com.simsilica.lemur.core

Class VersionedReference<T>

java.lang.Object

com.simsilica.lemur.core.VersionedReference<T>

public class VersionedReference<T>
extends java.lang.Object

Tracks an update version of a VersionedObject and can provide basic change tracking for a caller. Calling code can hold a VersionedReference to some value and call update() to update the local version field and detect if the version has changed since the last check.

This is an upside-down way of doing change notification that does not have the event overhead or listener-leak potential of a typical event/listener framework. It is not appropriate for all cases but can be used in cases where values are often changed frequently and/or it's ok to ignore stacks of events in favor of the latest value. Common applications are things like sliders, document models, etc. for which some view will update itself only when the watched object changes, but otherwise doesn't care about the specific granularity of events.

Constructor Summary

Constructors

Constructor and Description
VersionedReference(VersionedObject<T> object)

Method Summary

Modifier and Type	Method and Description
T	get() Returns the current version of the referenced object.
long	getLastVersion() Returns the version of the referenced object that last time update() was called.
long	getObjectVersion() Returns the current version of the referenced object.
boolean	needsUpdate() Returns true if the current version of the object differs from the version the last time update() was called.
boolean	update() Updates the referenced version to the current version and returns true if the referenced version was changed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

VersionedReference

public VersionedReference(VersionedObject<T> object)

Method Detail

getLastVersion

public long getLastVersion()

Returns the version of the referenced object that last time update() was called.

getObjectVersion

public long getObjectVersion()

Returns the current version of the referenced object.

needsUpdate

public boolean needsUpdate()

Returns true if the current version of the object differs from the version the last time update() was called.

update

public boolean update()

Updates the referenced version to the current version and returns true if the referenced version was changed.

get

public T get()

Returns the current version of the referenced object.