A smart-pointer that automatically creates and manages the lifetime of a shared static instance of a class. More...

#include <juce_SharedResourcePointer.h>

Collaboration diagram for SharedResourcePointer< SharedObjectType >:

Classes
struct	SharedObjectHolder

Public Member Functions
	SharedResourcePointer ()
	Creates an instance of the shared object. More...

	SharedResourcePointer (const SharedResourcePointer &)

	~SharedResourcePointer ()
	Destructor. More...

SharedObjectType &	get () const noexcept
	Returns the shared object. More...

SharedObjectType &	getObject () const noexcept
	Returns the object that this pointer references. More...

int	getReferenceCount () const noexcept
	Returns the number of SharedResourcePointers that are currently holding the shared object. More...

	operator SharedObjectType * () const noexcept
	Returns the shared object. More...

SharedObjectType *	operator-> () const noexcept
	Returns the shared object. More...

Private Member Functions
void	initialise ()

SharedResourcePointer &	operator= (const SharedResourcePointer &)=delete

Static Private Member Functions
static SharedObjectHolder &	getSharedObjectHolder () noexcept

Private Attributes
SharedObjectType *	sharedObject

Detailed Description

template<typename SharedObjectType>
class SharedResourcePointer< SharedObjectType >

A smart-pointer that automatically creates and manages the lifetime of a shared static instance of a class.

The SharedObjectType template type indicates the class to use for the shared object - the only requirements on this class are that it must have a public default constructor and destructor.

The SharedResourcePointer offers a pattern that differs from using a singleton or static instance of an object, because it uses reference-counting to make sure that the underlying shared object is automatically created/destroyed according to the number of SharedResourcePointer objects that exist. When the last one is deleted, the underlying object is also immediately destroyed. This allows you to use scoping to manage the lifetime of a shared resource.

Note: the construction/deletion of the shared object must not involve any code that makes recursive calls to a SharedResourcePointer, or you'll cause a deadlock.

Example:

// An example of a class that contains the shared data you want to use.
struct MySharedData
{
    // There's no need to ever create an instance of this class directly yourself,
    // but it does need a public constructor that does the initialisation.
    MySharedData()
    {
        sharedStuff = generateHeavyweightStuff();
    }
    Array<SomeKindOfData> sharedStuff;
};
struct DataUserClass
{
    DataUserClass()
    {
        // Multiple instances of the DataUserClass will all have the same
        // shared common instance of MySharedData referenced by their sharedData
        // member variables.
        useSharedStuff (sharedData->sharedStuff);
    }
    // By keeping this pointer as a member variable, the shared resource
    // is guaranteed to be available for as long as the DataUserClass object.
    SharedResourcePointer<MySharedData> sharedData;
};

Constructor & Destructor Documentation

◆ SharedResourcePointer() [1/2]

template<typename SharedObjectType>

SharedResourcePointer< SharedObjectType >::SharedResourcePointer ( )

inline

Creates an instance of the shared object.

If other SharedResourcePointer objects for this type already exist, then this one will simply point to the same shared object that they are already using. Otherwise, if this is the first SharedResourcePointer to be created, then a shared object will be created automatically.

References SharedResourcePointer< SharedObjectType >::initialise().