Reflective discovery of styleable properties

[Thiago Milczarek Sayão]

Hi,

Reflection is probably already being used in JavaFX and I think it's
probably fine, but there's the case of graalvm native compiled JavaFX apps.

-- Thiago.


Em ter., 5 de dez. de 2023 às 08:42, John Hendrikx <john.hendrikx at gmail.com>
escreveu:

> It looks good, and IMHO would be a major clean up, and would simplify
> creating stylable properties for users tremendously.
>
> I see you added a public API in CssMetaData, but I think you can just
> leave that private in CssMetaDataCache.  Users won't need it, as they
> should no longer be overriding getCssMetaData.  Old implementations are
> backwards compatible, so they won't need it either.
>
> Any new Nodes/Controls need not (or should not) provide the static
> getClassCssMetaData or override getCssMetaData.
>
> +1
>
> --John
>
> On 04/12/2023 07:02, Michael Strauß wrote:
> > Following up the discussion around the CssMetaData API, I'd like to
> > chime in with yet another idea. To recap, here's Nir's summary of the
> > current API [0]:
> >
> > "Let's look at what implementation is required from a user who wants
> > to write their own styleable control:
> > 1. Create styleable properties.
> > 2. Create a list of these properties to be passed on.
> > 3. Create a public static method that returns the concatenation of
> > this list with the one of its parent. (This method happens to be
> > poorly documented, as mstr said.)
> > 4. Create a public non-static method that calls the static method in a
> > forced-override pattern because otherwise you will be calling the
> > wrong static method. (This method's docs seem to be just wrong because
> > you don't always want to delegate to Node's list.)"
> >
> >
> > I think this could reasonably be replaced with the following
> > implementation requirements:
> > 1. Create styleable properties.
> > 2. That's it.
> >
> > Let's look at what we're actually trying to do: create a list of
> > CSS-styleable property metadata of a class. But we can easily do that
> > without all of the boilerplate code.
> >
> > When ´Node.getCssMetaData()` is invoked, all public methods of the
> > class are reflectively enumerated, and metadata is retrieved from
> > `Property` and `StyleableProperty` getters. This is a price that's
> > only paid once for any particular class (i.e. not for every instance).
> > The resulting metadata list is cached and reused for all instances of
> > that particular class.
> >
> > As a further optimization, metadata lists are also cached and
> > deduplicated for Control/Skin combinations (currently every Control
> > instance has its own copy of the metadata list).
> >
> > Another benefit of this approach is that the CssMetaData can now be
> > co-located with the property implementation, and not be kept around in
> > other parts of the source code file. Here's how that looks like when a
> > new "myValue" property is added to MyClass:
> >
> >      StyleableDoubleProperty myValue =
> >              new SimpleStyleableDoubleProperty(this, "myValue") {
> >
> >          static final CssMetaData<MyClass, Number> METADATA =
> >              new CssMetaData<MyClass, Number>(
> >                  "-fx-my-value",
> >                  SizeConverter.getInstance(),
> >                  USE_COMPUTED_SIZE) {
> >              @Override
> >              public boolean isSettable(MyClass node) {
> >                  return !node.myValue.isBound();
> >              }
> >
> >              @Override
> >              public StyleableProperty getStyleableProperty(
> >                      MyClass node) {
> >                  return node.myValue;
> >              }
> >          };
> >
> >          @Override
> >          public CssMetaData getCssMetaData() {
> >              return METADATA;
> >          }
> >      };
> >
> >      public final DoubleProperty myValueProperty() {
> >          return myValue;
> >      }
> >
> > It is not required to override the `getCssMetaData()` method, nor is
> > it required to redeclare a new static `getClassCssMetaData()` method.
> > It is also not required to manually keep the list of styleable
> > properties in sync with the list of CSS metadata.
> >
> > I've prototyped this concept for the `Node`, `Region` and `Control`
> classes [1].
> >
> > [0]
> https://mail.openjdk.org/pipermail/openjfx-dev/2023-December/044046.html
> > [1] https://github.com/openjdk/jfx/pull/1299
>
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