RFR: JDK-8304439: Subscription based listeners [v2]

[John Hendrikx]

On Mon, 17 Apr 2023 23:42:10 GMT, Nir Lisker <nlisker at openjdk.org> wrote:

>> John Hendrikx has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Move Subscription method for invalidations to Observable
>>   
>>   - moved Subscription class to the Observable package
>
> modules/javafx.base/src/main/java/javafx/beans/Subscription.java line 85:
> 
>> 83:             other.unsubscribe();
>> 84:         };
>> 85:     }
> 
> This looks like a special case of the `of` method:
> 
> default Subscription and(Subscription other) {
>    return of(this, other);
> }
> 
> although this implementation creates an array, which might be what you're trying to avoid.

I think having both the "combine" / "of" method and this "and" method gives you a bit of flexibility.  Sometimes you may already have a subscription, then calling:

     subscription = subscription.and(otherSubscription);

... is nicer than:

    subscription = Subscription.combine(subscription, otherSubscription);

When creating a list of subscriptions, `Subscription::of` / `Subscription::combine` is going to be nicer than having to chain multiple `and` calls.

-------------

PR Review Comment: https://git.openjdk.org/jfx/pull/1069#discussion_r1169369137