carto::const_ref< T > Class Template Reference

Constant Ref to an object of class T. More...

#include <cartobase/smart/rcptr.h>

Inheritance diagram for carto::const_ref< T >:

Collaboration diagram for carto::const_ref< T >:

Public Types
typedef T	referenced_type

Public Member Functions
	const_ref ()
	const_ref (const T *pObject)
	const_ref (const T *pObject, bool externalowner)
template<class U>
	const_ref (std::auto_ptr< U > r)
	const_ref (const ref< T > &other)
	const_ref (const const_ref< T > &other)
template<class R>
	const_ref (const ref< R > &o)
template<class R>
	const_ref (const const_ref< R > &other)
	~const_ref ()
const_ref< T > &	operator= (const ref< T > &other)
const_ref< T > &	operator= (const const_ref< T > &other)
bool	isNull () const
bool	operator== (const ref< T > &other) const
bool	operator== (const T *pointer) const
bool	operator== (const const_ref< T > &other) const
bool	operator!= (const ref< T > &other) const
bool	operator!= (const const_ref< T > &other) const
bool	operator!= (const T *pointer) const
const T *	operator-> () const
const T &	operator* () const
const T *	pointer () const
int	refCount () const
Public Member Functions inherited from carto::RefData< T >
int	count () const

Friends
class	DefaultRefConstruction
class	RCObject
template<class R>
class	ref

Detailed Description

template<class T>
class carto::const_ref< T >

Constant Ref to an object of class T.

The purpose of this class is to provide a way to reference dynamically allocated objects without worrying about their destruction. To avoid confusion with built-in C++ references we call a Ref an object of class const_ref or ref.

A Ref act as a pointer on a dynamically allocated object (with new). The main difference between a Ref an a pointer is the link that exists between the Ref lifetime and the pointed object lifetime. An object pointed to by a Ref is destroyed when the last Ref pointed to it is destroyed. Therefore a Ref contains two things: a pointer to an object and a reference counter. Each time a Ref is created, the counter is incremented. When a Ref is destroyed, the counter is decremented and if the counter is null, the object is destroyed (with delete).

A Ref can be used to reference any object created by new. Therefore it can be used with existing classes.

Warning

It is the responssability to the programmer to avoid cyclic references or memory leak can occur. For example, in the following program, the objects of class A and B are never destroyed.

#include <iostream>
#include <rcptr.h>
 
using namespace carto;
 
class A;
class B;
 
class A {
public:
 
  A();
  ~A();
 
  ref<B> rb;
};
 
class B
{
public:
 
  B();
  ~B();
 
  ref<A> ra;
};
 
A::A()  { cerr << "Construction of A" << endl; }
A::~A() { cerr << "Destruction of A" << endl; }
 
B::B() { cerr << "Construction of B" << endl; }
B::~B() { cerr << "Destruction of B" << endl; }
 
int main()
{
  ref<A> ra = new A;
  ref<B> rb = new B;
 
  ra->rb = rb;
  rb->ra = ra;
}

In the general case the pointer returned by new can be used to build only one Ref. If it is used to build several Ref, the object will be destroyed several times and the program will crash. See RCObject to avoid this problem.

Definition at line 289 of file rcptr.h.

Member Typedef Documentation

referenced_type

template<class T>

typedef T carto::const_ref< T >::referenced_type

Definition at line 303 of file rcptr.h.

Constructor & Destructor Documentation

const_ref() [1/8]

template<class T>

carto::const_ref< T >::const_ref ( )

inline

Definition at line 304 of file rcptr.h.

Referenced by const_ref(), const_ref(), operator!=(), operator=(), operator=(), and operator==().

const_ref() [2/8]

template<class T>

carto::const_ref< T >::const_ref ( const T * pObject )

inlineexplicit

Definition at line 306 of file rcptr.h.

const_ref() [3/8]

template<class T>

carto::const_ref< T >::const_ref ( const T * pObject, bool externalowner )

inlineexplicit

Definition at line 311 of file rcptr.h.

const_ref() [4/8]

template<class T>

template<class U>

carto::const_ref< T >::const_ref ( std::auto_ptr< U > r )

inline

Definition at line 327 of file rcptr.h.

const_ref() [5/8]

template<class T>

carto::const_ref< T >::const_ref ( const ref< T > & other )

inline

Definition at line 333 of file rcptr.h.

