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WeakReference< ObjectType, ReferenceCountingType > Class Template Reference

This class acts as a pointer which will automatically become null if the object to which it points is deleted. More...

Classes

class  Master
 This class is embedded inside an object to which you want to attach WeakReference pointers. More...
 
class  SharedPointer
 This class is used internally by the WeakReference class - don't use it directly in your code! More...
 

Public Types

typedef ReferenceCountedObjectPtr< SharedPointerSharedRef
 

Public Member Functions

 WeakReference () noexcept
 Creates a null SafePointer. More...
 
 WeakReference (ObjectType *object)
 Creates a WeakReference that points at the given object. More...
 
 WeakReference (const WeakReference &other) noexcept
 Creates a copy of another WeakReference. More...
 
 WeakReference (WeakReference &&other) noexcept
 Move constructor. More...
 
WeakReferenceoperator= (const WeakReference &other)
 Copies another pointer to this one. More...
 
WeakReferenceoperator= (ObjectType *newObject)
 Copies another pointer to this one. More...
 
WeakReferenceoperator= (WeakReference &&other) noexcept
 Move assignment operator. More...
 
ObjectType * get () const noexcept
 Returns the object that this pointer refers to, or null if the object no longer exists. More...
 
 operator ObjectType * () const noexcept
 Returns the object that this pointer refers to, or null if the object no longer exists. More...
 
ObjectType * operator-> () noexcept
 Returns the object that this pointer refers to, or null if the object no longer exists. More...
 
const ObjectType * operator-> () const noexcept
 Returns the object that this pointer refers to, or null if the object no longer exists. More...
 
bool wasObjectDeleted () const noexcept
 This returns true if this reference has been pointing at an object, but that object has since been deleted. More...
 
bool operator== (ObjectType *object) const noexcept
 
bool operator!= (ObjectType *object) const noexcept
 

Detailed Description

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
class WeakReference< ObjectType, ReferenceCountingType >

This class acts as a pointer which will automatically become null if the object to which it points is deleted.

To accomplish this, the source object needs to cooperate by performing a couple of simple tasks. It must embed a WeakReference::Master object, which stores a shared pointer object, and must clear this master pointer in its destructor.

E.g.

class MyObject
{
public:
MyObject()
{
// If you're planning on using your WeakReferences in a multi-threaded situation, you may choose
// to create a WeakReference to the object here in the constructor, which will pre-initialise the
// embedded object, avoiding an (extremely unlikely) race condition that could occur if multiple
// threads overlap while creating the first WeakReference to it.
}
~MyObject()
{
// This will zero all the references - you need to call this in your destructor.
masterReference.clear();
}
private:
// You need to embed a variable of this type, with the name "masterReference" inside your object. If the
// variable is not public, you should make your class a friend of WeakReference<MyObject> so that the
// WeakReference class can access it.
friend class WeakReference<MyObject>;
};
OR: just use the handy JUCE_DECLARE_WEAK_REFERENCEABLE macro to do all this for you.
// Here's an example of using a pointer..
MyObject* n = new MyObject();
WeakReference<MyObject> myObjectRef = n;
MyObject* pointer1 = myObjectRef; // returns a valid pointer to 'n'
delete n;
MyObject* pointer2 = myObjectRef; // returns a null pointer
See also
WeakReference::Master

Member Typedef Documentation

◆ SharedRef

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
typedef ReferenceCountedObjectPtr<SharedPointer> WeakReference< ObjectType, ReferenceCountingType >::SharedRef

Constructor & Destructor Documentation

◆ WeakReference() [1/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( )
noexcept

Creates a null SafePointer.

◆ WeakReference() [2/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( ObjectType *  object)

Creates a WeakReference that points at the given object.

◆ WeakReference() [3/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( const WeakReference< ObjectType, ReferenceCountingType > &  other)
noexcept

Creates a copy of another WeakReference.

◆ WeakReference() [4/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( WeakReference< ObjectType, ReferenceCountingType > &&  other)
noexcept

Move constructor.

Member Function Documentation

◆ operator=() [1/3]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference& WeakReference< ObjectType, ReferenceCountingType >::operator= ( const WeakReference< ObjectType, ReferenceCountingType > &  other)

Copies another pointer to this one.

◆ operator=() [2/3]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference& WeakReference< ObjectType, ReferenceCountingType >::operator= ( ObjectType *  newObject)

Copies another pointer to this one.

◆ operator=() [3/3]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference& WeakReference< ObjectType, ReferenceCountingType >::operator= ( WeakReference< ObjectType, ReferenceCountingType > &&  other)
noexcept

Move assignment operator.

◆ get()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
ObjectType* WeakReference< ObjectType, ReferenceCountingType >::get ( ) const
noexcept

Returns the object that this pointer refers to, or null if the object no longer exists.

Referenced by ModalCallbackFunction::forComponent().

◆ operator ObjectType *()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
WeakReference< ObjectType, ReferenceCountingType >::operator ObjectType * ( ) const
noexcept

Returns the object that this pointer refers to, or null if the object no longer exists.

◆ operator->() [1/2]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
ObjectType* WeakReference< ObjectType, ReferenceCountingType >::operator-> ( )
noexcept

Returns the object that this pointer refers to, or null if the object no longer exists.

◆ operator->() [2/2]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
const ObjectType* WeakReference< ObjectType, ReferenceCountingType >::operator-> ( ) const
noexcept

Returns the object that this pointer refers to, or null if the object no longer exists.

◆ wasObjectDeleted()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
bool WeakReference< ObjectType, ReferenceCountingType >::wasObjectDeleted ( ) const
noexcept

This returns true if this reference has been pointing at an object, but that object has since been deleted.

If this reference was only ever pointing at a null pointer, this will return false. Using operator=() to make this refer to a different object will reset this flag to match the status of the reference from which you're copying.

◆ operator==()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
bool WeakReference< ObjectType, ReferenceCountingType >::operator== ( ObjectType *  object) const
noexcept

◆ operator!=()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
bool WeakReference< ObjectType, ReferenceCountingType >::operator!= ( ObjectType *  object) const
noexcept

The documentation for this class was generated from the following file: