org.eclipse.core.databinding.observable
Class ObservableTracker
java.lang.Object
org.eclipse.core.databinding.observable.ObservableTracker
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public class ObservableTracker
- extends
Object
This class makes it possible to monitor whenever an IObservable is read from.
This can be used to automatically attach and remove listeners. How to use it:
If you are implementing an IObservable, invoke getterCalled(this) whenever a
getter is called - that is, whenever your observable is read from. You only
need to do this once per method call. If one getter delegates to another, the
outer getter doesn't need to call the method since the inner one will.
If you want to determine what observables were used in a particular block of
code, call runAndMonitor(Runnable). This will execute the given runnable and
return the set of observables that were read from.
This can be used to automatically attach listeners. For example, imagine you
have a block of code that updates some widget by reading from a bunch of
observables. Whenever one of those observables changes, you want to re-run
the code and cause the widget to be refreshed. You could do this in the
traditional manner by attaching one listener to each observable and
re-running your widget update code whenever one of them changes, but this
code is repetitive and requires updating the listener code whenever you
refactor the widget updating code.
Alternatively, you could use a utility class that runs the code in a
runAndMonitor block and automatically attach listeners to any observable used
in updating the widget. The advantage of the latter approach is that it,
eliminates the code for attaching and detaching listeners and will always
stay in synch with changes to the widget update logic.
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Since:
- 1.0
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Methods inherited from class java.lang.
Object
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clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
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ObservableTracker
public ObservableTracker()
runAndMonitor
public static
IObservable[] runAndMonitor(
Runnable runnable,
IChangeListener changeListener,
IStaleListener staleListener)
- Invokes the given runnable, and returns the set of IObservables that were
read by the runnable. If the runnable calls this method recursively, the
result will not contain IObservables that were used within the inner
runnable.
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Parameters:
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runnable - runnable to execute -
changeListener - listener to register with all accessed observables -
staleListener - listener to register with all accessed observables, or
null if no stale listener is to be registered
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Returns:
- an array of unique observable objects
runAndCollect
public static
IObservable[] runAndCollect(
Runnable runnable)
- Invokes the given runnable, and returns the set of IObservables that were
created by the runnable. If the runnable calls this method recursively,
the result will not contain IObservables that were created within the
inner runnable.
NOTE: As of 1.2 (Eclipse 3.5), there are unresolved problems with this API, see
bug 278550. If we cannot
find a way to make this API work, it will be deprecated as of 3.6.
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Parameters:
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runnable - runnable to execute
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Returns:
- an array of unique observable objects
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Since:
- 1.2
runAndIgnore
public static void runAndIgnore(
Runnable runnable)
- Runs the given runnable without tracking dependencies.
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Parameters:
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runnable - -
Since:
- 1.1
getterCalled
public static void getterCalled(
IObservable observable)
- Notifies the ObservableTracker that an observable was read from. The
JavaDoc for methods that invoke this method should include the following
tag: "@TrackedGetter This method will notify ObservableTracker that the
receiver has been read from". This lets callers know that they can rely
on automatic updates from the object without explicitly attaching a
listener.
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Parameters:
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observable -
observableCreated
public static void observableCreated(
IObservable observable)
- Notifies the ObservableTracker that an observable was created.
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Parameters:
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observable - the observable that was created -
Since:
- 1.2
Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.