References ref.

const_ref() [6/8]

template<class T>

carto::const_ref< T >::const_ref ( const const_ref< T > & other )

inline

Definition at line 343 of file rcptr.h.

References const_ref().

const_ref() [7/8]

template<class T>

template<class R>

carto::const_ref< T >::const_ref ( const ref< R > & o )

inline

Definition at line 354 of file rcptr.h.

References ref.

const_ref() [8/8]

template<class T>

template<class R>

carto::const_ref< T >::const_ref ( const const_ref< R > & other )

inline

Definition at line 367 of file rcptr.h.

References const_ref().

~const_ref()

template<class T>

carto::const_ref< T >::~const_ref ( )

inline

Definition at line 377 of file rcptr.h.

Member Function Documentation

isNull()

template<class T>

bool carto::const_ref< T >::isNull ( ) const

inline

Definition at line 383 of file rcptr.h.

operator!=() [1/3]

template<class T>

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

inline

Definition at line 388 of file rcptr.h.

References const_ref().

operator!=() [2/3]

template<class T>

bool carto::const_ref< T >::operator!= ( const ref< T > & other ) const

inline

Definition at line 387 of file rcptr.h.

References ref.

operator!=() [3/3]

template<class T>

bool carto::const_ref< T >::operator!= ( const T * pointer ) const

inline

Definition at line 389 of file rcptr.h.

References pointer().

operator*()

template<class T>

const T & carto::const_ref< T >::operator* ( ) const

inline

Definition at line 395 of file rcptr.h.

operator->()

template<class T>

const T * carto::const_ref< T >::operator-> ( ) const

inline

Definition at line 391 of file rcptr.h.

operator=() [1/2]

template<class T>

const_ref< T > & carto::const_ref< T >::operator=

(

const const_ref< T > &

other

)

Definition at line 445 of file rcptr.h.

References const_ref().

operator=() [2/2]

template<class T>

const_ref< T > & carto::const_ref< T >::operator=

(

const ref< T > &

other

)

Definition at line 427 of file rcptr.h.

References const_ref(), and ref.

Referenced by carto::ref< T >::operator=(), and carto::weak_shared_ptr< T >::operator=().

operator==() [1/3]

template<class T>

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

inline

Definition at line 386 of file rcptr.h.

References const_ref().

operator==() [2/3]

template<class T>

bool carto::const_ref< T >::operator== ( const ref< T > & other ) const

inline

Definition at line 384 of file rcptr.h.

References ref.

operator==() [3/3]

template<class T>

bool carto::const_ref< T >::operator== ( const T * pointer ) const

inline

Definition at line 385 of file rcptr.h.

References pointer().

pointer()

template<class T>

const T * carto::const_ref< T >::pointer ( ) const

inline

Definition at line 399 of file rcptr.h.

Referenced by operator!=(), and operator==().

refCount()

template<class T>

int carto::const_ref< T >::refCount ( ) const

inline

Definition at line 403 of file rcptr.h.

Friends And Related Symbol Documentation

DefaultRefConstruction

template<class T>

friend class DefaultRefConstruction

friend

Definition at line 296 of file rcptr.h.

References DefaultRefConstruction.

Referenced by DefaultRefConstruction.

RCObject

template<class T>

friend class RCObject

friend

Definition at line 297 of file rcptr.h.

References RCObject.

Referenced by RCObject.

ref

template<class T>

template<class R>

friend class ref

friend

Definition at line 299 of file rcptr.h.

References ref.

Referenced by const_ref(), const_ref(), operator!=(), operator=(), operator==(), and ref.

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

• cartobase/smart/rcptr.h