RFR: JDK-8304439: Subscription based listeners [v13]

[John Hendrikx]

On Thu, 13 Jul 2023 21:15:47 GMT, John Hendrikx <jhendrikx at openjdk.org> wrote:

>> I'm not entirely sure about this; the `Subscription` interface is pretty neutral in how it can be used, and does not have any direct link to observables at all; it's more of a token that you get that can be used to cancel a previous action, it doesn't actively do anything (unless you count the wrapper that it puts around the provided function).
>> 
>> As it is, they don't even need to be associated with `Observable` or `ObservableValue` at all.  Just as easily you could do:
>> 
>>        FileInputStream inputStream = .. ;
>>        Subscription combined = Subscription.combine(
>>               property.subscribe(this::invalidated),
>>               () -> inputStream.close()
>>        );
>> 
>>        combined.subscribe();  // closes input stream and removes invalidations subscriber
>> 
>> Although I think it is a good description, I'm not sure it belongs on this class.
>
> I put your changes (that we agree upon so far) in #1177 
> 
> As I said I'm not sure about the description for the Subscription class, and it's not included yet, and so I also haven't yet removed the duplicated texts about GC-ability from the `subscribe` methods.

I also now wonder if `Subscription` perhaps is in the wrong package (javafx.beans currently).  Perhaps it should have been in javafx.util ?

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PR Review Comment: https://git.openjdk.org/jfx/pull/1069#discussion_r1263065227