Lambdafication (was Re: Default methods in JFX-8)

Sven Reimers sven.reimers at gmail.com
Sun Oct 6 07:58:57 PDT 2013 

Ok. So here are the results of trying to add lambda and diamond to the
controls module:

1. A lot of generics and typing to be fixed (esp. in tests). Seems you can
get  some anonymous inner classes type checked by the compiler, but not the
lambda equivalent.. very interesting.

2.  279 Files modified (including tests)

3. A lot of the automatic replacements could probably be nicer e.g.

ft.setOnFinished(new EventHandler<ActionEvent>() {
                        @Override public void handle(ActionEvent
actionEvent) {
                          getChildren().remove(tm.textNode);
                        }
                    });

was replaced to:

ft.setOnFinished((ActionEvent actionEvent) -> {
    getChildren().remove(tm.textNode);
});

most unobtrusive code probably:

ft.setOnFinished((actionEvent) -> getChildren().remove(tm.textNode));

4. A lot of illegal forward reference errors - these were result of missing
this in the automatic transformation from anonymous inner to lambdas (seems
the rules are not identical - you have to add "this." as prefix if using
lambdas - not sure this is the expected way it should work)

5. Should we enable more -Xlint warnings in OpenJFX build?

6. Any chances anything of this can still go in 8 (e.g. get rid of warnings

7. Probably more things I just can't think of at the moment...

How to take this forward? If there is interest in the change I could make
available...

Comments? Ideas?

-Sven



On Fri, Oct 4, 2013 at 2:19 PM, Sven Reimers <sven.reimers at gmail.com> wrote:

