Class CBase

class CBase;

Description

Base class for all classes to be instantiated on the heap.

By convention, all classes derived from CBase have a name beginning with the letter 'C'.

The class has two important features:

1. A virtual destructor that allows instances of derived classes to be destroyed and properly cleaned up through a CBase* pointer. All CBase derived objects can be pushed, as CBase* pointers, onto the cleanup stack, and destroyed through a call to CleanupStack::PopAndDestroy().

2. Initialisation of the CBase derived object to binary zeroes through a specific CBase::operator new() - this means that members, whose initial value should be zero, do not have to be initialised in the constructor. This allows safe destruction of a partially-constructed object.

Note that using C++ arrays of CBase-derived types is not recommended, as objects in the array will not be zero-initialised (as there is no operator new[] member). You should use an array class such as RPointerArray instead for arrays of CBase-derived types.

Members

Defined in CBase:
CBase(), Delete(), Extension_(), operator new(), operator new(), operator new(), operator new(), operator new(), ~CBase()

See also:

• CleanupStack

inline CBase();

Description

Default constructor

virtual IMPORT_C ~CBase();

Description

Virtual destructor.

Enables any derived object to be deleted through a CBase* pointer.

inline TAny *operator new(TUint aSize, TAny *aBase) __NO_THROW;

Description

Initialises the object to binary zeroes.

Parameters

TUint aSize The size of the derived class. This parameter is specified implicitly by C++ in all circumstances in which a derived class is allocated. TAny *aBase Indicates a base address which is returned as the object's address.

Return value

TAny * A pointer to the base address.

inline TAny *operator new(TUint aSize) __NO_THROW;

Description

Allocates the object from the heap and then initialises its contents to binary zeroes.

Parameters

TUint aSize The size of the derived class. This parameter is specified implicitly by C++ in all circumstances in which a derived class is allocated.

Return value

TAny * A pointer to the allocated object; NULL if memory could not be allocated.

inline TAny *operator new(TUint aSize, TLeave);

Description

Allocates the object from the heap and then initialises its contents to binary zeroes.

Parameters

TUint aSize The size of the derived class. This parameter is specified implicitly by C++ in all circumstances in which a derived class is allocated. TLeave

Return value

TAny * A pointer to the allocated object; the TLeave parameter indicates that the operation leaves if allocation fails with out-of-memory.

inline TAny *operator new(TUint aSize, TUint aExtraSize) __NO_THROW;

Description

Allocates the object from the heap and then initialises its contents to binary zeroes.

Use of this overload is rare.

Parameters

TUint aSize The size of the derived class. This parameter is specified implicitly by C++ in all circumstances in which a derived class is allocated. TUint aExtraSize Indicates additional size beyond the end of the base class.

Return value

TAny * A pointer to the allocated object; NULL if memory could not be allocated.

inline TAny *operator new(TUint aSize, TLeave, TUint aExtraSize);

Description

Allocates the object from the heap and then initialises its contents to binary zeroes.

Use of this overload is rare.

Parameters

TUint aSize The size of the derived class. This parameter is specified implicitly by C++ in all circumstances in which a derived class is allocated. TLeave TUint aExtraSize Indicates additional size beyond the end of the base class.

Return value

TAny * A pointer to the allocated object; the TLeave parameter indicates that the operation leaves if allocation fails with out-of-memory.

static IMPORT_C void Delete(CBase *aPtr);

Description

Deletes the specified object.

Parameters

CBase *aPtr Pointer to the CBase derived object to be deleted.

protected: virtual IMPORT_C TInt Extension_(TUint aExtensionId, TAny *&a0, TAny *a1);

Description

Extension function

Parameters

TUint aExtensionId TAny *&a0 TAny *a1

Return value

TInt