[announce] InhiBeans: mitigate redundant recalculations

Tomas Mikula tomas.mikula at gmail.com
Mon Dec 16 23:24:29 PST 2013

I had a quick look at Java 8 streams and I'm afraid they are of no use
for reactive programming. The fundamental problem is that in
java.util.stream, computation is driven by the stream consumer, rather
than the stream source, which is a complete opposite of "reactive".

On the other hand, JavaFX ObservableValue doubles as a poor man's
event stream, but it would be confusing to use it as such. Not to
mention that we still want map, filter, etc... on an event stream.


On Mon, Dec 16, 2013 at 8:34 PM, Richard Bair <richard.bair at oracle.com> wrote:
> I agree, that's more of what I was thinking.
> On Dec 16, 2013, at 10:31 AM, John Smith <John_Smith at symantec.com> wrote:
>> Perhaps reactive programming is different from the problem Tomas is solving, but I think a research project which combined some of the principles of functional reactive programming (http://lampwww.epfl.ch/~imaier/pub/DeprecatingObserversTR2010.pdf) with JavaFX properties using Java 8 lambdas and streams would be quite interesting and perhaps very useful.
>> John
>> -----Original Message-----
>> From: openjfx-dev-bounces at openjdk.java.net [mailto:openjfx-dev-bounces at openjdk.java.net] On Behalf Of Tomas Mikula
>> Sent: Monday, December 16, 2013 9:19 AM
>> To: Richard Bair
>> Cc: openjfx-dev at openjdk.java.net
>> Subject: Re: [announce] InhiBeans: mitigate redundant recalculations
>> As a matter of fact, I have. Only to the extent of the "Principles of Reactive Programming" [1] course that is currently in progress on Coursera. From what I have seen so far, it's all about asynchronous composition (with emphasis on both "asynchronous" and "composition").
>> I didn't see it addressing this specific problem of multiple redundant updates, but I might be wrong. The truth is, this problem doesn't even exist if you don't have any eager observers (i.e. when you don't ever attach any ChangeListeners, and InvalidationListeners only propagate invalidation and never require the value to be recomputed). The problem is, although you can design your component without any eager evaluation (JavaFX bindings are already composed this way), you then bind a Label.textProperty() to the end of a binding chain and it all becomes eager.
>> Regards,
>> Tomas
>> [1] https://www.coursera.org/course/reactive
>> On Mon, Dec 16, 2013 at 5:30 PM, Richard Bair <richard.bair at oracle.com> wrote:
>>> Have you looked at https://github.com/Netflix/RxJava by chance? I've been dying to see somebody do an RxJava in JavaFX ever since devoxx and it looks like you may have inadvertently started down that path :-).
>>> Richard
>>> On Dec 16, 2013, at 8:09 AM, Tomas Mikula <tomas.mikula at gmail.com> wrote:
>>>> On Mon, Dec 16, 2013 at 1:47 AM, Tomas Mikula <tomas.mikula at gmail.com> wrote:
>>>>> On Mon, Dec 16, 2013 at 1:07 AM, Scott Palmer <swpalmer at gmail.com> wrote:
>>>>>> Interesting, no worse than John's pattern though.
>>>>>> I thought of using a try/finally to make sure release was called
>>>>>> and that naturally lead to thinking of try-with-resources, where
>>>>>> the "resource" in this case is a binding of some sort (or a wrapper
>>>>>> around a binding) that is invalidated on close() if needed.
>>>>> That is an interesting idea. I didn't intend blockWhile() to be safe
>>>>> with respect to exceptions, but merely
>>>>> void blockWhile(Runnable r) {
>>>>>   block();
>>>>>   r.run();
>>>>>   release();
>>>>> }
>>>>> Enhancement you are suggesting could be fleshed out as block()
>>>>> returning an AutoCloseable and the usage would be
>>>>> try(AutoCloseable a = relaxedArea.block()) {
>>>>>   obj.setWidth(w);
>>>>>   obj.setHeight(h);
>>>>> }
>>>> OK, done. I implemented both:
>>>> 1. added the blockWhile() method;
>>>> 2. made bindings AutoCloseable, and block() returns `this`.
>>>> Tomas

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