This is the class for pointers to objects that use the smart pointer system. More...

#include <smartptr.h>

Inheritance diagram for PSmartPointer:

Collaboration diagram for PSmartPointer:

Public Member Functions
Construction
	PSmartPointer (PSmartObject *obj=NULL)
	Create a new smart pointer instance and have it point to the specified `PSmartObject` instance. More...

	PSmartPointer (const PSmartPointer &ptr)
	Create a new smart pointer and point it at the data pointed to by the `ptr` parameter. More...

virtual	~PSmartPointer ()
	Destroy the smart pointer and decrement the reference count on the object being pointed to. More...

PSmartPointer &	operator= (const PSmartPointer &ptr)
	Assign this pointer to the value specified in the `ptr` parameter. More...

Overrides from class PObject
virtual Comparison	Compare (const PObject &obj) const
	Determine the relative rank of the pointers. More...

Pointer access functions
PBoolean	IsNULL () const
	Determine if the smart pointer has been set to point to an actual object instance. More...

PSmartObject *	GetObject () const
	Get the current value if the internal smart object pointer. More...

Public Member Functions inherited from PObject
__inline unsigned	GetTraceContextIdentifier () const
	Get PTRACE context identifier. More...

__inline void	SetTraceContextIdentifier (unsigned id)

__inline void	SetTraceContextIdentifier (const PObject &obj)

__inline void	SetTraceContextIdentifier (const PObject *obj)

__inline void	CopyTraceContextIdentifier (PObject &obj) const

__inline void	CopyTraceContextIdentifier (PObject *obj) const

virtual	~PObject ()

__inline const char *	GetClass () const

__inline bool	IsClass (const char *name) const

__inline const PObject *	PTraceObjectInstance () const

virtual PObject *	Clone () const
	Create a copy of the class on the heap. More...

template<class CLS >
CLS *	CloneAs () const
	As for Clone() but converts to specified type. More...

virtual PINDEX	HashFunction () const
	This function yields a hash value required by the `PDictionary` class. More...

virtual Comparison	CompareObjectMemoryDirect (const PObject &obj) const
	Determine the byte wise comparison of two objects. More...

bool	operator== (const PObject &obj) const
	Compare the two objects. More...

bool	operator!= (const PObject &obj) const
	Compare the two objects. More...

bool	operator< (const PObject &obj) const
	Compare the two objects. More...

bool	operator> (const PObject &obj) const
	Compare the two objects. More...

bool	operator<= (const PObject &obj) const
	Compare the two objects. More...

bool	operator>= (const PObject &obj) const
	Compare the two objects. More...

virtual void	PrintOn (ostream &strm) const
	Output the contents of the object to the stream. More...

virtual void	ReadFrom (istream &strm)
	Input the contents of the object from the stream. More...

Protected Attributes
PSmartObject *	object
	Object the smart pointer points to. More...

Protected Attributes inherited from PObject
unsigned	m_traceContextIdentifier

Additional Inherited Members
Public Types inherited from PObject
enum	Comparison { LessThan = -1, EqualTo = 0, GreaterThan = 1 }
	Result of the comparison operation performed by the `Compare()` function. More...

Static Public Member Functions inherited from PObject
static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject &to, const PObject *from)

static __inline void	CopyTraceContextIdentifier (PObject *to, const PObject &from)

static __inline void	CopyTraceContextIdentifier (PObject to, const PObject from)

static __inline const char *	Class ()

static __inline const PObject *	PTraceObjectInstance (const char *)

static __inline const PObject *	PTraceObjectInstance (const PObject *obj)

template<typename T >
static Comparison	Compare2 (T v1, T v2)
	Compare two types, returning Comparison type. More...

static Comparison	InternalCompareObjectMemoryDirect (const PObject obj1, const PObject obj2, PINDEX size)
	Internal function caled from CompareObjectMemoryDirect() More...

Protected Member Functions inherited from PObject
	PObject ()
	Constructor for PObject, made protected so cannot ever create one on its own. More...

Detailed Description

This is the class for pointers to objects that use the smart pointer system.

In conjunction with the PSmartObject class, this class references objects that can have the automatic deletion of the object instance when there are no more smart pointer instances pointing to it.

A PSmartPointer carries the pointer to a PSmartObject instance which contains a reference count. Assigning or copying instances of smart pointers will automatically increment and decrement the reference count. When the last instance that references a PSmartObject instance is destroyed or overwritten, the PSmartObject is deleted.

A NULL value is possible for a smart pointer. It can be detected via the IsNULL() function.

Note that a PSmartPointer is not 100% thread safe. The case of assigment to and from a pointer at the same time is not handled. Consider the assignment code for A = B in one thread and C = A in another, when A was unique at the time of A = B.

if ((object != NULL) && (–object->referenceCount == 0)) context switch here delete object;

object = ptr.object; if (object != NULL) ++object->referenceCount;

The A = B operation in thread 1 is interrupted after it has decremented the count, then C = B then copies the pointer "object" in thread 2. Thread 1 then deletes it leaving C pointing to a deleted pointer.

Constructor & Destructor Documentation

PSmartPointer::PSmartPointer ( PSmartObject * obj = NULL )

inline

Create a new smart pointer instance and have it point to the specified PSmartObject instance.

Parameters

obj	Smart object to point to.

PSmartPointer::PSmartPointer ( const PSmartPointer & ptr )

Create a new smart pointer and point it at the data pointed to by the ptr parameter.

The reference count for the object being pointed at is incremented.

Parameters

ptr	Smart pointer to make a copy of.

virtual PSmartPointer::~PSmartPointer ( )

virtual

Destroy the smart pointer and decrement the reference count on the object being pointed to.

If there are no more references then the object is deleted.

Member Function Documentation

virtual Comparison PSmartPointer::Compare ( const PObject & obj ) const

virtual

Determine the relative rank of the pointers.

This is identical to determining the relative rank of the integer values represented by the memory pointers.

Returns: EqualTo if objects point to the same object instance, otherwise LessThan and GreaterThan may be returned depending on the relative values of the memory pointers.

Parameters

obj	Other smart pointer to compare against.

Reimplemented from PObject.

PSmartObject* PSmartPointer::GetObject ( ) const

inline

Get the current value if the internal smart object pointer.

Returns: pointer to object instance.

References object.

Referenced by PNotifierTemplate< PChannel::AsyncContext & >::GetTarget(), and PNotifierTemplate< PChannel::AsyncContext & >::operator()().

PBoolean PSmartPointer::IsNULL ( ) const

inline

Determine if the smart pointer has been set to point to an actual object instance.

Returns: true if the pointer is NULL.

PSmartPointer& PSmartPointer::operator= ( const PSmartPointer & ptr )

Assign this pointer to the value specified in the ptr parameter.

The previous object being pointed to has its reference count decremented as this will no longer point to it. If there are no more references then the object is deleted.

The new object being pointed to after the assignment has its reference count incremented.

Parameters

ptr	Smart pointer to assign.

Member Data Documentation

PSmartObject* PSmartPointer::object

protected

Object the smart pointer points to.

Referenced by GetObject(), and PSmartPtr< T >::operator T *().

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

smartptr.h

Public Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation