Discussion: Naming API method

[Kevin Rushforth]

I also think this will be a useful feature to get into JavaFX.

As for the name of the method, the only one of them I don't like is 
"conditionOn". That name doesn't suggest (to me anyway) what its purpose 
is. I think any of the ones with "when" in the name would work. I have a 
slight preference for "updateWhen", but could be talked into one of the 
others.

-- Kevin


On 11/14/2022 6:52 AM, John Hendrikx wrote:
> Hi,
>
> I'm working on https://github.com/openjdk/jfx/pull/830 where I asked 
> for some opinions on the naming of a new method I'd like to introduce 
> in ObservableValue.
>
> I wrote a (perhaps too large) comment about the possible names and 
> rationales: 
> https://github.com/openjdk/jfx/pull/830#issuecomment-1304846220
>
> I'd like to ask what others think what would be a good name for this 
> new method (Observable#when in the PR) in order to move the PR 
> forward, as I think it offers a very compelling feature to JavaFX 
> (moving from weak reference to deterministic behavior when it comes to 
> listener management).  My opinion has always been that using weak 
> listeners for listener management is a crutch that relies far too much 
> on the internal workings of the JVM and Garbage Collector which offer 
> no guarantees as to the timely clean up of these references and the 
> listeners related to them.
>
> Leading contenders are (but not limited to these, if you have a better 
> name):
>
> 1) conditionOn
>
> 2) updateWhen
>
> 3) when
>
> 4) whenever
>
> Usage in code is nearly always going to be something like these 
> constructs:
>
>       // keeps text property in sync with longLivedProperty when label 
> is shown:
> label.textProperty().bind(longLivedProperty.**when**(label::isShownProperty)); 
>
>
>       // keeps text property in sync with longLivedProperty when 
> container is shown:
> label.textProperty().bind(longLivedProperty.**when**(container::isShownProperty)); 
>
>
> It can also be used to make a listener only actively listen when a 
> condition is met (the listener is added/removed immediately when the 
> condition changes, facilitating GC):
>
>       // listen to changes of longLivedProperty when container is shown:
>       longLivedProperty.when(container::isShownProperty)
>             .addListener((obs, old, current) -> { ... change listener 
> ... });
>
> Or it can be used to disable updates temporarily (or permanently):
>
>         BooleanProperty allowUpdates = new SimpleBooleanProperty(true)
>
>         // keeps text property in sync when updates are allowed:
>         name.textProperty().bind(model.title.when(allowUpdates));
> detail.textProperty().bind(model.subtitle.when(allowUpdates));
> asyncImageProperty.imageHandleProperty().bind(model.imageHandle.when(allowUpdates)); 
>
>
> This last example can be useful in Skin#dispose, but has uses outside 
> of skins as well, for example when you want to prevent updates until 
> things have settled down.
>
> Thanks for reading!
>
> --John
>
>