On Sun, 4 Sep 2022 19:49:42 GMT, John Hendrikx <jhendr...@openjdk.org> wrote:
>> This PR adds a new (lazy*) property on `Node` which provides a boolean which >> indicates whether or not the `Node` is currently part of a `Scene`, which in >> turn is part of a currently showing `Window`. >> >> It also adds a new fluent binding method on `ObservableValue` dubbed `when` >> (open for discussion, originally I had `conditionOn` here). >> >> Both of these together means it becomes much easier to break strong >> references that prevent garbage collection between a long lived property and >> one that should be shorter lived. A good example is when a `Label` is bound >> to a long lived property: >> >> >> label.textProperty().bind(longLivedProperty.when(label::isShowingProperty)); >> >> The above basically ties the life cycle of the label to the long lived >> property **only** when the label is currently showing. When it is not >> showing, the label can be eligible for GC as the listener on >> `longLivedProperty` is removed when the condition provided by >> `label::isShowingProperty` is `false`. A big advantage is that these >> listeners stop observing the long lived property **immediately** when the >> label is no longer showing, in contrast to weak bindings which may keep >> observing the long lived property (and updating the label, and triggering >> its listeners in turn) until the next GC comes along. >> >> The issue in JBS also describes making the `Subscription` API public, but I >> think that might best be a separate PR. >> >> Note that this PR contains a bugfix in `ObjectBinding` for which there is >> another open PR: https://github.com/openjdk/jfx/pull/829 -- this is because >> the tests for the newly added method would fail otherwise; once it has been >> integrated to jfx19 and then to master, I can take the fix out. >> >> (*) Lazy means here that the property won't be creating any listeners unless >> observed itself, to avoid problems creating too many listeners on >> Scene/Window. > > John Hendrikx has updated the pull request incrementally with one additional > commit since the last revision: > > Small wording fixes The docs of `when` look good now (I left one minor comment). I actually didn't think about the name of the method, compared to ReactFX's `conditionOn` for example, but this is good enough until others review. I haven't looked at the addition to `Node` closely yet. I will look at the implementation and tests of the method itself first because `Node` is a use case. modules/javafx.base/src/main/java/javafx/beans/value/ObservableValue.java line 296: > 294: * > label.textProperty().bind(longLivedProperty.when(label::isShownProperty)); > 295: * }</pre> > 296: * @param condition a boolean {@code ObservableValue}, cannot be > {@code null} New line before `@param`. ------------- Changes requested by nlisker (Reviewer). PR: https://git.openjdk.org/jfx/pull/830
