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

[Richard Bair]

OK. It seems to me that we have no choice but to break source compatibility in this case. This will definitely need to be included in the release notes.

Richard

On Aug 27, 2012, at 8:02 AM, 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
>