On Thu, 1 Sep 2022 17:38:39 GMT, Nir Lisker <[email protected]> wrote:
>> Edit: I missed some nuance, below is the correct version.
>>
>> There are three objects involved here: the parent observable, the new
>> observable and the conditional.
>>
>> What `when` should achieve is to make the new observable and conditional
>> easy to garbage collect when the conditional is `false` (the parent
>> observable is considered to be long lived so GC doesn't really apply there).
>> The conditional and new observable refer to each other so they must have a
>> similar life cycle.
>>
>>> What happens if they are GC'd and the conditional becomes `true` later?
>>
>> This can't happen, the conditional refers to the new observable, their life
>> cycles are tied to each other.
>>
>> Strong references look like this when conditional is `true`:
>>
>> conditional <--> new observable <--> parent observable
>>
>> When it is `false`:
>>
>> conditional <--> new observable --> parent observable
>>
>> Conditional must have a similar life cycle as new observable if your purpose
>> is to use `when` to break strong references to allow for GC.
>
> If I have a (dumb) method
>
>
> void someMethod(ObservableValue<String> longLivedProperty) {
> ObservableValue<Boolean> condition = new SimpleBooleanProperty(true);
> ObservableValue<String> whenProperty = longLivedProperty.when(condition)
> }
>
>
> then shouldn't `condition` and `whenProperty` be eligible for GC even when
> `condition` holds `true`? If not, do I not get a memory leak because I can't
> change `condition` to `false` to allow garbage collection?
@nlisker is this adequate, or should the docs reflect this better?
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PR: https://git.openjdk.org/jfx/pull/830
