[API Review] RT-21094 - Styleable interface

[David Grieve]

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