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:: com :: sun :: star :: uno ::
interface XAggregation
  Base Hierarchy
      XInterface
       |
       +-XAggregation
Description Objects which implement this interface can become aggregates of a delegator. That means if an object "A" aggregates "B", "A" can provide all or some of the interfaces of "B". Whenever the method XInterface::queryInterface() is called on either of the objects, the call will be forwarded to object "A". Object "A" now can determine whether to use the interfaces of "A" or "B" or neither. Actually, any number of aggregates can be used, even nested ones (aggregated objects which are delegators by themselves). The following rules are to be observed: All calls to XInterface::acquire() which are made before the delegator was set (using the method setDelegator() ) must not be taken back (using the method XInterface::release() ) before the delegation is removed by calling `xAggregation->setDelegator(NULL)` . The constructor of a delegator has to increment its own reference count by calling its method XInterface::acquire() before it sets itself to any aggregate using the method setDelegator() . After that call it has to reset its own reference count without the destructor getting called. The destructor of a delegator has to reset the delegator in its aggregated objects by calling their method setDelegator() with NULL before it releases its reference to its aggregated objects. Developers Guide 4.4.8 Writing UNO Components - Core Interfaces to Implement - XAggregation 4.4 Writing UNO Components - Core Interfaces to Implement

Methods' Summary
setDelegator | sets the object to which all calls to the method XInterface::queryInterface() have to be forwarded. @
queryAggregation | is similar to XInterface::queryInterface() , but it is to be processed directly without being forwarded to the delegator. @

Methods' Details
setDelegator
void setDelegator( | [in] XInterface | pDelegator );
  Description sets the object to which all calls to the method XInterface::queryInterface() have to be forwarded. @ Parameter xDelegator specifies the object which handles the calls to XInterface::queryInterface() . If xDelegator is NULL , the delegator is removed and thus the object becomes its own delegator and has to handle calls to the method XInterface::queryInterface() itself. Example :Java
       void setDelegator( com.sun.star.uno.XInterface aDelegator )
       {
       pDelegator =aDelegator;
       }

       com.sun.star.uno.XInterface queryInterface( com.sun.star.uno.Uik aUik )
       {
       com.sun.star.uno.XInterface pRet = null;

       // pDelegator may be already set
       if( pDelegator == null )
       pRet = queryAggregation( aIFace );
       else
       pRet = pDelegator->queryInterface( aIFace );
       return pRet;
       }
See also XAggregation::queryAggregation
queryAggregation
any queryAggregation( | [in] type | aType );
  Description is similar to XInterface::queryInterface() , but it is to be processed directly without being forwarded to the delegator. @ This method is only called from within an implementation of XInterface::queryInterface() or XAggregation::queryAggregation() . This method is to be called by the delegator if it does not implement the interface itself. An object which got aggregated cannot depend on getting its own interface when it calls the method XInterface::queryInterface() . Example :Java
       Class queryAggregation( Class aIFace )
       {
       // The Uno-System provides information about their own interfaces
       Class pRet = Uno.getInterface( this, aIFace );

       if( pRet == null )
       // not an own interface, thus forward to the aggregated object
       pRet = aMyAggObj->queryAggregation( aIface );
       return pRet;
       }
See also XAggregation::setDelegator

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