API review: fix for TableViewBuilder- reference to create is ambiguous (RT-24272)

[Eva Krejcirova]

On 27.8.2012 18:17, Kevin Rushforth wrote:
> I think Richard's question is more about whether an existing binary 
> class file compiled with 2.2 will run on FX 8.
Yes, it will (at least I hope that I tested this correctly :-)).

Eva

> In other words, does this break just source compatibility or both 
> source and binary compatibility?
>
> -- Kevin
>
>
> Eva Krejcirova wrote:
>> Hi Richard,
>>
>> On 8/24/2012 4:14 PM, Richard Bair wrote:
>>> One question: you mention that this is a source incompatible change. 
>>> But is it a runtime incompatible change? That is, if I have a JavaFX 
>>> app already compiled against Java 6, and I run it on Java 7 or Java 
>>> 8, will it break? Or is it only something I have to do to my sources 
>>> at compile time?
>> If I tested it correctly, if you have JavaFX app which you compiled 
>> with JavaFX 2.2 (with any version of Java) you will be able to run it 
>> with JavaFX 8 after this change (because of type erasure).
>> This is the reason why I left the second version of create (<?, ?> 
>> create()) in the proposal - so that it hides the <?> create() from 
>> Region.
>>
>> Eva
>>
>>> Thanks
>>> Richard
>>>
>>> On Aug 24, 2012, at 6:50 AM, Eva Krejcirova wrote:
>>>
>>>> Hi All,
>>>>
>>>> We are having problems with the way our builders are created -
>>>>
>>>> Basically, this code:
>>>> ChoiceBoxBuilder.<String>create()
>>>>         .id("choiceBox")
>>>>         .items(FXCollections.observableArrayList("item1", "item2"))
>>>>         .build();
>>>>
>>>> or this one:
>>>>
>>>> TableView<Job>  tableView1 = TableViewBuilder.<Job>create();
>>>>
>>>> doesn't compile anymore in JavaFX 8.0 when using Java 7 - it fails 
>>>> with error: reference to create is ambiguous, both method create() 
>>>> in RegionBuilder and method<T>create() in ComboBoxBuilder match
>>>>         ComboBox<String>  combo = 
>>>> ComboBoxBuilder.<String>create().build();
>>>>   where T is a type-variable:
>>>>     T extends Object declared in method<T>create()
>>>>
>>>> Unfortunately there is no simple solution for this and the one I am 
>>>> proposing requires some incompatible API changes which are the 
>>>> reason for this email.
>>>>
>>>> First some background:
>>>> We didn't have this problem up until now because all ancestors of 
>>>> ChoiceBox and other controls were abstract, so there was just one 
>>>> create() method in their builders.
>>>> (this one: public static<T>  
>>>> javafx.scene.control.ChoiceBoxBuilder<T, ?>  create() )
>>>> Now however, Control extends Region which is not an abstract class, 
>>>> which means that TableViewBuilder now extends RegionBuilder and 
>>>> inherits create() method from RegionBuilder (this one: public 
>>>> static javafx.scene.layout.RegionBuilder<?>  create()). And the 
>>>> compiler doesn't know which one of the create() methods to pick 
>>>> (Java 6 compiles this just fine, this issue manifest itself when 
>>>> compiled with Java 7).  Since the behavior of Java 7 is correct, 
>>>> this must be fixed on our side.
>>>>
>>>> My proposal is to add another create method to parametrized classes 
>>>> which would take the type as an argument e.g.
>>>>
>>>>     public static<T>  javafx.scene.control.ChoiceBoxBuilder<T, ?>  
>>>> create(final Class<T>  type) {
>>>>         return new javafx.scene.control.ChoiceBoxBuilder();
>>>>     }
>>>>
>>>> and make the create() without arguments non-generic, so it hides 
>>>> the create in Region:
>>>>
>>>>     public static javafx.scene.control.ChoiceBoxBuilder<?, ?>  
>>>> create() {
>>>>         return new javafx.scene.control.ChoiceBoxBuilder();
>>>>     }
>>>>
>>>> This way, the user can create the builder like this:
>>>> ChoiceBoxBuilder.create(String.class)
>>>>         .id("choiceBox")
>>>>         .items(FXCollections.observableArrayList("item1", "item2"))
>>>>         .build();
>>>>
>>>> Unfortunately this change will break some already existing code 
>>>> (but I don't see any better way for solving this).
>>>> E.g. this code:
>>>> ChoiceBox chb = 
>>>> ChoiceBoxBuilder.<String>create().items(FXCollections.observableArrayList("one", 
>>>> "two")).build();
>>>> will still not be compilable and will have to be rewritten (but at 
>>>> least there will be a way to do it).
>>>>
>>>> I already have the fix ready and I tested that it works but am open 
>>>> to other suggestions how to solve this problem if anybody has some 
>>>> better ones :-)
>>>>
>>>> Thanks,
>>>> Eva
>>