharedPointer< T > & other )

default

Copy constructs a new QSharedPointer from other. The current shared pointer shares ownership with other.

template<typename T >

QSharedPointer< T >::QSharedPointer ( QSharedPointer< T > && other )

default

Move constructs a new QSharedPointer from other.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer ( const QSharedPointer & p )

noexcept

Copy constructs a new QSharedPointer from p. This shared pointer shares ownership with other. The template parameter U must inherit from T.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer ( QSharedPointer && p )

noexcept

Creates a QSharedPointer which shares ownership with p. The template parameter U must inherit from T.

template<typename T >

template<typename U >

QSharedPointer< T >::QSharedPointer ( const QWeakPointer & p )

explicit

Creates a QSharedPointer by converting the weak pointer p to a shared pointer. The template parameter U must inherit from T.

See also: QWeakPointer::toStrongRef()

Method Documentation

template<typename T >

void QSharedPointer< T >::clear ( )

Set the current QSharedPointer to a nullptr.

If the current QSharedPointer is not a nullptr, then the internal reference count is decremented. If the reference count is zero then the object it is pointing to will be destroyed.

template<typename T >

template<typename U >

QSharedPointer QSharedPointer< T >::constCast ( ) const

Returns a QSharedPointer to the current object. The shared pointer is cast from type T to type U using a const_cast.

See also: dynamicCast(), staticCast()

template<typename T >

QSharedPointer< T > QSharedPointer< T >::create ( Args &&... args )

Creates a new QSharedPointer pointing to a new object of type T. This method can be more efficient than calling new to create the object and using the constructor which accepts a raw pointer.

int arg1  = 5;
bool arg2 = true;
 
// preferred
QSharedPointer<T> ptrA = QSharedPointer<T>::create(arg1, arg2);
 
// equiveleant, usually slower
T *rawPtr = new T(arg1, arg2);
QSharedPointer<T> ptrB(rawPtr);

template<typename T >

T * QSharedPointer< T >::data ( ) const

Returns the value of the pointer referenced by this object.

Note: Do not delete the object pointed to by the raw pointer returned by this method. This will cause undefined behavior.

template<typename T >

template<typename U >

QSharedPointer QSharedPointer< T >::dynamicCast ( ) const

Returns a QSharedPointer to the current object. The returned shared pointer is cast from type T to type U using a dynamic_cast. If the cast fails this method will return a nullptr.

The U must have the same cv-qualifiers (const and volatile) that T has. If you need to cast away either of these qualifiers then use constCast().

See also: constCast(), staticCast()

template<typename T >

bool QSharedPointer< T >::isNull ( ) const

Returns true if the current QSharedPointer contains a nullptr.

template<typename T >

template<typename U >

QSharedPointer QSharedPointer< T >::objectCast ( ) const

Equivalent to calling dynamicCast().

template<typename T >

QSharedPointer< T >::operator bool ( ) const

Returns true if the current QSharedPointer is not a nullptr. This method is called when a shared pointer is used in an "if statement" or another context where a boolean value is expected. Since this method is explicit it is not possible to assign a QSharedPointer to a boolean.

// example 1
if (mySharedPtr) {
   // ...
}
 
// example 2
bool isTest_A = mySharedPtr;                    // will *not* compile
 
bool isTest_B = (mySharedPtr != nullptr);       // compiles, valid code
 
bool isTest_C = bool(mySharedPtr);              // compiles, valid code

template<typename T >

bool QSharedPointer< T >::operator! ( ) const

Returns true if this object is a nullptr. This method is called when a shared pointer is used in an "if statement" or another context where a boolean value is expected.

if (! mySharedPtr) {
   // ...
}

See also: operator bool()

template<typename T >

bool QSharedPointer< T >::operator!= ( const QSharedPointer< T > & other ) const

Returns true if this QSharedPointer is not equal to other, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator!= ( const T * ptr ) const

Returns true if this QSharedPointer is not equal to ptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator!= ( std::nullptr_t ) const

Returns true if this QSharedPointer is not equal to a nullptr, otherwise returns false.

template<typename T >

T & QSharedPointer< T >::operator* ( ) const

Returns a reference to the object the current QSharedPointer is pointing to.

template<typename T >

T * QSharedPointer< T >::operator-> ( ) const

Returns a pointer to the object the current QSharedPointer is pointing to.

template<typename T >

bool QSharedPointer< T >::operator< ( const QSharedPointer< T > & other ) const

Returns true if this QSharedPointer is less than other, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator< ( const T * ptr ) const

Returns true if this QSharedPointer is less than ptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator< ( std::nullptr_t ) const

Returns true if this QSharedPointer is less than a nullptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator<= ( const QSharedPointer< T > & other ) const

Returns true if this QSharedPointer is less than or equal to other, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator<= ( const T * ptr ) const

Returns true if this QSharedPointer is less than or equal to ptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator<= ( std::nullptr_t ) const

Returns true if this QSharedPointer is less than or equal to a nullptr, otherwise returns false.

template<typename T >

QSharedPointer & QSharedPointer< T >::operator= ( const QSharedPointer< T > & other )

default

Copy assigns from other and returns a reference to this object.

