[API Review] RT-21094 - Styleable interface

[Tom Schindl]

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