[API Review] RT-21094 - Styleable interface

[Richard Bair]

Curse you generics!!!! (shakes fist)

On Jan 23, 2013, at 5:59 PM, David Grieve <david.grieve at oracle.com> wrote:

> Thanks for the feedback. I think I have it straight now:
> 
>    List<CssMetaData<? extends Styleable, ?>> getCssMetaData(); 
> 
> e.g., 
> 
>    CssMetaData<Node, Number> OPACITY;
> 
>    @Override
>    public List<CssMetaData<? extends Styleable, ?>> getCssMetaData() {
>        List<CssMetaData<? extends Styleable, ?>> list;
>        list = new ArrayList<CssMetaData<? extends Styleable, ?>>();
>        list.add(OPACITY);
>        return list;
>    }
> 
> On Jan 22, 2013, at 6:00 PM, Tom Schindl <tom.schindl at bestsolution.at> wrote:
> 
>> Hi,
>> 
>> I didn't understand what <S extends Styleable> ... would be good for
>> because this will lead to a warning in the subclasses:
>> 
>>> public class Node implements Styleable {
>>> 
>>> 	@Override
>>> 	public List<CssMetaData<Node, Object>> getMetaData() {
>>> 		// TODO Auto-generated method stub
>>> 		return null;
>>> 	}
>>> 	
>>> }
>> 
>>>> Type safety: The return type List<CssMetaData<Node,Object>> for getMetaData() from the type Node needs unchecked conversion to conform to List<CssMetaData<? extends Styleable,Object>> from the type Styleable
>> 
>> And I think the value should not be ? but Object. What we'd really need
>> here are self-references but Java does not have them.
>> 
>> One of the problems with generic lists is that they are not covariant
>> 
>> List<Styleable,Object> v = ...;
>> List<Node,Object> l = ...;
>> v = l; // illegal
>> 
>> and so one can not overload them in subclasses and return a more
>> specific one, same goes for adding/removing elements:
>> 
>> List<CssMetaData<Styleable,Object>> l = ...;
>> CssMetaData<Button,Boolean> v = ...
>> l.add(v); // illegal
>> 
>> So something is going wrong here!
>> 
>> Tom
>> 
>> Am 22.01.13 23:15, schrieb David Grieve:
>>> The JIRA is public now, thanks for pointing that out. 
>>> 
>>> The getCssMetaData() API should be 
>>> 
>>>   <S extends Styleable> List<CssMetaData<S, ?>> getCssMetaData();
>>> 
>>> 
>>> On Jan 22, 2013, at 4:42 PM, Tom Schindl <tom.schindl at bestsolution.at
>>> <mailto:tom.schindl at bestsolution.at>> wrote:
>>> 
>>>> Hi,
>>>> 
>>>> The problem I see with this is that CssMetaData accepts 2 generic
>>>> parameters but your API returns a RAW-Type, this looks bogus to me!
>>>> 
>>>> BTW the JIRA is not public.
>>>> 
>>>> Tom
>>>> 
>>>> Am 22.01.13 22:09, schrieb David Grieve:
>>>>> http://javafx-jira.kenai.com/browse/RT-21094
>>>>> 
>>>>> There is a class in private implementation called Styleable which
>>>>> allows SceneBuilder to look at a Tooltip (for example) and get the
>>>>> info it needs for styling. What I'd like to do is make Styleable part
>>>>> of the public API _and_ have Node and PopupControl (there may be a
>>>>> couple of other controls) implement Styleable. From the CSS
>>>>> standpoint, Styleable contains the API that CSS needs to match
>>>>> selectors and set calculated values on properties.
>>>>> 
>>>>> By making Styleable public API, I can change CssMetaData from
>>>>> CssMetaData<N extends Node, V> to CssMetaData<N extends Styleable,
>>>>> V>. This is important to do now before the CSS API is fully baked so
>>>>> that we can, in the future, have Scene be Styleable.
>>>>> 
>>>>> public interface Styleable {
>>>>> 
>>>>>  /**
>>>>>   * The type of this {@code Styleable} that is to be used in
>>>>> selector matching.
>>>>>   * This is analogous to an "element" in HTML.
>>>>>   * (<a href="
>>>>> http://www.w3.org/TR/CSS2/selector.html#type-selectors">CSS Type
>>>>> Selector</a>).
>>>>>   */
>>>>>  String getType();
>>>>> 
>>>>>  /**
>>>>>   * The id of this {@code Styleable}. This simple string identifier
>>>>> is useful for
>>>>>   * finding a specific Node within the scene graph. While the id of
>>>>> a Node
>>>>>   * should be unique within the scene graph, this uniqueness is not
>>>>> enforced.
>>>>>   * This is analogous to the "id" attribute on an HTML element
>>>>>   * (<a
>>>>> href="http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier">CSS
>>>>> ID Specification</a>).
>>>>>   * <p>
>>>>>   * For example, if a Node is given the id of "myId", then the
>>>>> lookup method can
>>>>>   * be used to find this node as follows:
>>>>> <code>scene.lookup("#myId");</code>.
>>>>>   * </p>
>>>>>   */
>>>>>  String getId();
>>>>> 
>>>>>  /**
>>>>>   * A list of String identifiers which can be used to logically group
>>>>>   * Nodes, specifically for an external style engine. This variable is
>>>>>   * analogous to the "class" attribute on an HTML element and, as
>>>>> such,
>>>>>   * each element of the list is a style class to which this Node
>>>>> belongs.
>>>>>   *
>>>>>   * @see <a
>>>>> href="http://www.w3.org/TR/css3-selectors/#class-html">CSS3 class
>>>>> selectors</a>
>>>>>   */
>>>>> List<String> getStyleClass();
>>>>> 
>>>>>  /**
>>>>>   * The inline style. This is analogous to the "style" attribute of an
>>>>>   * HTML element.
>>>>>   */
>>>>> String getStyle();
>>>>> 
>>>>>  /**
>>>>>   * Return the parent of this Styleable, or null if there is no
>>>>> parent.
>>>>>   */
>>>>>  Styleable getStyleableParent();
>>>>> 
>>>>>  /**
>>>>>   * The CssMetaData of this Styleable
>>>>>   */
>>>>>  List<CssMetaData> getCssMetaData();
>>>>> 
>>>>> }
>>>>> 
>>>> 
>>>> 
>>>> -- 
>>>> B e s t S o l u t i o n . a t                        EDV Systemhaus GmbH
>>>> ------------------------------------------------------------------------
>>>> tom schindl                 geschäftsführer/CEO
>>>> ------------------------------------------------------------------------
>>>> eduard-bodem-gasse 5-7/1   A-6020 innsbruck     fax      ++43 512 935833
>>>> http://www.BestSolution.at                      phone    ++43 512 935834
>>> 
>> 
>> 
>> -- 
>> B e s t S o l u t i o n . a t                        EDV Systemhaus GmbH
>> ------------------------------------------------------------------------
>> tom schindl                 geschäftsführer/CEO
>> ------------------------------------------------------------------------
>> eduard-bodem-gasse 5-7/1   A-6020 innsbruck     fax      ++43 512 935833
>> http://www.BestSolution.at                      phone    ++43 512 935834
>