Class TSwizzle

TSwizzle<class T>

Support

Supported from 5.0

Description

Maintains a dual representation for an object. The representation is:

• by stream id, if the object is not in memory (the stream contains the external representation of that object).

• by pointer, if the object is in memory.

The template class defines the type of object for which the swizzle is a representation. Full access to the represented object is available through the swizzle.

Maintaining a dual representation for an object allows the loading of objects into memory from a store to be deferred; this is particularly important in complex applications.

Derivation

TSwizzle Maintains a dual representation for an object TSwizzleBase Implementation class for swizzles TSwizzleCBase Base class for swizzles

Defined in TSwizzle:
AsPtr(), ExternalizeL(), TSwizzle(), operator T*(), operator*(), operator->(), operator=()

Inherited from TSwizzleCBase:
AsId(), InternalizeL(), IsId(), IsPtr(), operator!=(), operator==()

TSwizzle();

Description

Constructs an uninitialised swizzle. It is necessary because there are also non-default constructors in this class.

TSwizzle(T* aPtr);

Description

Constructs a swizzle for a class T type object, represented by a pointer.

Parameters

T* aPtr A pointer to a class T type object.

TSwizzle(TStreamId anId);

Description

Constructs a swizzle for a class T type object, represented as a stream id.

Parameters

TStreamId anId The id of a stream containing the external representation of a class T type object.

void ExternalizeL(RWriteStream& aStream) const;

Description

Externalises the stream id of the stream associated with this swizzle.

This function presupposes that:

• a store map, i.e. an object of type CStoreMap, has been constructed

• the id of the stream containing the external representation of the represented type T object has been bound to this swizzle and added to the store map.

• the concrete stream referenced by aStream has been constructed, specifying the store map as an externaliser.

The presence of this function means that the standard templated operator<<() can be used.

Parameters

RWriteStream& aStream Stream to which the stream id should be externalised.

See also:

• CStoreMap

T* AsPtr() const;

Description

Returns a pointer to the object which this swizzle represents.

Note that the indirect component selector operator->() can be used to access members of the represented object.

Return value

T* A pointer to the class T type object represented by this swizzle.

operator T*() const;

Description

Converts the swizzle to a T* type.

Typically, the compiler inserts a call to this operator when a TSwizzle<class T> type is passed as a parameter to a function or operation which requires a pointer as a formal argument type.

See also:

• Using the conversion to T* operator

T& operator*() const;

Description

Returns a reference to the type T object which this swizzle represents.

Return value

T& A reference to the type T object represented by this swizzle.

See also:

• Using the indirection operator

T* operator->() const;

Description

Gives access to members of the type T object which this swizzle represents.

Note, use the AsPtr() member function to return a pointer to the object itself.

Return value

T* A pointer to the T type object; not explicitly accessible.

See also:

• Using the indirect component selector

TSwizzle<T>& operator=(T* aPtr);

Description

Sets this swizzle to represent the in-memory type T object, pointed to by the specified T* pointer.

Parameters

T* aPtr A pointer to an object of type T which the swizzle is to represent.

Return value

TSwizzle<T>& A reference to this swizzle representing the object of type T.