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EODelayedObserver


Inherits from:
(com.apple.client.eocontrol) Object
(com.apple.yellow.eocontrol) NSObject
Implements:
EOObserving
(com.apple.client.eocontrol only) NSInlineObservable
Package:
com.apple.client.eocontrol
com.apple.yellow.eocontrol

Class Description

The EODelayedObserver class is a part of EOControl's change tracking mechanism. It is an abstract superclass that defines the basic functionality for coalescing change notifications for multiple objects and postponing notification according to a prioritized queue. For an overview of the general change tracking mechanism, see "Tracking Enterprise Objects Changes" in the introduction to the EOControl Framework.

EODelayedObserver is primarily used to implement the interface layer's associations and wouldn't ordinarily be used outside the scope of a Java Client or Application Kit application (not in a command line tool or WebObjects application, for example). See the EODelayedObserverQueue class specification for general information.

You would never create an instance of EODelayedObserver. Instead, you use subclasses-typically EOAssociations (EOInterface). For information on creating your own EODelayedObserver subclass, see "Creating a Subclass of EODelayedObserver".




Constants

EODelayedObserver defines the following int constants to represent the priority of a notification in the queue:


ObserverPriorityImmediate ObserverPriorityFourth
ObserverPriorityFirst ObserverPriorityFifth
ObserverPrioritySecond ObserverPrioritySixth
ObserverPriorityThird ObserverPriorityLater

EODelayedObserver also defines the following int constant to identify the number of defined priorities (8 by default).



Interfaces Implemented

EOObserving
objectWillChange
NSInlineObservable
observerData
setObserverData


Method Types

Change notification
subjectChanged
Canceling change notification
discardPendingNotification
Getting the queue and priority
observerQueue
priority


Instance Methods


discardPendingNotification

public void discardPendingNotification()

Sends a dequeueObserver message to the receiver's EODelayedObserverQueue to clear it from receiving a change notification. A subclass of EODelayedObserver should invoke this method when its done observing changes.

See Also: observerQueue


objectWillChange

public void objectWillChange(Object anObject)

Implemented by EODelayedObserver to enqueue the receiver on its EODelayedObserverQueue. Subclasses shouldn't need to override this method; if they do, they must be sure to invoke super's implementation.

See Also: observerQueue, enqueueObserver (EODelayedObserverQueue), objectWillChange (EOObserving)


observerQueue

public EODelayedObserverQueue observerQueue()

Overridden by subclasses to return the receiver's designated EODelayedObserverQueue. EODelayedObserver's implementation returns the default EODelayedObserverQueue.

See Also: defaultObserverQueue (EODelayedObserverQueue)


priority

public int priority()

Overridden by subclasses to return the receiver's change notification priority, one of:

EODelayedObserver's implementation returns ObserverPriorityThird. See the EODelayedObserverQueue class specification for more information on priorities.


subjectChanged

public abstract void subjectChanged()

Implemented by subclasses to examine the receiver's observed objects and take whatever action is necessary. EODelayedObserver's implementation does nothing.


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