UIDRef Class Reference

#include <UIDRef.h>

Public Types
typedef base_type	data_type

Public Member Functions
	UIDRef (IDataBase *db, UID id)
IDataBase *	GetDataBase () const
UID	GetUID () const
void	ResetUID (UID newUID)
bool16	operator== (const UIDRef &other) const
bool16	operator!= (const UIDRef &other) const
bool16	operator< (const UIDRef &other) const
bool16	operator! () const
	operator void * () const
bool16	ExistsInDB () const
IPMUnknown *	Instantiate (PMIID iid) const

Static Public Attributes
static const UIDRef	gNull

Detailed Description

UIDRef

A UIDRef is a reference to a persistent object. Persistent objects are created in databases, by creating new UIDs. An open InDesign document is associated with a database, and the persistent objects stored with the document are managed and maintained by the database. If you have a pointer to the object in memory (for instance, a pointer to an interface of the object), that pointer is only good as long as the object is in memory. When it's released, the pointer can no longer be used to refer to the object. A UID is a persistent reference to an object that is good across instantations, and can be stored in the document as well. A UIDRef is a pair of <database, UID> that gives us a way to refer to an object as long as the document it is in is open.

Member Typedef Documentation

typedef base_type UIDRef::data_type

This declares that UIDRef's have binary copy semantics. This means they can be copied byte-wise if necessary for performance reasons.

Constructor & Destructor Documentation

UIDRef::UIDRef ( IDataBase *  db, UID  id  )

inline

Create a new UIDRef to the specified object in the database.

Member Function Documentation

bool16 UIDRef::ExistsInDB ( ) const

inline

            ---- This function returns kTrue if the UIDRef is valid

                and the UID exists in its database. Else returns kFalse

                Common usage is to check and see if a UID can be

                instantiated.

                e.g.        

                <pre>

                UID myUIDRef(aDB, aUID);

                if (myUIDRef.IsExistsInDB() {

OK to instantiate UIDRef InterfacePtr<ISomeInterface> theIFace(myUIDRef, IID_ISOMEINTERFACE); theIFace->DoWork(); } else { UID ref is invalid or does not exist myUIDRef = UIDRef::gNull }

Returns

kTrue if the UIDRef is valid and the UID exists in its database

IDataBase* UIDRef::GetDataBase ( void  ) const

inline

Get the database.

Returns

IDataBase* the database the UIDRef is in

UID UIDRef::GetUID ( ) const

inline

Get the UID

Returns

UID of the UIDRef

IPMUnknown * UIDRef::Instantiate ( PMIID  iid ) const

inline

Get a pointer to the object in memory, reading it from disk if necessary.

Parameters

iid	which interface of the object to return (use IID_IUNKNOWN if you don't care).

Returns

IPMUnknown* a pointer to the requested interface of the object, or nil if the object couldn't be found.

UIDRef::operator void * ( ) const

inline

Returns a nil pointer if the UIDRef is nil, non-nil otherwise.

Returns

nil pointer if the UIDRef has nil database or kInvalidUID.

bool16 UIDRef::operator! ( ) const

inline

Test to see if the UIDRef is nil

Returns

kTrue if the UIDRef has nil database or kInvalidUID.

bool16 UIDRef::operator!= ( const UIDRef &  other ) const

inline

Compare two UIDRefs for inequality

Parameters

other

the UIDRef to compare to

Returns

kTrue if the UIDRefs are not the same

bool16 UIDRef::operator< ( const UIDRef &  other ) const

inline

Compare two UIDRefs for inequality

Parameters

other

the UIDRef to compare to

Returns

kTrue if this < other

bool16 UIDRef::operator== ( const UIDRef &  other ) const

inline

Compare two UIDRefs for equality

Parameters

other

the UIDRef to compare to

Returns

kTrue if the UIDRefs are the same

void UIDRef::ResetUID ( UID  newUID )

inline

Reset the value of the UIDRef, so it refers to a different object in the same database.

Parameters

newUID

new value for the UIDRef.