# Glib::RefPtr< T_CppObject > Class Template Reference

RefPtr<> is a reference-counting shared smartpointer. More...

`#include <glibmm/refptr.h>`

List of all members.

## Public Member Functions

| RefPtr ()
| Default constructor.
| ~RefPtr ()
| Destructor - decrements reference count.
| RefPtr (T_CppObject* pCppObject)
| For use only by the create() methods.
| RefPtr (const RefPtr< T_CppObject >& src)
| Copy constructor.
template<class T_CastFrom >
| RefPtr (const RefPtr< T_CastFrom >& src)
| Copy constructor (from different, but castable type).
void | swap (RefPtr< T_CppObject >& other)
| Swap the contents of two RefPtr<>.
RefPtr< T_CppObject >& | operator= (const RefPtr< T_CppObject >& src)
| Copy from another RefPtr:
template<class T_CastFrom >
RefPtr< T_CppObject >& | operator= (const RefPtr< T_CastFrom >& src)
| Copy from different, but castable type).
bool | operator== (const RefPtr< T_CppObject >& src) const
| Tests whether the RefPtr<> point to the same underlying instance.
bool | operator!= (const RefPtr< T_CppObject >& src) const
| See operator==().
T_CppObject* | operator-> () const
| Dereferencing.
| operator bool () const
| Test whether the RefPtr<> points to any underlying instance.
void | clear ()
void | reset ()
| Set underlying instance to 0, decrementing reference count of existing instance appropriately.

## Static Public Member Functions

template<class T_CastFrom >
static RefPtr< T_CppObject > | cast_dynamic (const RefPtr< T_CastFrom >& src)
| Dynamic cast to derived class.
template<class T_CastFrom >
static RefPtr< T_CppObject > | cast_static (const RefPtr< T_CastFrom >& src)
| Static cast to derived class.
template<class T_CastFrom >
static RefPtr< T_CppObject > | cast_const (const RefPtr< T_CastFrom >& src)
| Cast to non-const.

## Related Functions

(Note that these are not member functions.)
template<class T_CppObject >
void | swap (RefPtr< T_CppObject >& lhs, RefPtr< T_CppObject >& rhs)

## Detailed Description

### template <class T_CppObject>
class Glib::RefPtr< T_CppObject >

RefPtr<> is a reference-counting shared smartpointer.

Some objects in gtkmm are obtained from a shared store. Consequently you cannot instantiate them yourself. Instead they return a RefPtr which behaves much like an ordinary pointer in that members can be reached with the usual `object_ptr->member` notation. Unlike most other smart pointers, RefPtr doesn't support dereferencing through `* object_ptr`.

Reference counting means that a shared reference count is incremented each time a RefPtr is copied, and decremented each time a RefPtr is destroyed, for instance when it leaves its scope. When the reference count reaches zero, the contained object is deleted, meaning you don't need to remember to delete the object.

RefPtr<> can store any class that has reference() and unreference() methods. In gtkmm, that is anything derived from Glib::ObjectBase, such as Gdk::Pixmap.

See the "Memory Management" section in the "Programming with gtkmm" book for further information.

Examples:

  thread/dispatcher.cc.

## Constructor & Destructor Documentation

template <class T_CppObject>

Glib::RefPtr< T_CppObject >::RefPtr | ( |  | ) | `[inline]`

Default constructor.

Afterwards it will be null and use of -> will cause a segmentation fault.

template <class T_CppObject>

Glib::RefPtr< T_CppObject >::~RefPtr | ( |  | ) | `[inline]`

Destructor - decrements reference count.

template <class T_CppObject>

Glib::RefPtr< T_CppObject >::RefPtr | ( | T_CppObject * | pCppObject | ) | `[inline, explicit]`

For use only by the create() methods.

template <class T_CppObject>

Glib::RefPtr< T_CppObject >::RefPtr | ( | const RefPtr< T_CppObject >& | src | ) | `[inline]`

Copy constructor.

