juce::WeakReference< ObjectType, ReferenceCountingType > Class Template Reference

#include <juce_WeakReference.h>

Classes
class	SharedPointer
class	Master

Public Types
using	SharedRef = ReferenceCountedObjectPtr<SharedPointer>

Public Member Functions
	WeakReference ()=default
	WeakReference (ObjectType *object)
	WeakReference (const WeakReference &other) noexcept
	WeakReference (WeakReference &&other) noexcept
WeakReference &	operator= (const WeakReference &other)
WeakReference &	operator= (ObjectType *newObject)
WeakReference &	operator= (WeakReference &&other) noexcept
ObjectType *	get () const noexcept
	operator ObjectType * () const noexcept
ObjectType *	operator-> () const noexcept
bool	wasObjectDeleted () const noexcept
bool	operator== (ObjectType *object) const noexcept
bool	operator!= (ObjectType *object) const noexcept

Static Private Member Functions
static SharedRef	getRef (ObjectType *o)

Private Attributes
SharedRef	holder

Detailed Description

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>
class juce::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.

Note that WeakReference is not designed to be thread-safe, so if you're accessing it from different threads, you'll need to do your own locking around all uses of the pointer and the object it refers to.

E.g.

class MyObject
{
public:
    MyObject() {}
 
    ~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.
    WeakReference<MyObject>::Master masterReference;
    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..
 
auto* n = new MyObject();
WeakReference<MyObject> myObjectRef = n;
 
auto pointer1 = myObjectRef.get();  // returns a valid pointer to 'n'
delete n;
auto pointer2 = myObjectRef.get();  // now returns nullptr

See also

WeakReference::Master

@tags{Core}

Member Typedef Documentation

SharedRef

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

using juce::WeakReference< ObjectType, ReferenceCountingType >::SharedRef = ReferenceCountedObjectPtr<SharedPointer>

Constructor & Destructor Documentation

WeakReference() [1/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

juce::WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( )

inlinedefault

Creates a null WeakReference.

WeakReference() [2/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

juce::WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( ObjectType * object )

inline

Creates a WeakReference that points at the given object.

WeakReference() [3/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

juce::WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( const WeakReference< ObjectType, ReferenceCountingType > & other )

inlinenoexcept

Creates a copy of another WeakReference.

WeakReference() [4/4]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

juce::WeakReference< ObjectType, ReferenceCountingType >::WeakReference ( WeakReference< ObjectType, ReferenceCountingType > && other )

inlinenoexcept

Move constructor

Member Function Documentation

get()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

ObjectType * juce::WeakReference< ObjectType, ReferenceCountingType >::get ( ) const

inlinenoexcept

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

getRef()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

SharedRef juce::WeakReference< ObjectType, ReferenceCountingType >::getRef ( ObjectType * o )

inlinestaticprivate

operator ObjectType *()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

juce::WeakReference< ObjectType, ReferenceCountingType >::operator ObjectType * ( ) const

inlinenoexcept

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

operator!=()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

bool juce::WeakReference< ObjectType, ReferenceCountingType >::operator!= ( ObjectType * object ) const

inlinenoexcept

operator->()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

ObjectType * juce::WeakReference< ObjectType, ReferenceCountingType >::operator-> ( ) const

inlinenoexcept

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

operator=() [1/3]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

WeakReference & juce::WeakReference< ObjectType, ReferenceCountingType >::operator= ( const WeakReference< ObjectType, ReferenceCountingType > & other )

inline

Copies another pointer to this one.

operator=() [2/3]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

WeakReference & juce::WeakReference< ObjectType, ReferenceCountingType >::operator= ( ObjectType * newObject )

inline

Copies another pointer to this one.

operator=() [3/3]

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

WeakReference & juce::WeakReference< ObjectType, ReferenceCountingType >::operator= ( WeakReference< ObjectType, ReferenceCountingType > && other )

inlinenoexcept

Move assignment operator

operator==()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

bool juce::WeakReference< ObjectType, ReferenceCountingType >::operator== ( ObjectType * object ) const

inlinenoexcept

wasObjectDeleted()

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

bool juce::WeakReference< ObjectType, ReferenceCountingType >::wasObjectDeleted ( ) const

inlinenoexcept

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.

Member Data Documentation

holder

template<class ObjectType, class ReferenceCountingType = ReferenceCountedObject>

SharedRef juce::WeakReference< ObjectType, ReferenceCountingType >::holder

private

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

• /home/runner/work/lmms-fork/lmms-fork/plugins/CarlaBase/carla/source/modules/juce_core/memory/juce_WeakReference.h