Using default methods in Java8 is exactly how we plan to allow
specifying method bodies without using JSOs. We are also going to
introduce a new annotation, @JsFinal to declare these methods final
(which you can't do on interfaces) to make it a compile time error for
subclasses to override them.
Why? One of the reasons why JSOs are efficient is that they are not
polymorphic, and essentially turn into static method calls, e.g.
getState() is rewritten as getState(SwitchElement this$static) /*-{
return this$static.bootstrapSwitch("state"); }-*/; which is
inlineable by the compiler.
Polymorphic methods are not inlineable and if there is a concrete
implementor, it forces the compiler to insert a trampoline, e.g
.
@JsType
interface JsArray<T> {
default <T> get(int x) { return js("this[$0]", x); }
}
If we didn't have @JsFinal, and someone did class Blah implements
JsArray { ... }, it would slow down every single JsArray call in the
entire program, because the compiler has to emit code like this:
jsArray.get ? jsArray.get(i) : this[i];
That is, it has to check to see if the method is implemented and call
it, otherwise fall back to the default.
This is why the full JsInterop will require Java8, because it makes
syntax so much better, and without it, things get verbose and
boilerplatey.
Java8 support is very close to landing. After that, a bunch of
JsInterop changes will go in. Then Elemental 2.0 will follow on top of
that which implements all of the code browser APIs you see at
html5index.org
On Sat, Oct 4, 2014 at 3:29 PM, Cristian Rinaldi <[email protected]> wrote:
> +Ray Cromwell:
> Suppose the following definition:
>
> @JsType(prototype = "jQuery")
> public interface JQueryElement {
> JQueryElement append(JQueryElement element);
>
> @JsProperty
> JQueryElement html();
>
> void data(String key, String value);
>
> Object val();
>
> void on(String event,
> com.workingflows.js.jscore.client.api.Function<?,?> fn);
>
> void attr(String attr, Object value);
> }
>
> Now suppose that there is an element called SwitchElement, the item is a
> JQueryElement but has a particual implementation of a method, for example:
>
> public class SwitchElement extends JavaScriptObject {
>
> protected SwitchElement() {
> }
>
> public final native boolean getState()/*-{
> return this.bootstrapSwitch("state");
> }-*/;
>
> public final native void setState(boolean state)/*-{
> this.bootstrapSwitch("state", state);
> }-*/;
> }
>
> The problem is, if the JQueryElement interface is implemented, all methods
> must be implemented. In fact, the implementation of JQueryElement is
> performed by the compiler, and I have no access to that implentación.
>
> 1) The solution can be: define an Java8 interface with methods implemented
> by default?
>
> 2) It is possible to access a Prototype implementation of JQueryElement, by
> example:
>
> public class SwitchElement extends JQueryElement.Prototype{
> protected SwitchElement() {
> }
>
> public final native boolean getState()/*-{
> return this.bootstrapSwitch("state");
> }-*/;
>
> public final native void setState(boolean state)/*-{
> this.bootstrapSwitch("state", state);
> }-*/;
>
> }
>
> But for this, it is necessary to use APT or the JsType generation process,
> is performed by APT.
> I'm right, or very far from reality.
>
> :)
>
>
> El sábado, 4 de octubre de 2014 15:24:19 UTC-3, Ray Cromwell escribió:
>>
>> Yes, but it will require Java8, which allows interfaces to contain
>> static methods. Here's how you'll do it soon when the Java8 stuff
>> lands:
>>
>> @JsType
>> public interface ImageUtils {
>> public static Texture loadTexture(String url) { return
>> js("$wnd.THREE.ImageUtils.loadTexture($0)", url); }
>> }
>>
>> ImageUtils.loadTexture(url);
>>
>>
>>
>> On Sat, Oct 4, 2014 at 8:18 AM, confile <[email protected]>
>> wrote:
>> > Consider the following static JavaScript function:
>> >
>> > THREE.ImageUtils = {
>> > loadTexture: function (url) { ... }
>> >
>> > }
>> >
>> > The way I use to create the static function with JsInterop is to create
>> > an
>> > interface for ImageUtils and then create an inner abstract class
>> > MyStatic
>> > which contains the static methods implemented with JSNI.
>> >
>> > Here is an example of the above class:
>> >
>> > @JsType
>> > public interface ImageUtils {
>> >
>> > public static abstract class MyStatic {
>> >
>> > public static native Texture create(String url) /*-{
>> > return new $wnd.THREE.ImageUtils.loadTexture(url);
>> > }-*/;
>> > }
>> >
>> > }
>> >
>> >
>> > I don't think this is the best solution. Is there a better way to handle
>> > static functions with JsInterop?
>> >
>> > --
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>> >
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