This increments the shared reference count.

template <class T_CppObject>
template <class T_CastFrom >

Glib::RefPtr< T_CppObject >::RefPtr | ( | const RefPtr< T_CastFrom >& | src | ) | `[inline]`

Copy constructor (from different, but castable type).

Increments the reference count.

## Member Function Documentation

template <class T_CppObject>
template <class T_CastFrom >

static RefPtr<T_CppObject> Glib::RefPtr< T_CppObject >::cast_const | ( | const RefPtr< T_CastFrom >& | src | ) | `[inline, static]`

Cast to non-const.

The RefPtr can't be cast with the usual notation so instead you can use

     ptr_unconst = RefPtr<UnConstType>::cast_const(ptr_const);

template <class T_CppObject>
template <class T_CastFrom >

static RefPtr<T_CppObject> Glib::RefPtr< T_CppObject >::cast_dynamic | ( | const RefPtr< T_CastFrom >& | src | ) | `[inline, static]`

Dynamic cast to derived class.

The RefPtr can't be cast with the usual notation so instead you can use

     ptr_derived = RefPtr<Derived>::cast_dynamic(ptr_base);

template <class T_CppObject>
template <class T_CastFrom >

static RefPtr<T_CppObject> Glib::RefPtr< T_CppObject >::cast_static | ( | const RefPtr< T_CastFrom >& | src | ) | `[inline, static]`

Static cast to derived class.

Like the dynamic cast; the notation is

     ptr_derived = RefPtr<Derived>::cast_static(ptr_base);

template <class T_CppObject>

void Glib::RefPtr< T_CppObject >::clear | ( |  | ) | `[inline]`

Deprecated:
  Use reset() instead because this leads to confusion with clear() methods on the underlying class. For instance, people use .clear() when they mean ->clear().

template <class T_CppObject>

Glib::RefPtr< T_CppObject >::operator bool | ( |  | ) | const`[inline]`

Test whether the RefPtr<> points to any underlying instance.

Mimics usage of ordinary pointers:

     if (ptr)
         do_something();

template <class T_CppObject>

bool Glib::RefPtr< T_CppObject >::operator!= | ( | const RefPtr< T_CppObject >& | src | ) | const`[inline]`

See operator==().

template <class T_CppObject>

T_CppObject* Glib::RefPtr< T_CppObject >::operator-> | ( |  | ) | const`[inline]`

Dereferencing.

Use the methods of the underlying instance like so: `refptr->memberfun()`.

template <class T_CppObject>

RefPtr<T_CppObject>& Glib::RefPtr< T_CppObject >::operator= | ( | const RefPtr< T_CppObject >& | src | ) | `[inline]`

Copy from another RefPtr:

template <class T_CppObject>
template <class T_CastFrom >

RefPtr<T_CppObject>& Glib::RefPtr< T_CppObject >::operator= | ( | const RefPtr< T_CastFrom >& | src | ) | `[inline]`

Copy from different, but castable type).

Increments the reference count.

template <class T_CppObject>

bool Glib::RefPtr< T_CppObject >::operator== | ( | const RefPtr< T_CppObject >& | src | ) | const`[inline]`

Tests whether the RefPtr<> point to the same underlying instance.

template <class T_CppObject>

void Glib::RefPtr< T_CppObject >::reset | ( |  | ) | `[inline]`

Set underlying instance to 0, decrementing reference count of existing instance appropriately.

Since glibmm 2.16:

template <class T_CppObject>

void Glib::RefPtr< T_CppObject >::swap | ( | RefPtr< T_CppObject >& | other | ) | `[inline]`

Swap the contents of two RefPtr<>.

This method swaps the internal pointers to T_CppObject. This can be done safely without involving a reference/unreference cycle and is therefore highly efficient.

## Friends And Related Function Documentation

template <class T_CppObject >

void swap | ( | RefPtr< T_CppObject >& | lhs,
|  | RefPtr< T_CppObject >& | rhs |
| ) |  |  | `[related]`