> Oh and btw - would you go for lambda with or without additional type info
>  before parameter name?
>
> -Sven
>
>
> On Fri, Oct 4, 2013 at 2:05 PM, Sven Reimers <sven.reimers at gmail.com>wrote:
>
>> Ok. Here you go...
>>
>> I just did an inspection run for the controls module and my IDE came up
>> with  (drum roll) 888 possible lambda conversions..
>>
>> Looking through them I discovered that usage of <> (aka diamond syntax)
>> is   not used (or at least not used a lot) in at least the controls
>> modules. My IDE showed me 1171 occurrences.
>>
>> Is there a good reason not to use diamonds?
>>
>> Will now try to apply all those changes and figure out if this still
>> builds... up next: go through the other modules...
>>
>> -Sven
>>
>>
>> On Fri, Oct 4, 2013 at 1:35 AM, Richard Bair <richard.bair at oracle.com>wrote:
>>
>>> Brian was telling me at J1 that whether parallel gets you performance or
>>> not depends on the size of the collection and the complexity of the work to
>>> perform. There is definitely a point at which parallel helps -- and a point
>>> at which it hurts.
>>>
>>> Richard
>>>
>>> On Oct 3, 2013, at 3:33 PM, Hervé Girod <herve.girod at gmail.com> wrote:
>>>
>>> > Here is a nice example, taking advantage of the ease of going
>>> parallel. Apparently the performance without parallel will also further
>>> improve.
>>> http://blog.hersen.name/blog/2013/10/01/project-lambda-it-was-worth-the-wait/
>>> >
>>> > Hervé
>>> >
>>> > Sent from my iPad
>>> >
>>> >> On 4 oct. 2013, at 00:20, David Grieve <david.grieve at oracle.com>
>>> wrote:
>>> >>
>>> >> And what about Stream? I like the declarative code that comes from
>>> using Stream and I can see places in the code where Stream could be used,
>>> but I wonder about its performance relative to iterators and/or enhanced
>>> for loops.
>>> >>
>>> >> On Oct 3, 2013, at 4:45 PM, Richard Bair <richard.bair at oracle.com>
>>> wrote:
>>> >>
>>> >>>> Hello, OpenJFX Community.
>>> >>>>
>>> >>>> There's a question about using Java 8 features in FX.
>>> >>>>
>>> >>>> I've been working on the support for InputMethods in JFXPanel which
>>> is an important feature for many users who speak hieroglyphic languages.
>>> >>>> The issue is tracked under:
>>> https://javafx-jira.kenai.com/browse/RT-13248
>>> >>>>
>>> >>>> In order to have a high-quality support we need to change
>>> javafx.scene.input.InputMethodRequests interface and introduce 3 new
>>> methods. This is not needed for pure FX applications right now, but
>>> absolutely required for InputMethods in the JFXPanel. However, the
>>> interface is public and it was present since FX2.0, so changing it would
>>> become a breaking change. So the only way to avoid the problem is using the
>>> default methods. Those would return some stub values, the JDK is OK with
>>> that, as it would not crash or throw exceptions, but text composition would
>>> not work correctly.
>>> >>>>
>>> >>>> I know that we want to avoid using the Java 8 features in the
>>> JFX-8, so I wanted to ask - is it OK to use the default methods here?
>>> >>>>
>>> >>>>
>>> >>>> If you are staying away from JDK8 features for the JFX78 backport,
>>> don't worry.  There are more issues with new JDK8 APIs than with the new
>>> language features.
>>> >>>>
>>> >>>> For example there were default methods put into some collections
>>> classes that we solved by pushing them down to the first implements.  But
>>> the Date and Time picker depends on the new time package.  The threeten
>>> backport won't be updated until after 8 ships, so that has been removed so
>>> far.
>>> >>>>
>>> >>>> I'de be interested to know what a wholesale lamdaization would
>>> result in speed wise and code size wise (both source and compiled).  From
>>> what I can tell the IDEs can lambda and de-lambda fairly easily, so it jsut
>>> makes the backport more of a busy work proposition.  If there were
>>> performance gains it would also make a great front page story in the next
>>> java magazine or a case study..
>>> >>>
>>> >>> After having used Lambda's for JavaOne, I'd love to make the
>>> conversion, even if in the end the performance was the same, because the
>>> savings in noise in the Java files is so big. At one time I just took the
>>> concurrent classes and lambda-ized them to measure the impact on those
>>> classes. You could maybe pick a package and just lambda-ize that one
>>> package and see what happens in terms of size reduction. We might see:
>>> >>>
>>> >>>  + A reduction in the overall class size (not pack-200'd)
>>> >>>  - An increase in startup time (have to spin up synthetic classes
>>> created at usage time)
>>> >>>  +/- And increase or decrease in performance
>>> >>>  + A decrease in source code
>>> >>>
>>> >>> It would be interesting to get some data for these points and see
>>> what effect lambda's have. Especially if an IDE can just do it in bulk…
>>> >>>
>>> >>> Richard
>>> >>
>>>
>>>
>>
>>
>> --
>> Sven Reimers
>>
>> * Senior Expert Software Architect
>> * NetBeans Dream Team Member: http://dreamteam.netbeans.org
>> * Community Leader  NetBeans: http://community.java.net/netbeans
>>                               Desktop Java:
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>>
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>>
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>>
>
>
>
> --
> Sven Reimers
>
> * Senior Expert Software Architect
> * NetBeans Dream Team Member: http://dreamteam.netbeans.org
> * Community Leader  NetBeans: http://community.java.net/netbeans
>                               Desktop Java:
> http://community.java.net/javadesktop
> * Duke's Choice Award Winner 2009
> * Blog: http://nbguru.blogspot.com
>
> * XING: https://www.xing.com/profile/Sven_Reimers8
> * LinkedIn: http://www.linkedin.com/in/svenreimers
>
> Join the NetBeans Groups:
> * XING: http://www.xing.com/group-20148.82db20
> * NUGM: http://haug-server.dyndns.org/display/NUGM/Home
> * LinkedIn: http://www.linkedin.com/groups?gid=1860468
>                    http://www.linkedin.com/groups?gid=107402
>                    http://www.linkedin.com/groups?gid=1684717
> * Oracle: https://mix.oracle.com/groups/18497
>



-- 
Sven Reimers

* Senior Expert Software Architect
* NetBeans Dream Team Member: http://dreamteam.netbeans.org
* Community Leader  NetBeans: http://community.java.net/netbeans
                              Desktop Java:
http://community.java.net/javadesktop
* Duke's Choice Award Winner 2009
* Blog: http://nbguru.blogspot.com

* XING: https://www.xing.com/profile/Sven_Reimers8
* LinkedIn: http://www.linkedin.com/in/svenreimers

Join the NetBeans Groups:
* XING: http://www.xing.com/group-20148.82db20
* NUGM: http://haug-server.dyndns.org/display/NUGM/Home
* LinkedIn: http://www.linkedin.com/groups?gid=1860468
                   http://www.linkedin.com/groups?gid=107402
                   http://www.linkedin.com/groups?gid=1684717
* Oracle: https://mix.oracle.com/groups/18497

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