If the current QSharedPointer is not a nullptr, then the internal reference count is decremented. If the reference count is zero then the object it is pointing to will be destroyed.

template<typename T >

template<typename U >

QSharedPointer & QSharedPointer< T >::operator= ( const QSharedPointer & p )

noexcept

Copy assigns from p and returns a reference to this object. The template parameter U must inherit from T.

If the current QSharedPointer is not a nullptr, then the internal reference count is decremented. If the reference count is zero then the object it is pointing to will be destroyed.

template<typename T >

template<typename U >

QSharedPointer & QSharedPointer< T >::operator= ( const QWeakPointer & p )

Converts the weak pointer p to a shared pointer and then assigns it to the current QSharedPointer. The template parameter U must inherit from T.

If the current QSharedPointer is not a nullptr, then the internal reference count is decremented. If the reference count is zero then the object it is pointing to will be destroyed.

template<typename T >

QSharedPointer & QSharedPointer< T >::operator= ( QSharedPointer< T > && other )

default

Move assigns from other and returns a reference to this object.

If the current QSharedPointer is not a nullptr, then the internal reference count is decremented. If the reference count is zero then the object it is pointing to will be destroyed.

template<typename T >

template<typename U >

QSharedPointer & QSharedPointer< T >::operator= ( QSharedPointer && p )

noexcept

Copy assigns from p and returns a reference to this object. The template parameter U must inherit from T.

If the current QSharedPointer is not a nullptr, then the internal reference count is decremented. If the reference count is zero then the object it is pointing to will be destroyed.

template<typename T >

bool QSharedPointer< T >::operator== ( const QSharedPointer< T > & other ) const

Returns true if this QSharedPointer is equal to other, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator== ( const T * ptr ) const

Returns true if this QSharedPointer is equal to ptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator== ( std::nullptr_t ) const

Returns true if this QSharedPointer is equal to a nullptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator> ( const QSharedPointer< T > & other ) const

Returns true if this QSharedPointer is greater than other, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator> ( const T * ptr ) const

Returns true if this QSharedPointer is reater than ptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator> ( std::nullptr_t ) const

Returns true if this QSharedPointer is greater than a nullptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator>= ( const QSharedPointer< T > & other ) const

Returns true if this QSharedPointer is greater than or equal to other, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator>= ( const T * ptr ) const

Returns true if this QSharedPointer is greater than or equal to ptr, otherwise returns false.

template<typename T >

bool QSharedPointer< T >::operator>= ( std::nullptr_t ) const

Returns true if this QSharedPointer is greater or equal to a nullptr, otherwise returns false.

template<typename T >

void QSharedPointer< T >::reset ( )

Equivalent to calling clear().

template<typename T >

void QSharedPointer< T >::reset ( U * value )

Resets the current QSharedPointer object to point to value. The template parameter U must inherit from T.

template<typename T >

void QSharedPointer< T >::reset	(	U *	value,
		Deleter	d
	)

Resets the current QSharedPointer object to point to value and updates the Deleter to d. The template parameter U must inherit from T.

template<typename T >

void QSharedPointer< T >::reset	(	U *	value,
		Deleter	d,
		Alloc	a
	)

Resets the current QSharedPointer object to point to value and updates the Deleter to d. The value for a is an allocator object and will be used when QSharedPointer needs to allocate memory. The template parameter U must inherit from T.

template<typename T >

template<typename U >

QSharedPointer QSharedPointer< T >::staticCast ( ) const

Returns a QSharedPointer to the current object. The returned shared pointer is cast from type T to type U using a static_cast.

See also: constCast(), dynamicCast()

template<typename T >

void QSharedPointer< T >::swap ( QSharedPointer< T > & other )

Swaps the current QSharedPointer with other. This method is very fast and never fails.

template<typename T >

QWeakPointer< T > QSharedPointer< T >::toWeakRef ( ) const

Returns a QWeakPointer which shares the internal reference count with the current QSharedPointer.

template<typename T >

long QSharedPointer< T >::use_count ( ) const

noexcept

Returns the reference count for the current QSharedPointer.

Friends And Related Function Documentation

QSharedPointer< T > QMakeShared ( Args &&... args )

QSharedPointer<MyFileClass> filePtr = QMakeShared<MyFileClass>( myFileName.path() );

QSharedPointer qSharedPointerConstCast ( const QSharedPointer< T > & other )

QSharedPointer qSharedPointerDynamicCast ( const QSharedPointer< T > & other )

QSharedPointer qSharedPointerObjectCast ( const QSharedPointer< T > & other )

QSharedPointer qSharedPointerStaticCast ( const QSharedPointer< T > & other )

Public Typedefs

Public Methods

Related Functions

Detailed Description

template<typename T> class QSharedPointer< T >

Thread Safety

Member Typedef Documentation

Constructor & Destructor Documentation

Method Documentation

Friends And Related Function Documentation

template<typename T>
class QSharedPointer< T >